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Graft take rates in low-risk and high-risk patients with negative pressure wound therapy vs tie-over dressings

by Brent H Bernstein DPM1, Yvonne Cha DPM1*, Justin Guiliana DPM1

The Foot and Ankle Online Journal 12 (2): 6

Establishing a reliable method of securing skin grafts over wounds of the lower extremities remains a challenge, particularly in high-risk patients. Studies have reported on the use of negative pressure wound therapy using reticulated open-cell foam (NPWT/ROCF) as delivered by V.A.C.® Therapy (KCI Licensing, Inc., San Antonio, TX) as a bolster dressing over split- thickness skin grafts in various populations. The aim of this study was to compare take rates of lower extremity grafts in high-risk patients who received NPWT/ROCF versus tie-over dressings. We also retrospectively evaluated graft take rates in low-risk (no comorbidities) versus high-risk (≥1 comorbidity) graft patients who received post-graft NPWT/ROCF versus tie-over dressings. Forty-seven STSG patient records were analyzed. In the high-risk patient group, a significantly higher number of patients obtained ≥80% graft take rate in the NPWT/ROCF versus tie-over group (p=0.008). Graft take rates were similar between the two dressings in low-risk patients. In this study, NPWT/ROCF appears to improve STSG take compared to tie-over dressings in high-risk patients, which may be related to an improved contact zone between the graft and wound site.

Key words: negative pressure wound therapy, V.A.C. therapy, split-thickness skin graft

ISSN 1941-6806
doi: 10.3827/faoj.2018.1202.0006

1 – St. Luke’s University Health Network- Allentown, Pennsylvania
* – Corresponding author: yvonne0cha@gmail.com


Closure of lower extremity wounds remains a challenge in patients with considerable comorbidities. An ever-increasing number of closure options have prompted us to adopt a “reconstructive elevator” approach to our modern lower extremity practice (Figure 1). Typically in our practice, anatomic location, biomechanics and bony pressure points dictate plastic closure selection. Wounds with bone, joint, or tendon exposure without periosteum or paratenon larger than 0.5 cm in diameter are treated with flaps. Wounds located on the weight-bearing areas of the foot are typically treated with secondary intention or preferably cultured cellular grafts. In the literature, a split-thickness skin graft (STSG) is considered by some surgeons to be the preferred method of repair for moderate to large soft tissue defects on non-weight-bearing areas of the extremities [1-5].

Split-thickness skin grafting is a method of transposition of human skin (epidermal and a portion of the dermal layers) from a harvest to recipient site. The stages of STSG healing are: plasmatic imbibition, inosculation, and capillary ingrowth. A skin graft survives the first 48 hours through imbibition, or diffusion, of exudate through the host bed that supplies nutrients and removes waste products. The next step is inosculation, in which the graft develops connections with the recipient blood vessels. 

Figure 1 The “reconstructive elevator” approach to modern lower extremity practice.

Finally, capillary in-growth occurs when new vessels grow into the graft from the host bed and actively innervate the graft to establish blood supply [6, 7]. 

Patient comorbidities, such as diabetes mellitus (DM), lymphedema, and peripheral vascular disease (PVD) are known to impede wound healing [8], and can lead to graft failure. Other reasons for graft failure include ischemia, seroma/hematoma formation, fluid collection, shearing forces, infection, desiccation, and rejection. Reported skin graft failure rates vary dramatically, depending on wound etiology and a host of other factors. The method used to secure the graft can be a critical element in reducing opportunities for failure. Goals of a bolster dressing are to provide even pressure, immobilization and restriction of shearing to the graft, as well as prevent seroma or hematoma formation while providing a moist wound bed beneath the STSG [7]. 

During the past several years, adjunctive use of negative pressure wound therapy using reticulated open-cell foam (NPWT/ROCF) as delivered by V.A.C.® Therapy (KCI Licensing, Inc., San Antonio, TX) has become a well-established method of securing the graft to the recipient bed. NPWT/ROCF can act as both a temporizing bridge to STSG closure as well as the dressing over the STSG [4, 5, 8-12]. Obtaining successful graft take requires that the skin graft remain immobilized for 2-5 days or until revascularization occurs [13]. The compressed NPWT/ROCF foam maintains continuous, firm contact between the graft and wound bed while the negative pressure actively removes exudates and infectious material from the wound bed. Foam pliability allows relative movement of the wound surface without compromising pressure [4]. 

While many studies have reported on the use of NPWT/ROCF over STSGs, its relative efficacy versus traditional tie-over bolster dressings has been debated in the literature. We hypothesized that the use of NPWT/ROCF creates an improved contact zone between the graft and wound site as compared to tie-over dressings, which may result in higher graft take rates. We further hypothesized that among high-risk patients with known comorbidities, application of NPWT/ROCF over STSGs on lower extremity wounds leads to higher graft take rates compared to tie-over dressings. To test these hypotheses, we performed a retrospective cohort analysis examining skin graft take rates of high-risk patients treated with NPWT/ROCF versus tie-over cotton bolster dressings. 

Patients and Methods

We retrospectively reviewed the charts of consecutive patients who received an STSG procedure performed by the leading author as primary surgeon between March 1994 and May 2007. Records were divided into four groups: 1) High-risk NPWT/ROCF, 2) High-risk tie-over bolster, 3) Low-risk NPWT/ROCF and 4) Low-risk tie-over bolster. Patients were considered high-risk if they had any of the following comorbidities: DM, end-stage renal disease (ESRD), contralateral lower-extremity amputation, lymphedema, smoking, peripheral nerve disorders, spinal cord injuries (SCI) or disorders, PVD, venous insufficiency, immunocompromised, or connective tissue disorders. A hospital IRB Waiver of Authorization was obtained to perform this retrospective data analysis, based on its minimal risk level to patients. All tie-over bolster and NPWT/ROCF dressings were similarly fashioned and placed by the same surgeon. Tie-over patients were treated with a post-graft bolster dressing consisting of normal saline soaked absorbent cotton balls and tied over the graft using 3-0 monofilament nylon sutures. 

Figure 2 NPWT application diagram.

STSGs in the NPWT/ROCF-treated groups were covered with an available (eg, ADAPTIC®) porous non-adherent layer, an NPWT/ROCF dressing and semi-permeable drape with tubing. The tubing was connected to the subatmospheric pressure unit with -125mmHg applied for 3-5 days (Figure 2). The authors’ medical records, digital photograph archives, and surgical logs were reviewed, and percentage of graft take at 14 days post-operative was recorded for each patient. Total number patients with ≥80% and ≥50% graft take were compared between both treatment arms for both high- and low-risk groups. Fisher’s exact two-tailed test was utilized to compare the groups by percentage of graft take.

Results

Forty-seven patients met the study inclusion criteria. 15 patients in the NPWT/ROCF group and 21 in the tie-over group were classified as high-risk. There were 5 patients in the NPWT/ROCF group and 6 patients in the tie-over group that were classified as low-risk. 

Frequencies of patient comorbidities are listed in Table 1. Wound etiologies in the low-risk patient group included traumatic wounds, post-debridement wounds from necrotizing fasciitis or bites, post-lesion excision sites, and decubitus ulcers. 

Table 1 Graft rate take rate.

There was a significant difference between the two treatment arms of high-risk patients that achieved a graft take rate ≥80%: 13 of 15 for the NPWT/ROCF group versus 9 of 21 for the tie-over group (p=0.008) (Table 1). The number of patients in the high-risk cohort that achieved ≥50% graft take was also significantly lower in the tie over patient group (14/21) versus the NPWT/ROCF group (15/15; p=0.027). Complete graft failure (0% graft take) was reported in the remaining 7 tie-over and 1 NPWT/ROCF high-risk patients. The average percent graft take rates for high-risk patients in the NPWT/ROCF versus tie-over groups were 90.3% vs. 55.2%, respectively. When subgrouped by comorbidities, the average graft take rate in the NPWT/ROCF-treated patients was higher than the tie-over patients in each of the subgroups, but the difference was not significant, owing to low populations in all subcategories (Table 1). All low-risk NPWT/ROCF and tie-over patients achieved a graft take rate of 80% or greater (Table 2). 

Discussion

The retrospective analysis demonstrated significantly improved STSG take rates and survival in high-risk patients who received NPWT/ROCF, compared to traditional tie-over dressings. Our graft take rates in both the high- and low-risk NPWT/ROCF groups—90.3% and 100%, respectively—mirror that which is reported in the literature [14-16]. In 1997, Argenta and Morykwas first demonstrated effective use of NPWT/ROCF as a bolster for STSGs on a variety of acute and chronic wounds [14]. Blackburn et al [15] showed a ≥95% STSG take rate with the use of NPWT/ROCF on contoured wounds in complex anatomic regions. 

Comorbidity High risk tie-over group  High risk NPWT/ROCF Group 
n Average % take 80% graft take (n) ≥50% graft take (n) n Average % take  ≥80% graft take (n) ≥50% graft take (n)
DM, ESRD, contralateral lower extremity amputation, PVD 14 57.9 6 4 13 93.1 12 1
SCI/peripheral neuropathy/congenital spinal cord lesion 0 n/a n/a n/a 0 n/a n/a n/a
Venous insufficiency 6 58.3 3 2 1 95 1 0
Connective tissue disorder/immunocompromised 0 n/a n/a n/a 1 50 0 0
smoker 1 0 0 1 0 n/a n/a n/a
total 21 55.2 9 7 15 90.3 13 1

Table 2 Comorbidity and graft rate take rate.

A consecutive case series of 61 STSG patients revealed a significant decrease in repeated STSGs for the NPWT/ROCF group as compared to the bolster dressing group, suggesting improved graft survival with adjunctive use of NPWT/ROCF [19]. Our patients have experienced other advantages of NPWT/ROCF reported in the literature, such as enhanced patient mobility, shorter hospital stay, and an earlier return to daily activities while the dressing is in place [2, 15, 17]. 

Our study’s similar graft take rates between the two treatment arms of the low-risk population somewhat support outcomes of other clinical studies that have reported no significant difference in STSG take rates between NPWT/ROCF and tie-over dressing groups [3, 18-19]. Moisidis et al [18] performed a prospective, blinded, randomized controlled trial comparing NPWT/ROCF to standard bolster dressings on 22 adult inpatients with wounds requiring skin grafting. There were no differences in quantitative graft take between the two groups, but NPWT/ROCF had a significantly better qualitative graft take as compared to the standard bolster dressing [18]. In a retrospective chart review, Stone et al also found similar graft take rates between NPWT/ROCF and bolster dressings in 40 trauma patients who underwent soft tissue loss and fasciotomies [3]. Our study results appear to suggest prudent use of NPWT/ROCF in low-risk patients, although the small sample sizes clearly warrant further study. 

This study has several limitations including its small size, retrospective nature, and lack of randomization and blinding. Unobserved covariates which could also account for differences in graft take, such as wound size, duration, or type of wound treatment prior to grafting, may also distort the conclusions of the study. Also, the author believes that as his practice changed from utilizing the tie-over dressing to the use of NPWT/ROCF over time, perhaps an improvement in surgical technique could have occurred as well over this period of time. This improvement in technique could have allowed an improved success in the latter portion of the cohort when NPWT/ROCF was utilized more often. 

To the authors’ knowledge, this study is the first to delineate between high- and low-risk patient populations in comparing NPWT/ROCF versus tie-over bolster treatment over STSGs. Our results suggest that the presence of patient comorbidities may be an important consideration when choosing a bolster dressing. Combining high and low-risk populations within cohorts may underestimate the utility of NPWT/ROCF in high-risk populations. Our preliminary results are promising and suggest that NPWT/ROCF may be a more efficacious dressing versus traditional tie-over dressings in high-risk patients whereby reliably uniform contact between the graft and dressing is critical to successful graft take.

References

  1. Llanos S, Danilla S, Barraza C, Hernandez I, Nava E, Diaz J. Effectiveness of negative pressure closure in the integration of split thickness skin grafts: a randomized, double-masked, controlled trial. Ann Surg 244(5):700-705, 2006. 
  2. Chang KP, Tsai CC, Lin TM, Lai CS, Lin SD. An alternative dressing for skin graft immobilization: negative pressure dressing. Burns 27(8):839-42, 2001. 
  3. Stone P, Prigozen J, Hofeldt M, Hass S, DeLuca J, Flaherty S. Bolster versus negative pressure wound therapy for securing split-thickness skin grafts in trauma patients. Wounds 16(7):219-223, 2004. 
  4. Schneider AM, Morykwas MJ, Argenta LC. A new and reliable method of securing skin grafts to the difficult recipient bed. Plast Reconstr Surg 102(4):1195-1198, 1998. 
  5. Repta R, Ford R, Hoberman L, Rechner B. The use of negative-pressure therapy and skin grafting in the treatment of soft-tissue defects over the Achilles tendon. Ann Plast Surg 55(4):367-70, 2005. 
  6. Warriner RA. Wound assessment. In Wound Care Practice, pp75-100, edited by PJ Sheffield, APS Smith, CE Fife. Best Publishing Company, Flagstaff, 2004. 
  7. Gupta S, Gabriel A, Shores J. The perioperative use of negative pressure wound therapy in skin grafting. Ostomy Wound Manage 50(4A Suppl):32-34, 2004. 
  8. Armstrong DG, Lavery LA, Diabetic Foot Study Consortium. Negative pressure wound therapy after partial diabetic foot amputation: a multicentre, randomised controlled trial. Lancet 366(9498):1704-1710, 2005. 
  9. Eginton MT, Brown KR, Seabrook GR, Towne JB, Cambria RA. A prospective randomized evaluation of negative-pressure wound dressings for diabetic foot wounds. Ann Vasc Surg 17(6):645-649, 2003. 
  10. Morris GS, Brueilly KE, Hanzelka H. Negative pressure wound therapy achieved by vacuum-assisted closure: Evaluating the assumptions. Ostomy Wound Manage 53(1):52-57, 2007. 
  11. Carson SN, Overall K, Lee-Jahshan S, Travis E. Vacuum-assisted closure used for healing chronic wounds and skin grafts in the lower extremities. Ostomy Wound Manage 50(3):52-58, 2004. 
  12. Isago T, Nozaki M, Kikuchi Y, Honda T, Nakazawa H. Skin graft fixation with negative-pressure dressings. J Dermatol 30(9):673-678, 2003. 
  13. Rudolph R, Ballantyne DL, Jr. Skin Grafts. In Plastic Surgery, pp 221-274, edited by JG McCarthy, Saunders, Philadelphia, 1990. 
  14. Argenta LC, Morykwas MJ. Vacuum-assisted closure: a new method for wound control and treatment: clinical experience. Ann Plast Surg 38(6):563-576, 1997. 
  15. Blackburn JH, Boemi L, Hall WW et al. Negative pressure dressings as a bolster for skin grafts. Ann Plast Surg 40(5):453-457, 1998. 
  16. Molnar JA, DeFranzo AJ, Marks MW. Single-stage approach to skin grafting the exposed skull. Plast Reconstr Surg 105(1):174-177, 2000. 
  17. Sposato G, Molea G, Di CG, Scioli M, La R, I, Ziccardi P. Ambulant vacuum- assisted closure of skin-graft dressing in the lower limbs using a portable mini- VAC device. Br J Plast Surg 54(3):235-237, 2001. 
  18. Moisidis E, Heath T, Boorer C, Ho K, Deva AK. A prospective, blinded, randomized, controlled clinical trial of topical negative pressure use in skin grafting. Plast Reconstr Surg 114(4):917-922, 2004. 
  19. Scherer LA, Shiver S, Chang M, Meredith JW, Owings JT. The vacuum assisted closure device: A method of securing skin grafts and improving graft survival. Arch Surg 137(8):930-934, 2002.

Surgical excision of Morton’s neuroma: Does it provide a reliable outcome?

by Muhammad Murtaza Khan1*, and Dakshinamurthy Sunderamoorthy2

The Foot and Ankle Online Journal 12 (2): 5

This study involves a retrospective analysis of the surgical intervention for treatment of Morton’s neuroma of the foot for patients that were treated over three years period. The aim of this study is to evaluate the long-term outcome following operative removal of the Morton’s neuroma of foot using MOXFQ. We retrospectively evaluated the outcome of 13 patients (14 feet) who were operated from February 2015 to March 2018 for excision of Morton’s neuroma using a dorsal approach. We evaluated the outcome was using clinical follow up notes, examination findings and the Manchester Oxford Foot Questionnaire score. Thirteen patients (14 feet) were operated during this period, out of which 12 were females and one male with a mean age of 58 years. One patient had bilateral symptomatic disease. 11 out of 13 patients (84.6 %) were satisfied with their results of surgery after a mean follow-up period of 34.42 ± 9.81 months. Biopsy supported the clinical diagnosis in 13/14 case (92.857%). Preoperative diagnosis was confirmed by radiologist as Morton’s neuroma on 12/14 cases (85.71%). The predominant modality of choice was ultrasound of feet, however, MRI of the foot was advised in one case only. Statistically significant difference was appreciated between preoperative and postoperative MOXFQ score (41.92 ± 10.47 verses 8± 15.11), respectively, with a p value < 0.0001 CI 95% SI 4.913. Our study shows surgical excision of Morton’s neuroma is a reliable procedure and it gives a good outcome and it is maintained over a period of 3 years.

Keywords: Morton’s neuroma, MOXFQ, dorsal approach

ISSN 1941-6806
doi: 10.3827/faoj.2018.1202.0005

1 – 6 Saxby House Church lane Scunthorpe (DN15 7HY)
2 – Northern Lincolnshire and Goole Foundation NHS Trust (DN15 7BH)
* – Corresponding author: Murtazakhan142@yahoo.com


Morton’s neuroma is non-malignant enlargement of the common plantar digital nerve, usually seen at the 2nd or 3rd intermetatarsal spaces [1,2]. It is one of the most common causes of metatarsalgia and majority of clinicians consider the clinical diagnosis as an indication to treatment [3]. Morton’s neuroma should be considered as part of differential diagnosis in any patient complaining of forefoot pain [5]. The most common presenting complaint is burning pain on the plantar aspect of the foot between the metatarsal heads of corresponding toes [3]. Others complain of walking on a lump on the ball of the great toe, shooting pain and tingling in the involved digits [5]. Pain is particularly aggravated by walking and wearing tight shoes and is relieved by rest [3]. Researchers were not able to identify the definitive cause of this condition. Some consider it due to hypermobility of 4th ray over the cuboid as part of the etiology, explaining why the third metatarsal space is commonly associated with the disease [3].

It may also be due to entrapment of nerve at the distal metatarsal ligament or may be due to trauma, equinus deformity or autonomic neuropathy [5]. Considering the variable presentation of patient symptoms, the modality of choice and surgical approach is also subjected to active debate over the years. Surgery is considered the treatment of choice with either dorsal or plantar approach. However, few consider equal efficacy of either dorsal or plantar approach for excision [7]. Others considered dorsal approach only in cases of recurrent disease [8].

Some advocate conservative treatment as part of regimen. However, it is associated with variable success rate and many patients ultimately underwent surgery after initial period of successful non-surgical management. Moreover, the role of corticosteroids with local anesthetic is also considered futile in long term follow-up [1] (6 months). 

The use of histology was considered as an essential part of postoperative work-up for consideration of the diagnosis, however, others considered it as an economic burden unless it is a recurrent disease or ambiguity regarding diagnosis during surgery [5].

Materials and Methods 

We retrospectively evaluated our thirteen cases (fourteen feet) from 2015 to 2018 and the postoperative outcome was evaluated using Manchester Oxford Foot and Ankle Questionnaire. All patients with neuroma were considered for the study. Any patient with recurrent disease, diagnosed case of other foot pathology like rheumatoid arthritis, associated injuries in the metatarsophalangeal joint, any patient operated for recurrent disease or not willing to answer the questionnaire over the phone were excluded from the study. In order to avoid any bias during study we evaluated the patient outcome following surgery not only through clinical notes, radiology reports (USG/ MRI) histopathology but also used operative summaries. Moreover, additional information was extracted by ringing the patients using their documented contact numbers and after taking verbal consent we asked question as in MOXFQ, thus cross checking the information provided in the post-operative follow up pathway in terms of patient satisfaction/ dissatisfaction status. 

Figure 1 Patient demographics.

Figure 2 Management characteristics.

The results were evaluated by calculating the mean, standard deviation, standard error for values obtained. For evaluation whether the pre and post-operative MOXFQ score is statistically significant we calculated the p value using the mean values of pre and post-operative MOXFQ score.  P value <0.05 was considered as significant.  

Results

Thirteen patients (14 feet) were operated during this period, out of which 12 were females and one male with a mean age of 58 years (Figure 1). Fifty percent (7/14) were operated in 2014. Thirty six percent (5/14) in 2016. Seven percent in both 2017 & 2018 (1/14) in each year.  One patient had bilateral symptomatic disease. Eight out of 14 cases (57%) have disease confined to third metatarsal space and 6/14 cases (43%) have disease in second metatarsal space. Eleven out of 13 patients (84.6 %) were satisfied with their results of surgery after a mean follow up period of 34.42 ± 9.81 months. 

Biopsy supported the clinical diagnosis in 13/14 cases (92.85%). Preoperative diagnosis was confirmed by radiologist as Morton’s neuroma on 12/14 cases (85.71%). The predominant modality of choice was ultrasound of feet (Figure 3). 

Figure 3 Method of diagnosis.

Figure 4 Pre- and postoperative MOXFQ scores.

However, MRI foot was advised in one case only. Conservative treatment was opted by 5/14 patients (35%). Out of these one was offered injection of local anesthetic with corticosteroid in clinic and 4/14 (28.5%) were given ultrasound guided injection of local anesthetic with steroid. However, the mean relief period was 1.22± 2.2 months for all 5 patients and they ultimately opted for surgery (Figure 2). Statistically significant difference was appreciated between pre-operative and post-operative MOXFQ score (41.92 ± 10.47 Verses 8± 15.11) respectively with p value < 0.0001 CI 95% SI 4.913 (Figure 4).

Discussion

Our results showed a patient satisfaction rate of 84.6%, which is higher than the documented success rate of surgery. It is variably reported in literature however, it never exceeds 80% [1]. Some researchers have raised concerns regarding the use of dorsal approach for surgery compared to the plantar approach, but our results do not support this argument. In fact, we were able to treat our patient with satisfactory results using a dorsal approach.

The literature supports the use of dorsal approach as it provides good exposure, less healing problems and good exposure of deep metatarsal transverse ligament. Moreover, there was a significant delay in full-weight bearing for the plantar incision and increased risk of wound healing problems [3]. Another study demonstrating the efficacy of plantar approach claiming a complication rate of 4 to 36% for plantar approach compared to 2 to 34% for dorsal approach [6]. Another group of researchers claim that equal satisfactory results can be obtained from either a plantar or dorsal approach and choice should be left for surgeon experience and personal preference [7]. Similarly, some surgeons prefer using a planter approach for recurrent disease, as surgery can be complicated by scar tissue if the neuroma is approached through the site of a previous incision [8].

In our case series, the predominant affected population were females with a mean age of 58 years. Again, this finding matches with already established research, as women in the middle ages are prone to disease with an average age of 50 years and female-to-male ratio of 4:1[3].

However, the literature supports the disease predominance in the third metatarsal space; in our study, although 57% of patients had the disease in the said space but 43% patient demonstrated Morton’s neuroma in 2nd intermetatarsal space. As per existing evidence, the presence of disease in 3rd intermetatarsal and second metatarsal space is 66% and 21% respectively [3]. In one study, however, they were able to report equal incidence of disease in 2nd and 3rd intermetatarsal space [5].

In this series, we offered conservative treatment in every case before moving towards surgery. Five out of 14 patients accepted the offer and went for ultrasound guided injection and one opted the option of blind injection in the foot by clinician. Although, some support the use of ultrasound guided injection, other prefer identification of pain spot in the clinic and infiltration of local anesthetic and steroid at the most tender point claiming favorable/comparable results with blind injection [1].  

In our case series, the results of conservative management using local anesthetic and steroid were disappointing with a mean relief of just 1.22 ± months and all patients ultimately opted to go for surgery.

This finding is very much coherent with existing evidence as all patients managed conservatively for Morton’s neuroma ultimately opted for surgery as long-term results are usually disappointing [2]. Based on our experience, we don’t recommend the use of steroid and local anesthetic as a definitive treatment of choice for Morton’s neuroma unless the patient is deemed unfit for surgery. Despite the evolution of less invasive modalities and development in radiological techniques, most of the existing literature still favors surgery as a definitive treatment of this disease [4].

Our set of patients diagnosis is supported by tissue diagnosis of neuroma in 13/14 (92%) cases thus consolidating our clinical assessment. This is much higher than the reported value in one study involving the prospective analysis of Morton’s neuroma disease of the foot where they were able to prove the histological diagnosis in only 78% of operated patients [2]. Moreover, the exceptional results in terms of resolution of symptoms also points toward correct treatment regimen.

Regarding tissue diagnosis, it has been considered as a burden to the health system by some researchers. The reason extracted from the literature narrated the fact that unless there is doubt during surgery it should not be subjected to tissue diagnosis [9]. However, others always give weightage to radiological and histological diagnosis. Few consider the clinical examination as the gold standard for diagnosis [4]. However, others have questioned this technique in modern era of evidence-based medicine [3].

We recommend the support of histology, even if the clinician is sure of diagnosis. Not only does it save any future discomfort in terms of medicolegal issues, but it also excludes an important cause of forefoot pain for future treatment in case the results of surgery are disappointing. Additionally, patients can be counselled regarding the management and guarded prognosis in case of recurrent disease [2].

The modality of choice in our series was ultrasound of foot. Although MRI was requested by clinician in one case only, but it did not add any extra information or change in treatment plan for the patient. Researchers recommend use of both modalities, however, the diagnosis of asymptomatic neuroma is high, especially with ultrasound and it is reported as 54% in some literature. Thus, clinical findings should be correlated with radiological evidence [2]. MRI has sensitivity and specificity of 93% and 68% respectively compared to ultrasound which has sensitivity and specificity of 90% and 88% respectively [3].

In our opinion, long term follow-up is vital for this disease, as in our experience initially satisfied patients may complain of return of symptoms after a mean interval of three months with complaint of pain of similar nature that was experienced before the surgery. 

In our experience, we would recommend reconsidering the diagnosis if it is not proven by radiological work up as it may be one of the factors that can lead to poor outcome after surgery. Although evidence regarding this recommendation is weak in existing literature [2]. Surgical excision of Morton’s neuroma can give excellent outcome after surgery provided patients are chosen wisely.

References

  1. Lizano-díez X, Ginés-cespedosa A, Alentorn-geli E, et al. Corticosteroid Injection for the Treatment of Morton’s Neuroma: A Prospective, Double-Blinded, Randomized, Placebo-Controlled Trial. Foot Ankle Int. 2017;38(9):944-951.
  2. Bucknall V, Rutherford D, Macdonald D, Shalaby H, Mckinley J, Breusch SJ. Outcomes following excision of Morton’s interdigital neuroma: a prospective study. Bone Joint J. 2016;98-B(10):1376-1381.
  3. Di caprio F, Meringolo R, Shehab eddine M, Ponziani L. Morton’s interdigital neuroma of the foot: A literature review. Foot Ankle Surg. 2018;24(2):92-98.
  4. Reichert P, Zimmer K, Witkowski J, Wnukiewicz W, Kuliński S, Gosk J. Long-Term Results of Neurectomy Through a Dorsal Approach in the Treatment of Morton’s Neuroma. Adv Clin Exp Med. 2016;25(2):295-302.: .
  5. Adams WR. Morton’s neuroma. Clin Podiatr Med Surg. 2010;27(4):535-45.
  6. Nery C, Raduan F, Del buono A, Asaumi ID, Maffulli N. Plantar Approach for a Morton’s Neuroma: Surgical Technique. JBJS Essent Surg Tech. 2012;2(3):e14.
  7. Habashy A, Sumarriva G, Treuting RJ. Neurectomy Outcomes in Patients With Morton’s Neuroma: Comparison of Plantar vs Dorsal Approaches. Ochsner J. 2016;16(4):471-474.
  8. Richardson DR, Dean EM. The recurrent Morton’s neuroma: what now?. Foot Ankle Clin. 2014;19(3):437-49.
  9. Mallina RK, Al-dadah K, Patel K, Ramesh P. Is Histopathological Analysis of Interdigital Morton’s Neuroma Necessary?. Foot Ankle Spec. 2017;10(6):520-523.

Talectomy (astragalectomy) and tibiocalcaneal arthrodesis following traumatic talus fracture-dislocation

The Foot and Ankle Online Journal 12 (2): 4

by Dr Alison Zander, MBBCh, BSc (hons), MSc (PHNutr)1, Mr Anirudh Gadgil, MBBS, M.S. (Orth), FRCS (Ed), FRCS (Trauma & Ortho)2, Derek Protheroe, BSc(Hons), MSc, PgDip3*

Talus fractures occur rarely but are often associated with complications and functional limitations. Urgent reduction of associated dislocations is recommended with open-reduction and internal fixation of displaced fractures when adjacent soft tissue injury permits [1]. However, it is important to remember that there is a high incidence of long term complications, along with a significant impact on activities of daily living and quality of life.  This case report describes the successful treatment of a severely comminuted talar fracture dislocation with primary talectomy and tibio-calcaneal arthrodesis. A reminder that in selected cases that the talectomy (astragalectomy) may be a viable alternative.

Keywords: talus, comminuted, tibiocalcaneal arthrodesis, fusion, talectomy, astragalectomy, trauma, avascular-necrosis, AVN

ISSN 1941-6806
doi: 10.3827/faoj.2018.1202.0004

1 – DLSHTM Foundation Year 1 Doctor, Cardiff and Vale University Health Board, University Hospital of Wales, Heath Park, Cardiff
2 – Consultant Orthopaedic Surgeon, Cardiff and Vale University Health Board, University Hospital of Wales, Heath Park, Cardiff
3 – Advanced Podiatry Practitioner, Prince Philip Hospital, Bryngwyn Mawr, Llanelli, Wales, SA14 8QF
* – Corresponding author: Derek.Protheroe@wales.nhs.uk


Talus fractures account for less than 1% of all fractures, they may be caused by high-energy trauma, and any other form of forced dorsiflexion injury to the ankle and foot [1]. Talar fractures may be classified anatomically as head, neck, body, lateral or posterior processes, displaced or non-displaced. A range of classifications have been established such as the original Hawkins, then modified by Canale & Kelly and then the Sneppe classification [2]. These sub-classifications help to guide treatment options[3]. Non-displaced fractures may be treated conservatively with a non-weight-bearing short-leg cast, whereas displaced fractures require open-reduction and internal fixation. Reconstruction after a talus fracture poses the greater surgical challenge if restoration of the articular surfaces is precluded secondary to comminution [4]. The talus is the second largest of the tarsal bones, with more than half of its surface being covered with articular cartilage, with no muscular attachments[1]. Therefore, the vascular supply of the talus is well-known to be tenuous, therefore predisposing the talus to significant ischemic injury after fractures [5]. Risk of post-traumatic avascular necrosis (AVN) increases with the magnitude of injury [6]. Extensive intraosseous anastomoses are present throughout the talus and are responsible for its survival during severe injuries. At least one of the three main anastomoses preserved may potentially allow adequate circulation via anastomotic channels [1].

Using the Hawkins’s classification system; 0-13% for grade I, 20-50% for grade II, 83-100% for grade III, and 100% for grade IV fracture dislocations result in AVN [1,6]. 

Clinical experience of talar fracture assessment and management is limited by their infrequent incidence, which is further exacerbated by the numerous sub-classifications of fracture, as previously alluded to. Case reports, although regarded as level V evidence can aid and develop an understanding of the risks and benefits of treatment options to achieve optimal patient outcomes [7].  Clinicians should maintain a high index of suspicion for AVN, which can only be diagnosed radiographically six to eight weeks following injury [8].  Furthermore, the potential for long term issues, such as hind-foot arthrosis and further revisionary surgery must be considered, alongside risks of repeated anesthetics for multiple procedures after complications. Approximately 25% of talus dislocations treated with internal reduction require additional surgery, including secondary arthrodesis [9].

Operative treatment measures for this area may be broadly split into two categories; joint sparing procedures – such as protected weight bearing, patella loading splints and bone graft or joint sacrifice procedures – such as talectomy and arthrodesis. Total talectomy and tibiocalcaneal arthrodesis may be viewed as a salvage procedure in this case report due to the case of severe comminuted fracture, where it may be impossible to anatomically reduce the talus and allow for adequate stable fixation. 

A literature search was performed using the keywords ‘talectomy’, ‘astragalectomy’, ‘fracture’, ‘tibiocalcaneal arthrodesis’ and Boolean search terms. Ovid SP databases (including embase & medline) was used with no exclusion dates to allow for a search of all historical literature. It appears that there was only one other reference in 1955 to such a procedure following a traumatic fracture to the talus body [10]. Historically, this case involved a Royal Navy soldier, where following a dislocated fracture a primary talectomy and tibiocalcaneal arthrodesis was performed.

Figure 1 Preoperative radiographs lateral and AP views.

Case Report

A sixty eight-year-old lady with no significant past medical history presented to Accident and Emergency.  She had been a seat-belted, front-seat passenger of a car that suffered a high-speed head-on road traffic collision.  She sustained a grade I (Gustilo-Anderson) open, comminuted fracture dislocation of the talus (Figure 1) with puncture wounds on the lateral aspect of the talus.  The foot was neurovascularly intact initially. The ankle was manipulated and back-slab applied. Apart from body ache and multiple minor abrasions and bruises there were no other injuries.  Whilst she was waiting on the ward to have a CT scan performed she developed increasing pain in foot, numbness of toes and sluggish capillary refill in the toes, which were not relieved even after removing the plaster slab.  She was counselled that she would need to be rushed to the operating room to attempt to reestablish circulation to her foot with a plan to open reduce the fracture and stabilize it. She was also made aware of the possibility of having to excise the fragments if it was not possible to operatively stabilize the fracture.

Procedure

Under spinal anaesthesia, antibiotic cover and usual sterile draping, the lateral puncture wounds were thoroughly debrided and lavaged with saline.  The fracture was exposed using an anterior approach between tibialis anterior and extensor hallucis longus, carefully protecting the neuro-vascular bundle throughout the procedure.  The displaced fracture fragments of the talus, the medial malleolus and the medial hematoma all appeared to have caused pressure on the posterior tibial neurovascular bundle. 

Figure 2 One year follow-up radiographs.

This was relieved after opening the fracture and the toes regained their color.  Intra-operatively, it became apparent that the fracture could not be anatomically reduced and fixated adequately due to the severe degree of comminution, and lack of any soft tissue attachments to the majority of the fragments. Hence, the original plan of anatomical reduction and internal fixation of the fracture was abandoned.  All loose fragments were excised, which involved removing all of the posterior process and body of the talus. Using the cancellous bone from the excised fragments as autogenous graft, the calcaneal and tibial articular surfaces were fused using three 7.5 mm cannulated AO screws (Figure 2). A small lateral malleolar avulsion fragment was excised.  The medial malleolus fragment was reduced and fixed with a cancellous 4mm AO screw (Figure 2). Post-operatively, the foot was observed to be well-vascularised. The lateral wounds were allowed to heal with regular dressings and a plaster of Paris splint was applied.  

Postoperative care protocol

Postoperatively, the patient received intravenous antibiotics for 24 hours, limb elevation for 48 hours and prophylactic anticoagulation for six weeks. Mobilization started with physiotherapy, consisting of non-weight bearing for six weeks, partial-weight bearing in air cast boot for two weeks and then allowed to fully-weight bear with an air cast boot.  The patient was advised to stop using the air cast boot at three months. The wounds healed well and there were no other complications.  

Outcomes

Due to the urgency of care required and history of trauma it was not deemed appropriate to use any form of patient reported outcome measure at the time of incident. However, the patient was reviewed frequently for eight weeks until the wounds healed. Then, accordingly, when she was allowed to weight bear, again at six months, one year and two years post-injury.  At six months, the patient had no pain or tenderness, with some dorsiflexion and plantar flexion possible at the mid-tarsal level. One-year follow-up showed that the tibio-calcaneal fusion was solid via plain x-ray (Figure 2). Final follow up at two years, she had a 2 cm shortening of her right leg measured in a weight bearing manner (measured blocks) and appropriate footwear adaptations were incorporated on the right side.  She is very happy with the outcome, has no pain and is fully mobile and weight bearing without support. 

Discussion

Talus fractures occur rarely and are commonly associated with complications and functional limitations [11].  The main complication being osteonecrosis, Vallier et al reviewed 100 talus fractures and reported osteonecrosis with collapse (31%), ankle arthritis (18%), subtalar arthritis (15%). Operative intervention was complicated by superficial (3.3%) and deep infection (5%), wound dehiscence (3.3%), delayed union (1.7%) and non-union (3.3%) [11]. Restoration of the axial alignment has been recommended to ensure optimisation of ankle and hindfoot function. It has been reported that tibiotalar and subtalar ranges of motion are reduced by up to 50% and arthrosis occurs in roughly 50% of fractures classified as Hawkins type III and IV [4]. The original paper proposing Hawkins classification even stated that comminuted fractures or those involving the body of the talus, were believed to be more problematic injuries and outside the scope of his original article [12].

A range of classifications for talus fractures exist, the most famous being the original Hawkins classification [2]. 

Historically, cases of talus injuries date as far back to as 1608. Interestingly, a term was coined known as ‘aviator’s astragalus’ due to its high frequency of injury in aircraft accidents [12]. The first case of talectomy for compound fracture was reported in 1609 by Hildanus  [13]. The patient had jumped over a ditch and turned his ankle on landing, causing the talus to dislocate completely out of the skin.  The talus was removed completely, following which the man was seen walking without apparent discomfort. In 1931, Whitman reported use of astragalectomy in correction of a calcaneus deformity of the foot [14]. Although these accounts are reported anecdotally, they demonstrate that the procedures used then are used in a similar fashion to case descriptions today. Talectomy has been used as a salvage procedure in correction of pathological deformity in conditions like  Charcot-Marie-Tooth, neglected idiopathic clubfoot, neurogenic clubfoot, cerebral palsy, gunshot wound, hemiplegia secondary to head trauma, Volkmann ischaemic contracture, poliomyelitis, arthrogryposis, myelomeningocele, and Charcot arthropathy  [15-18]. Talectomy has been used for patients with osteomyelitis or osteonecrosis of the talus [19,20]. We found only one study which reported 4 cases of total talectomy for Hawkins Type III fractures dislocations of talus in 1993 [21].  However, tibiocalcaneal arthrodesis was formally not carried out in the patients in this series.

Detenbeck and Kelley (1969) reported dire results following total dislocation of the talus in nine cases, of which seven were open [22]. Eight of the nine developed sepsis; seven required secondary talectomy, five with tibio-calcaneal fusion. This report highlights the serious consequences of this kind of injury. Their recommendations were to apply a more aggressive approach to initial treatment using talectomy and some form of tibio-calcaneal arthrodesis as the primary treatment for fracture-dislocation of the talus.  

Predominantly, cases of tibio-calcaneal (TC) arthrodesis are described for treatment of post-traumatic AVN of the talus or for treatment of rheumatoid arthritis [23-25]. Authors have reported TC arthrodesis of nine ankles in eight patients; seven were for post-traumatic talar AVN and one for rheumatoid arthritis [25]. Fixation was achieved using 6.5 or 7mm cannulated screws or multiple staples, with autologous cancellous bone graft.  Fusion was achieved in all patients between 12 and 40 weeks with a 2cm leg length discrepancy. Complications included local infection, malunion, wound dehiscence, prominent fibula and two patients required supplemental external fixation.  

In 1972, Reckling reported early TC fusion after displaced talus fractures in eight feet; Steinmann pins were used to achieve fixation without the use of bone grafting [26].  No wound complications were reported and bone union was achieved within 17 weeks. 

The main draw-back of TC fusion is the shortening of 2 to 3 cm that is produced in the limb.  It is also possible that secondary arthrosis of other joints of the foot may occur over time after TC fusion.

Using the technique of tibio-calcaneal fusion there is a potential to increase the calcaneal pitch angle. Intra-operatively, the surgeon must be careful to keep this in mind and achieve a well-aligned position of the foot. 7.5 mm cannulated AO screws were utilised providing stable compression across the fusion surfaces and encouraged rapid fusion of the inferior tibial surface to calcaneal articular surface.  There are other modes of fixation discussed within the literature such as intramedullary nail, pre-contoured plates or an external fixator. This would depend not only the surgeon’s experience and preference but in this case the setting (trauma) and clinical scenario due to the compromised blood supply.

Dennison et al treated six patients who had previous failed surgery and suffered post-traumatic AVN of the talus [27]. The necrotic body of the talus was excised and TC fusion achieved using an Ilizarov frame, combined with corticotomy and a lengthening procedure.   Patients were aged between 27 and 67 years. Shortening was corrected in four patients, and bony fusion achieved in all. Four out of six patients reported good or excellent results. 

Thomas and Daniels in 2003 reported using talonavicular and subtalar arthrodesis as a primary fusion to treat a three week old Hawkins type IV traumatic comminuted neck of talus fracture in a 29-year-old man [28]. Their case had similarities to ours, in that open reduction internal fixation had been planned, however, this was not possible anatomically due to the degree of comminution.  The patient underwent 16 months of follow-up and despite successful fusion without avascular necrosis, he was unable to return to his job as a roofer. 

Hantira et al reported treating a comminuted open fracture of the body of the talus on the same day of injury by tibio-talar fusion using the Blair technique [29].  Küntscher nails and cancellous screws remained in situ while the graft healed and they were removed at four and eight weeks post-surgery, respectively.  The patient started active and assisted foot exercises 14 weeks following surgery, with partial-weight bearing on crutches 20 weeks after the injury.  Fusion was complete at 10 months after injury and the patient was reportedly almost pain free.

Conclusion

The severity of talus fractures has increased over the last 3 decades due to modern safety equipment resulting in higher survival rates from serious accidents [2]. Due to recent advances in surgical and fixation techniques, the tendency is to reduce the talar fractures as anatomically as possible and stabilize them with screws.  

It is worthwhile considering the option of a talectomy in conjunction with a primary tibiocalcaneal arthrodesis. although cases of talus fractures with comminuted dislocations are rare. In this particular case study, to attempt to perform an open reduction and internal fixation procedure may have increased the potential risk and complications associated with these procedures, mainly AVN, traumatic hind foot arthrosis both potentially requiring further surgery. Ultimately, increasing the potential for a high rate of long-term complications and a significant impact on activities of daily living and quality of life after such treatment [30].

In summary, surgeons should be flexible in their approach in regards to consideration of treatment options in order to maximise patient outcomes.  This case highlights that the procedure choice of a primary talectomy and tibio-calcaneal arthrodesis is a viable treatment option for traumatic dislocated comminuted talar fractures, which intra-operatively was unable to be anatomically reduced and fixated.

Funding declaration: None  

Conflict of interest declaration: None

References

  1. Fortin PT and Balazsy JE.  Talus Fractures: Evaluation and Treatment. Journal of the American Academy of Orthopaedic Surgeons. 2001; 9(2):114-127. 
  2. Dale JD, Ha AS, Chew FS (2013). Update on Talar Fracture Patterns. A Large Level 1 Trauma Center Study. American Journal of Roentgenology. 201:1087-1092.
  3. Lamothe JM and Buckley RE. Talus fractures: a current concepts review of diagnoses, treatments, and outcomes. Acta Chir Orthop Traumatol Cech. 2012; 79(2):97-106.
  4. Ptaszek, A (1999) Immediate Tibiocalcaneal Arthrodesis with Interposition Fibular Autograph for Salvage After Talus Fracture: A Case Report. Journal of Orthopaedic Trauma. 13(8): 589-592.
  5. Pearce DH, Mongiardi CN, Fornasier VL, Daniels TR. Avascular necrosis of the Talus: A pictorial essay. RadioGraphics. 2005; 25(2):399-410. 
  6. Balaji GG and Arockiaraj J. Bilateral talus fracture dislocation: is avascular necrosis inevitable? BMJ Case Rep. Aug 25;2014. pii: bcr2014205367. doi: 10.1136/bcr-2014-205367
  7. Cutler L and Boot DA. Complex fractures, do we operate on enough to gain and maintain experience? Injury. 2003; 34(12):888-91.
  8. Melenevsky Y, Mackey RA, Abrahams RB, Thomson NB. Talar Fractures and Dislocations: A Radiologist’s Guide to Timely Diagnosis and Classification. Radiographics. 2015; 35(3):765-79.
  9. Weston JT, Liu X, Wandtke ME, Liu J, Ebraheim NE.  A Systematic Review of Total Dislocation of the Talus. Orthop Surg. 2015; 7(2):97-101. 
  10. Marsden CM (1955). Ankle fusion after complete talectomy in fracture dislocation of the talus. Journal of the Royal Army Medical Corps. 101(1):60-2.
  11. Vallier HA, Nork SE, Barei DP, Benirschke SK, Sangeorzan BJ. Talar neck fractures: results and outcomes. Journal of Bone & Joint Surgery. 86: 1616-1624.
  12. Alton T, Patton DJ, O.Gee A (2015) Classification in Brief: The Hawkins Classification for Talus Fractures. Clinical Orthopaedics and Related Research. 473(9): 3046-49.
  13. Hilandus F (1608): Report quoted in Opera, quae extant omnia (1946), Obs. 67, p. 140. Francofurti ad Moenum : Beyer.
  14. Whitman A , Astragalectomy – Ultimate Result.  Americal Journal of Surgery. 1931; 11(2):357–358.
  15. Gursu S, Bahar H, Camurcu Y, Yildirim T, Buyuk F, Ozcan C, et al.  Talectomy and Tibiocalcaneal Arthrodesis with Intramedullary Nail Fixation for Treatment of Equinus Deformity in Adults. Foot Ankle Int. 2015 Jan; 36(1):46-50. doi: 10.1177/1071100714550649
  16. Ruet A, Desroches A, Pansard E, Schnitzler A, Denormandie P.  Role of talectomy in management of severe equinovarus deformity in adults. Annals of Physical and Rehabilitation Medicine. 2014 May; 57:e197. doi: 10.1016/j.rehab.2014.03.719
  17. Joseph TN and Myerson MS. Use of talectomy in modern foot and ankle surgery  Foot Ankle. Clin N Am. 2004; 9:775–785.
  18. Daghino W, Di Gregorio G, Cerlon R. Surgical reconstruction of a crush injury of the talar body: a case report. J Bone Joint Surg Am. 2011 Jul; 93(14):e80.
  19. Stapleton JJ, Zgonis T. Concomitant Osteomyelitis and Avascular Necrosis of the Talus Treated with Talectomy and Tibiocalcaneal Arthrodesis. Clin Podiatr Med Surg. 2013 Apr; 30(2):251-6. doi: 10.1016/j.cpm.2013.01.001
  20. Kharwadkar N, Nand S, Walker AP. Primary talectomy for severe fracture-dislocation of the talus with a 15-year follow up: case report. Foot Ankle Int. 2007; 28(2):272-275.
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Use of an iPad based in-shoe plantar pressure system in a diabetic orthotic clinic

Joshua Young BSc.(Hons), MBAPO Orthotist1,2*

The Foot and Ankle Online Journal 12 (2): 3

In diabetes, the ability of the foot to respond to loading experienced during movement is frequently compromised, which may lead to complications including ulceration and amputation. Foot orthoses (FOs) can reduce the incidence of ulceration and amputation, by modifying the loads transmitted to the plantar tissues of the foot. It is recommended that instrumented plantar pressure measurement is used in the prescription and evaluation of FOs, although this may be challenging in clinical practice. This study reports on initial experiences using an iPad based in-shoe plantar pressure measurement system in a diabetic orthotic clinic. Peak plantar pressure (PPP) was measured at regions of interest (ROIs) with prescribed custom FOs, and with 3.2mm polyurethane (Poron) inlays as a baseline comparison. Data was collected for 24 subjects and 32 separate ROIs. Mean baseline PPP was 331.8kPa (range 56.3 – 447.7), mean PPP with FO was 170.4kPa (range 34.8 – 296.0). Mean percentage reduction in PPP was 48.2% (range 10.8 – 81.8%). Use of the system was found to be feasible, although due to time pressures, it was not used with every patient. Results indicate that the custom FOs reduced PPP and the plantar pressure system used was sensitive to these changes. An iPad based in-shoe plantar pressure system may be a useful way to increase the use of instrumented analysis in the clinical prescription and evaluation of FOs in diabetes.

Keywords: diabetes, pressure, orthoses, orthotics, orthotist

ISSN 1941-6806
doi: 10.3827/faoj.2018.1202.0003

1 – Roehampton Rehabilitation Centre, Queen Mary’s Hospital. St George’s University Hospitals NHS Foundation Trust.
2 – Opcare, Oxfordshire, UK.
* – Corresponding author: Joshua.Young1@nhs.net


In diabetes the ability of the foot to respond to loading experienced during movement is compromised, which may lead to complications including ulceration and amputation. This is due to factors including neuropathy, arterial disease, deformity, limited joint mobility and changes in plantar tissues [1–5]. Foot orthoses (FOs) can reduce the incidence of ulceration and amputation, by modifying the loads transmitted to the plantar tissues of the foot [6,7]. It is recommended that instrumented plantar pressure measurement is used in the prescription and evaluation of FOs [8], although this is challenging in clinical practice. Clinical use of plantar pressure measurement equipment may increase in feasibility as it becomes more portable and lower in cost. This study reports on initial experiences using an iPad based in-shoe plantar pressure measurement system in a diabetic orthotic clinic.

Methods

Data was gathered in a weekly diabetic orthotic clinic. The clinic was conducted by a single orthotist in the context of a large prosthetic and orthotic service within an NHS rehabilitation centre, with an on-site prosthetic and orthotic workshop. 

Gender Female 3/24 (12.5%) Male 21/24 (87.5%)
Age Mean 63.91 years (range 36-77, SD 9.59)
Diagnosis Diabetes 15/24 (62.5%)

Diabetes and charcot foot 9/24 (37.5%) 

Table 1 Patient characteristics.

Regions of interest n Mean baseline peak plantar pressure (kPa) Mean peak pressure reduction with orthoses
1st MPJ 15/32 (46.9%) 342.7 44.7%
2nd MPJ 8/32 (25.0%) 389.3 47.6%
4th MPJ 1/32 (3.1%) 447.0 74.0%
5th MPJ  1/32 (3.1%)  56.3 51.5%
All MPJs 25/32 (78.1%) 350.3 47.1%
Plantar lateral midfoot 4/32 (12.5%) 273.8 50.0%
Plantar central midfoot 1/32 (3.1%) 146.8 67.0%
Plantar medial midfoot 1/32 (3.1%)  356.3 69.4%
All midfoot 6/32 (18.8%)  266.4 53.4%

Table 2 Regions of interest and corresponding peak plantar pressures. 

Inclusion criteria were a diagnosis of diabetes, aged over 18 years. Peak plantar pressure (PPP) was measured using the Pressure Guardian pressure measurement system (Tillges technologies, USA) with an iPad tablet (Apple, USA). The Pressure Guardian system consists of sensors and a small transmitter unit which are attached to the lower limb. An iPad or iPhone application is used to monitor the data (Figure 1). Sensors were applied to ROIs and PPP was measured in two conditions – 1) 3.2mm polyurethane inlay (Grey Poron 4000, Algeos, UK) and 2) custom FOs. Custom FOs were manufactured from an impression of the feet in a foam impression box using a computer aided design and manufacture (CAD-CAM) system (Paromed, Neubeuern, Germany). All FOs were made in ethylene-vinyl acetate (EVA) with a minimum base density of 30 shore A and a maximum base density of 70 shore A. The total thickness of the base of the orthosis ranged from 4mm to 13mm. 

Figure 1 Example graphs from Pressure Guardian reports, showing peak plantar pressure with 3.2mm poron inlay only (top) and with custom foot orthosis (bottom).

Raised additions such as metatarsal bars were used to increase focal loading. Cut out sections and focal areas of low density material were also used to reduce PPP in focal areas. Soft cover materials were used for many of the orthoses. In many of the orthoses medial or lateral rear foot posting was used. Subjects walked at self selected speed in a straight corridor and wore the same pair of footwear for both conditions. The pressure measurement system was calibrated once at the beginning of each day of use. Calibration, use of poron inlays for a baseline, and other aspects of the described measurement process were all standardised due to the use of a department clinical protocol. The primary endpoint was PPP reduction. The secondary endpoint was the proportion of ROIs above and below proposed danger level of 200kPa [9]. The project protocol was reviewed by the local NHS research governance office and defined as a service evaluation. 

Results

Data for 32 ROIs was included in the analysis, representing 24 individual patients. Patient characteristics are described in table 1. Mean baseline peak pressure was 331.8kPa (range 56.3 – 447.7), mean peak pressure with FOs was 170.4kPa (range 34.8 – 296.0). Mean percentage reduction in PPP was 48.2% (range 10.8 – 81.8%). PPP reduction was similar in the <200kPa baseline group (45.0%) and >200kPa group (45.2%). PPP reduction was also similar in the Charcot group (49.8%) and non-Charcot group (46.1%). ROIs and corresponding PPP and PPP reductions are described in table 2. At baseline, 27/32 (84.4%) ROIs were above the 200kPa threshold. With custom FOs, this reduced to 10/32 (31.3%) above 200kPa.

Discussion

Use of the system was found to be feasible in a pressurised NHS clinic environment. Due to time limitations it was not used with every patient, and was typically reserved for aiding decision making and high risk patients. As the system is relatively simple and possible to operate using a tablet or smartphone, it seems likely to involve less clinical burden than more complex systems.

ROIs treated covered the forefoot and midfoot, mainly the 1st metatarsal phalangeal joint (MPJ), 2nd MPJ, and lateral plantar midfoot. There was an apparent trend towards higher baseline PPPs at the forefoot compared to the midfoot (+84kPa) however reductions were comparable in both regions. As this study looked at single ROIs, the interaction between changes in loading at different sites was not explored. For example, might reducing PPP at the forefoot increase PPP in neighbouring sites.

The data indicates positive outcomes in terms of PPP reduction. In the literature different offloading techniques including orthoses, footwear and total contact casts report approximately 20-80% PPP reduction compared to controls [9,10]. Reductions in forefoot pressure of 16-52% is reported with footwear and insoles, compared to control conditions [10]. The mean peak pressure reduction of 48% and range from 11-82% in this study seems in line with these values. The proportion of patients with peak pressure above the proposed dangerous level of 200kPa also decreased from 84% to 31%.

Results indicate that the custom FOs reduced PPP and the plantar pressure system was sensitive to these changes. To date no other results have been published using this system of which the author is aware, which highlights a need for further validation work. In addition to limited existing validation of the pressure measurement system used, data recorded and reported on the orthosis designs used is limited, which is a further weakness of the study. Investigation of orthosis design was not the aim of the study however.

Conclusion 

Use of an iPad based in-shoe plantar pressure system was practical in clinic, when used for selected patients. Custom FOs manufactured using CAD-CAM and evaluated using instrumented plantar pressure measurement achieved clear reductions in plantar pressures in patients with diabetes. An iPad based in-shoe plantar pressure system may be a feasible way to increase the use of instrumented analysis in the clinical prescription and evaluation of FOs in diabetes.

Funding declaration: This work received no specific funding.

Conflict of interest declaration: At the time of completing this work the author is employed by Opcare, a company providing prosthetic and orthotic care within the NHS. Neither the author or the author’s affiliations have any financial interests in the plantar pressure system described.

References

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  9. Bus SA. Priorities in offloading the diabetic foot. 2012 [cited 2019 Jan 3]; Available from: https://onlinelibrary.wiley.com/doi/pdf/10.1002/dmrr.2240
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Utilization of a peroneus brevis muscle flap for calcaneal fat pad atrophy secondary to radiation treatment: A case report and treatment course

by Amanda Kamery DPM1*, Byron Hutchinson DPM FACFAS2

It has been well-documented that peroneus brevis muscle flaps are an excellent option for coverage of small to medium sized soft tissue defects of the distal lateral lower extremity. They are widely used due to their reliable blood supply, minimal donor site morbidity and lower technical demand as compared to other lower extremity muscle flaps. To our knowledge, no study has evaluated the efficacy of the use of a peroneus brevis muscle flap for an intractable calcaneal scar tissue. We present a unique case in which the peroneus brevis muscle flap was used to assist with eliminating pain from an intractable calcaneal scar secondary to radiation treatment.

Keywords: Muscle flap, rear foot, lower extremity, reconstructive surgery

ISSN 1941-6806
doi: 10.3827/faoj.2018.1202.0002

1 – Franciscan Foot and Ankle Institute- St Francis Hospital, Federal Way, WA PGY-3
2 – Research Director, Franciscan Foot and Ankle Institute- St Francis Hospital, Federal Way, WA
* – Corresponding author- akamery@kent.edu


Peroneus brevis muscle flaps are widely used for distal lateral lower extremity soft tissue defects due to their reliable blood supply, minimal donor site morbidity and lower technical demand as compared to other muscle flaps [1-3]. The efficacy and utility of this muscle flap has been well-documented in the literature. Since the first discussion of a distally based peroneus brevis flap in 1997, the indications for this flap have vastly expanded and the technique has since been simplified into 5 steps [4]. It has been documented that partial or full flap necrosis is a common complication, with an occurrence of up to 41% [4]. However, with advancements in postoperative dressings and wound care modalities, this complication can be well managed [3,4]. In this case report, we present a patient with a unique indication for a distally based peroneus brevis flap.

Case Report

The patient is a 40-year-old male who presented with a painful lateral calcaneal scar after removal of clear cell sarcoma and subsequent radiation treatment years ago (Figure 1). The patient complained of significant pain to the area with activity and irritation from shoe gear. He had undergone numerous conservative treatment options without relief of symptoms. He was unable to perform duties required of his job due to pain. His goal was for pain reduction to help return to normal activity levels at work. 

A staged procedure was planned. The index procedure included scar excision, a peroneus brevis muscle flap and application of an external fixator to allow for stability of the flap and to allow full flap incorporation (Figure 2). A secondary procedure, performed 7 weeks later, included external fixator removal and skin graft application (Figure 3).   

Figure 1 Pre-operative clinical picture.  

Figure 2 Intraoperative picture of muscle flap after placement.

Intra-operatively adequate bulk and length from the peroneus brevis muscle to cover the calcaneus and aid in scar revision (Figure 2). Slight distal tip necrosis was seen at 2 weeks post-index procedure, but was managed adequately with serial in-office debridements and local wound care. 

Following the secondary procedure, epithelialization was seen over the majority of the muscle flap. Complete muscle flap incorporation and donor site closure with 90% epithelialization was noted at 6 months post-index procedure. At 12 months post-index procedure, a small soft tissue defect with granular base remained on the plantar lateral aspect of the calcaneus (Figure 4). This small soft tissue defect closed at 16 months postoperatively. The patient reports significant improvements in pain scores, subjective ambulatory tolerance, ability to return to work at full capacity and improved quality of life. 

Figure 3 Intraoperative picture of skin graft placement.

Figure 4 Twelve-month post-index procedure clinical picture.

Discussion

The traditional applications for the peroneus brevis muscle flap are well-recognized and utilized. Painful calcaneal cicatrix is a less commonly seen pathology; however, when assessing these patients the peroneus brevis muscle flap should be considered as a viable option to eliminate intractable scar, relieve pain and improve patient function. Our case example demonstrates successful use of the peroneus brevis muscle flap for this novel indication.

References

  1. Eren S, Ghofrani A, Reifenrath M. The distally pedicled peroneus brevis muscle flap: a new flap for the lower leg. Plast Reconstr Surg. 2001;107(6):1443-8.
  2. Bach AD, Leffler M, Kneser U, Kopp J, Horch RE. The versatility of the distally based peroneus brevis muscle flap in reconstructive surgery of the foot and lower leg. Ann Plast Surg. 2007;58(4):397-404.
  3. Lorenzetti F, Agostini T, Pantaloni M, Lazzeri D. The versatility of the distally based peroneus brevis muscle flap. Plast Reconstr Surg. 2011;127(4):1751-2.
  4. Troisi L, Wright T, Khan U, Emam AT, Chapman TWL. The Distally Based Peroneus Brevis Flap: The 5-Step Technique. Ann Plast Surg. 2018;80(3):272-276.

Staged correction of equinovarus in a diabetic patient: A case report

by Amanda Kamery DPM1*, Byron Hutchinson DPM FACFAS2

The Foot and Ankle Online Journal 12 (2): 1

A rigid equinovarus deformity in the diabetic patient is a challenge for many surgeons. The utilization of a single stage, acute correction of the deformity can lead to soft tissue compromise and neurovascular complications. Using gradual correction by means of external fixation, with subsequent internal fixation for arthrodesis, provides a viable option for limb salvage in this difficult patient cohort.

Keywords: Reconstructive surgery, diabetes, external fixation, lower extremity 

ISSN 1941-6806
doi: 10.3827/faoj.2018.1202.0001

1 – Franciscan Foot and Ankle Institute- St Francis Hospital, Federal Way, WA PGY-3
2 – Research Director, Franciscan Foot and Ankle Institute- St Francis Hospital, Federal Way, WA
* – Corresponding author- akamery@kent.edu


The diabetic patient with a rigid equinovarus deformity subsequent to soft tissue contracture is a unique and challenging patient [1]. Limb salvage options for this patient population are limited and complex. The utilization of gradual correction with external fixation proves to be an adequate treatment option that has less complications and leads to a stable and functional foot in this at risk group [1]. Single stage acute correction is another viable option, however, this can lead to limb length discrepancy due to significant bone resection or neurovascular compromise [2,3]. Longstanding soft tissue contracture of the medial ankle can lead to a rigid equinovarus deformity, in this setting acute correction is not a viable option due to the risk of neurovascular compromise and the delicate soft tissue envelope [4].

Case Report

A 59 year-old female presented to the clinic with a rigid equinovarus deformity secondary to multiple medial malleolar wound debridement. The patient developed this deformity over several months of wound care, which resulted in soft tissue contracture to the medial ankle. She presented to our service non-ambulatory and unbraceable due to progression of the deformity (Figure 1). She subsequently developed a wound on the lateral malleolus. 

Staged surgical correction was planned due to severe contracture and questionable medial neurovascular and soft tissue compromise. It was felt that a single stage correction would not be ideal in this particular patient. A dynamic circular frame was placed for gradual correction (Figure 2). Five days post initial procedure, the patient was educated on how to perform distraction with a total of 2 degrees of angular correction daily. The patient was non-weight bearing during the correction process. 

After 42 days, approximately 84 degrees of correction was obtained (Figure 3). At this point, a clinical decision was made to proceed with a Tibio-talo-calcaneal (TCC) fusion. 

Figure 1 Pre-operative AP foot radiograph showing severe equinovarus deformity.

Figure 2 Intra-operative clinical picture.  

Figure 3 Clinical picture after 42 days of correction.

It was determined that enough correction had occurred to relax the medial soft tissue envelope. The patient was returned to the operating room for the secondary procedure. This included external fixator removal and TCC arthrodesis with an intramedullary nail.  The patient remained non-weight bearing for 6 weeks until bony consolidation was seen on x-ray (Figure 4). 

The patient was then transitioned to protected weight bearing for 2 weeks in a controlled ankle motion (CAM) boot. The patient eventually successfully transitioned into a Charcot restraint orthotic walker (CROW) (Figure 5). The patient has remained ambulatory in a CROW for 6 months.

Figure 4 Six-week post secondary procedure. 

Figure 5 Clinical picture six weeks post secondary procedure.

Discussion

The diabetic patient with a severe lower extremity deformity and soft tissue compromise presents a challenging case for foot and ankle surgeons. Staged correction of these deformities utilizing gradual correction by external fixation and subsequent internal fixation with arthrodesis proves to be a viable option to help with limb preservation in these patients. Our case presentation demonstrates the efficacy of staged correction in these challenging patients and that limb salvage and return to ambulation in a CROW can be obtained and maintained. 

References

  1. Cuttica DJ, Decarbo WT, Philbin TM. Correction of rigid equinovarus deformity using a multiplanar external fixator. Foot Ankle Int. 2011;32(5):S533-9.
  2. Mirzayan R, Early SD, Matthys GA, Thordarson DB. Single-stage talectomy and tibiocalcaneal arthrodesis as a salvage of severe, rigid equinovarus deformity. Foot Ankle Int. 2001;22(3):209-13.
  3. Paley, D., Herzenberg, JE. Ankle and Foot Considerations In: Principles of Deformity Correction. 2002. 571-646.
  4. Bellamy JL, Holland CA, Hsiao M, Hsu JR. Staged correction of an equinovarus deformity due to pyoderma gangrenosum using a Taylor spatial frame and tibiotalar calcaneal fusion with an intramedullary device. Strategies Trauma Limb Reconstr. 2011;6(3):173-6.

Issue 12(1), 2019

Initial experiences with clinical assessment of plantar tissue hardness in diabetes: A brief case series
by Joshua Young BSc.(Hons), MBAPO


Evaluation of the subtalar joint during gait using 3-D motion analysis: Does the STJ achieve neutral position?
by James M. Mahoney DPM, Eric So DPM, David Stapleton BS, Kevin Renner DPM, Alayna Puccinelli DPM, Vassilios Vardaxis


Evaluation of the subtalar joint during gait using 3-D motion analysis: Does the STJ achieve neutral position?

by James M. Mahoney DPM1*, Eric So DPM1, David Stapleton BS2,3, Kevin Renner DPM1,2, Alayna Puccinelli DPM1,2, Vassilios Vardaxis2,3

The Foot and Ankle Online Journal 12 (1): 4

Background: One theory of hindfoot biomechanics claims that the subtalar joint (STJ) reaches neutral position during midstance, while another maintains that the STJ stays in an everted position throughout.  There is also evidence that STJ position during midstance changes with walking speed. The present study will compare four distinct STJ static positions to 3D kinematics of the STJ during self-selected and fast gait in over-ground level walking.
Methods: The right lower leg of 20 male participants was placed in three clinically used subtalar joint neutral static positions using biomechanical examination: SJNR (STJ neutral by calculation method), SJNP (STJ neutral by palpation method), NCSP (neutral calcaneal stance position), as well as in the resting bilateral standing posture RCSP (resting calcaneal stance position).  An eight-camera 3D motion capture system was used to capture and analyze the kinematics of the ankle complex during self-selected and fast walking conditions, as well as, the four static postures.
Results: The 3D subtalar joint movement pattern did not coincide with any of the three subtalar joint neutral positions (SJNR, SJNP and NCSP) during the midstance phase of self-selected or fast walking. Specifically, the subtalar joint remained in a significantly more everted and abducted position with greater deviations from neutral under the fast-walking condition.
Conclusions: None of the clinically used STJ neutral positions agree with the 3D pattern of the STJ during self-selected and fast gait. These results have implications related to clinical practice and the use of the STJ neutral position for evaluation and treatment purposes.    

Keywords: subtalar joint, biomechanics, gait

ISSN 1941-6806
doi: 10.3827/faoj.2018.1201.0004

1 – College of Podiatric Medicine and Surgery, Des Moines University, Des Moines, IA, United States
2 – Human Performance Laboratory, Des Moines University, Des Moines, IA, United States
3 – Department of Physical Therapy, Des Moines University, Des Moines, IA, United States
* – Corresponding author: James.Mahoney@dmu.edu


One of the prevailing concepts of STJ function was first advocated by Root [1].  He described his theory of subtalar joint neutral during walking as follows: “Shortly before heel lift, the subtalar joint reaches its neutral position.  During the remaining midstance period, the subtalar joint continues to supinate, and the rearfoot moves into a supinated position.” The validity of Root’s observation of subtalar joint neutral position, however, has been questioned in the biomechanics literature [2]. McPoil and Cornwall published a study in 1994, where they determined the pattern of the rear foot motion on the frontal plane during gait and compared it to the subtalar joint in the neutral position [3]. Contrary to Root’s theory, their findings concluded that the neutral position of the rearfoot during stance more closely resembled the resting calcaneal stance position than subtalar joint neutral position.  

Pierrynowsi et al. questioned the 2-D motion capture used by McPoil and Cornwall as describing the relative rear foot frontal plane motion accurately for only the first 4-36% of the gait cycle, and determined that 3-D motion capture was required to properly assess STJ motion during gait [4].  Pierrynowski et al. improved motion capture methodology and also concluded that the rearfoot did not achieve subtalar neutral position during the stance phase in gait. However, in their study, motion capture of the rearfoot, was taken while subjects walked at a slow speed on treadmill set at 0.89 meters/seconds the same for all subjects. The treadmill as the walking surface seems to affect foot motion during gait and as such it may alter the true rearfoot kinematics during the stance phase of gait [5].

Walking speed itself may also influence STJ position. Tulchin et al [6] findings concluded that when evaluating foot kinematics during gait it was imperative to account or control for walking speed because of the changes that occur with sagittal plane motion in the foot as walking speed increases; namely, an increase in plantarflexion of both the hindfoot and forefoot.  Rosenbaum et al [7] showed that with increasing walking speed there was also an increase in pronation. However, both Torburn and later Dubbledam showed that rearfoot motion in the frontal plane was not influenced by walking speed [8,9].

To further understand the function of the STJ during gait, we compared the 3D subtalar position during the midstance phase of gait at self-selected and fast walking speeds on a level walkway to three common clinically used subtalar joint neutral positions and the resting bilateral stance.

MATERIALS AND METHODS

Subjects

Twenty unimpaired, healthy adult male subjects volunteered to participate in the study (age 24.7 ± 1.7 years; mass 79.3 ± 12.0 kg; height 180 ± 7 cm). Inclusion criteria consisted of subjects who were active adults, free from injury over the last year, able to ambulate barefoot without the need for assistive devices, without any lower extremity/foot malalignment or had use of arch supports, shoe pads or foot orthoses. The study was reviewed and approved by the Institutional Review Board.

Experimental protocol

The subtalar joint neutral position is defined in three different ways.  Two involve non-weight bearing measurements: one by mathematical calculation and the second by palpation. The third way is in a weight bearing bilateral stance position.  In our study, we refer to the non-weightbearing mathematical calculation as SJNR (subtalar joint neutral by range of motion). Root provided a detailed explanation of how to find the subtalar neutral position in the non-weight bearing position which involved establishing the total range of motion for inversion and eversion followed by calculations with a formula he provided  which calculated the neutral position as 1/3 of the total range of subtalar joint inversion and eversion from the maximally everted position [10]. The second non-weightbearing STJ neutral position method employs a palpatory technique which we refer to as SJNP (subtalar joint neutral by palpation). This technique was not originally advocated by Root, but instead was adapted and modified over time based on Root’s principles. It involves palpating for the congruency of the talar head [11].   This SJNP technique is like that employed by McPoil and Pierrynowski [3, 4]. The third STJ neutral position is weight bearing NCSP (neutral calcaneal stance position). Root described it as follows: with the subject weightbearing in the normal angle and base of gait, the clinician “palpates the congruity of the medial and lateral edges of the talus in relationship to the calcaneus at the subtalar joint”, in addition to making sure “the concavity of the lateral surface of the foot is parallel to the concavity on the lateral surface of the leg”, and finally that “the lateral surface of the foot describes a straight line in the area of the calcaneocuboid joint” [12].  This technique has been modified over time so that it is most commonly measured by palpating for congruency of the medial and lateral aspects of the talus with the patient standing in the normal angle and base of gait [11]. Root also provided a technique for measuring the frontal plane position of the calcaneus, in the relaxed bilateral stance position, relative to the weightbearing surface which requires one to stand “in normal angle and base of gait” [12]. In the present study, this method is referred to as RCSP (relaxed calcaneal stance position) [See Table 1].

Data collection commenced after obtaining consent from each subject. First a clinical/biomechanical exam was performed on each subject bilaterally. During the clinical/biomechanical exam, subjects’ feet were inspected for any visible deformities and standard goniometric measurements were taken for the subtalar joint inversion, eversion range of motion (ROM), as well as the subtalar varus/valgus angle at each of the SJNR, SJNP, NCSP, and RCSP static positions (in random order), using frontal plane bisection lines of the posterior calcaneus and distal shank, according to Root’s protocol [10,12]. At the completion of the clinical exam, disposable, adhesive, radiopaque skin markers (2.0 mm pellets) were attached along the bisection line of the calcaneus and distal shank (0.33 mm diameter line), as well as the sustentaculum tali and the peroneal tubercle. Posterior and lateral x-rays were taken, and the relative locations of the radiopaque markers were used along with palpation for accurate skin adhered motion analysis marker placement for better bone alignment representation purposes.

The 3D rear foot joint angles at the four static positions and the average 3D rear foot joint angles over the midstance phase for the two different gait speeds were compared in this study. Two trials for each of the standing (RCSP and NCSP) and prone (SJNR and SJNP) static positions were collected prior to the walking trials. Each static trial captured consisted of three seconds while the positions described above were maintained. The gait speeds were self-selected typical and self-selected fast barefoot walking on a level grade walkway. The subjects were asked to walk first at their preferred typical self-selected speed (SSG) and then at a self-selected faster speed (FWS). Five successful gait trials per speed condition were captured after familiarization with the laboratory environment. A trial was deemed successful if the subject’s right foot completely contacted one of the force plates, while the subject did not adjust his step pattern. The average self-selected typical gait speed was 1.27 ± 0.11 m/s, with an average stride length of 1.38 ± 0.09 m, cadence of 109.6 ± 5.8 steps/min, and stance phase duration of 60.9 ± 1.4 % of the gait cycle. The respective gait parameters for the self-selected fast gait were the following: gait speed of 1.70 ± 0.20 m/s, with an average stride length of 1.82 ± 0.12 m, cadence of 124.9 ± 11.1steps/min, and stance phase duration was 58.7 ± 1.7 % of the gait cycle.

The shank (including tibia and fibula) and the calcaneus segments were assumed to be rigid and were tracked in the laboratory reference frame using retro reflective markers (7.9 mm diameter) adhered to the skin at specific anatomical landmarks to construct the respective segmental anatomical reference frames. Specifically: for the shank, markers were placed on the tip of the lateral malleolus (LM), the tip of the medial malleolus (MM), the tip of the fibular head (FH), and the top and bottom of the shank bisection line (TSB) and (BSB), respectively. For the hind foot, markers were placed at the top and bottom of the calcaneus bisection line (TC) and (BC) respectively, the lateral apex of the peroneal tubercle (PT), and the medial apex of the sustentaculum tali (ST).  Redundant markers on the shank and calcaneus were placed in the following places for tracking purposes: top and bottom lateral shank (TSL) and (BSL), along the line of the lateral epicondyle of the knee and the lateral malleolus; top and bottom tibia (TT) and (BT) on the medial surface; and the medial and lateral aspect of the calcaneus (MC) and (LC) on a transverse plane passing through the midpoint between TC and BC with the subject standing in the RCSP position. In addition, a toe marker was placed on the second metatarsal head (SMH), which was used as a guide to identify the midpoint between the posterior calcaneus markers TC and BC, at which level the MC and LC were placed, using a laser level during RCSP standing static position. The entire marker set was used for the two standing static positions (RCSP and NCSP), as well as a standing static reference position with the feet at shoulder width apart parallel to each other. The MM, PT and ST markers were removed and were created virtually for the two prone static positions and the dynamic gait captures.

Given the above marker placement, the anatomical reference frames were defined: (1) right shank; the frontal plane was defined by the mid-malleolus point MMP (mid-point between the MM and LM), the LM and the FH; the sagittal plane orthogonal to the frontal, containing the MMP and the mid-shank point MSP (mid-point between the TSB and BSB); the transverse plane for the shank was mutually perpendicular to its frontal and sagittal planes, (2) right hind foot (calcaneus); the sagittal plane was defined using the TC, BC and the midpoint between the MC and LC; the transverse plane orthogonal to the sagittal, containing the midpoints of the TC and BC, and the MC and LC; the frontal plane for the hind foot was mutually perpendicular to its sagittal and transverse planes.

The three-dimensional joint angles of the calcaneus with respect to the shank (representing both the subtalar and the talocrural joints) were calculated using Cardan angles. The sequence of rotations used was sagittal (plantarflexion (-) / dorsiflexion (+)), frontal (eversion (-) / inversion (+)), and then transverse (abduction (-) / adduction (+)) plane [13].   

The kinematics data was collected at 120 Hz, using an eight-camera motion capture system (Motion Analysis Corporation, Santa Rosa, CA). Ground reaction force data was collected at 1200 Hz using three force plates (AMTI, Watertown, MA) mounted flush with the walking surface and aligned in the direction of walking. A 10 N threshold for the vertical component of the ground reaction force (GRF) was used to determine the stance phase of the gait cycle (heel contact to toe-off).

To remain consistent with Root’s theory that “shortly before heel lift, the subtalar joint reaches its neutral position”, the midstance phase is operationally defined here as the portion of the stance phase were the foot is flat on the ground from the instant of toe-down to the instant of heel-off. This is consistent with the “Ankle Rocker” definition of Jacquelin Perry where the foot is plantigrade with foot-flat support [14]. The timing of the toe-down and heel-off events were determined using a simple algorithm of threshold crossings of the vertical coordinate of the toe (SMH) and virtual heel (midpoint of TC and BC) markers relative to the average height of these markers during the RCSP static position. Specifically, the toe-down event was identified as the frame following the negative crossing when the vertical coordinate of the SMH marker crossed its respective level of the static RCSP position, and the heel-off event was identified as the frame prior to the positive crossing were the vertical coordinate of the virtual heel marker crossed its respective level plus 3mm higher than the static RCSP position. The plus 3mm level adjustment was needed for consistent event detection to account for the decompression of the heel pad.  

One-way repeated measures ANOVA design was used to test for differences in the subtalar joint position across all four static conditions and the mean STJ position during midstance for SSG and FWS gait for each of the 3D planes (at α < 0.05). A set of a priori comparisons were performed to test for significant differences in STJ position between gait and each of the 4 static conditions, controlling for Type I error with a Bonferroni adjustment by setting the alpha (α) level to 0.05/4 = 0.0125. Paired t-test procedures were used to test for subtalar joint position differences between SSG and FWS gait (at α < 0.05).  The Statistical Package for the Social Sciences (SPSS Version 24.0, Chicago, IL) was used for all data analysis.

RESULTS

The three-dimensional angles of the calcaneus with respect to tibia during the stance phase of gait are shown in Fig. 1. Specifically, the average kinematic curve patterns of an individual subject are shown for the (a) sagittal, (b) frontal, and (c) transverse planes along with his five individual trials during typical self-selected (SSG) walking speed. In the sagittal plane, the three functional arcs are visible starting with the plantarflexion motion of the calcaneus with respect to the tibia approximately until the toes are down (TD). This plantarflexion action is followed by a prolonged dorsiflexion arc where the tibia moves forward on the plantigrade foot, as the load on the foot moves towards the forefoot, and continues this dorsiflexion action beyond heel-off (HO). The final arc is a rapid motion of the calcaneus with respect to the tibia in the plantarflexion direction, probably due to high forces produced by the triceps surae during propulsion.  

In the frontal plane, the calcaneus remains in a relatively fixed inverted position until toe-down, followed by an eversion arc while the foot is plantigrade well beyond the heel-off, and during the latter part of the stance we see a rapid relative inversion motion until toe-off.

Figure 1 Exemplar single subject temporal profiles (5 trials and mean), of the three dimensional angles of the calcaneus with respect to tibia during stance phase of self-selected speed gait. (a) to (c) represent the sagittal, frontal and transverse planes, respectively. The midstance phase is identified between toe-down (TD) and heel-off (HO). Thin dashed lines denote individual trials (N=5), thick solid line is the average pattern.  

The transverse plane motion is characterized by two arcs, a rapid initial abduction until toe-down followed by a gradual prolonged adduction that lasts until toe-off. Overall, there was no difference in the shape of the kinematic curve patterns between trials, subjects, and walking speeds (Figure 1).

The calcaneus to tibia average midstance phase angles show the subtalar joint for the fast gait condition (FWS) in significantly greater dorsiflexion (p=0.026) and eversion (p=0.000) position relative to the self-selected (SSG) gait condition (Table 2).  

The one-way repeated measures ANOVA reveal significant differences in all three planes across all the static positions and the dynamic gait conditions (p<0.000). The calcaneus is in a significantly greater inversion (Figure 2) and adduction (Figure 2) position for all three subtalar neutral positions (NCSP, SJNP and SJNR) as related to the average midstance phase position during typical (SSG) and fast walking speed (FWS) gait. The non-weight bearing subtalar neutral joint positions (SJNP and SJNR) place the subtalar joint in a significantly greater plantarflexion position relative to the average subtalar joint position during the midstance phase of both SSG and FWS gait. The weight bearing subtalar neutral position (NCSP) places the subtalar joint in a significantly greater dorsiflexion position relative to the self-selected gait position (Figure 2).

The calcaneus to tibia joint position during the resting calcaneal stance position (RCSP) showed no differences with the average midstance phase position of the subtalar joint during either one of the gait conditions (SSG and FWS) on the sagittal plane (Figure 2). While the calcaneus was found to be everted and adducted with respect to the tibia during the RCSP static position which is consistent with the average midstance phase position during gait, it showed significantly less eversion and adduction angles (Figure 2).    

DISCUSSION

In the current study, we compared the average midstance position (toe-down to heel-off) of the STJ to the resting calcaneal stance position and the three STJ neutral positions: calculation by taking 1/3 of the total range of STJ motion from the maximally everted position (SJNR), palpation of the medial and lateral sides of the talar head non-weight bearing (SJNP), and neutral calcaneal stance position (NCSP).  Our data showed that the STJ during midstance in gait was everted and abducted relative to these three STJ neutral positions. We also found that eversion and adduction of the calcaneus in relation to the tibia increased during fast walking speed.

The protocol that we followed to measure the movement of the STJ during gait is based on the work of Leardini et al [15] who demonstrated that dynamic foot function is best measured by considering the foot as a multisegment structure, rather than a single, rigid body.  Furthermore, Tulchin [6] showed that increased walking speed changes the foot kinematics assessed using a multisegment foot model which led us to the protocol to evaluate the STJ motion during both self-selected and fast-walking gait.  

Figure 2 Group means (S.D.) of the calcaneus with respect to tibia angles (º), of the average midstance phase of the self-selected (SSG) and fast walking (FWG) speed gait, and the four static conditions (RCSP, NCSP, SJNP, and SJNR) for: (a) sagittal, (b)  frontal, and (c) transverse plane. Bonferroni adjusted significant differences ( p<0.0125) between SSG and FWG for each of the static conditions are denoted by * and † respectively.

Contrary to Root [1], our data showed that the STJ was in a relative everted throughout the midstance portion of gait, rather than achieving neutral position, in agreement with McPoil [3] and Pierrynowski [4], despite their methodological limitations of 2D analysis and fixed low walking treadmill speed, respectively.  

Recently, Buldt et al. [18] showed that clinical static foot postural and mobility measures can explain only a small amount of variation seen in foot kinematics during walking amongst asymptomatic individuals. Their data suggests that the clinical practice measures of foot posture (such as the STJ neutral) and mobility have limited application to foot function during dynamic tasks.   

One of the major points of contradiction between the work of Root and others regarding STJ neutral position during gait is probably due to Root’s misinterpretation of previously published data. Sobel and Levitz [16] maintain that Root developed his theories of STJ neutral from the work of Wright [17].  In his study, what Wright referred to as the RCSP, Root interpreted as STJ neutral. Whether it was the RCSP or neutral position that was described by Root, our data showed that the actual position of the STJ during gait was everted to both.

Measuring the neutral position of the STJ in a static position has been critical in clinical practice for predicting the “ideal” position of the foot as it functions during gait.  Root advocated that STJ neutral was the most stable position of the foot during gait [1], and therefore, foot pathology occurs when there is deviation from this “ideal” neutral position.  This applies to the fabrication of foot orthoses, when casts of the feet are taken in either static non-weight bearing or weightbearing STJ neutral position.

While our data showed a significant discrepancy between the static relaxed and the STJ neutral position(s) commonly used in clinical practice against the average dynamic STJ during the midstance phase of gait, there is a substantial concern in the literature related to the lack of STJ neutral position intra- and inter-rater reliability. According to Pierrynowski , experienced practitioners were within ±1° of the subtalar joint non-weight bearing neutral position only 41.3% of the time (within ±3°, 90% of the time)[19].  In Van Gheluwe et al’s study, five experienced podiatric physicians showed a high intra-rater reliability when measuring STJ pronation and supination, NCSP, and RCSP but very poor inter-rater reliability except for RCSP [20]. Elveru reviewed the literature concerning the non-weight bearing measurement of subtalar joint neutral position and subtalar joint passive range of motion and concluded that “their reliability is less than optimal [21].” Open and closed kinetic chain measurement of STJ neutral yielded poor intra-rater and inter-rater reliabilities when performed by two inexperienced testers, according to Picciano [22].  Smith-Oricchio found that measurements of calcaneal inversion and eversion and STJ neutral had low to moderate inter-rater reliability [23].

CONCLUSIONS

Our study has shown that the STJ during midstance in gait was more everted and abducted relative to all three STJ neutral positions performed under weightbearing or non-weight bearing conditions. This discrepancy between the STJ position during gait and the STJ neutral positions brings into question the clinical practice use of the STJ neutral position to determine the “ideal” functional position for the foot, as well as its use for orthosis prescription purposes.

Conflict of Interest

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article:  Des Moines University College of Podiatric Medicine and Surgery.

Abbreviation Definition Load
RCSP Relaxed calcaneal stance position Weight Bearing
NCSP Neutral calcaneal stance position Weight Bearing
SJNP Subtalar joint neutral by palpation Non-weight Bearing
SJNR Subtalar joint neutral by range of motion Non-weight Bearing

Table 1 Abbreviations, definitions and load conditions for the neutral and relaxed subtalar static positions of the foot.

Variable Self-selected speed gait (SSG) Fast walking speed gait (FWS)
Mean ± SD 95% CI Mean ± SD 95% CI t p
Sagittal Plane – DF:(+) -0.44 ± 2.35 -2.66 to 5.29 0.22 ± 2.80 -2.22 to 7.48 2.41 .026
Frontal Plane – IN:(+) -3.80 ± 1.66 -6.56 to -1.39 -4.80 ± 2.10 -9.57 to -1.95 4.46 .000
Transverse Plane – AD:(+) -3.51 ± 1.53 -6.31 to -0.75 -4.17 ± 2.17 -8.36 to -1.07 1.99 .061

Table 2 Calcaneus to tibia during midstance (toe down to heel off) average position parameters during gait. Mean, standard deviation, and 95% confidence interval for typical and fast self-selected walking speeds. Differences with walking speed: t-statistic and p values are shown.  

REFERENCES

  1. Root ML, Orien WP, Weed JH, et al: “Normal Motion of the Foot and Leg in Gait,” in Biomechanical Examination of the Foot, Vol 2, p. 127, Clinical Biomechanics Corporation, Los Angeles, 1971.
  2. Levitz SJ, Sobel E. The root controversy.  Podiatry Management 1997 Sept;16:61-67.
  3. McPoil TG , Cornwall MW. Relationship between neutral subtalar joint position and pattern of rearfoot motion during walking.  Foot Ankle Int 1994 Mar;15(3):141-145.
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  5. Barton CJ, Kappel SL, Ahrendt P, Simonsen O, Rathleff.  Dynamic navicular motion measured using a stretch sensor is different between walking and running, and between over-ground and treadmill conditions.  J Foot Ankle Res 2015;8:5.
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  7. Rosenbaum D, Hautmann S, Gold M, Claes L. Effects of walking speed on plantar pressure patterns and hindfoot angular motion.  Gait Posture 1994 Sept;2:191-197.
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  16. Sobel E, Levitz SJ.  Reappraisal of the negative impression cast and subtalar joint neutral position.  J Am Podiatr Med Assn 1997 Jan;67(1):32-33.
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Initial experiences with clinical assessment of plantar tissue hardness in diabetes: A brief case series

by Joshua Young BSc.(Hons), MBAPO1,2*

The Foot and Ankle Online Journal 12 (1): 2

Plantar tissue assessment is important in the management of diabetic foot problems. As clinical assessment of plantar tissue hardness typically relies on palpation and observation only, durometer assessment is a potentially useful and feasible addition. This brief case series reports on initial experiences with the use of plantar tissue hardness measurement in 5 patients, together with plantar pressure measurement data. The results suggest some relationship between tissue hardness and peak plantar pressures (PPPs) at the forefoot. The data may suggest cut-off values, with forefoot tissue hardness <40 predicting safe PPPs and tissue hardness 60+ predicting dangerous PPP. However further research would be required to clarify these initial findings. Use of a durometer was found to be feasible within a clinical setting, and some initial data for comparison is provided. While assessment of plantar tissue hardness alone is unlikely to be a singular value which can guide treatment, it may offer a helpful addition to existing clinical assessments.

Keywords: diabetes, tissue hardness, durometer, tissue assessment, pressure

ISSN 1941-6806
doi: 10.3827/faoj.2018.1201.0002

1 – Roehampton Rehabilitation Centre, Queen Mary’s Hospital. St George’s University Hospitals NHS Foundation Trust
2 – Orthotist, Opcare, Oxfordshire, UK.
* – Corresponding author: joshua.young1@nhs.net


Foot ulcers are a major source of morbidity in diabetes [1]⁠. Risk factors for the development of foot ulcers include peripheral arterial disease, neuropathy and foot deformity [2,3]. Limited joint mobility⁠ and altered plantar tissue characteristics have also been shown to increase risk of ulceration [3, 4]. Plantar tissues in diabetes may become thinner, stiffer⁠ and harder [5, 6, 4]⁠.

Plantar tissue hardness can be measured relatively easily using a durometer and this has been explored in experimental studies, including studies of people with diabetes [4,7,8]⁠. Given that clinical assessment of plantar tissues typically relies on palpation, observation and subjective judgement only, the addition of durometer assessment is potentially helpful. This brief case series reports on initial experiences with the clinical use of plantar tissue hardness measurement, together with plantar pressure measurement data.

Methods

Skin hardness was measured with a durometer using the Shore O scale. The patient was positioned in supine and the durometer was applied perpendicularly to the foot for 3 seconds before taking the reading. Selected peak plantar pressures (PPP) were also recorded as part of the assessment, using the Pressure Guardian system (Tillges technologies, USA). Plantar pressures were recorded during walking at self-selected pace, with the subject wearing their usual shoes with a 3.2mm grey poron 4000 polyurethane inlay (Algeos, UK) only inside the shoe, in line with the department’s protocol. Recorded PPP were compared to the 200kPa threshold, which has been tentatively proposed as a dangerous level of pressure [9]⁠. Patients gave written informed consent for use of the information in this article.

Case 1

Subject 1 is a 60-year old male with type 2 diabetes and a left sided trans-tibial amputation. The remaining right foot has a history of ulceration at the interphalangeal joint of the hallux only, and the foot has been intact for over 1 year. The plantar tissues appeared in good condition except a small area of discolouration at the 1st metatarsal-phalangeal joint (MPJ), representing a small ‘blood blister’. Plantar tissue hardness was tested at the heel and all MPJs (Figure 1) and ranged between 28 – 41 shore O. PPP were measured at MPJs 1 and 3 in addition to the heel. Only the heel exceeded 200kPa (Table 1).

Figure 1 View of plantar tissues with shore hardness values (peak plantar pressures exceeding 200kPa indicated by ‘*’) – Subject 1.

Location Hardness (Shore O) of skin – Right foot [kPa  with 3mm poron]
1st MPJ 191 [191.26]
3rd MPJ 80 [80.19]
Heel 236* [235.73]

Table 1 Plantar tissue hardness and peak plantar pressures – subject 1.

Case 2

Subject 1 is a 70-year old male with type 2 diabetes and a right amputation through the first metatarsal. There is a history of ulceration at the right 2nd MPJ and distal aspect of the left 3rd toe and the right 2nd MPJ ulcer has been open within the prior 3 months . The plantar tissues appeared thin and dry, with reduced padding under the MPJs. Callus was visible particularly at the right 2nd MPJ and left 1st and 2nd MPJ. Plantar tissue hardness was tested at the heel, all MPJs and the cut end of the right 1st metatarsal (Figure 2) and ranged between 20 – 70 shore O. PPP were measured at MPJs 1 (cut end of metatarsal on right), 2 and 5 in addition to the heel. The right 2nd MPJ and left MPJs 1-2 exceeded 200kPa (Table 2).

Figure 2 View of plantar tissues with shore hardness values (peak plantar pressures exceeding 200kPa indicated by ‘*’) – Subject 2.

Location Hardness (Shore O) of skin – Right foot (1st ray amputation) Hardness (Shore O) of skin – Left foot
1st MPJ 20 (cut end of 1st metatarsal)  [118.52] 50* [423.34]
2nd MPJ 70* [563.99] 40* [254.62]
3rd MPJ 45 35
4th MPJ 55 40
5th MPJ 45 [78.74] 45 [74.46]
Heel 30 [108.11] 30 [123.35]

Table 2 Plantar tissue hardness and peak plantar pressures – Subject 2 (*location which exceeds 200kPa when walking on 3mm grey poron. Note sites tested for pressure = 1st MPJ, 2nd MPJ, 5th MPJ, heel).

Case 3

Subject 3 is a 70-year old male with type 2 diabetes. He has an amputation through the right first metatarsal in addition to removal of the right second toe. There is a history of ulceration at the left 1st MPJ and distal aspect of the right 4th toe but the feet have been ulcer free for over 12 months. The plantar tissues appeared generally good, with reasonable padding under most of the MPJs, but callus present at the left 1st MPJ and distal aspect of the right 4th toe. Plantar tissue hardness was tested at the heel, all MPJs, the cut end of the right 1st metatarsal and medial/lateral aspects of the plantar midfoot (Figure 3) and ranged between 28 – 60 shore O. PPPs were measured at MPJs 1 (cut end of metatarsal on right), 2 and 5 in addition to the heel. The right cut end of 1st metatarsal and left 1st MPJs exceeded 200kPa (Table 3).

Figure 3 View of plantar tissues with shore hardness values (peak plantar pressures exceeding 200kPa indicated by ‘*’) – Subject 3.

Location Hardness (Shore O) of skin – Right foot (1st ray amputation) [peak plantar pressure on 3mm poron / custom foot orthosis – kPa] Hardness (Shore O) of skin – Left foot [peak plantar pressure on 3mm poron / custom foot orthosis – kPa]
1st MPJ 55 (cut end of 1st metatarsal)* [234/177] 60* [330/306]
2nd MPJ 45 [157/55] 45 [25/132]
3rd MPJ 40 30
4th MPJ 50 40
5th MPJ 40 [113/39] 55 [18/26]
Medial arch 59 36
Lateral arch 40 41
Heel 30 [138/165] 28* [221/136]

Table 3 Plantar tissue hardness and peak plantar pressures – Subject 3 (*location which exceeds 200kPa when walking on 3mm grey poron. Note sites tested for pressure= 1st MPJ, 2nd MPJ, 5th MPJ, heel).

Case 4

Subject 4 is a 60-year old female with type 2 diabetes. She has a right trans-tibial amputation and a history of Charcot foot on the left in addition to removal of the left 5th toe. There is a history of ulceration, most recently at the dorsal hallux but the feet have been ulcer free for over 12 months. The plantar tissues appear in generally good condition, with reduced padding under the MPJs, and a very prominent lateral plantar midfoot. Plantar tissue hardness was tested at the heel, MPJs 1,3 and 5, medial arch, lateral plantar Charcot midfoot prominence and the skin adjacent to the midfoot prominence (Figure 4) and ranged between 30-70 Shore O. PPPs were only measured at the lateral plantar Charcot midfoot prominence, and exceeded 200kPa (Table 4).

Figure 4 View of plantar tissues with shore hardness values – Subject 4.

Location Hardness (Shore O) of skin
1st MPJ 30
2nd MPJ 32
3rd MPJ 32
4th MPJ 33
5th MPJ 70
Medial arch 32
Lateral midfoot Charcot prominence under cuboid region 70* [509kPa]
Tissue adjacent to Charcot prominence 40
Heel 45

Table 4 Plantar tissue hardness and peak plantar pressures – Subject 4. (*location which exceeds 200kPa when walking on 3mm grey poron. Note site tested for pressure = Lateral midfoot Charcot prominence under cuboid region).

Case 5

Subject 5 is a 75-year old male with type 2 diabetes. He has a history of Charcot foot on the right side, causing medial collapse around the talonavicular joint. There is a history of ulceration, and at the most recent assessment there were active ulcers at the right medial navicular/cuneiform region and right 5th toe.  The plantar tissues appear dry, with reduced padding under the MPJs, and callus under the 1st and 2nd MPJs bilaterally (Figure 5). Plantar tissue hardness was tested at the heel, MPJs 1,2 and 3, and ranged between 40-78 Shore O. PPPs were measured at the heel, MPJs 1,2 and 3, and exceeded 200kPa at the 1st and 2nd MPJs bilaterally (Table 5).

Figure 5 View of plantar tissues with shore hardness values (peak plantar pressures exceeding 200kPa indicated by ‘*’) – Subject 5.

Location Hardness (Shore O) of skin – Right (Charcot side) [peak plantar pressure on 3mm poron / custom foot orthosis – kPa] Hardness (Shore O) of skin – Left [peak plantar pressure on 3mm poron / custom foot orthosis – kPa]
1st MPJ 60* [307 / 91] 73* [291 / 94]
2nd MPJ 78* [257 / 65] 50* [360 / 136]
3rd MPJ 40 [32 / 27] 42 [152 / 71]
Heel 45 [61 / 26] 45 [169 / 111]

Table 5 Plantar tissue hardness and peak plantar pressures – Subject 5 (*location which exceeds 200kPa when walking on 3mm grey poron).

Discussion

A wide range of tissue hardness values were recorded, ranging between 20-78 Shore O. PPP also varied widely, between 18-564kPa. Considering the plantar heel, a smaller range of hardness values was recorded, between 28-45 Shore O. This is similar to the 35-50 (Shore A) reported in a diabetic group by another author [8]. Two heels exceeded 200kPa when tested – their hardness values were 28 and 41 Shore O (mean 35). The remaining heels with both durometer and pressure data (n=5) had a mean hardness of 36 Shore O. This, combined with the fact that the two hardest heels (45 Shore O) did not exceed the pressure threshold, does not seem to show an obvious prediction of high pressures by testing tissue hardness at the heel. The forefoot included higher hardness values, ranging between 28-78 Shore O. This is a wider range than the 45-50 Shore A reported by Martinez Santos [8]. Eight MPJs tested exceeded 200kPa; the average tissue hardness of these sites was 60 Shore O. In comparison, the remaining MPJs with both durometer and pressure data (n=18) had a mean tissue hardness of 42 Shore O. Forefoot hardness values of 60 Shore O or higher always predicted PPPs exceeding 200kPa. However of 11 sites exceeding 200kPA, five (45%) had tissue hardness values below 60 Shore O. Forefoot hardness values below 40 were never associated with PPP exceeding 200kPa. While these observations seem to show some relationship between forefoot tissue hardness and dynamic PPP, which has been observed elsewhere ⁠, it would appear that other factors also influence PPP [10]. The data may suggest cut-off values, with all tissue hardness <40 predicting safe PPPs and all tissue hardness 60+ predicting dangerous PPP. This could suggest that durometer testing of forefoot tissues offers an alternative to instrumented pressure measurement, in contexts where this technology is unavailable. However further research would be required to clarify these initial findings.

Conclusion

Use of a durometer was found to be feasible within a clinical setting, and some initial data for comparison is provided. Hardness testing offers quantification of more subjective assessment methods such as palpation. While plantar tissue hardness alone is unlikely to be a singular value which can guide treatment, it may offer a helpful addition to existing clinical assessments.

Acknowledgements

This work was completed while affiliated with the above organisations, however, at the time of publication the author is affiliated with: John Florence Limited, Paediatric Orthotic Centre, Foundry Lane, Lewes, East Sussex, BN7 2AS, UK

References

  1. Vileikyte L. Diabetic foot ulcers: a quality of life issue. Diabetes Metab Res Rev. 2001 Jul 1;17(4):246–9.
  2. Boyko EJ, Ahroni JH, Stensel V, Forsberg RC, Davignon DR, Smith DG. A prospective study of risk factors for diabetic foot ulcer. The Seattle Diabetic Foot Study. Diabetes Care. 1999 Jul 1;22(7):1036–42.
  3. Pham H, Armstrong DG, Harvey C, Harkless LB, Giurini JM, Veves A. Screening techniques to identify people at high risk for diabetic foot ulceration: a prospective multicenter trial. Diabetes Care. 2000 May 1;23(5):606–11.
  4. Thomas VJ, Patil KM, Radhakrishnan S, Narayanamurthy VB, Parivalavan R. The role of skin hardness, thickness, and sensory loss on standing foot power in the development of plantar ulcers in patients with diabetes mellitus–a preliminary study. Int J Low Extrem Wounds. 2003;2(3):132-9.
  5. Chao CYL, Zheng Y-P, Cheing GLY. Epidermal Thickness and Biomechanical Properties of Plantar Tissues in Diabetic Foot. Ultrasound Med Biol. 2011 Jul 1;37(7):1029–38.
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  7. Piaggesi A, Romanelli M, Schipani E, et al. Hardness of Plantar Skin in Diabetic Neuropathic Feet. J Diabetes Complications. 1999 May 1;13(3):129–34.
  8. Martínez Santos A. An investigation into the effect of customised insoles on plantar pressures in people with diabetes [thesis]. University of Salford; 2016. Available from: http://usir.salford.ac.uk/41408/1/Ana Martinez Santos Thesis.pdf
  9. Bus SA, Ulbrecht JS, Cavanagh PR. Pressure relief and load redistribution by custom-made insoles in diabetic patients with neuropathy and foot deformity. Clin Biomech. 2004 Jul 1;19(6):629–38.
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Issue 11(4), 2018

 


Case study of rare incidence of gas gangrene caused by Raoultella Ornithinolytica
by Edward Mirigliano DPM, MBA, Kyle Hopkins DPM, Samantha Banga, DPM


Staged treatment of plantar midfoot ulceration with use of a Hemisoleus Muscle Flap, application of external fixation and split-thickness skin graft
by Stephanie Oexeman, DPM; Mallory J. Schweitzer, DPM, MHA; Craig E. Clifford DPM, MHA, FACFAS, FACFAOM


Open tongue-type calcaneal fracture treated with the external fixation bent wire technique
by Dalton Ryba DPM, Jordan James Ernst DPM MS, Kyle Duncan DPM, Alan Garrett DPM FACFAS