Tag Archives: first metatarsal

Prolidase Deficiency: A child with persistent lower extremity ulcerations

by Morris Tyrone Haywood, DPM

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

This case report describes a pediatric patient with prolidase deficiency, a rare, autosomal recessive metabolic disorder with severe dermatological manifestations, particularly ulcers of the lower extremities. While this condition has seldom been reported, it may be more common than previously acknowledged. An eight year-old Amish girl with prolidase deficiency presents with ulcerations on the feet and lower legs. Clinical presentation and the pathogenesis of prolidase deficiency are discussed. During the past five years various treatment options have been attempted. These have included ointments containing growth hormones, amino acids, antibiotics and numerous over the counter products. Skin grafts were also attempted for this patient. To date, no treatment has proved significantly successful. Currently there is no cure for this condition.

Key words: Energy consumption, First metatarsophalangeal joint, First metatarsal, Insolia Flex, Comfort.

Accepted: February, 2011
Published: April, 2011

ISSN 1941-6806
doi: 10.3827/faoj.2011.0404.0004

Prolidase deficiency (PD) is a rare, inherited, autosomal recessive, inborn error of amino acid metabolism that affects collagen maturation. Eighty-five percent of the patients present with dermatological symptoms, including lower extremity ulcers, with pedal ulcers as the common clinical finding at diagnosis in 50% of the patients. [1] These chronic leg ulcers are usually irregularly shaped with prominent granulation tissue. They are often resistant to various topical, systemic, and surgical treatments making them slow to heal. [2]

In 1968, Goodman, et al., were the first to describe prolidase deficiency. [3] Powell, et al., in 1974 further defined the clinical characteristics by documenting the absence of prolidase enzyme in association with the characteristic clinical features of prolidase deficiency. [4] Prolidase enzyme cleaves iminodipeptides with C-terminal proline or hydroxyproline. The gene encoding this enzyme is located at chromosome 19. Prolidase deficiency has an incidence of 1-2 per 1,000,000 persons with an estimated 60 cases described in the literature. [5]

The clinical features observed with prolidase deficiency vary from asymptomatic to a range of symptoms, including chronic leg ulcers, recurrent infections, characteristic facies, mental retardation, and splenomegaly. [4] These symptoms normally occur in the first year of life but can remain dormant in an affected individual until the second decade of life. [6,7]

In acute ulcerations, vascular changes including occlusion of medium-sized vessels with amyloid deposits and perivascular infiltration of neutrophils have been observed. [9] Additionally, Pierand, et al., cited vascular wall thickening and infiltration of mononuclear cells and neutrophils in pre-ulcerative indurated lesions. [10] Yasuda, et al., believed the difference in the severity of skin lesions and the mental retardation between two patients may have been related to the relative superoxide-generating activity of polymorphonuclear cells (PMN). [11] These vascular and tissue changes result in chronic lower extremity ulcerations and other dermatological conditions, including scarring, scaly abnormally thick skin, photosensitivity telangiectasia, poliosis, and lymphedema. [12] Researchers have yet to determine why these chronic ulcers occur mainly in the lower extremities. [13]

Case Report

An 8 year-old Amish girl (patient x) presented with a six year history of lower extremity ulcerations, primarily on her feet. Recently, the number of ulcerations has increased, causing her more pain and discomfort. The patient’s past medical history is significant for chronic lower extremity ulcers associated with prolidase deficiency.

A physical examination of the lower extremity revealed multiple lesions in various stages of healing on her feet and legs. (Figs.1, 2A AND 2B and 3) The ulcerations on the right foot also had diffuse dyspigmentation, erythema and scaly skin. (Fig. 3) However, digital clubbing was more visible on her hands compared to her feet. She was in significant pain with ambulation and compensated by toe walking. Her parents confirmed that their child is still primarily a toe walker to avoid plantar foot pressure. Both of the patient’s feet rest in a pronounced equinus type position non- weightbearing. The patient uses bactroban and topical zinc daily on the ulcers and takes Tylenol #3 for the foot pain. Although flexible, the patient has dorsiflexion at the ankle that can reach only 90° with effort and some discomfort.

Figure 1   Irregularly shaped, intact skin with subcutaneous micro-vascular bleeding lesions.


Figures 2A and 2B  Dorsal left foot with erythema, edema at digits and scar tissue from healed ulcerations. (A)  Plantar right foot with scaly erythematous skin. (B)

Figure 3   Close-up of plantar right foot with scaly erythematous skin.

The patient has tight Achilles tendons bilaterally. Additionally, the patient exhibits pronounced ligamentous laxity in many upper and lower body joints. For shoe gear, she wears a child’s size 13 extra depth sneaker with velcro straps. The shoe also has an inner sole, comprised of a 1/16-inch pink plastazote cover on top of a 1/16-inch layer of white poron. At the heel plantarly, a small portion of Neo-Sponge covers the white poron.

In the first sixth months of her life, the patient was healthy and normal. However, at seven months, she developed petechia associated with anemia and thrombocytopenia. Then at age two, the patient was diagnosed with prolidase deficiency (PD) and underwent an allogenic umbilical cord blood transplant from her HLA identical sister to treat the disease. This initial treatment modality failed to resolve the patient’s condition.

The patient’s first lower extremity lesion was prior to the transplant. A superficial puncture wound resulted in a small, but difficult-to-heal lesion. Multiple lesions appeared on her feet and legs approximately 3 months after her transplant. These lesions became a chronic condition with the foot ulcers being most resistant to treatment and somewhat compromised by socks and shoe gear.

These foot ulcers, which have been positive for fungus in the past, have resolved with using clotrimazole.

In regards to the patient’s development, the mother had a full term delivery with no complications. The patient met all her milestones without much delay, except she began walking at around 18 months. Although she is within the appropriate percentile on the chart, she is short in stature which her primary care physician attributes to the prolonged use of steroids. However, the patient is not deficient in growth hormone as cited in the literature of other prolidase deficiency patients. She is very limber; in her mother’s words the patient is very double-jointed.

Currently, the patient is seen approximately monthly in the Pediatric Hematology/ Oncology Clinic to receive intravenous immunoglobulin G therapy to treat hypogammaglobulinemia. The patient also suffers with other immune-deficiency-related illnesses, including recurrent pulmonary and eye infections for which she often takes prophylactic medications. Additionally, she has reactive airway disease requiring the periodic use of rescue and preventive inhalers as well as a cystic fibrosis vest and oxygen. She also has a history of adrenal and thyroid deficiency involving periodic replacement. Finally, she has some developmental delay but has a 90 to 100 percent psychosocial performance score. Although none of the patient’s siblings experienced similar medical problems, two paternal 1st male cousins died from complications of PD at 13 months and 7 years of age.

Diagnosing Prolidase Deficiency

Diagnosis is based on decreased prolidase activity in erythrocytes, leukocytes and skin fibroblasts as well as urinary excretion of C-terminal proline and hydroxyproline iminodipeptides with glycylproline dominating.10 Like most genetic disorders, PD can also be diagnosed in utero using amniocentesis or chorionic villus sampling.

Often laboratory abnormalities associated with prolidase deficiency include iron-deficiency anemia, thrombocytopenia, elevated liver enzymes, decreased growth hormone, and elevated serum immunoglobulins. [10,14] However, the patient in this study has hypoimmuglobulin, requiring monthly replacement.

The low incidence and prevalence of PD and its range of phenotypes makes the diagnosis of PD a challenge. Signs and symptoms normally occur in the first year of life, but can remain latent until the second decade.15 This possible delay results in early symptoms of PD being linked to many medical conditions and diagnoses. Often patients with PD may struggle for many years to obtain the correct diagnosis. In most cases, PD patients receive multiple medical treatments for the chronic symptoms with providers having no real understanding of the disease process or the incurable prognosis. To date, therapeutic intervention of PD focuses on healing the chronic lower extremity ulcers with minimal attention given to the underlying etiology of PD. This lack of an accurate diagnosis lends patients to often feel disenfranchised in hoping for a cure for their disease.

Difficulty in Treatment

A characteristic feature of the lower extremity ulcers in this disorder is resistance to most forms of treatment, including rejection of skin grafts. The difficulty in treating PD lower extremity ulcers is probably related to the abnormal collagen degradation and synthesis cycle, which cause urinary excretion of proline and glycine as well as the vascular changes in ulcerated tissue. The collagen comprising the dermal layer is frail in PD, causing skin to break down from normal physiological stress. Furthermore, the wound healing process is altered, because of the tissue lacking normal tension, thus causing the patient to be prone to dehiscence. Additionally, occluded vessels and abnormal infiltration of neutrophils contribute to an altered immune response comprised wound healing. These tissue and vascular changes predispose patients with PD to numerous recalcitrant wounds.


During the past five years, the patient’s parents in this study have tried numerous products for treatment of their daughter’s lower extremity lesions. Some of these topical creams and ointments have been more beneficial than others. For instance, lidocaine ointment has been mixed with various other products to relieve pain. However, with each new product, some successes were gained for several months, then, as if her body had become accustomed to the medication, the lesions returned significantly worse or at least to the degree at the time treatment was initiated. For other ointments, a negative effect was sometimes immediately experienced by the patient or later developed.

Regranex, a growth hormone ointment FDA approved for diabetic ulcerations was used for one week before being discontinued because the patient experienced burning sensations. Several over the counter (OTC) ointments for treating burns and wounds were also tried, including B & W Ointment, an organic Amish product comprised of lanolin and honey; Wound-Be-Gone, a hydrophilic gel; and Merpelex, an emulsifying wax and paraffin. Unfortunately, all of these OTC products made the lesions dry and caused painful fissures. Another local product Wood’s Poultice made of bentonite clay and pine tar oils caused dry painful fissures on the feet but not the legs. Currently, the patient’s parents are applying an inexpensive triple antibiotic with zinc oxide on the feet and Wood’s Poultic to the legs. They have used this combination with daily dressing for over 12 months. Although this treatment regimen is not a cure, it keeps the lesions moist while slowly healing.

The literature has reported minimal results with other topical agents, vitamins, and antibiotics including dapsone, bactroban, ascorbic acid, and manganese. [14] The use of systemic and topical growth hormones, oral vitamins, and other supplements has provided minimal relief for a brief time. Lastly, surgical intervention using skin grafts has also been performed with limited success.

Some therapies target the pathophysiology of the disease by replacing the PD enzyme in the blood and providing collagen products to the wound. Enzyme replacement has been tried through blood transfusions, containing manganese activated prolidase enzyme, yet this costly treatment resulted in only a brief elevation in prolidase activity level. [16] There are some reports on the use of collagen dressings; however, most show no true benefits even though collagen products are thought to stimulate fibroblast activity and to improve the healing cascade. Finally, pulsed corticosteroid treatment has shown good results by inhibiting abnormal infiltration of neutrophils. [11]

While the patient’s current treatment is helpful, a different regiment will be attempted when this particular approach is no longer satisfactory. A combination ointment of proline and glycine has been described several times in the literature as beneficial. [17,18] The parent’s of this patient made several attempts of applying a compounded topical combination ointment of 5% proline and 5% glycine. After ointment application, an Adaptic wound dressing and dry gauze was then applied. Surprisingly, this treatment also was unsuccessful for this patient. She complained the ointment either burned when applied or made her itch. The ointment was temporarily discontinued for further evaluation. In the near future this combination may be manufactured with smaller percentages and/or other products. Tendon contractures resulting in foot deformity has been cited in this patient population, usually as a consequence of chronic ulcerations and scare tissue. [2] Additionally, the patient will possibly undergo an Achilles tendon lengthening procedure.

The main problem posed in the treatment of PD is that it is a rare disease, and therefore, attracts little interest from the pharmaceutical industry. [16] However, ulcerations in many disease processes are still a challenge to treat in a reasonable time frame. As the technology in wound care advances for treating our most common lesions, hopefully the treatment of chronic ulcers in PD will also improve.


1. Der Kaloustian VM, Freij BJ, Kurban AK. Prolidase deficiency: An inborn error of metabolism with major dermatological manifestations. Dermatology 164: 293-304, 1982.
2. Leoni A, Cetta G, Tenni R, Pasquali-Ronchetti I, Bertolini F, Guerra D, Dyne K, Castellani A. Prolidase deficiency in two siblings with chronic leg ulcerations: Clinical, biochemical, and morphologic aspects. Arch Dermatol 123: 493-499, 1987.
3. Goodman SI, Solomons CC, Muschenheim F, Mclntyre CA, Miles B, O’Brien D. A syndrome resembling lathyrism associated with iminodipeptiduria. Am J Med 45:152-159, 1968.
4. Powell GF, Rasco MA, Maniscalco RM. A prolidase deficiency in man with iminopeptiduria. Metabolism: Clinical Experimental 23: 505-513, 1974.
5. Kelly JJ, Freeman AF, Wang H, Cowen EW, Kong HH. An Amish boy with recurrent ulcerations of the lower extremities, telangiectases of the hands, and chronic lung disease. J Am Academy Dermatol 62: 1031-1034, 2010.
6. Lopes I, Marques L, Neves E, Silva A, Taveira M, Pena R, Vilarinho L, Martins E. Prolidase deficiency with hyperimmunoglobulin E: A case report. Pediatric Allergy Immunology 13: 140-142, 2002.
7. Shrinath M, Walter JH, Haeney M, Couriel, J M; Lewis, M A; Herrick, A L. Prolidase deficiency and systemic lupus erythematosus. Archives Disease in Childhood 76: 441-444, 1997.
8. Sekiya M, Ohnishi Y, Kimura K. An autopsy case of prolidase deficiency. Virchows Archiv Pathological Anatomy Histopathology 406:1 25-131, 1985.
9. Ogata A, Tanaka S, Tomoda T, Murayama E, Endo F, Kikuchi I. Autosomal recessive prolidase deficiency: Three patients with recalcitrant leg ulcers. Arch Dermatol 117: 689-694, 1981.
10. Milligan A, Graham-Brown RAC, Burns DA, Anderson I. Prolidase deficiency: a case report and literature review. Brit J Dermatol 121: 405-409, 1989.
11. Yasuda K, Ogata K, Kariya K, Kodama H, Zhang J, Sugahara K, Sagara Y, Kodama H. Corticosteroid treatment of prolidase deficiency skin lesions by inhibiting iminodipeptide-primed neutrophil superoxide generation. Brit J Dermatol 141: 846-851, 1999.
12. Arata J, Umemura S, Yamamoto Y, Hagiyama M, Nohara N. Prolidase deficiency: Its dermatological manifestations and some additional biochemical studies. Arch Dermatol 115: 62-67, 1979. 13. Jackson SH, Dennis AW, Greenberg M. Iminodipeptiduria: a genetic defect in recycling collagen; a method for determining prolidase in erythrocytes. Canadian Med Assoc J 113: 762-763, 1975.
14. Bissonnette R, Friedmann D, Giroux JM, Dolenga M; Hechtman P; Der Kaloustian V M; Dubuc R. Prolidase deficiency: a multisystemic hereditary disorder. J Am Academy Dermatol 29(5 Pt 2): 818-821, 1993.
15. Klar A, Navon-Elkan P, Rubinow A, Branski D, Hurvitz H, Christensen E, Khayat M, Falik-Zaccai TC. Prolidase deficiency: it looks like systemic lupus erythematosus but it is not. European J Pediatrics 169(6):727-732, 2010.
16. Viglio S, Annovazzi L, Conti B, Genta I, Perugini P, Zanone C, Casado B, Cetta G, Iadarola P. The role of emerging techniques in the investigation of prolidase deficiency: from diagnosis to the development of a possible therapeutical approach. J Chromatography B, Analytical technologies Biomedical Life Sciences 832: 1-8, 2006.
17. Arata J, Hatakenaka K, Oono T. Effect of topical application of glycine and proline on recalcitrant leg ulcers of prolidase deficiency. Arch Dermatol 122: 626-627, 1986.

Address Correspondence to: Morris T. Haywood, DPM. Ohio College of Podiatric Medicine, 16000 Rockside Woods Blvd N.,Independence, Ohio 44131-2330

1  Ohio College of Podiatric Medicine, 16000 Rockside Woods Blvd N.,Independence, Ohio 44131-2330

© The Foot and Ankle Online Journal, 2011

Gait Efficiency and the Use of Insolia® Flex to Promote First Metatarsophalangeal Joint Dorsiflexion

by Sarah A. Curran, PhD, BSc(Hons), FCPodMed, FHEA , Janette Davis 1, Joanna L. Tozer 1, Laura Watkeys 2

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

Background: Dorsiflexion of the first metatarsophalangeal (MTP) joint during walking is an important characteristic that assists efficient forward progression. In spite of a range of foot orthoses used to encourage motion at this joint, little is known how they influence energy efficiency during walking. The aim of this study was to determine if a mass market, insole modification (Insolia® Flex) influenced energy consumption and improved forefoot comfort.
Materials and Method: Fifteen healthy male volunteers (mean age 29 years) were randomly assigned 2 pairs of identical and commercially available footwear, one of which contained the Insolia® Flex. Heart rate (HR), volume of oxygen consumed in liters per kilogram (VO2/kg), respiration exchange ratio (RER), physiological cost index (PCI) and the number of steps (NoS) were monitored whilst walking on a treadmill at a speed of 4.2km/hour and 0% incline for 20 minutes. The Footwear Comfort Scale was also completed following each condition.
Results: Paired t tests showed that HR, VO2/kg and the PCI were significantly reduced for the Insolia® Flex condition (p<0.001). No significant differences (p>0.05) were noted for the RER (p<0.05), but significantly less NoS were taken during the Insolia® Flex condition (p<0.001). A significantly improved overall and forefoot comfort rating (p<0.001) was noted for the Footwear Comfort Scale.
Conclusions: The findings of this study show that energy consumption measures (i.e. HR and VO2/kg) and the PCI (a proxy measure) are influenced by first MTP joint function and suggests that efficiency is improved with the use of a modified insole that promotes function at this joint. Further research is required to clarify these findings.

Key words: Energy consumption, First metatarsophalangeal joint, First metatarsal, Insolia® Flex, Comfort.

Accepted: March 2011
Published:: April 2011

ISSN 1941-6806
doi: 10.3827/faoj.2011.0404.0002

During human bipedal walking, the storage and exchange of potential and kinetic energy in compliant structures is considered an important energy saving mechanism. [1-3] Approximately 10,000 steps is the target value that should be taken each day by the average person, and is achieved by a style of gait that progresses the body forward in a safe and efficient manner. [4] Whilst numerous and complex mechanisms are involved, the energy provided during subsequent steps is a result of momentum and pulling action of the swinging limb and stability of the stance limb. Critical to achieving this, is hip extension of the swinging limb and adequate dorsiflexion at the first metatarsophalangeal (MTP) joint of the stance limb.

This latter view is based on the reliance of the first MTP joint to engage in a series of autosupport mechanisms (i.e. Hicks windlass, [5,6] high [transverse] propulsion [7,8]) which act in a timely manner during terminal stance to provide stability of the foot for efficient forward advancement of the body. [9-14]

Whilst normal walking requires 65º – 75º of dorsiflexion for efficient forward momentum of the body, the key to understanding the importance of first MTP joint motion is the recognition of first metatarsal function and stability. [15,16] Although the initial 20º of hallux dorsiflexion is achieved without motion of the first metatarsal during stance, to obtain further motion, the hallux relies upon first metatarsal plantarflexion, which couples approximately 1º of plantarflexion for every 3º of hallux dorsiflexion. [17] A dorsiflexed first metatarsal is frequently implicated as a contributing factor to limited mobility of the first MTP joint and include conditions such as functional hallux limitus, hallux limitus and hallux rigidus. This is supported by various forms of foot orthoses that attempt to reposition the first metatarsal (i.e. encourage plantarflexion). [18-21]

Although several studies have shown the kinematic and kinetic improvements of these devices, the effects of these orthoses on energy efficiency are unknown. This is an important omission since normal function at the 1st MTP joint is considered essential for an efficient and fluent gait pattern. Previous studies have shown that methods used to record energy consumption such as volume of oxygen consumed in liters per kilogram (VO2/kg), heart rate (HR), the Physiological Cost Index (PCI) and the frequency of steps taken are responsive allowing differences between various conditions to be determined. [4,22-31] These observations include alterations in high heeled footwear alone; [31-33] high heeled footwear and pre-fabricated foot orthoses, [34] as well as patients with post cerebral vascular accident and rheumatoid arthritis. [35]

The following study attempts to address this imbalance and at the same time explores the influence of a mass market, insole modification – Insolia® Flex. This new product is designed to permit both plantarflexion and eversion of the first metatarsal head during the latter part of the stance phase of walking. The combination of plantarflexion and eversion facilitates improved first metatarsal function and the prevention and development of conditions such as functional hallux limitus and hallux limitus. The aim of this present study therefore was to examine if Insolia® Flex changed energy consumption and improved perceived comfort at the forefoot.


Participants and materials

A total of 15 male university staff and students volunteered to take part in the study. The mean age was 28.9 years (standard deviation [SD] 7.7, range 19 – 48 years), mean weight of 81.2 kilogram (kg) (SD 14.6, range 57.2 – 105.5 kg), mean height of 171.3 centimeters (cm) (SD 8.2, 158.5 – 190.5cm), and mean shoe size of 7.8 (SD 2.1; range 4.5 – 11.5). Ethical approval was sought from the School of Health Sciences Ethics Committee, University of Wales Institute, Cardiff before the study began. The study’s purpose and procedures was fully explained to each participant. Informed consent was obtained from all participants before taking part.

All participants were screened to ensure they had adequate range of dorsiflexion (extension) at the first MTP joint. Participants with <15º (i.e. hallux rigidus) did not take part in the study. The following inclusion criteria was met for all participants: no reported history of injury to the lower extremity within the last 12 months; no reported history of cardiovascular or neurological problems (i.e. angina, high blood pressure, dizziness); experience of walking on a treadmill; must be able to wear the allocated standardized footwear (female UK sizes 4.5, 5.5, 6.5 or 7.5, and male UK sizes 8.5, 9.5, 10.5 or 11.5). Finally, all participants had to tolerate wearing a mask which covers the mouth and nose (oxygen consumption measurement).

The footwear used in this study was commercially available (Bostonian, USA). (Fig. 1) Two pairs of each available size were provided, and one pair had the Insolia® Flex (Insolia®/HBN Shoe, LLC, Salem, New Hampshire, USA) built within the main insole. (Fig. 2) Insolia® Flex is manufactured as a gel component to approximate the same softness of the plantar fat pad of the foot. Specifically, under the 1st metatarsal head, there is a subtle depression within the device. This is, however, not round, but rather a skewed ovoid, in which the plantar surface is tapered to evert the 1st metatarsal head. The combination of plantarflexion and eversion facilitates improved 1st metatarsal function. In order to blind the process, participants were not informed as to whether they were wearing footwear with or without Insolia® Flex. The order of assessment for each experimental condition was randomly assigned for each participant.

Figure 1 Standardized footwear used in the study.

Figure 2 Example of male insole removed from two identical pairs of footwear. Photo A shows the underside of the insole with the gel component (InsoliaÒ Flex) in situ and photo B illustrates the top surface. Photos A and B provide a visual representation of the underside (C) and topside (D) of the non-modified insole.


A Woodway (Desmo, Germany) treadmill was used. The VO2/kg and RER were collected and calculated at one minute intervals using a Metalyzer 3B-R2 (Cortex, Germany). (Fig. 3) The RER is the carbon dioxide (CO2) divided with O2 consumption. HR was monitored using a VFIT monitor (Polarexpress Ltd, London), which was attached to the participant’s chest by a strap. This telemetry system records the electrical signals generated from the heart by the transmitter worn on the chest and displayed on a wristwatch receiver.

Figure 3 Experimental set up showing the treadmill and Metalyzer 3B-R2 used to record HR, VO2/kg and the RER.

A pedometer was used to record the NoS taken (WSG™ Digital Pedometer). The sensitivity of the pedometer was determined using the ‘shake test’ as described by Vincent and Sidman [24] before data collection began. The pedometer was found to be within 3% of the actual number of shakes. The pedometer was positioned according to manufacturer’s instructions, and before data began the step number was cleared.

Footwear Comfort Scale

Following each walking trial the Footwear Comfort Scale [36] was used to determine the perceived comfort for the 2 conditions. This scale has been used by various authors [37,38] and is based on a series of 8 questions that focus on specific areas of the footwear. Perceived comfort is rated using a 15mm visual analogue scale (VAS), with 0 (= 0 comfort point) labeled as ‘not comfortable at all’ and 15 as the ‘most comfortable condition imaginable’ (= 15 comfort points).

Since this current project focused on first metatarsal/ray function, only questions 1 (overall comfort) and 3 (forefoot cushioning) were analyzed. For consistency, each participant was advised not to take into account the style and cosmetics of the footwear during comfort rating. In addition, on completion of both sets of experiments, each participant was asked the following question: Which footwear would you choose if you had to walk all day? (i.e. condition 1 or condition 2).


Data was collected in a quiet physiology laboratory set at an ambient temperature in 1 session and lasted approximately 80 minutes. Prior to testing, the order for each experimental condition was randomly assigned to the participant to eliminate order effects. Each participant was given a 5 minute acclimatization period on the treadmill for each of the 2 experimental conditions before data collection began. The speed of walking was standardized to 4.2km/hour with a 0% incline. This speed was chosen since it falls within the mean comfortable speed for females and males. [28,38-40]

Following acclimatization, data were collected over a further 20 minutes at the same standardized speed. To minimize fatigue, each participant was allowed a 10 minute rest between each experimental condition and/or until their HR returned to its resting value. Each participant was instructed to look straight ahead whilst walking on the treadmill. The procedure was terminated if data failed to be recorded or the participant felt uncomfortable, showed an unsteady gait, signaled to stop or when the walking period was completed.

Data and statistical analysis

The mean, SD and range were calculated for all of the measures investigated. The PCI was calculated using the following equation: Walking heart rate – resting heart rate divided by speed (m/min).29 A series of Kolmogorov-Smirnov tests were performed and showed all data to have a normal distribution (p<0.001). All variables were analyzed using paired t test and 95% confidence intervals (CI) to establish differences between each of the two conditions. The software package SPSS® (version 17.0, London, UK) was used to analyze the data and the significance level was set at p<0.05.


Differences: Metabolic variables and efficiency
The mean, SD and range values produced from the male group for HR, VO2/kg, RER, NoS and PCI for each of the experimental condition are summarized in table 1. Significant differences were observed between the two experimental conditions for HR (95% CI -6.26707 to -3.53293; t=-8.000; df 14, p<0.001); VO2/kg (95% CI -1.95845 to -.82155; t=-3.452; df 14; p=0.004), and the PCI (95% CI -.15187 to -.02546; t=-3.009, df 14; p=0.009). It was noted that HR, VO2/kg, and the PCI was reduced by 6.1% (5.3), 9.7% (1.3) and 25.8% (0.08) respectively. A reduction of 6% (4.5 beats/min) for heart rate, 10.6% (1.4 ml/min/kg) for VO2/kg and 20% (0.07) for PCI was noted for the Insolia® Flex condition. Whilst no significant differences were noted for the RER (95% CI -.02964 to .00897; t=.797; df 14; p=0.1219), the NoS taken by males were significantly differently with 7.4% (143 steps) (95% CI 37.11719 to 248.11719; t=2.898; df 14; p=0.012) increase noted for the Insolia® Flex condition.

Table 1 Mean, SD and range of each condition and variable measured for the male group (*significant differences p<0.05, paired t test).

Footwear Comfort Scale

Significantly higher rating values were noted for the male group for ‘overall comfort’ (95% CI .50693 to 4.29307; t=2.719, df 14, p=0.017) and forefoot cushioning (95% CI 1.31402 to 7.61931; t=3.0339; df 14; p=0.009) for the Insolia Flex® condition. Overall comfort increased by 29.6% (2.4), whilst forefoot comfort showed a higher increase of 49.5% (4.5) Figure 4 illustrates the comparison of perceived comfort ratings for each of the two conditions for the female and male groups. Eleven males chose the Insolia® Flex condition to walk all day (no Insolia Flex®: n = 4). (Fig. 4)

Figure 4 Comparisons for ratings of overall comfort and forefoot rating (Insolia Flex®  ; no Insolia Flex ® ). Indicates significant differences at p<0.05* and p<0.01**).


The aim of this study was to investigate if Insolia® Flex changed energy consumption and improved perceived comfort at the forefoot. The findings of this study suggest that traditional measures of energy consumption (i.e. HR and VO2/kg) and a proxy measure (i.e. PCI) are influenced by 1st metatarsal function suggesting that efficiency is improved.

Energy efficiency measures and the number of steps

For this study, a range of energy efficiency variables namely HR, VO2/kg, RER and PCI were analyzed during treadmill walking for a period of 20 minutes. This is a popular method employed by many [34,43,44] and provides a controlled experiment condition (i.e. speed of walking). Whilst treadmill walking could be criticized for being ‘unnatural’, previous evidence does suggest is that walking on a treadmill identical to routine walking. [45] The only difference however comes from air resistance which can be considered as insignificant during normal speed walking. HR, VO2/kg and PCI were all significantly reduced for the Insolia® Flex condition. Whilst direct comparisons cannot be made with other studies due to the nature of the product investigated (Insolia® Flex), the findings of the present study does share similarities with a previous study that showed that insoles can improve energy efficiency. [34]

During level walking at a constant speed, the mechanical work undertaken at the beginning of stride acts to lift the centre of mass (CoM). When the CoM is lowered (referred to as negative work), the potential energy attributable to the rise in the CoM is turned into kinetic energy. [10,13,14,46] Contact of the foot with the supporting surface uses some of this energy to raise the CoM, and can be illustrated as two curves which are symmetrical and out-of-phase. [47] Studies of ‘normal’ weight individuals have shown that walking is less efficient when mass is placed on the lower legs or thighs compared with waist loads. [48] This increase could be due to the mechanical work required to swing the limb forwards which essentially have an increased mass and moment of inertia. [49] In this study, it was found that the Insolia® Flex significantly reduced the NoS. This perhaps was a surprise finding, since a significant reduction in HR, VO2/kg and PCI was observed it was thought that there would be a change in the NoS taken. There could however be a number of reasons for this. For example, the speed of the treadmill for the males which was set at 4.2 km/hour may have been too slow. Nevertheless, the Insolia® Flex condition may have allowed for a longer stride and more efficient (negative energy) phase as more motion was afforded at the 1st MTP joint. This is may have corresponded with enhanced hip extension and initiated an improvement in the foot’s autosupport mechanisms (i.e. Hicks windlass, calcancaneocuboid joint locking).

Perceived comfort and standardized footwear

Perceived overall comfort and forefoot comfort for the Insolia® Flex showed a significant difference. It was noted that the mean comfort value improved from 2.1 to 8.1 for overall comfort, and 4.6 to 9.1 for forefoot comfort. The increase for the latter rating could be due to an increased in space within the forefoot as well as the cushioning effect from the product. Seventy three percent of the males preferred the Insolia® Flex condition.

Limitations of the study and future work

The equipment used in this study was simple and the method employed was clear, however, it is acknowledged that there were inherent limitations. For example, whilst a relatively long period of walking was undertaken to obtain the energy measures (i.e. 20 minutes), the time can be considered as a snapshot, which may not represent an overall picture of efficiency. In acknowledging the limitations previously discussed, future work should be undertaken to clarify the findings presented in this study. For example, it would particularly useful to examine kinematic changes at the hip, knee and ankle with the Insolia® Flex as well as the pressure distribution using an in-shoe plantar pressure measurement system (i.e. Pedar®, Novel, Munich, Germany, GmbH). Moreover, providing a strict inclusion criteria is devised, further inquiry could be undertaken using participant’s own footwear. This should provide a more global understanding of Insolia® Flex, particularly as it will be promoted as a mass market, insole modification. Further work could also explore the use of this new product on individuals who have limited 1st MTP joint mobility (i.e. functional hallux limitus). This could be coupled with walking on a 5% incline on a treadmill to determine the efficiency and influence of Insolia® Flex on high (transverse) gear propulsion, a component of the foot’s autosupport mechanism.


This study set out to explore the differences in energy efficiency and comfort of a mass market, insole modification that improves plantarflexion/eversion of the 1st metatarsal and 1st MTP joint function. The findings revealed that the Insolia® Flex improved efficiency during a period of 20 minutes (HR, VO2/kg, PCI). Although the NoS were only significantly reduced with Insolia® Flex, there are some logical reasons why this may have happened and include the role of stride length and the standardized speed used to collect the data. future work should explore the role of this new modified insole in participants with limited 1st MTP joint dorsiflexion whilst wearing their own footwear.


SAC received funding from Insolia (Insolia®/HBN Shoe, LLC, Salem, New Hampshire, USA) to undertake this project.

Competing interests

SAC is the Chief Editor of the Foot and Ankle Online Journal and was removed from the peer review process and editorial decision for this manuscript.


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Address correspondence to: Sarah A. Curran PhD, BSc(Hons), FCPodMed, FHEA. Senior Lecturer, Wales Centre for Podiatric Studies, University of Wales Institute, Cardiff, Western Avenue, Cardiff, CF5 2YB, UK. Email: scurran@uwic.ac.uk; Phone +44 (0) 29 2041 7221.

1 Wales Centre for Podiatric Studies, University of Wales Institute, Cardiff, Western Avenue, Cardiff, CF5 2YB, UK..
2 Centre for Biomedical Sciences, University of Wales Institute, Cardiff, Western Avenue, Cardiff, CF5 2YB, UK.

© The Foot and Ankle Online Journal, 2011

Opening Base Wedge Osteotomy of the First Metatarsal Using the Arthrex Low Profile Plate and Screw System™

by Mark A. Hardy, DPM, FACFAS1 , Jason R. Grove, DPM2

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

A number of procedures have been described for the high-end hallux valgus deformity. The authors describe a modification of the proximal opening wedge osteotomy utilizing the Arthrex Low Profile Plate and Screw System™. The system allows for stable fixation of the osteotomy without the need of a bone graft to maintain position. It is hoped that this article will generate a renewed interest in this highly effective procedure.

Key words: Hallux abductovalgus deformity, open wedge base osteotomy, first metatarsal

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.  It permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ©The Foot and Ankle Online Journal (www.faoj.org)

Accepted: April, 2007
Published: April, 2009

ISSN 1941-6806
doi: 10.3827/faoj.2009.0204.0002

First metatatarsal base osteotomies have been performed for many years to correct moderate to severe intermetatarsal angles of the hallux abducto valgus deformity. A plethora of procedures have been described. Some of the most common include the crescentic, closing base wedge osteotomy and the chevron osteotomy. In contrast, the opening base wedge osteotomy has not been commonly used among surgeons. Most authors have stated that the opening base wedge is more technically demanding, requiring longer healing time due to the use of a graft, and can lead to joint jamming at the metatarsophalangeal joint.

Arthrex, Inc. has introduced a low profile titanium plate with a central spacer to allow accurate and more stable correction of the opening base wedge osteotomy. (Figs. 1,2) Furthermore, the use of the Arthrex Low Profile Plate and Screw System™ eliminates the need for a bone graft to hold the metatarsal in the corrected position. This makes the procedure less cumbersome than it may have been in the past.

Figure 1   The Arthrex Low Profile Plate and Screw System™.

Figure 2   The opening wedge plate.

Surgical technique

The incision should begin just proximal to the first metatarsocuneiform joint and end at the base of the proximal phalanx of the hallux. (Fig. 3) A modified McBride procedure is performed and the medial eminence is harvested for the future bone graft. The base of the first metatarsal is then exposed both medially and dorsally.

Figure 3   The standard incision allowing for interspace dissection and access to performing the opening base wedge osteotomy.

The first metatarsocuneiform joint is identified and a skin scribe is used to mark the dorsolateral cortex 1cm distal to the metatarsocuneiform joint. (Fig. 4) A 0.045 inch Kirschner wire is then driven from dorsal to plantar at the site already marked. The wire is driven perpendicular to the weight bearing surface to serve as an axis guide as is similarly done when performing a closing base wedge osteotomy. (Fig. 5 and 6)

Figure 4   Measuring 1-1.5cm distal to the metatarsal-cuneiform joint for placement of the osteotomy.


Figures 5 and 6   Placement of the axis guide wire perpendicular to the weight-bearing surface.

The technique guide recommends performing the osteotomy halfway between and perpendicular to the metatarsal and the weight bearing surface; we prefer to make this cut entirely perpendicular to the weight bearing surface, as we feel this effects less sagittal plane elevation.

Once the k-wire is in the proper position, a sagittal saw is utilized to make a single osteotomy. This is done by aligning the saw blade parallel to the k-wire. Care is taken to ensure that the lateral cortex is left intact. The medial wedge is created. This is done by inserting a series of three osteotomes. (Fig. 7) The 12mm osteotome is inserted first, followed by the 10mm osteotome, and lastly the 5mm osteotome. All three osteotomes are then removed.

Figure 7   Multiple placement of osteotomes to incrementally distract the osteotomy.  Care is taken to not break the lateral cortical hinge.

The osteotomy distractor is then placed medially and the wedge is opened to the desired width. (Fig. 8) Fluoroscopy is used to ensure that the intermetatarsal angle is adequately corrected.

The plate may then be placed directly on the medial surface of the metatarsal with the spacer flush against the proximal and distal edges of the wedge. The plate should be oriented such that the L-shaped portion is proximal to the osteotomy.

Figure 8   Demonstration of the Arthrex Osteotomy spreader. This is used to “dial in” the desired correction.

The screws can then be used to fixate the opening wedge plate to the bone. The screws closest to the osteotomy should be inserted first. A 1.7mm drill is passed through both cortices and the hole is measured with a depth gauge. The 2.3mm fully threaded cortical screw is then inserted. (Fig. 9)

Figure 9  Placement of the low profile open wedge plate and measurement of appropriate screw length with the depth gauge.

Once all screws are placed and the plate secured, the remaining void of the osteotomy should be filled with bone graft. This is usually done with a combination of the bone graft harvested from the medial eminence of the metatarsal head as well as allogenic cancellous bone chips. (Fig. 10 and 11) In hallux abduco valgus with larger intermetatarsal angles, there is a greater chance for compromise of the lateral cortical hinge. Should this occur, one can place an oblique screw across the osteotomy or even use a static plate from the Arthrex set. This can be applied dorsally along the first metatarsal to help prevent secondary elevatus. (Fig. 12, 13 and14)

Figures 10 and 11   Pre and post operative films demonstrating the use of the Arthrex Low Profile Plate and Screw™.

Figures 12 and 13   Use of an additional dorsal plate after compromise of the lateral cortex.  For larger hallux valgus deformities, this helps prevent secondary post-operative elevatus.

Figure 14   Lateral view showing the dorsal metatarsal plate in place.


The opening base wedge technique was first described by Trethowin in 1923. [1] In 1983, Beronio described using the medial eminence of the first metatarsal as a graft for the opening wedge osteotomy. [2] Sollitto, et al., described an opening base wedge osteotomy with implant arthroplasty of the first metatarsophalangeal joint. They utilized the resected metatarsal head as a wedge graft. [3] In the retrospective study of 20 patients, the average intermetatarsal angle was reduced from 16.13 to 3 degrees six months postoperatively. Limbirdm, et al., in 1989, reported results after performing an opening base wedge osteotomy and modified McBride bunionectomy in 15 patients. The intermetatarsal angle averaged 15 degrees preoperatively and 8 degrees postoperatively. [4]

The indications for an opening base wedge osteotomy include a short first metatarsal, intermetatarsal angle of 15 degrees or greater, adequate bone stock, and a compliant patient who understands the need for non-weight bearing. [3]

Fixation for the opening base wedge osteotomy has varied. Trethowin felt that an intact lateral cortex and a properly fitting wedge graft were adequate and no further fixation was required. Other authors have agreed that no internal fixation was needed. [3,4] Varied forms of internal fixation include screws, staples, cerclage wire, plates, and crossing pins. Amarnek, et al., described the use of the Hoffman miniature external fixator for immobilization of the first metatarsal osteotomy after bunionectomy. [5]

The opening base wedge osteotomy has had its critics. Many surgeons have felt that the opening wedge is difficult to perform and prefer to use other base wedge procedures. In the past, a bone graft had to be harvested and accurately sized in order to maintain proper correction of the metatarsal. The bone graft must be incorporated resulting in prolonged healing times. Scranton and Zuckerman noted that there was a rapid recurrence of the hallux abducto valgus deformity in 3 of 5 patients. [6]

They argued that the lengthening created with the opening wedge results in tightening of the soft tissue about the metatarsophalangeal joint, “promoting early hallux valgus recurrence.” The lengthening of the metatarsal has also been thought to predispose the metatarsophalangeal joint to jamming and subsequent arthritis. [7] Other authors have also noted that the quality of the bone graft collected from the medial metatarsal head is suboptimal for incorporation. [7]

With the development of the low profile plate and screw system by Arthrex, Inc., many of the aforementioned pitfalls can be prevented. The spacer on the plate acts as a pillar holding the wedge at the desired width. The Arthrex system eliminates the need for the bone graft to act as scaffolding for new bone growth. Moreover, it is not imperative that the surgeon make a precise fitting wedge of bone, allowing for the use of cancellous bone chips that will be more likely to incorporate into the bone. The plate is a permanent fixation device and will eliminate the risk of bunion recurrence.

About the Low Profile Plate and Screw System

The plates are titanium and have a thickness of 0.5mm. The plate spacers range from 2mm to 7mm in 0.5mm increments. The titanium screws are 2.3mm in diameter with a length ranging from 10mm to 30mm in 1mm increments. The screws are fully threaded, self-tapping cortical design. The thread hole drill bit is 1.7mm.


It is hoped that the Arthrex Low Profile Screw and Plate System™ will stimulate renewed interest of the opening base wedge osteotomy as a viable option for surgical correction of the hallux abducto valgus deformity. Many of the difficulties and complications seen in the past may be alleviated with this new design. The procedure is simple, offers adequate fixation of the osteotomy site, and ensures permanent correction.


1. Trethowan J. “Hallux valgus.” In: Choyce CC (Ed), A System of Surgery. New York, P.B. Hoeber, 1046 – 1049, 1923.
2. Beronio JP. One approach to a viable method of obtaining cancellous bone for grafting. J Foot Surg, 22: 240 – 242, 1983.
3. Sollitto RJ, Hart TJ, Sergi AR. Opening base wedge osteotomy with first metatarsophalangeal joint implantation arthroplasty: A retrospective study. J Foot Surg: 30 (2) 165 – 169, 1991.
4. Limbird TJ, DaSilva RM, Green NE. Osteotomy of the first metatarsal base for metatarsus primus varus. Foot & Ankle. 9 (4): 158 – 162, 1989.
5. Amarnek DL, Juda EJ. Opening base wedge osteotomy of the first metatarsal utilizing rigid external fixation. J Foot Surg 25(4): 321 – 326, 1986.
6. Scranton PE, Zuckerman JD: Bunion surgery in adolescents: results of surgical treatment. J Pediatr Orthopaed 4 (1): 39 – 43, 1984.
7. Mothershed RA. Osteotomies of the first metatarsal base. In: Banks AS, Downey MS, Martin DE, Miller SJ (Eds) McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery. Philadelphia, Lippincott Williams & Wilkins , 2001.

Address correspondence to: Mark A. Hardy, DPM, FACFAS
Kaiser Permanente Foundation Department of Podiatric Surgery
12301 Snow Road Parma, OH 44130
E-mail: Markhardy@sbcglobal.net.

1  Director, Foot & Ankle Trauma Service, Kaiser Permanente, Cleveland, Ohio. Cleveland Clinic Foundation Residency Program.

2  Second-year resident (PGY-2), Kaiser Permanente/Cleveland Clinic Foundation Residency Program, Cleveland, Ohio.

© The Foot and Ankle Online Journal, 2009