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Arthroscopy of septic ankle and subtalar joints: A case report

by Karl Dunn, DPM, FACFAS1; Jordan Haber2*

The Foot and Ankle Online Journal 13 (1): 1

Infection of the ankle and subtalar joints is a serious and potentially debilitating condition. Of the few reported cases, results have varied. Traditionally open procedures have been performed, some of which even led to amputation. In the case presented, the authors demonstrate a successful result utilizing arthroscopic techniques in combination with intravenous antibiotic therapy. At two-year follow-up the patient has remained infection free.

Keywords: arthroscopy, infection, osteomyelitis, septic joint, pyarthrosis

ISSN 1941-6806
doi: 10.3827/faoj.2018.1301.0001

1 – Mid-Michigan Orthopaedic Institute, A Division of Compass Healthcare; East Lansing, MI 
2 – Undergraduate Researcher of the Honors College of Michigan State University; East Lansing, MI
* – Corresponding author: haberjor@msu.edu


Joint sepsis is a severe condition with an annual incidence of 2-10 per 100,000 individuals per year [1]. Possible morbidity following joint sepsis includes chronic pain, irreversible joint damage, dysfunction, disability and a mortality rate in 11.5% of cases [2]). The prognosis is directly influenced by the promptness of the diagnosis and initiation of antibiotics [3]. Although administration of culture specific antibiotics with joint decompression are the cornerstones of treatment in a septic joint, debate in the literature exists between open versus arthroscopic approaches.

Larger, over smaller, joints seem to have a predilection, with the hip and knee constituting the majority (60%) of all septic joints [4]. Several risk factors are associated with the development of a septic joint: history of joint prostheses, rheumatoid arthritis, intravenous drug abuse, alcoholism, diabetes, previous intra-articular corticosteroid injection, immunosuppression therapy, among others [5]. 

Interestingly, the false perception is that pyarthrosis is overwhelmingly monoarthritic, as the literature supports polyarticular sepsis 22% of the time [6]. Pyarthrosis has also been reported within the ankle [7,8], metatarsal-phalangeal joints [9], and interphalangeal joints [10]. The presence of joint sepsis in the subtalar joint is extremely rare, as only two other cases have been recorded in the medical literature [5,11]. To the authors’ knowledge, the case presented is the only polyarticular septic arthritis report in which arthroscopic methods were utilized in successful treatment of the subtalar joint.

Case Study

A 68-year-old female presented to the author’s clinic, in May 2016, for evaluation of a tender and swollen left foot and ankle. She reported 9 days prior to arrival, while living in her retirement home in Florida, she suffered a severe and sudden amount of pain to her left foot and ankle while attempting to stand. As a result of the pain, she then fell to the ground. She denied a history of trauma as the inciting event, as the pain occurred prior to her fall. Due to her inability to bear weight, the patient presented to an urgent care clinic, in which radiographs were noted to be negative for fracture. She was placed in a supportive ankle brace and was given non-steroidal anti-inflammatories. She states over the next several days it was difficult to bear weight while her ankle became more edematous. She states she was concerned about her condition and elected to drive back to her permanent residence. Seven days following her first episode of pain she stopped en route to Michigan at a major university hospital in Ohio due to increased pain during her travels. Standard repeat ankle radiographs were negative and she was started on an oral methylprednisolone course. A venous Doppler was negative for deep venous thrombosis.

Upon arrival in the office, the patient was non-diaphoretic, afebrile and in pain. Her past medical history was pertinent for rheumatoid arthritis, treated with bi-weekly injections of adalimumab. Physical examination revealed a mildly edematous foot and ankle, without calor or erythema. Neurovascular status was intact. Range of motion to her ankle and midtarsal joints was severely painful and limited. There was diffuse tenderness of her entire foot and ankle, with maximum tenderness to her lateral foot and posterior ankle. As a result, a lower extremity magnetic resonance image (MRI) was ordered for the patient.

Two days after her MRI, she reported a dramatic increase in pain and presented to her closest emergency department. The patient was afebrile, and her vitals and lab markers revealed no findings of sepsis or leukocytosis. The emergency department physicians’ primary differential diagnosis was continued pain due to ankle sprain. She was discharged from the hospital and was sent directly to our office again as the MRI report was still pending. Upon review of the MRI the radiologist was unable to determine if the large joint effusions were infectious or aseptic due to lack of contrast in the imaging study (Figure 1). There were joint effusions and reactive synovium noted at the ankle, as well as the subtalar joint, with a large expansion noted at the posterior recess (Figure 2). As a result, a joint aspiration was performed from the anterior aspect of the ankle joint. Greater than 3 cc of yellow purulent material was aspirated and the patient was directly admitted to the hospital upon findings of a septic joint. 

Figure 1 Axial MRI T2 weighted image displaying posterior abscess.

Figure 2 Sagittal MRI image which displays reactive bone marrow edema consistent with early osteomyelitis, large posterior fluid collection adjacent to subtalar and ankle joint consistent with abscess.

Upon arrival at the hospital, broad spectrum antibiotics were initiated with previous cultures pending. Infectious disease was consulted for management of antibiotics. Pertinent laboratory findings revealed a white blood count (WBC) of 9,300 WBC/mcL, a C-reactive protein (CRP) of 11.1 mg/L, and an erythrocyte sedimentation rate (ESR) of 47 mm/hr. Except for a small abrasion to her index finger two weeks prior, the patient did not have any other portals of infection. Blood cultures were taken upon presentation and were negative. Due to the patient’s immunosuppression on adalimumab, the medication was stopped indefinitely as this was thought to have predisposed the patient to the infection. She was taken to the operating room the next day for an arthroscopic debridement of the septic joints.

Initial Surgery

After general anesthesia was administered, a well-padded thigh tourniquet was placed. The ipsilateral thigh was placed in a thigh holder and the limb was held in a gravity dependent position. The limb was prepped, draped, and the tourniquet was inflated to 325 mmHg. The subtalar joint was first approached with aspiration to confirm the presence of joint sepsis in this location. An 18-gauge needle was placed on a leur-locked syringe, and the subtalar joint was first accessed for aspiration. The subtalar joint was approached from the sinus tarsi, upon which purulent fluid was aspirated (Figure 3). We traced the distal aspect of the fibula posteriorly, and the 18-gauge needle was placed from posterior to anterior just lateral to the Achilles tendon. Approximately 5 mL of purulent fluid was extracted from the posterior recess of the subtalar joint. Arthroscopic portals were then established, two to the lateral hindfoot at the level of the sinus tarsi, with a third at the posterior recess for an auxiliary suction portal. Upon initial evaluation, the joint was cloudy with purulent material. The joint had elements of infected synovium which was debrided. After establishing a view of the interosseous ligament, the debridement then continued from anterior to posterior and into the posterior facet. There was noted to be loose and degraded cartilage, which exposed the underlying subchondral bone. All loose material was debrided, and the subchondral bone was noted to be firm without obvious signs of infection. After a thorough debridement, 3 liters of fluid was used for irrigation until the joint fluid appeared translucent.

Attention was then directed to the ankle joint for arthroscopy. Anteromedial and anterolateral portals were established and a standard 21-point examination ensued. 

Figure 3 Subtalar joint aspiration with purulence; the accessory portal during arthroscopic irrigation and debridement placed in the same posterior recess.

The joint fluid was initially cloudy, with a lesser degree of loose bodies as the subtalar joint. The ankle cartilage was largely intact, and less irrigation was needed than the subtalar joint to establish a lucent joint and a clear picture with the arthroscopic equipment. Following the thorough irrigation, debridement, and removal of infected synovium, all equipment was removed from the ankle. The portals from the subtalar and ankle joints were left open to allow for joint decompressions and continue to drain.

On postoperative day one, the patient reported an immediate reduction in pain and no postoperative events recorded. The patient remained improved on post-operative day two as well. Culture results from the initial aspiration yielded a Methicillin-resistant Staphylococcus aureus (MRSA) pathogen which was sensitive to vancomycin. She reported a mild increase in pain on postoperative day three and as a result a repeat MRI was ordered with and without contrast to further scrutinize the septic joints. There was noted contrast enhancement of the synovium of the ankle and subtalar joints was noted with joint effusion, with new findings of marrow edema and contrast enhancement of the joint surfaces of the subtalar and ankle joints indicative of acute osteomyelitis. Following a lengthy discussion with the patient regarding possible limb salvage potential with a conversation regarding further arthroscopic versus an open approach, the patient agreed to a second arthroscopic approach to her ankle and subtalar joints.

Second Surgery

The subtalar joint was again approached first with an attempted aspiration. No fluid or purulence was able to be extracted from the sinus tarsi nor the posterior recess of the joint. Arthroscopic equipment was re-introduced in the similar approach, with the posterior drainage portal established as well. There was continued loose cartilage and infected synovium, and an aggressive debridement was performed to the joint. Following copious irrigation, the equipment was removed and the ankle was inspected as well. The joint fluid remained relatively clear, and the cartilage was intact. Following an aggressive synovectomy and irrigation all instrumentation was removed. The portals were again left open to decompress the joint.

Recovery

The patient recovered well following the second arthroscopic procedure, and was prescribed a 6-week course of intravenous vancomycin. Two days following the second procedure, the patient was discharged home with a peripherally inserted central catheter (PICC) line for continued antibiotic administration. Inflammatory lab markers were followed on a weekly basis. Four weeks after discharge, her CRP and ESR normalized and did not re-elevate following her course of antibiotics. Her skin incisions healed without complications by three weeks succeeding the second surgery.

The patient was gradually able to increase her weight bearing status, first with a fixed walking boot for 4 weeks following her hospitalization, and transitioning to an ankle brace thereafter. The patient was sent for extensive physical therapy to aid in her recovery back to full weight bearing. She was eventually able to forego any bracing or assistance 6 months following her hospitalizations with mild pain which was treated with oral NSAIDs. Upon most recent follow-up at fourteen months, she was able to return to all pre-injury activities. No continued signs of infection were noted on clinical exam.

Discussion

The subtalar joint is a highly complex articulation of the talus and calcaneus. There are usually three distinct facets (anterior, middle, posterior) which may differ in the context of a tarsal coalition. There is a degree of variability in the ligamentous contents and joint capsular attachments as well. Arthroscopic evaluation of the subtalar joint remains a lesser utilized procedure, likely due to the complexity of the joint and the relatively small surface area which may be difficult for an unfamiliar arthroscopist to visualize. 

To the authors’ knowledge, no other cases have been reported in the literature in the successful arthroscopic treatment of a septic subtalar joint. Two other cases were identified in the literature but utilized an open approach in combination with antibiotic therapy. A Danish report displayed an isolated septic subtalar joint caused by Neisseria gonorrhoeae [5]. A second, more recent case study depicted an open approach to an infection caused by Mycoplasma hominis [12]. In both cases the infection was rapidly identified, treated, and the patients recovered fully. In the present case, two major risk factors were identified which likely predisposed the patient to her septic joint: rheumatoid arthritis and concomitant immunosuppression therapy. Patients with RA are more likely to develop joint sepsis both due to the disease process itself and due to the immunosuppressive therapy that they receive. Dissimilar to the previous reports is the fact that the patient was successfully treated with an arthroscopic approach, which did not require an open method with antibiotics, to cure the infection.

A joint aspiration of a joint is considered the gold standard in diagnosis of a septic joint, and should be performed with a low threshold when pyarthrosis is considered as a differential diagnosis. Once the diagnosis has been confirmed, rapid initiation of antibiotics should be employed. Arthroscopic and open approaches are useful tools in the irrigation and debridement of the septic joint. Advantages are inherent to an arthroscopic versus open approach: decreased soft tissue damage, which may lead to a shorter hospital stay, possible overall faster patient recovery. Repeat open versus arthroscopic lavage and debridement may be required until the infection has been controlled. This especially holds true when there has been a delay in the diagnosis and initiation of antibiotics from time of initial presentation, such as the case presented.

Conclusion

Due to the proximity of the ankle and subtalar joint, which share a capsular connection, the authors advocate that the subtalar joint may be affected more commonly than previously thought when a septic ankle is encountered. Prognosis of a septic ankle shows probable infection of the subtalar joint, causing a septic subtalar joint. The pyarthrosis of the septic ankle can be polyarthritic [6]. The infection can spread from the septic ankle to the subtalar joint through the sinus tarsi, causing infection of the subtalar joint. Performing a procedure to prevent infection transmission through the sinus tarsi may hinder the ease of the infection to spread; the procedure would counteract the close proximity of the ankle and subtalar joints, preventing a monoarthritis diagnosis from developing into a polyarthritic case.

Given the case encountered, an arthroscopic approach may be beneficial over an open approach when a septic subtalar joint is encountered. An arthroscopic approach is less invasive, leading to a less cumbersome recovery and quicker recovery time for the patient. Arthroscopic aspiration of purulent fluid is more effective in comparison to an open approach. A late diagnosis of a septic subtalar joint is more effectively combated by an arthroscopic approach, as multiple open lavages and debridements are required to accomplish what could be completed by a single arthroscopic approach. Although the literature does not have copious studies regarding open irrigation vs. arthroscopic irrigation, when comparing both methods used during treatment of acute native knee septic arthritis, 71% of the open treatment group required repeat irrigation compared to 50% in the arthroscopic treatment group [12]. Lowered chance of repeated irrigation serves as an assuring factor that an arthroscopic approach would withhold the need of multiple joint irrigations, leading to a quickened overall patient recovery.

The septic subtalar joint cases described in the literature used a combination of an arthroscopic and open procedure to eradicate infection. This is the first described case of a 68-year-old patient with a septic ankle and subtalar joint that was successfully treated with an arthroscopic approach alone. Open procedures are not necessary for proper treatment of septic arthritis. An open procedure combined with antibiotic therapy will likely lead to a more arduous path for patient recovery. Although up to physician preference, research is spreading the belief that arthroscopic procedures are less invasive and more efficient for patient recovery.  

Acknowledgements: None

Funding Declaration: None

Conflict of Interest Declaration: None

References

  1. Kaandorp CJE, Dinant HJ, van de Laar MAFJ, Moens HJB, Prins APA, Dijkmans BAC. Incidence and sources of native and prosthetic joint infection: a community based prospective survey. Ann Rheum Dis. 1997;56:470–475
  2. Weston VC, Jones AC, Bradbury N, Fawthrop F, Doherty M. Clinical features and outcome of septic arthritis in a single UK Health District 1982–1991. Ann Rheum Dis. 1999;58:214–219.
  3. Weston VC, Jones AC, Bradbury N, et al. Clinical features and outcome of septic arthritis in a single UK Health District 1982–1991. Ann Rheum Dis 1999; 58:214–219.
  4. Mathews CJ, Coakley G. Septic arthritis: current diagnostic and therapeutic algorithm. Curr Opin Rheumatol. 2008;20(4):457-62.
  5. Wynes J, Harris IV W, Hadfield RA, Malay DS. Subtalar Joint Septic Arthritis in a Patient with Hypogammaglobulinemia. Journal Foot and Ankle Surgery 2013; 52:242-248.
  6. Dubost JJ, Fis I, Denis P, et al. Polyarticular septic arthritis. Medicine (Baltimore) 1993; 72:296–310.
  7. Margaretten ME, Kohlwes J, Moore D, Bent S. Does this adult patient have septic arthritis?. JAMA. 2007;297(13):1478-88.
  8. Newman JH. Review of septic arthritis throughout the antibiotic era. Ann Rheum Dis 35:198–205, 1976.
  9. Velilla-Moliner J, Martinez-Burgui JA, Cobeta-Garcia JC, Fatahi-Bandpey ML. Podagra, is it always gout? Am J Emerg Med 22:320–321, 2004.
  10. Brower AC. Septic arthritis. Radiol Clin North Am 34:293–309, 1996.
  11. Larsen LS, Nielsen DC, Terslev L, Amris K. Infectious monoarthritis in the subtalar joint due to N. gonorrhoeae. Ugeskr Laeger 169:324–325, 2007.
  12. Johns, B P, et al. “Open Compared with Arthroscopic Treatment of Acute Septic Arthritis of the Native Knee.” PubMed.gov, NCBI, 15 Mar. 2017, www.ncbi.nlm.nih.gov/pubmed/28291

Progression of a digital or partial ray amputation to transmetatarsal amputation and below knee amputation: Time frames and associated comorbidities, a three-year retrospective study

by Carmen Bruno DPM1*, Susan Wiersema DPM2, Nneka Meka DPM3

The Foot and Ankle Online Journal 11 (2): 1

A history of lower extremity ulceration increases the risk for further ulceration, infection, and subsequent amputation. The best predictor of amputation is a history of previous amputation. The transmetatarsal amputation is often performed as a secondary procedure when infection has recurred after a digital or partial ray amputation.  Patients with a digital or partial ray amputation are at a higher risk for a more proximal amputation such as a transmetatarsal amputation (TMA) or a below knee amputation (BKA). The primary objective of this study is to determine the time frame between a digital or a partial ray amputation to TMA or a BKA, with a secondary objective to focus on the co-morbidities of the research patients. Our aim is to study the time frame from initial to subsequent amputations, in order to identify a “critical period” in which increased intervention may be beneficial. The study design consists of a three-year retrospective chart review of patients who initially received a digital or partial ray amputation and subsequently required a TMA or a BKA. The median time from digital or partial ray amputation to transmetatarsal amputation was 55 days. The median time from digital or partial ray amputation to below knee amputation was 21 days. A possible explanation for the median number of days to BKA being shorter than the median number of days to TMA could be that the patients with more serious comorbidities were more likely to require a BKA emergently. The interventions during the critical period include tighter glucose control and lower extremity angiograms with close follow-up to address the underlying comorbidities of these patients.  Further research is needed regarding the degree of effectiveness of these interventions and their ultimate success in limb salvage.

Keywords: transmetatarsal amputation, below knee amputation, infection, digital amputation

ISSN 1941-6806
doi: 10.3827/faoj.2018.1102.0001

1 – Chief Resident, Department of Podiatry, Ochsner Health System, New Orleans, LA
2 – Second year resident, Department of Podiatry Ochsner Health System , New Orleans, LA
3 – Staff Physician, Department of Podiatry Ochsner Health System, New Orleans, LA
* – Corresponding author: carmen.bruno@ochsner.org


Diabetic patients are generally at a higher risk for developing non-healing ulcerations of the lower extremity. It is estimated that 15% of patients with diabetes will develop lower extremity ulcerations at some point in their lifetime [1]. The overall incidence of diabetic lower extremity amputations in the United States is 195 per 100,000 per year [2]. A few of the common diabetes-related risk factors for developing ulcerations include peripheral neuropathy, vascular disease, and a history of ulceration or amputation [3].

Microvascular and macrovascular disease are complications of diabetes. Hyperglycemia can lead to microvascular complications such as diabetic neuropathy, nephropathy, and retinopathy. Macrovascular disease can lead to complications including coronary artery disease and peripheral arterial disease (PAD). Peripheral arterial disease is commonly seen in diabetics and can result in prolonged healing of ulcerations secondary to arterial insufficiency. Additionally, PAD can lead to lack of oxygenation and difficulty in delivering antibiotics to the infection site, thus impairing the ability to resolve infections [4].

A history of a lower extremity ulceration increases the risk for further ulceration, infection and subsequent amputation. The best predictor of amputation is a history of previous amputation [4, 5]. The transmetatarsal amputation is often performed as a secondary procedure when infection has recurred after a digital or partial ray amputation.  Patients with a digital or partial ray amputation are at a higher risk for a more proximal amputation such as a TMA or a BKA [6].

To our knowledge, the period between the initial amputation to a more proximal amputation such as a TMA or a BKA has not been well studied. Our aim is to study the time frame from initial to subsequent amputations, in order to identify a “critical period” in which increased intervention may be beneficial.

The primary objective of this study is to determine the time frame between a digital or a partial ray amputation to TMA or a BKA, with a secondary objective to focus on the co-morbidities of the research patients. Co-morbidities related to the microvascular and macrovascular disease including end stage renal disease (ESRD) and PAD, respectively, will be included.

Methods

The study design consists of a three-year retrospective chart review of patients who initially received a digital or partial ray amputation who subsequently required a TMA or a BKA. After approval was obtained by the Ochsner IRB, the research data miner was provided with the procedure codes and inclusion criteria. The charts were then further analyzed to see if they met the inclusion criteria. The inclusion criteria are displayed in Figure 1. Data was analyzed utilizing quantitative methods to determine the time frame from a distal amputation to transmetatarsal amputation of the same limb. Data was also analyzed to determine the time frame from a digital or partial ray amputation to a BKA or TMA of the same limb. The comorbidities of diabetes, PAD, and ESRD from the research patients were also included in the study for further analysis. Statistical analysis was completed utilizing SAS version 9.4. Tests were performed with significance level of α=0.05.

Patients undergoing transmetatarsal amputation in the past 3 years of the same limb.
Patients undergoing a below knee amputation in the past 3 years of the same limb.

Figure 1 Inclusion criteria.

Results

From 2012 to 2015, there were 96 transmetatarsal amputations and 91 below knee amputations performed at Ochsner Clinic Foundation. From the patients with a history of transmetatarsal amputation, 41% (40) had previously undergone digital or partial ray amputation. From the patients with a history of below knee amputation, 25% (23) had previously undergone digital or partial ray amputation. Of the patients with a history of transmetatarsal amputation, 87% (35) had diabetes, 70% (28) had PAD and 57% (23) had ESRD. Of the patients with a history of a BKA, 86% (20) had diabetes, 86% (20) had PAD and 56% (13) had ESRD. This information is displayed in Figure 2.

For the patients with a history of BKA, the comorbidities of ESRD, PAD and diabetes were all found to be statistically significant risk factors with p-value of 0.0001, 0.0068 and 0.0058 respectively.

Figure 2 Comorbidities of BKA and TMA patients.

For patients with a history of TMA, the comorbidity of diabetes was found to be a statistically significant risk factor with a p-value of 0.00029. The comorbidities of ESRD and PAD were not found to be statistically significant risk factors in patients with a history of TMA. The median time from digital or partial ray amputation to transmetatarsal amputation was 55 days. The median time from digital or partial ray amputation to below knee amputation was 21 days. This information is displayed in Figure 3.

Discussion

A limitation of this study is that the complete list of comorbidities for each patient was not taken into account. Some patients may have had more severe comorbidities than others, leading to a skewed time frame between digital or partial ray amputation to TMA and BKA.  Additionally, the studied cohorts were not matched in terms of age, gender, and complete list of comorbidities as previously mentioned. There was no overlap between patients included in the TMA and BKA cohorts.

A possible explanation for the median number of days to BKA being shorter than the median number of days to TMA could be that the patients with more serious comorbidities were more likely to require a BKA emergently. However, the difference in days to a more proximal amputation was not statistically significant between the separate groups, with a p-value of 0.0709.

Figure 3 Median days to BKA and TMA.

Total Patients BKA Patients TMA Patients P-value Wilcoxon Test
N=63 N=23 N=40
Days to procedure, Median (q1-q5 Range) Median: 21

(13-79)

Median: 55

(19-204)

0.0709 Z = -1.8063

Figure 4 Median and range (q1-q5) of days to BKA and TMA.

Conclusion

Patients with a digital or partial ray amputation are at a higher risk for more proximal amputations such as a transmetatarsal amputation and below knee amputation. The average time frame from a distal amputation to a more proximal amputation could provide additional information regarding the “critical period” in which intervention is key to prevention. The “critical period” for this study refers to the median time frame from a distal amputation to a TMA or a BKA, which were 55 days and 21 days respectively. 90% of patients requiring a BKA had the procedure done within 79 days, and 90% of patients requiring a TMA had the procedure done within 204 days.

A conclusion that can be drawn from the data is that patients should be carefully monitored for at least two months after an initial digital or partial ray amputation. A more conservative approach, using the 90th percentile data, is to monitor patients for a longer time frame of up to seven months to reduce the incidence of more proximal amputations.

The interventions during the critical period include tighter glucose control and lower extremity angiograms with close follow-up to address the underlying comorbidities of these patients.  Further research is needed regarding the degree of effectiveness of these interventions and their ultimate success in limb salvage.

Funding Declaration

Financial Support for this project was provided from Ochsner Health System.

Conflict of Interest

None reported.

Acknowledgements

We would like to thank the research department at Ochsner Medical Center for their assistance with this project.

References

  1. Elsharawy MA. Outcome of midfoot amputations in diabetic gangrene. Ann Vasc Surg. 2011;25(6):778-82.
  2. Suckow BD, Newhall KA, Bekelis K, et al. Hemoglobin A1c Testing and Amputation Rates in Black, Hispanic, and White Medicare Patients. Ann Vasc Surg. 2016;36:208-217.
  3. Frykberg RG, Zgonis T, Armstrong DG, et al. Diabetic foot disorders. A clinical practice guideline (2006 revision). J Foot Ankle Surg. 2006;45(5 Suppl):S1-66.
  4. Borkosky SL, Roukis TS. Incidence of re-amputation following partial first ray amputation associated with diabetes mellitus and peripheral sensory neuropathy: a systematic review. Diabet Foot Ankle. 2012;3
  5. Fowler MJ. Microvascular and Macrovascular Complications of Diabetes. Clinical Diabetes 2008 Apr; 26(2): 77-82.
  6. Gambardella GV. Blume PA.  Understanding The Biomechanics of the Transmetatarsal Amputation. Podiatry Today. 2013;26(3):46-56.

A rare presentation of posterior compartment abscess in a diabetic patient: A case study

by Anthony Romano DPM/PGYIII1, Kaitlyn L. Ward DPM/PGYIII1,  Byron Hutchinson, DPM FACFAS1*

The Foot and Ankle Online Journal 11 (1): 4

This case outlines the management of a 61-year-old undiagnosed diabetic female who presented to the emergency department with signs and symptoms consistent with an acute Achilles rupture. The patient was referred to the foot and ankle clinic for routine management. Due to inconsistent clinical findings and progressive worsening of status in clinical exam, additional tests were ordered which revealed a 11.4 cm abscess in the posterior compartment of the right leg and an intact Achilles tendon. The patient underwent a staged incision and drainage with removal of all nonviable tissue resulting in a 4 cm x 1.4 cm defect. She underwent negative pressure wound VAC therapy resulting in full closure of the wound. This treatment led to resolution of the infection, limb salvage and preserved limb functionality.

Keywords: leg abscess, diabetes mellitus, Achilles tendon rupture, infection

ISSN 1941-6806
doi: 10.3827/faoj.2018.1101.0004

1 – Franciscan Foot & Ankle Institute, Federal Way, WA
* – Corresponding author: byronhutchinson@chifranciscan.org


We present a unique case in which an undiagnosed diabetic patient presented to the emergency department with symptomatology and history consistent with an acute Achilles tendon rupture. Despite having no constitutional symptoms, the patient was found to have a large abscess of the posterior compartment of the right lower leg.

This case report describes the diagnostic tests, surgical intervention and wound care techniques that eventually led to resolution of the infection and preserved limb functionality. It also draws attention to the fact that uncontrolled diabetes has the propensity to allow for large-scale infections in patients that have no open wounds or obvious sources of infection.

Diabetes mellitus (DM) presents a wide variety of systemic complications for affected patients. Of interest to this case is the diabetic individual’s reduced ability to mount an immune response, thereby masking the constitutional signs and symptoms of infection (fever, tachycardia, hypotension and tachypnea) [1]. In the previously undiagnosed patient, this abnormal presentation may delay and/or prevent proper diagnosis and treatment. The primary mechanism of immunosuppression is due to the altered structure and function of the diabetic polymorphonuclear cells, monocytes and macrophages compared to non diabetics [2,3]. The diabetic patient is also at an increased risk for infection as certain microorganisms become more virulent in a high glucose environment [4]. Microorganisms also demonstrate an increased adherence to diabetic cells as compared to non diabetic cells [5,6]. For this reason, physicians caring for diabetics need to have a high index of suspicion for possible infection even if vital signs and lab results remain within normal ranges, or if no clear source of infection is apparent [1,6].  

Case Report

A 61-year-old Caucasian female presented to the emergency department due to increasing right calf pain, tenderness, swelling and inability to bear weight. Per the emergency department physician’s notes, the patient reported stepping out of an RV when she heard a pop and felt like her Achilles tendon was “overstretched”. She was not able to plantarflex on initial exam. No other injuries were reported. She denied fever, chills, nausea or vomiting. Vital signs were as follows: Blood pressure (BP) 158/75, Pulse 114, Temperature (Temp.) 36 °C (96.8 °F), Respiration rate (RR) 16 bpm, blood oxygen saturation (SpO2) 95%.

Pertinent past medical history included obesity and hypertension. She reported prior hand ganglion cyst excision, temporomandibular joint surgery and tonsillectomy. Her family medical history was remarkable for maternal diabetes and maternal aortic valve disease. She was a former smoker (1 pack/day, quit 5 years prior) and consumed 1-2 alcoholic beverages a month.

The review of systems upon arrival in the emergency department was negative. No abnormal integumentary findings were noted, specifically rash or erythema. Physical exam was positive for calf tenderness with palpation. A positive Thompson test was also documented. Vascular status was intact. Radiographs were ordered and revealed no bony abnormality or evidence of acute fracture (Figures 1a and b). The patient was diagnosed with an acute right Achilles tendon rupture and subsequently discharged. She was given a prescription of Vicodin and Ibuprofen and instructed to follow up with podiatry within a week.

Figure 1a and b Lateral (a) and AP (b) radiographs obtained in emergency room at initial presentation revealed no bony abnormality or evidence of acute fracture.

The patient followed up as instructed two days later at the foot and ankle clinic.  She stated that she developed a blister to her right posterior heel and noticed redness to her right calf. She rated her pain as 10/10. She denied nausea, fever, vomiting, chills and diarrhea. Vital signs were as follows: BP 155/89, Pulse 89, Temp. 36.7 °C (98.1 °F), RR 16, SpO2 96%.

On physical exam, she was neurovascularly intact. Significant global non-pitting edema was noted to the right ankle. A superficial bulla was noted to right posterior heel with serous drainage. Erythema was also present involving the posterior leg and foot. The musculoskeletal exam was positive for extreme guarding to right lower extremity. There was a negative Thompson’s test, in contrast to what the emergency department provider had documented. There was suspicion for infection; however, no obvious portal of entry was evident.

The patient’s diagnosis was then modified to acute right Achilles tendon rupture with cellulitis. The cellulitis was thought to have stemmed from the bulla secondary to traumatic edema. The patient was placed in a CAM boot, instructed to perform daily dressing changes to the bulla and to return to clinic in two days for re-evaluation. A venous duplex was ordered and reported as negative for deep vein thrombosis. An MRI was also ordered at that time due to suspicion of infection.

Figure 2 Sagittal sections from MRI revealed 114 mm large posterior compartment abscess. Intact Achilles tendon demonstrated (a-c). Axial bilateral T2 MRI showing the fluid collection in the right posterior compartment (d).

The patient returned to the podiatry clinic two days later. She stated she had been compliant with non-weight bearing and dressing changes. She reported a perceived increase in posterior heel edema. Her vitals were as follows: BP 163/89, Pulse 94, Temp. 36.3 °C (97.4 °F), Resp. 15, SpO2 95%.  

Upon repeat clinical exam, the patient remained neurovascularly intact and extreme tenderness along the posterior lower leg was noted. Erythema and edema had worsened. Redness extended from her heel to the knee, both anterior and posteriorly. Expressible purulence was noted from the bulla which had increased in size and spread to her lateral heel. The posterior heel at the Achilles insertion site was enlarged and there was noticeable fluctuance, indicating an underlying abscess.

A CBC was ordered and revealed a WBC count of 17,700 with a left shift. Although the patient had no previous diagnosis of DM, her fasting glucose was 268 mg/dL with an HbA1C of 10.5%.  ESR was 105 and CRP was 23.7. Cultures were taken from the purulent bulla and revealed methicillin resistant staphylococcus aureus bacteria.

The patient was admitted to the hospital and started on IV Vancomycin. The previously ordered MRI revealed an 11.4 cm fluid collection present in the posterior compartment of the leg (Figure 2a-d). The Achilles tendon was fully intact with no signs of rupture (Figure 2c).

The patient was consented for an incision and drainage of the purulent bulla in the operating room to be performed the following day. The incision and drainage was performed with the patient in the prone position. After an appropriate sterile prep was achieved, attention was directed to the bulla at the Achilles tendon insertion on the posterior aspect of the right heel where a stab incision was made (Figure 3). The stab incision was extended proximally until purulent drainage ceased at the level of the mid-calf.

Approximately, 75 cc of purulent drainage was evacuated from the leg. Three liters of normal saline was used for irrigation of the leg. Upon completion of the procedure, major muscular and tendinous structures, namely the Achilles tendon, were noted to be viable. The infection was confined to the posterior compartment only. The macerated, non-viable skin where the original bulla had been located was excised leaving an approximately 4 cm x 1.4 cm void over the Achilles tendon insertion [Figure 4]. The wound was reapproximated using a combination of retention sutures and a vessel loop to reduce tension to the area (Figure 4). The wound was then packed and covered with a sterile dressing. Daily packing changes were performed with a repeat washout of the leg performed 72 hours later.

Figure 3 Purulent drainage from the bulla on the posterior leg upon stab incision.

Figure 4 Postoperative clinical appearance, demonstrating the extent of the incision required to ensure complete evacuation of the purulence. Vessel loop employed in a crisscross fashion in order to relieve tension. Note void with exposed Achilles tendon.

At the second wash-out, all purulence was noted to be absent and all muscular and tendinous structures remained viable. Partial primary closure was performed at the proximal aspect of the incision. The distal portion could not be closed. A vessel loop in a crisscross fashion was again employed to assist with reapproximation. Vacuum assisted closure therapy of the wound (wound VAC) was then initiated over the exposed Achilles tendon and along the incision. The patient’s WBC normalized three days postoperatively. The patient was medically managed for her undiagnosed diabetes.

Figure 5 Granulation tissue beginning to cover exposed Achilles tendon.

Figure 6 Clinical appearance 26 months postoperatively: Complete granularization and re-epithelialization over posterior wound.

Wound VAC changes were performed every other day while the patient was hospitalized. Upon discharge from the hospital, the patient received daily infusions of intravenous (IV) vancomycin for two weeks and all dressing changes were performed by enterostomal therapists. Although the infection had been eradicated, the challenge of keeping the exposed Achilles tendon viable for limb functionality remained.

Results

Over the next several weeks, the patient remained non-weightbearing and continued wound VAC therapy. At four weeks postoperatively, granulation tissue began to form over the tendon (Figure 5). The tendon appeared viable throughout the entire process; however, there was noticeable contracture during this period of non-weight bearing. The patient continued this course with regular wound VAC and dressing changes at a wound care center. At approximately four months postoperatively, complete granulation over the Achilles tendon and skin re-epithelialization was noted. No additional surgical intervention was needed.

Upon complete closure of the wound, the patient began physical therapy to regain ankle range of motion, strength and stability. After eight weeks of therapy, she was able to attain adequate ankle dorsiflexion. She remains completely healed with a functional limb 26 months post initial presentation (Figure 6).

Discussion

To our knowledge this is the first case report of deep posterior leg compartment infection in an undiagnosed diabetic patient initially misdiagnosed as an Achilles tendon rupture. On initial presentation to the emergency department and initial follow-up at the podiatry clinic, the patient’s large infection was masked due to the fact she was diabetic, albeit undiagnosed. She did not exhibit any constitutional symptoms of infection including fever, tachycardia, hypotension, or tachypnea. Additionally, there was no obvious portal of entry for the infection at the time of presentation.

In this case, there were key steps that ultimately led to limb salvage. The first was made by the emergency department physician by stressing the importance of prompt follow-up at the foot and ankle clinic for immediate management. The second key step was the foot and ankle physician performing the repeat physical exam from presentation to the emergency department. The negative repeat Thompson test led the provider to consider a broader differential diagnosis (Achilles tendon rupture with cellulitis vs deep vein thrombosis vs infection). Additional tests were then ordered to help narrow the differential even though the patient wasn’t demonstrating any constitutional signs of infection.

The two day follow up period as ordered by the foot and ankle specialist facilitated a prompt diagnosis and admission to the hospital immediately after review of the newly ordered labs and imaging. The timely diagnosis, admission, and incision and drainage ensured that the infection did not spread to other compartments or render the Achilles tendon nonviable.

Following initial management, additional steps were also taken to ensure full future functionality of the limb. The repeat incision and drainage allowed appropriate assessment of the infected structures prior to definite closure to ensure limb viability. The decision to maintain daily infusions of IV antibiotics for two weeks postoperatively prevented recurrence and non-weight bearing status allowed for appropriate granulation tissue to form over the tissue void and exposed tendon. Alternative wound care products which may have resulted in faster would closure were unavailable due to the patient’s insurance. Despite this limitation, wound VAC therapy was successful at gaining full would closure.

The final step which ensured limb viability and functionality was the referral to physical therapy in order to address the acquired equinus contracture. This referral was purposefully delayed until full would closure was achieved as early mobilization may have resulted in wound opening, and compromised healing, ultimately prolonging the course of treatment.

In conclusion, diabetic infections present unique challenges; however, when the proper precautions are taken limb salvage can be achieved.

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