SLR - April 2017 - Caitlin Miner

Total Ankle Arthroplasty vs. Ankle Arthrodesis: A Comparative Analysis of Arc of Movement and Functional Outcomes

Reference: Pedowitz DI, Kane JM, Smith GM, Saffel HL, Comer C, Raikin SM. Total Ankle Arthroplasty vs. Ankle Arthrodesis: A Comparative Analysis of Arc of Movement and Functional Outcomes. Bone Joint J. 2016 May; 98-B(5): 634–40.

Reviewed By: Caitlin Miner, DPM
Residency Program: Hoboken University Medical Center, Hoboken, NJ  

Podiatric Relevance: End-stage ankle joint arthritis is a common condition seen by podiatric physicians. Patients may experience psychological and physical disabilities, which can be severely impairing. Traditionally, the gold standard surgical treatment was tibiotalar arthrodesis; however, long-term studies have shown decreased function due to arthritis of adjacent joints. Recent improvements in the design of total ankle arthroplasty implants have shown improved long-term success rates and an ability to closely mimic the biomechanics of the foot and ankle. To date, few studies compare biomechanics following total ankle arthroplasty and tibiotalar arthrodesis. The purpose of this study was to compare overall sagittal plane mobility following total ankle arthroplasty and tibiotalar arthrodesis.

Methods: A level III retrospective cohort study was performed comparing 68 total patients who received either tibiotalar arthrodesis (27) or total ankle arthroplasty (41). Primary outcomes included overall arc of movement and talonavicular movement in the sagittal plane, which were assessed using weightbearing lateral radiographs. Functional outcomes were then assessed using the Short Form-12 version 2.0 questionnaire, VAS pain scores and the Foot and Ankle Ability Measure (FAAM).

Results: Arthroplasty patients had a greater overall sagittal range of motion than the arthrodesis group (34.2 vs. 24.3 degrees). The entire arc of movement in the arthrodesis group came from the midfoot (24.3 degrees) whereas tibiotalar and tibionavicular joints both contributed to movement in the arthroplasty group (23.7 and 10.5 degrees at each joint respectively). Arthroplasty patients maintained a more normalized arc of movement about the talonavicular joint compared to the arthrodesis group (10.5 degrees vs. 22.8 degrees). There was no significant difference in the SF-12 scores; however, patients who underwent arthroplasty had a 12.84 lower VAS pain score than the arthrodesis group (12.05 vs. 24.89). The arthroplasty group also had significantly improved FAAM scores compared to the arthrodesis group (82 vs. 71.67 for ADL and 57 vs. 43.39 for sports, respectively).

Conclusions:
This is the first study to date to focus on tibiotalar joint range of motion and its contribution to foot and ankle biomechanics following ankle arthrodesis and total ankle arthroplasty. The results show that total ankle arthroplasty preserves a significantly greater motion and that range of motion following ankle arthrodesis arises from compensatory increased mobility about the midfoot. Such increased midfoot mobility following ankle arthrodesis may lead to subsequent midfoot arthritis and pain. Preservation of the foot and ankle biomechanics through total ankle arthroplasty may thus have the potential to prevent this arthritic progression. In light of these findings, podiatric physicians may want to consider total ankle arthroplasty as an evidence-based surgical option to improve the pain, function and mobility of patients with end-stage ankle arthritis. 

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