Microfracture of subchondral bone leads to persistent subchondral sclerosis and poorer functional outcomes following distraction arthroplasty of the ankle joint while biologic augment may improve recovery times

Abstract

Category: Ankle Arthritis Introduction/Purpose: Treatment of ankle osteoarthritis (OA) continues to remain a challenge. Previous reports have demonstrated the short-term benefits of using joint distraction for the treatment of ankle (OA), however, its efficacy in long term clinical outcomes and its role in preserving the joint space remains controversial. The purpose of this study is to establish whether microfracture or biologics improve the outcomes of ankle distraction. Methods: Records of patients that underwent an ankle distraction procedure between January 2009-December 2013 were retrospectively reviewed. Four groups were identified: Group 1: distraction with no additional treatment, Group 2: distraction with microfracture, Group 3: distraction with microfracture and BMAC/PRP, Group 4: distraction with BMAC/PRP. Demographic data was recorded. Pre-and-postoperative range of motion, Foot and Ankle Outcome Scores (FAOS), complication rate, and return to activity were evaluated. Radiographic images were used to assess the joint space changes pre-operatively and post-operatively. Global comparisons were performed using chi square testing, while individual between-group comparisons were made using robust, resistant regression and Wald tests. Results: Eighty-one patients with a mean age of 47 (range, 37-69) underwent ankle distraction with a mean follow up of 5 years (range, 3-6). All treatment strategies resulted in statistically significant improvements in FAOS (<0.001). Groups that underwent microfracture had a statistically significant decrease in post-operative plantarflexion, dorsiflexion, subtalar inversion and subtalar eversion (p=0.003) as well as an overall decrease in joint space (0.002) with persistence of subchondral bone sclerosis. Patients who underwent distraction with no microfracture treatment resulted in a significant increase in post-operative joint space (p=0.001) and decreased sclerosis in the subchondral bone. Average return to activity was 6 months in patients who received BMAC/PRP with ankle distraction compared to 12 months in patients who were treated with ankle distraction and microfracture (p<0.01). Conclusion: Distraction arthroplasty results in good functional outcomes at medium term follow up. The addition of microfracture seems to create functional outcome deterioration, whereas the addition of a biologic agent either BMAC or PRP appears to benefit earlier return to function. Longer-term studies will be required to see if these effects are sustained.