Purpose - Autologous chondrocyte implantation (ACI) for treating talar osteochondral defects has given successful results in the short-term. This study aimed to assess survival and functional outcome of chondrocyte implantation techniques at medium to long term follow-up and find predictors of survival.
Methods and Materials -We reviewed the survival until fusion or ankle replacement and functional outcomes of all 63 patients with osteochondral defects (OCD) of the talus managed with three generations of ACI at our Institution between June 1998 and October 2012. Survival was assessed using Kaplan-Meier survival analysis and predictors determined using penalised Cox proportional hazard models. Baseline and followup functional outcome were assessed using the Mazur and AOFAS score and analysed using multilevel models.
Results - The patients (41 male and 22 female) had a mean age of 35.2±10.2SD years at treatment and mean follow-up was 6.3 years (range 1.5-14.6). Mean ankle score increased from 52.6 (95%CI 47.9 to 57.3) preoperatively to 66.9 (95%CI 61.5 to 72.3) at one year (p<0.001), with no evidence of further change (p=0.11). Twelve patients needed ankle fusion or replacement, giving an overall survival of 70% at 10 years and 31% at 15 years (Fig. 1). A bone cyst, no defect on the tibia, no previous surgery and a higher baseline ankle score were associated with lower hazard rates. A prediction model based on these four risk factors had an optimism-corrected concordance of 0.72 and distinguishing four risk levels (0-3) that governed survival until fusion or replacement in our patients.
Conclusion - The results of our study suggest the medium-long term results of ACI for talar osteochondral lesions can be favourable, but that patient selection is important in achieving these results. We produced a risk score that will help patients and surgeons when planning treatment.