Midterm Clinical and Radiological Outcome After Autologous Matrix-induced Chondrogenesis (AMIC) for Osteochondral Lesions of the Talus

Abstract

Category: Ankle Introduction/Purpose: Autologous matrix-induced chondrogenesis (AMIC) has recently become an interesting treatment option for osteochondral lesions of the talus since it combines safety and efficacy with overcoming several drawbacks of other surgical techniques. With AMIC, donor side morbidity of osteochondral autografts is eliminated, two-step procedures like matrix-induced autologous chondrocyte implantation are minimized to a more cost-effective single step and restrictions due to limited availability of osteochondral allografts are resolved. The purpose of this study was to evaluate the therapeutic efficacy of AMIC by analyzing AMIC-repaired osteochondral talar lesions in consecutively treated patients after a minimum follow-up of 2 years. Methods: All patients with an osteochondral lesion of the talus treated with the AMIC technique completing a minimum follow-up of 2 years were enrolled in the study for clinical and radiological follow-up. Patients with additional procedures such as lateral ligament reconstruction or corrective calcaneal osteotomy were excluded. 31 of the 47 eligible patients (28 males, 13 females; mean age at surgery 35.7 (range, 13-75) years); body mass index 27.1+-4.7 kg/m2) could be retrospectively evaluated after a mean follow-up of 4.6 (range, 2.3-7.9) years. The preoperative defect size was 0.9+-0.5 (range 0.4-2.3) cm2. Only two osteochondral lesions were localized laterally. Data analysis included general demographics, the visual analogue scale (VAS) for pain, the American Orthopaedic Foot and Ankle Society (AOFAS) score for ankle function, the Tegner Score for sports activity, and the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring system for radiological evaluation. Results: The VAS improved significantly from 6.5+-2.0 preoperatively to 1.5+-2.2 at follow-up (p<0.001). The mean AOFAS score was 93.0+-8.2 (range, 74-100) points. The sports activity level improved significantly from 3.5+-1.8 points preoperatively to 4.9+-1.8 points at follow-up (p<0.001), but 29% did not reach their pre-injury level of activity. The MOCART score averaged 61.5+-21.2 (range, 0-95) points. Complete filling of the defect was seen in 41%, hypertrophy of the cartilage layer in 53%. Normal or nearly normal signal intensity was detected in 67%. All patients showed subchondral bone edema or cysts. The MRI findings did not correlate with the clinical outcome. 91% were satisfied with the outcome and would undergo the same procedure again. Conclusion: AMIC is a reliable procedure to treat osteochondral lesions of the talus. Significant pain reduction and high ankle function were observed after a mean midterm follow-up of 4.5 years. MRI findings did not reflect the good clinical results and therefore should only be performed to rule out other pathologies that might cause persistent symptoms.