Correlation Second-Look Arthroscopy and Magnetic Resonance Image after Arthroscopic Microfracture for Osteochondral Lesions of the Talus

Category: Ankle; Arthroscopy Introduction/Purpose: Arthroscopic microfracture is a commonly used surgical technique for treating osteochondral lesions of the talus. Long-term clinical outcomes have generally been found satisfactory. However, there are few studies that accurately evaluate the quality of cartilage repair after microfracture and its relationship with clinical outcomes. The purpose of this study is to analyze the status of cartilage repair after microfracture using second-look arthroscopy and magnetic resonance imaging (MRI), and compare it with clinical outcomes. Methods: Fifty patients underwent second-look arthroscopy and magnetic resonance imaging (MRI) 12.4 months after microfracture (range, 6-19 months). The MRI performed prior to the second-look arthroscopy was evaluated using the magnetic resonance observation of cartilage repair tissue (MOCART) score. Clinical outcomes were assessed using the Foot and Ankle Outcome Score (FAOS), the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale, and the Short Form-36 (SF-36) score. Results: In second-look arthroscopy, 13 ankles (39%) exhibited abnormal findings according to ICRS overall repair grades. The postoperative MOCART score was 74.2 (range, 25 to 95). 16 patients (32%) had a mismatch between the MRI and second-look arthroscopic findings. All functional score including FAOS, AOFAS and SF-36 were improved between the preoperative and last follow-up evaluation (p < 0.001). The mean postoperative FAOS scores were 88.8 for grade-I and II ankles (n=37) and 82.9 for grade-III and IV ankles (n=13). There was good correlation between FAOS scores and ICRS grades (p = 0.018). The analysis of the correlation between postoperative FAOS and factors for MOCART evaluation showed that the degree of defect infill (p < 0.001) and subchondral bone (p=0.014) had statistical significance. Conclusion: The second-look arthroscopic evaluation conducted 12.4 months after arthroscopic microfracture indicated incomplete healing in 39% of the lesions. A 32% mismatch between second-look arthroscopy and MRI highlights the challenge for MRI in precisely depicting cartilage repair. Nonetheless, even in the presence of this mismatch, clinical outcomes are predicted to be unfavorable when inadequate cartilage defect infill or the existence of subchondral bone edema is observed on MRI.