T2-mapping at 3 T after microfracture in the treatment of osteochondral defects of the talus at an average follow-up of 8 years.

PURPOSE: To compare repaired cartilage with native cartilage, and inter-observer reliability, using T2 mapping at 3 T for assessing cartilage repair in osteochondral defects of the talus after the microfracture technique. METHODS: We enrolled eight females and seven males undergoing arthroscopic microfracture for osteochondral defects of the talus at an average follow-up of 7.9 ± 2.2 years (range 5-13 years). Cartilage tissue was assessed using a 3-T magnetic resonance imaging unit with an 8-channel phased array foot and ankle coil (gradient strength, 50 mT/m; slew rate, 200 T/m/s). T2 maps were then calculated. Three independent boarded specialists evaluated the images, and magnetic resonance observation of cartilage repair tissue scores was used to assess the cartilage and joint status. Clinical results were assessed using the Hannover Scoring System (HSS) for the ankle and the American Orthopaedic Foot and Ankle Society (AOFAS) hind-foot score. RESULTS: No significant mean differences were found between the T2 properties of the repair tissue and those of the native reference cartilage (T2 = 38.6 ± 5.3 ms, range 30.2-55.8 ms vs. 40.3 ± 8.5 ms, range 31.4-59.8 ms, respectively; intra-class correlation coefficient = 0.94; confidence interval 0.84-0.99, P ≤ 0.001). Despite ≥50 % defect filling in all patients, subchondral bone changes were considerable. The HSS at the follow-up revealed a mean score of 87 ± 12 (range 51-97), and the AOFAS-Score was 90 ± 13 (range 59-100). CONCLUSIONS: 3 T T2 maps were similar in repaired and native cartilage with good inter-observer reliability. LEVEL OF EVIDENCE: IV.

Repair of retropatellar cartilage defects in the knee with microfracture and a cell-free polymer-based implant.

INTRODUCTION: To analyze magnetic resonance imaging (MRI) at 3T and the clinical outcome in a short-term pilot study after treatment of retropatellar cartilage defects with microfracturing and subsequent covering with the cell-free chondrotissue(®) polyglycolic acid-hyaluronan implant. METHODS: Five consecutive patients after microfracturing and defect coverage with the chondrotissue(®) implant immersed with autologous serum were included. After a mean follow-up of 21 months (range 11-31 months), defect fill and repair tissue quality was assessed by 3-T MRI followed by applying established MRI scoring systems. The patients' situation was assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS) and a patients' satisfaction questionnaire. RESULTS: Magnetic resonance imaging showed good to excellent defect fill with complete integration. The mean MOCART score was 61 (range 50-75) points. The mean Henderson score was 7 (range 6-9) points. All patients showed subchondral bone alterations. The KOOS showed good values in all sub-categories in 4 out of 5 patients and a mean overall score of 73 (range 40-90) points. Two patients rated the outcome as excellent, two as good and one as fair. All patients would have the procedure again and recommend it. CONCLUSIONS: In this small case series, the coverage of symptomatic retropatellar cartilage defects with the chondrotissue(®) implant after microfracturing was safe and feasible with improvement of the patients' situation at short-term follow-up. LEVEL OF EVIDENCE: IV, case series.