Evaluation of regenerated cartilage using T2 mapping methods after opening-wedge high tibial osteotomy with microfracture at the cartilage defect: a preliminary study

Abstract Purpose This study evaluated the regenerated cartilage after opening-wedge high tibial osteotomy (OWHTO) with concomitant microfracture by second-look arthroscopy, Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score and magnetic resonance imaging (MRI) T2 mapping. It was hypothesised that cartilage regeneration can be achieved by HTO, but the quality of regenerated cartilage is not normal cartilage. Methods OWHTO was performed in eight knees of seven patients (mean age, 57.6 ± 5.2 years). Microfracture for the cartilage defect was performed followed by OWHTO, and second-look arthroscopy was performed at the time of plate removal (14.1 ± 4.5 months after OWHTO). MRI was assessed at three months and one year after surgery. The status of articular cartilage regeneration was assessed by the ICRS grade, MOCART score and T2 value. Results The number of subjects in ICRS grade 1/2/3/4 changed significantly from 0/0/4/4 preoperatively to 0/2/6/0 postoperatively in the medial femoral condyle (MFC) (P < 0.05) and 0/0/0/8 preoperatively to 0/0/7/1 postoperatively in the medial tibial plateau (MTP) (P < 0.05). Mean MOCART scores for MFC and MTP at one year after surgery exhibited significant increases compared with the results at three months after surgery. Mean T2 values for MFC and MTP did not differ at three months and one year after surgery. Conclusion The appearance and morphological evaluation by ICRS grade and MOCART score of regenerated cartilage were improved after OWHTO with concomitant microfracture. However, there were no significant qualitative differences in T2 values. This suggests that the regenerated cartilage tissue was likely to be insufficient cartilage. Level of evidence Level IV, therapeutic case series