Longitudinal evaluation of cartilage repair tissue after microfracture using T2-mapping: a case report with arthroscopic and MRI correlation

A man sustained a left knee injury which led to full-thickness chondral defects of the trochlear groove and lateral femoral condyle. Both areas were treated with microfractures and evaluated at 5 months and 2 years with standard MRI scans, T2 relaxation maps, and arthroscopy. At 5-months post-microfracture repair, the patient complained of recurrent anterior knee pain. While standard MRI imaging was inconclusive with regards to a potential recurrent defect at the trochlear groove microfracture area, T2 relaxation maps established the integrity of the surface layer which was confirmed by arthroscopic evaluation. At 2 years, imaging studies revealed repair tissue loss with low T2 values at the trochlear repair site. The failure of the trochlear site and the integrity of the lateral femoral condyle repair sites were confirmed by arthroscopy. This case report is the first one to provide a correlation of T2 mapping MRI findings with arthroscopic confirmation in the context of microfracture repairs. The study provides evidence for the clinical utility of T2 relaxation maps for the postoperative assessment of microfractures and raises the potential for T2 mapping MRI as a tool to evaluate these repair procedures.