Radiological evaluation of cartilage after microfracture treatment: A long-term follow-up study

IntroductionRecent literature revealed good short-term results after microfracturing (MFX) of isolated focal cartilage defects in the knee joint. Study purpose was a long-term evaluation of patients who received MFX through a multimodal approach, correlating clinical scores and morphological pre- and postoperative MRI-scans.Materials and methodsBetween 2000 and 2007 158 patients were treated with MFX for focal femoral or tibial defects at our department. Patients with instabilities, secondary surgical intervention, patellofemoral lesions, a plica mediopatellaris or more than one cartilage defect site and age >55 were excluded. 15 patients were included. Minimum postoperative follow-up (FU) was 18 months (18–78 m). Mean age at surgery was 45 years (27–54), mean FU-interval 48 months (18–78 m). Male to female ratio was 9:6. For clinical assessment the Knee Osteoarthritis Outcome Score (KOOS) and Lysholm Score were used, radiological evaluation was performed with radiographs and 3Tesla-MRI.ResultsClinical knee function was rated good to excellent in 1 patient, fair in 2 and poor in 10 patients. 2/15 patients received full knee replacement due to insufficient cartilage repair through MFX during FU period. Evaluation of pre- and postoperative MRI showed good cartilage repair tissue in 1 (7.7%), moderate repair in 2 (15.4%) and poor fill in 10 patients (76.9%). In these 10 patients the defect size increased. Average defect size preoperatively was 187 mm2 (range 12–800 mm2) and postoperatively 294 mm2 (40–800 mm2). The KOOS-Pain averaged 60 (39–94), KOOS-Symptoms 60.6 (21–100), KOOS-ADL 69 (21–91), KOOS-Sports 35.7 (5–60) and KOOS-QUL 37.2 (6–81). The average Lysholm Score was 73.9 (58–94). 10 patients showed a varus leg axis deviation (Ø 5.9°), 3 had a neutral alignment. The alignment correlated positively with KOOS and especially with the Lysholm Score.ConclusionOur study demonstrated that MFX as a treatment option for cartilage defect in the knee did not show the anticipated clinical and radiological long-term results. In 12 of 15 patients the cartilage defect size had increased after MFX, in 2 patients indicating full-knee replacement. Especially those with a leg malalignment >5° in varus were more prone to suffer from an increase in defect size. In our cohort the clinical scores correlated with the radiological findings.