Factors affecting the outcome of osteochondral autografting (mosaicplasty) in articular cartilage defects of the knee joint: retrospective analysis of 152 cases

Abstract

The purpose of this retrospective study was to evaluate the results and prognostic factors affecting the outcome of osteochondral autografting (mosaicplasty) in articular cartilage defects of the knee joint. One hundred fifty-two patients who underwent mosaicplasty for femoral condylar cartilage defects (modified Outerbridge classification: Grade III and IV) of the knee joint between 1998 and 2007 in our institution were included. There were 126 male and 26 female patients with a mean age of 24.8±4.6years. The average size of the lesion was 2.7±0.7cm(2). Of these patients, 33 had concomitant meniscal and/or cruciate ligament injuries which were treated simultaneously. All patients were followed up with a mean of 18.2±4.2months (range 12-24months) using Lysholm knee score. We analyzed the relationship between the outcome variable (Lysholm knee score at the final follow-up) and the predictor variables (age, gender, lesion size, lesion grade, localization, accompanying intra-articular injuries and duration of follow-up). The mean preoperative Lysholm knee score was 55.2±3.6 points and increased to 88.2±2.5 points at the final follow-up. There was a significant increase in Lysholm score during follow-up period (p=0.0001). The results were excellent in 2 cases (1.3%), good in 144 cases (94.7%) and fair in 6 cases (3.9%). No patients had infection, systemic complication and revision surgery. Backward regression analysis showed that age, lesion size, localization and associated intraarticular injuries are the only predictors of the final Lysholm knee score in best fit model (R (2)=0.442, p=0.0001). The linear regression equation was (Lysholm score at final follow-up)=93.4-[0.2 (age of patient)+0.8 (lesion size)+0.9 (localization)+2.8 (presence of associated intraarticular injuries)]. Mosaicplasty is an effective technique for the treatment of articular cartilage defects of the knee joint which restores the joint function in a short period of follow-up. Furthermore, age, lesion size, localization, and concomitant surgical interventions are major factors affecting the final outcome. The final knee score deteriorates as the age of the patient and size of the lesion increases. Furthermore, concomitant surgical interventions and lesions located on the medial femoral condyle have a negative effect on the final knee score.