Medium-term outcome of mosaicplasty for grade III-IV cartilage defects of the knee.

PURPOSE: To evaluate the medium-term outcome of mosaicplasty for full-thickness cartilage defects of the knee joint in 17 patients.

METHODS

Records of 12 men and 5 women aged 16 to 57 (mean, 35) years who underwent mosaicplasty for grade III/IV osteochondral defects in the lateral (n=14) or medial (n=3) femoral condyle were reviewed. 12 of the patients had undergone knee surgeries. The mean size of the defects was 3.4 (range, 1-4) cm(2). Three patients had defects of >2 cm(2). All operations were performed by a single surgeon using mini-arthrotomy. The lateral edge of the trochlea was the donor site. Graft integration and the presence of any abnormality at the articular surface were assessed using magnetic resonance imaging (MRI). In addition, patients were evaluated using the International Knee Documentation Committee (IKDC) rating scale, the SF-36 health questionnaire, visual analogue scale (VAS) score for pain.

RESULTS

Two of the 17 patients developed necrosis and cystic degeneration of the grafts and underwent conversion to unicompartmental knee arthroplasty within 2 years. They were older than 45 years and had defects of >2 cm(2). Respectively in years 4 and 7, one and 4 patients were lost to follow-up, the mean IKDC score was 75% and 88%, the SF-36 score was 83% and 90%, and the VAS score was ≤3 in 13 of 14 patients at year 4 and in all 11 patients at year 7. At the 7-year follow-up, patient satisfaction with mosaicplasty was excellent in 8 patients, good in 3, and poor in 2 (who underwent unicompartmental knee arthroplasty). At year 4, MRI showed integration of the cartilage repair tissue and incorporation of the osseous portion of the graft into the bone in 13 of the 14 patients. The remaining patient had osteoarthritis at the graft donor site. At year 7, MRI showed good integration of the implant in all 11 available patients, but fissures were seen on the cartilage surface in 3 patients.

CONCLUSION

The medium-term outcome of autologous mosaicplasty for symptomatic osteochondral defects in the femoral condyle is good. Longer follow-up is needed to determine the structural and functional integrity of the graft over time.