Long-term results of abrasion arthroplasty of the medial femoral condyle of the knee for full-thickness chondral defects

Objectives: Abrasion arthroplasty is a technically simple and low cost procedure compared to other treatments for full thickness chondral injury. Nevertheless, there is little data on the long-term outcomes of this procedure. We present our results of medial femoral condyle abrasion arthroplasty, with a minimum 10-year follow-up. To our knowledge, this is the longest follow-up to date for this procedure. Methods: From 3/1990 to 12/2001, 76 consecutive patients (37 male and 39 female) suffering from a full thickness chondral defect of the medial femoral condyle underwent abrasion arthroplasty performed by a single surgeon. The average age of the cohort was 65 yrs (range:24-79,SD 15.44 yrs). Inclusion criteria were having undergone abrasion arthroplasty, with a minimum 10-yr follow-up (mean 16.1 yrs, range 10.2yrs-20.1yrs,SD 3.26). Patients with ligament injuries, multiple compartment involvement, varus angulation >10° and inflammatory arthritis were excluded from the study. Preoperative weight bearing radiographs were obtained in all cases. At final f-u patients completed a questionnaire based on their current knee symptoms and need for further surgery. The questionnaire included the IKDC subjective score and a question regarding medication used for the operated knee. Patients were considered to have a successful result if they had no pain or only occasional pain with activity, no limitation of their activities due to the knee, and had not undergone repeat surgery. Results: 65 patients (85.5%) were available for follow-up (3 patients died and 8 were lost at f-u). Patients with lesions less that 4cm2 (n=30) had a 73% success rate at final f-u. Patients with lesions greater than 4cm2 (n=32) had a 21% success rate which was statistically significant (p< 0.005). The differences in outcome with regard to meniscectomy, as well as the difference in distribution of large lesions between the two patient groups were not statistically significant. Patient's age did not affect outcomes, although there was a trend of poor outcomes associated with age of 50 years or older. The overall re-operation rate was a 31%. Re-operation was on average 6.2 yrs after the arthroscopic procedure. Conclusions: Abrasion arthroplasty aims to seal full thickness chondral defects, avoiding the continued degeneration that is the natural history of such lesions. It is a temporary measure to delay the progression of arthritis. In our series it seems that dimensions of the lesion was crucial for the quality of the result. The procedure is effective in minimizing the progression of symptoms at long-term follow-up for small lesions, regardless of patient age. The trend toward poor outcomes in patients over fifty is likely due to the higher percentage of large or lesions rather than patient age itself. Abrasion arthroplasty should not be performed in patients with chondral lesions larger than 4 cm2.