Arthroscopic microfracture treatment for osteonecrosis of the knee

Purpose: This study evaluated the results of arthroscopic subchondral microfracture performed on patients with spontaneous osteonecrosis (ON) (group 1) or secondary ON (group 2) of the knee joint. Type of Study: Retrospective clinical study. Methods: Group 1 included 26 patients (mean age, 48 years) who had spontaneous ON. Group 2 included 15 patients (mean age, 32 years) with ON secondary to inflammatory disease or steroid therapy. Seventy-six percent of the chondral defects were located in the medial femoral condyle. The average defect sizes in group I was 162 turn 2 and in group 2 was 362 mm(2). After debridement of the necrotic tissues, multiple perforations were placed into the subehondral bone to obtain revascularization. Results: There was an increase in the average Lysholm scores from 57 to 90 in group 1 after 27 months of mean follow-up (P <.05); 71% of patients could participate in strenuous sports with no or minimal limitation. The mean activity level in group 1 according to Cincinnati Knee Rating System was 6 preoperatively and 13.54 postoperatively. For group 2, the average scores showed significant improvement and patient satisfaction after surgery (preoperative and postoperative average Lysholm scores were 41 and 75, respectively, with mean follow-up of 37 months). Average activity level in group 2 increased from 2.67 to 11.73. Control magnetic resonance imaging scans of the cases revealed the continuity of normal cartilage with cartilage-like tissue in the treated areas. However, an increase of the size of ON in the subchondral bone was detected in 27% of the knees. Conclusions: The microftacture technique is safe, simple, and cost-effective, and may be an alternative procedure for treatment of ON of the knee, especially in young patients, before possible subsequent replacement surgery. Level of Evidence: Level IV.