Osteonecrosis of the knee after arthroscopic surgery for meniscal tears and chondral lesions.

PURPOSE: Avascular necrosis of the knee following arthroscopic surgery has been described. The purpose of this article is to report a large series of patients who developed avascular necrosis after arthroscopy of the knee in an effort to delineate casual factors and results of treatment. TYPE OF STUDY: Case series. METHODS AND MATERIALS: The charts, radiographs, and magnetic resonance imaging (MRI) scans of patients who developed osteonecrosis (ON) of the knee after routine arthroscopic surgery were reviewed. Only those patients with no evidence of ON on preoperative MRI performed 6 weeks or longer after symptom onset and who postoperatively developed ON confirmed by repeat MRI and/or by pathological testing (specimens obtained at subsequent total knee arthroplasty) were included in the study. Seven patients with average age of 60 years (range, 41 to 79 years) met these inclusion criteria. RESULTS: The lesions noted at arthroscopy included 4 medial meniscus tears, 3 lateral meniscal tears, 6 chondromalacia of the medial femoral condyle, 2 chondromalacia of the medial tibial plateau, 1 chondromalacia of the lateral femoral condyle, 1 chondromalacia of the lateral tibial plateau, and 2 chondromalacia of the patella. The location of postarthroscopy ON correlated geographically with pre-existing pathology. All 7 patients had meniscal and/or chondral lesions addressed surgically in the compartment that subsequently developed ON. Six of the 7 patients had an adjacent ipsilateral meniscus tear treated with partial meniscectomy (4 medial, 2 lateral). In addition, of the 4 patients who developed ON of the medial femoral condyle, all had overlying chondromalacia, 3 of whom were treated with arthroscopic chondroplasty. Of the 2 patients with lateral meniscal tears, 1 developed ON of the lateral femoral condyle and the other developed ON of the lateral tibial plateau. Three patients went on to require total knee arthroplasty, and 2 high tibial osteotomy. One patient's ON resolved and another patient was lost to follow-up. CONCLUSION: ON should be considered in patients who have worsening symptoms after arthroscopy of the knee. These findings suggest a possible relationship between arthroscopic treatment of chondral and meniscal lesions and later appearance of ON in some patients. The role of arthroscopy in the development of ON needs to be further studied. Those at risk are elderly patients with chondral and meniscus lesions.