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 Stu dy: Case series. Methods and Materials: The charts, radiographs, and magnet ic resonance imaging (MRI) scans of patients who developed osteonecrosis (O N) of the knee after routine arthroscopic surgery were reviewed. Only those patients with no evidence of ON on preopperative MRI performed 6 weeks or longer after symptom onset and who postoperatively developed ON confirmed b y repeat MRI and/or by pathological testing (specimens obtained at subseque nt total knee arthroplasty) were included in the study. Seven patients with average age of 60 years (range, 41 to 79 years) met these inclusion criter ia. Results: The lesions noted at arthroscopy included ii medial meniscus t ears, 3 lateral meniscal tears, 6 chondromalacia of the medial femoral cond yle, 2 chondromalacia of the medial tibial plateau, 1 chondromalacia of the lateral femoral condyle, 1 chondromalacia of the lateral tibial plateau, a nd 2 chondromalacia of the patella. The location of postarthroscopy ON corr elated geographically with pre-existing pathology. All 7 patients had menis cal and/or chondral lesions addressed surgically in the compartment that su bsequently developed ON. Six of the 7 patients had an adjacent ipsilateral meniscus tear treated with partial meniscectomy (4 medial, 2 lateral). In a ddition, 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 1 patients with lateral meniscal tears, 1 developed O N 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 sugge st a possible relationship between arthroscopic treatment of chondral and m eniscal lesions and later appearance of ON in some patients. The role of ar throscopy in the development of ON needs to be further studied. Those at ri sk are elderly patients with chondral and meniscus lesions.