Bilateral PCL hypoplasia resulting in posterior, posterolateral rotatory instability and tears of the lateral meniscus anterior horn.

This article describes a case of bilateral sagged knees presenting as posterior, posterolateral rotatory instability with tears of the anterior horn of the lateral meniscus. Each knee had identical tears of the lateral meniscus anterior horn. A 42-year-old woman reported bilateral anterior knee pain and painful instability during running or jarring exercises. She reported no major trauma to her knees. Arthroscopic findings of her right knee revealed a posterior cruciate ligament that looked hypoplastic but was without acute injury, and the anterior horn of the lateral meniscus showed chronic complex tears with some degeneration. Posterior cruciate ligament reconstruction, posterolateral corner sling, and meniscal repair of the lateral meniscus anterior horn was performed on her right knee. Three months later, a similar operation was performed on her left knee. However, menisectomy was performed because the lateral meniscus anterior horn tear was in the junction of the red-white and white zones. At 18 months postoperatively, the patient reported no symptoms and was satisfied with her results. Physical examination showed no joint line tenderness, and posterior stress radiographs on both knees showed grade I posterior instability. She showed no posterolateral subluxaion by supine dial test, and her prone dial test also improved approximately 15° on both knees. Lysholm score was 74 preoperatively and improved to 92 postoperatively.