Symptomatic dislocation of the anterior horn of the medial meniscus.

Anteromedial joint line pain of the knee represents both a diagnostic and therapeutic challenge. Dislocation of the anterior horn of the medial meniscus as a cause of anteromedial joint line pain is uncommon. O'Connor has reported this finding on internal and external rotation of the tibia during arthroscopy and Dashefsky has demonstrated a shadow sign associated with dislocating anterior horns. We have noted these findings plus anteromedial femoral condylar articular erosion associated with persistent anteromedial joint line pain in 13 patients. All 13 patients had persistent anteromedial joint line tenderness on physical examination present from 3 months to 3 years prior to surgery. Six of the 13 patients had a click in the knee with activity and only 4 of the 13 patients reported "giving away" episodes. Arthroscopic examination demonstrated a complete anterior horn dislocation of the medial meniscus as described by O'Connor and Dashefsky as well as degeneration of the anteromedial femoral condyle. Definitive treatment was performed in the 13 patients after arthroscopic confirmation of the diagnosis of dislocating anterior horn of the medial meniscus. The first four patients had traditional medial meniscectomies, the next four patients had repair of the anterior horn, and the last five patients had partial resection of the meniscus through the arthroscope. Excellent results occurred in three of four patients with repair of the anterior horn, and four of five patients with partial resection through the arthroscope. The one failure of repair subsequently underwent a complete medial meniscectomy with an excellent result.(ABSTRACT TRUNCATED AT 250 WORDS)