Arthroscopic Treatment of Symptomatic Discoid Meniscus in Children: Classification, Technique, and Results

Purpose: The purpose of this study was to review the operative results of children and young adults treated arthroscopically for symptomatic discoid lateral menisci. Methods: The medical records and radiographic studies of 27 consecutive patients (30 knees) who underwent arthroscopic treatment for symptomatic discoid meniscus between 1998 and 2002 were reviewed. Results: The mean patient age was 10.1 years (range, 3 to 20 years), with 19 female and 8 male patients. The mean duration of symptoms before surgery was 13.9 months, with 28 knees (93%) having pain and 20 knees (67%) having mechanical symptoms. All patients were treated arthroscopically. Arthroscopic saucerization was successful in 28 of 30 knees. In 2 cases with large complex tears meniscal salvage was not possible and a complete arthroscopic meniscectomy was performed. Operative classification of the menisci revealed 22 complete (4 Wrisberg type) and 8 incomplete discoid menisci, with meniscal tears being present in 23 of 30 (77%). Meniscal instability was noted in 77% of knees (23 of 30), with anterior horn instability in 53% (n = 16), posterior instability in 16% (n = 5), and combined anterior and posterior instability in 6% (n = 2). All cases of anterior horn instability were treated with an outside-in arthroscopic repair technique, whereas all cases of posterior horn instability were treated with meniscal repair via an inside-out arthroscopic technique. Twenty-one patients (23 knees) had full follow-up of greater than 1 year. For these 21 patients, the mean length of follow-up was 37.4 months (range, 12 to 77 months), and at final follow-up, all patients exhibited full knee flexion beyond 135°. Three patients reported residual knee pain, and four reported intermittent mechanical symptoms. At final follow-up, 2 patients felt that their activity level remained partially limited. Conclusions: Our results show the short-term efficacy of arthroscopic saucerization and repair to the capsule in selected cases of symptomatic discoid menisci. On the basis of this experience and other recent reports documenting a high rate of anterior horn instability, an arthroscopic classification system for discoid lateral menisci is proposed. Menisci are classified as complete or incomplete discoid and are then subclassified based on the presence of instability as a result of deficient capsular attachment and, finally, based on the location of the absent capsular attachment. Level of Evidence: Level IV, therapeutic case series.