Review Question - QID 216808

This patients, age, symptoms and radiographic findings of a widened lateral joint space and squaring of the lateral femoral condyle all suggest the diagnosis of a discoid meniscus.

A discoid meniscus is the abnormal development of the meniscus resulting in a hypertrophied and abnormally shaped meniscus. The lateral meniscus is most commonly involved. Patients often become symptomatic during adolescence and report mechanical type symptoms. While MRI is the study of choice, providers will often see radiographic changes suggestive of this diagnosis. These changes include widening of the lateral joint space, squaring of the lateral femoral condyle, cupping of the lateral tibial plateau, and a hypoplastic lateral intercondylar spine. No treatment is necessary for patients who are asymptomatic, however, partial meniscectomy with saucerization is the treatment of choice for those who become symptomatic.

Kocher et al review the diagnosis, management and outcomes of patients with a discoid meniscus. They report that this most commonly occurs to the lateral meniscus and that they're more prone to tearing secondary to increased thickness, poor tissue quality, and instability. They conclude that saucerization of the meniscus, with removal of the central disk and retention of the peripheral crescent is the treatment of choice.

Good et al review the arthroscopic management of symptomatic discoid menisci in children. They report that arthroscopic saucerization was successful in 93% of knees, while the remaining knees necessitated complete meniscectomy for complex tears. They conclude that saucerization provides good clinical outcomes for most patients with a symptomatic discoid meniscus.

Figure A is the AP radiograph of a knee demonstrating characteristics consistent with a discoid meniscus including widening of the lateral joint space and squaring of the lateral femoral condyle.

Incorrect Answers:
Answer 1: While OCD lesions and a discoid meniscus may both present with mechanical symptoms, the radiographs shown are more indicative of a discoid meniscus, making this the more likely diagnosis.
Answer 2: Plica presents more commonly with a snapping sensation and is more common on the medial side of the knee.
Answer 4: Osgood-Schlatter disease is a tibial tubercle apophysitis and presents with pain over the tibial tubercle.
Answer 5: Sinding-Larson-Johansson (SLJ) syndrome is an overuse injury seen in adolescents leading to anterior knee pain at the inferior pole of patella at the proximal patella tendon attachment.