Between July 2002 and February 2006, 100 consecutive patients who had a complete lateral discoid meniscus and another 100 patients without a discoid lateral meniscus (control group) were included. Two radiologists retrospectively reviewed all of the magnetic resonance images, paying particular attention to the presence and thickness of the Wrisberg ligament and the location of the attachment of the Wrisberg ligament to the medial femoral condyle (types I, II, or III). We assumed that type I Wrisberg ligaments had a higher location.

All 141 patients had a Wrisberg ligament (71%). There were 73 patients (73%) in the discoid group and 68 patients (68%) in the non-discoid group. The mean thickness of the Wrisberg ligament in the patients in the discoid and non-discoid groups was 2.1 mm (range, 0.4–4.7 mm; median, 2.1 mm) and 1.6 mm (range, 0.4–4.5 mm; median, 1.3 mm), respectively. The Wrisberg ligaments of the discoid group were thicker than the non-discoid group (p = 0.0002). The Wrisberg ligament was attached to the upper part of the medial femoral condyle in the discoid group more often than in the non-discoid group (p < 0.0001).