Post-operative deformation and extrusion of the discoid lateral meniscus following a partial meniscectomy with repair.

PURPOSE: The purpose of this study was to investigate the morphology of the discoid lateral meniscus sequentially following a partial meniscectomy with repair using magnetic resonance imaging (MRI).

METHODS: Nine patients with a symptomatic discoid lateral meniscus with a peripheral tear were enrolled in this study, and a partial meniscectomy with repair was performed arthroscopically. An MRI examination was performed 2 weeks after surgery (before weight bearing was permitted) and again 6 months after surgery (when sporting activities could resume). The width, height and distance of the discoid lateral meniscus were measured. The distance was defined as the distance between the edges of the discoid lateral meniscus and the tibia.

RESULTS: The width of the anterior, middle and posterior segments significantly decreased from 2 weeks to 6 months after surgery. The height of the middle and posterior segments significantly increased from 2 weeks to 6 months after surgery, whereas the height of the anterior segment did not significantly change. The distance of the anterior, middle and posterior segments significantly decreased from 2 weeks to 6 months after surgery.

CONCLUSION: The discoid lateral meniscus exhibited deformation and extrusion from 2 weeks to 6 months after a partial meniscectomy with repair. Therefore, the function of load transmission might not be maintained appropriately after surgery.

LEVEL OF EVIDENCE: IV.