Morphological Changes in the Residual Meniscus After Reshaping Surgery for a Discoid Lateral Meniscus

Background: Arthroscopic reshaping surgery is the first treatment option for a symptomatic discoid lateral meniscus (DLM) to preserve the peripheral rim. However, the degree of postoperative morphological change in the residual meniscus is unclear. Purpose/Hypothesis: The purpose of this study was to measure the meniscus after reshaping surgery for a DLM, to verify when the morphological change occurred, and to examine the related risk factors. The hypothesis was that the residual meniscal width would decrease throughout the postoperative course. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively reviewed the medical records of patients who underwent reshaping surgery for a symptomatic DLM and had undergone follow-up for ≥2 years. Magnetic resonance imaging (MRI) was routinely performed preoperatively and at 3, 6, 12, and 24 months postoperatively, and the width, height, and extrusion of the residual meniscus were measured. According to the width of the midbody on final MRI scans, we compared the preoperative and postoperative data for the preserved group (≥5 mm) and decreased group (