Bilateral discoid medial Meniscus: Two case reports

RATIONALE: Discoid meniscus is an anatomical congenital anomaly more often found in the lateral meniscus. A discoid medial meniscus is a very rare anomaly, and it is difficult to diagnose a bilateral discoid medial meniscus because not all the discoid medial menisci are symptomatic. Herein, we report 2 cases of bilateral discoid medial meniscus. PATIENTS CONCERNS: Case1: a 23-year-old man presented with complaints of pain and occasional clicking of the right knee for 6 years, the left knee was asymptomatic. Case 2: a 51-year-old woman had a 1-month history of pain and a feeling of “giving away” in both knees. DIAGNOSES: Based on physical examination and magnetic resonance imaging (MRI) findings, they were diagnosed with bilateral discoid medial meniscal tears. INTERVENTIONS: Case 1: partial meniscectomy and reshaping were performed for the torn discoid medial meniscus of the right knee only. Case 2: partial medial meniscectomy and reshaping were performed for the torn discoid medial meniscus on both knees. OUTCOMES: The postoperative pain and the recovery of joint function were observed. The average follow-up time of 2 patients was 1 year. The Lysholm score of 2 patients was improved from 55 to 95 and 40 to 90 respectively. The pain of knee joint was relieved and the symptoms of disharmony were obviously improved. LESSONS: We recommend preservation of the discoid medial meniscus in asymptomatic patients. Meniscectomy and reshaping for injured discoid medial meniscus produces promising short-term results.