Bilaterally Simultaneous Medial and Lateral Discoid Menisci

Abstract

Most discoid menisci are lateral and medial discoid meniscus is very rare. Several articles have reported on bilateral lateral discoid menisci as well as bilateral medial discoid menisci, and a few articles have reported simultaneous medial and lateral discoid menisci in the same knee. Only one case of simultaneous medial and lateral discoid menisci, bilaterally, has been reported. We present another case of a male patient with bilaterally simultaneous medial and lateral discoid menisci, diagnosed with magnetic resonance imaging and arthroscopy. The patient was treated by arthroscopic partial meniscetomy.Key words: meniscus, bilateral discoid meniscus, meniscectomy, magnetic resonance image CASE REPORTA 22-year-old male patient complained of pain and swelling on his left knee for three months with no precipitating traumatic event.From the medical history, he had undergone arthroscopic partial meniscectomy of contralateral knee at the age of 15-year-old in our hospital. He was diagnosed as having a complete medial discoid meniscus with horizontal tear and intact incomplete lateral discoid meniscus ( Fig. 1, 2). The patient was treated by arthroscopic partial meniscectomy for both medial and lateral menisci. And he had no complaint about the right knee.On physical examination, the patient had medial joint line tenderness and had pain on medial side in McMurray's test. A mild degree of effusion was found. Full range of motion was possible without any mechanical symptoms. No abnormalities were detected with simple radiographs. MRI of left knee showed both discoid medial and lateral menisci. Medial meniscus had horizontal tear and lateral meniscus had no tear (Fig. 3).At Arthroscopy, a complete discoid medial meniscus with horizontal tear in the body and intact complete discoid lateral meniscus were found (Fig. 4). Lateral discoid meniscus didn't have hypermobility or impingement. Partial meniscectomy of medial meniscus was performed. At the follow-up one year for left knee and seven years for right knee postoperatively, the patient was asymptomatic in left knee and also in right knee. Preoperative Lysholm score of left knee was 68 but right knee had no record. At the last followup, Lysholm score of left knee was 97 and right knee was 94. The radiologic findings had no definite interval changes including alignment of lower limb and gaps of both medial and lateral joint space. DISCUSSIONThe incidence of discoid lateral menisci ranges from 1.5% to 15.5% and the highest incidence rate of discoid medial menisci reported is 0.3%. 5) Jeannopoulos 3) reported the first case of simultaneous medial and lateral discoid meniscus in the same knee in