Multiple Epiphyseal Dysplasia With Knee Joint Locking Symptoms Caused by Intra-articular Loose Bodies.

Multiple epiphyseal dysplasia (MED) is a congenital disease causing epiphyseal dysplasia in long bones. Herein, we report a case of a middle-aged man with bilateral knee joint locking symptoms who was diagnosed with multiple epiphyseal dysplasia caused by Matrilin-3 (MATN3) pathogenic variants and was successfully treated with arthroscopic loose body removal. A 48-year-old man has had bilateral knee pain since his twenties and underwent loose body removal of both knees in his thirties. He visited our hospital for worsening locking symptoms in both knees. Twenty years ago, his son had been diagnosed with suspected multiple epiphyseal dysplasia. Genetic and imaging testing confirmed his diagnosis of multiple epiphyseal dysplasia due to Matrilin-3 pathogenic variants. Arthroscopic loose body removal was performed, and the locking symptoms disappeared after surgery. Arthroscopic loose body removal was effective for the locking symptoms in a mild adult case of multiple epiphyseal dysplasias caused by Matrilin-3 pathogenic variants.