An 11-year-old girl with painful mechanical symptoms in her
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A previously healthy 11-year-old girl presented to the orthopedic clinic with a 6-month history of “popping” when she bends her right knee. This mechanical symptom worsened with time. The “popping” was associated with pain and swelling that prevented her from playing soccer. She had no history of discreet trauma but reported multiple knee buckling episodes of the knee.

Physical exam revealed no malalignment, minimal knee effusion and tenderness along the lateral joint line. She had full range of motion (0° to 130°); however, there was a visible and palpable snapping on the lateral side of the knee. Her ligamentous exam was stable throughout and she had a positive McMurray sign. Radiographs of the knee showed open physes, normal alignment, subtle widening of the lateral joint space and a “squared off” appearance of the lateral tibial plateau. She underwent MRI, which demonstrated findings consistent with a lateral discoid meniscus.

Nonoperative management, meniscectomy, saucerization or meniscal repair are the treatment options. The patient completed a course of physical therapy and, after no significant improvement in symptoms, she underwent arthroscopic surgery to address her discoid meniscus. The lateral meniscus was saucerized and contoured using arthroscopic biters and shavers. The anterior and posterior roots were firmly attached, but the body of the meniscus was pathologically mobile. Using an outside-in approach, the body of the meniscus was stabilized to the joint capsule. The outside-in approach utilizes two percutaneous spinal needles to place vertical mattress stitches in the meniscus.

A small incision is made to tie the vertical mattress stitches over the joint capsule. On intraoperative physical exam, there was no reproducible snapping with flexion of the knee as there was preoperatively. At 2 months postoperatively, the patient was progressing well with physical therapy and denied any recurrent mechanical symptoms, which was confirmed by the intraoperative findings and procedures performed.

A discoid meniscus is a congenital variant involving abnormal morphology, increased size and potential instability of the meniscus. Discoid menisci are more prone to tearing due to abnormal anatomy, including decreased and disorganized collagen fibers and mucoid degeneration resulting in reduced tissue quality, abnormal vascularity, a larger and thicker size leading to impingement between the tibial and femoral surfaces, and occasionally a lack of normal meniscal-capsular attachments.