Case 5: A 15-year-old wrestler injured his knee in practice. He was taking someone down, and as his knee pad got stuck on the mat, he twisted his right knee. He can not fully extend the knee and has pain along the posterolateral joint line along with a small knee effusion.
The meniscus are the shock absorbers that cushion the knee and protect the femur and tibia from being bone on bone. They are C shaped structures that absorb shock with weight bearing activity. Meniscal injuries are not very common in adolescents although may occur after a traumatic twisting injury that may cause other ligament damage. Meniscal injuries cause pain along the posterior joint lines and athletes will have significant discomfort with full flexion or McMurray's testing of the knee. They may be unable to full straighten their knee and have a flexion contracture. Locked knees are orthopedic emergencies and anyone unable to full extend the knee should remain non-weightbearing on crutches. Radiographs are normal. MRIs usually show meniscal damage. Surgical repair or excision is necessary depending on the injury.
Some people are born with a congenital malformation where the meniscus are shaped like discs. Those with a discoid meniscus are predisposed to injuring or tearing the meniscus secondary to increased forces across the meniscus. These athletes may present with recurrent catching, locking, or swelling of the knee after activity or twisting. An MRI can help define a discoid meniscus. Recurrent mechanical symptoms or tears require surgical evaluation.
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