An unusual metallic foreign body in the lateral tibiofemoral compartment.

A child presented with pain and swelling of the knee caused by a fall on the snow. Medical imaging showed an unusual metallic foreign body in the lateral tibiofemoral compartment. Arthroscopy revealed the nature of the foreign body; a metallic piece of stone had penetrated skin and cartilage and was fastened in the cartilage of the lateral femoral condyle where it caused damage to the cartilage and the anterior horn of the lateral meniscus. A partial meniscectomy was performed.