Spontaneous vacuum phenomenon in the lateral compartment of the knee associated with a lateral tibial plateau fracture.

A case of spontaneous vacuum phenomenon in the lateral compartment of the knee is presented in an 83-year-old woman who attended the Accident and Emergency department two weeks after a twisting injury to the left knee. At the time of examination she still had a marked effusion in the knee with lateral joint line tenderness. X-rays showed a lateral tibial plateau fracture involving the entire lateral condyle and extending into the opposite compartment beneath the intercondylar eminence. The X-rays also demonstrated the presence of gas in the lateral joint line. This is the first reported case of vacuum phenomenon occurring on the same side as a lateral tibial plateau fracture. It is also demonstrated that the phenomenon may occur in the presence of an effusion.