Knee sprains and acute knee hemarthrosis: misdiagnosis of anterior cruciate ligament tears.

A retrospective study and a prospective study comprising 186 patients with "typical knee sprains" were conducted at the University of Cincinnati Sports Medicine Institute. We concluded that the commonly encountered mild knee sprain may actually be a serious knee injury whose severity is easy to underestimate. Traumatic hemarthrosis indicates a serious knee injury. Arthroscopy showed that a surprising 72 percent of the patients in the prospective study had disruption of the anterior cruciate ligament (partial tear in 28%, complete tear in 44%). In addition of the 72 percent of anterior cruciate ligament tears, associated injuries included meniscus tears (62%), osteochondral fractures or fissures to the joint surface (20%), and other significant ligament disruptions (20%). Any joint effusion within 24 hours of knee injury, no matter how trivial, suggests a need for further diagnostic tests beyond the initial examination. In our study, our clinical examination alone consistently underestimated the extent of injury, resulting in inadequate information for treatment descisions. Conversely, arthroscopy and examination under anesthesia provided information on the extent of injury, allowing an accurate diagnosis and formulation of a rational treatment program.