Diagnosis of patellar tendon rupture by emergency ultrasound.

A 46-year-old man presented to the Emergency Department (ED) with left knee pain after being assaulted and landing on a flexed knee. On physical examination, the patient had a large effusion of his left knee and the patella was retracted proximally. He was unable to bear weight on his left leg, range his knee, or hold his leg up against gravity due to pain. The left extremity was neurovascularly intact. X-ray studies of the knee and femur showed infrapatellar soft tissue swelling but no fracture. A disruption of the extensor mechanism of the knee was suspected, but due to patient discomfort, could not be certainly diagnosed. An ultrasound scan was performed by the emergency physician to evaluate for patellar tendon disruption. It demonstrated a hypoechoic area within the proximal patellar tendon that transversed the entire tendon. Dynamic ultrasound performed while the knee was passively flexed showed a separation of the proximal and distal parts of the patellar tendon with anechoic fluid filling the gap. These findings were consistent with a complete patellar tendon rupture, andOrthopedic Surgery was consulted. Surgery was recommended, and in the operating room, the patella tendon was found to be ruptured near the insertion site on the inferior pole of the patella. After surgical repair, the patient was placed