Patellar Tendon Rupture

This week's image of the week is brought to us by Dr. Sierra Beck.

The patient, a 47 year old man, came to the ED at GMH with a chief complaint of lower extremity weakness, unsteady gait, and limited mobility. The patient fell onto his knees approximately 4 weeks prior, went to a local ER due to the pain, and was sent home after normal radiographs. For the past few weeks he had difficulty walking and was using a wheelchair to get around. Physical exam showed preserved bilateral lower extremity strength with exception of severely limited right knee extension. Using bedside ultrasound, Dr. Beck confirmed her suspicion – a patellar tendon rupture.

The superficial location makes sonographic identification of the patellar tendon rather straightforward.  The patient's knee should be in approximately 30 degrees of flexion.  Place the linear probe longitudinally on the patient's knee between the patella and the tibial tuberosity with the indicator towards head.  Identify the hyperechoic patella and tibial tuberosity.  Between the boney structures, the normal tendon appears as a bundle of longitudinal parallel hyperechoic lines which create a characteristic fibrillar pattern.

NORMAL Left Patellar Tendon 

Real time passive knee extension under direct visualization may also help confirm visualization of the tendon.

In the setting of patellar tendon rupture, localized edema and inflammation occur. 

Right Patellar Tendon RUPTURE

Note the complete loss of the fibrillar architecture of the tendon and the significant edema compared to the first image. You can also appreciate the proximal and distal ends of the tendon highlighted by the yellow arrows. The patient was placed in a long leg brace, given crutches, and referred to orthopedics for definitive management.