What is your suspected diagnosis?

Quad tendon rupture. 

• Pearl: Quad tendon ruptures are often missed in the ED and are more common in older patients

What is your initial workup in the ED?

Unassisted straight leg raise: If a patient cannot lift their lower leg off the bed while lying flat there may be a failure of the extensor mechanism, such as from a patellar or quad tendon rupture, or patellar fracture.

What imaging confirms the diagnosis?

A quad tendon rupture is largely a clinical diagnosis, supported by a palpable defect in the tendon with inability to extend the lower leg at the knee. Bedside ultrasound can help confirm the diagnosis. 

What is your management and disposition?

Imaging is not necessary to make the diagnosis of quad tendon rupture. If the diagnosis is in question, ultrasound (Image 1)  or MRI (Image 2) can be used to confirm the diagnosis. MRI can be obtained on an outpatient basis. 

Image 2: MRI of the R knee demonstrating an acute tear of the quadriceps tendon with retraction. Robert Lystrup's images.

What is your management and disposition?

Patients with complete disruption of the quadriceps tendon should be made non-weight-bearing, splinted in knee extension, and referred to orthopedics within 1-3 days. Due to the powerful retractive forces of the quadriceps muscles, any operative intervention should be performed as quickly as possible [1].