IS Case 357: Quadriceps rupture with displaced patella fracture

Wade Hedegard, MD

2009 URMC Imaging Sciences
Publication Date: 2010-03-01


Patient is a 73-year-old male with knee pain after a fall.


Lateral view of the right knee shows obliteration of the quadriceps tendon shadow with a suprapatellar soft tissue mass-like density. There is also a severely displaced avulsion fracture of the superior patella and corresponding patella baja.


Quadriceps rupture with displaced patella fracture


Rupture of the quadriceps tendon is a rare injury that usually occur in adult patients greater than 40 years of age. The quadriceps muscle group consists of four muscles that serve as the primary extensors of the knee: the vastus medialis, vastus lateralis, vastus intermedius, and rectus femoris. Quadriceps tendon rupture is often due to a rapid, eccentric contraction of the quadriceps muscles. There may also be an associated patellar fracture. Tendon rupture usually occurs when the patient falls with their foot planted and the knee partially flexed. Other possible mechanisms of injury include direct blows, lacerations, and iatrogenic causes. Tendon rupture almost universally occurs in a pathologic abnormal tendon. The tendon may be weakened due to systemic diseases, such as diabetes or chronic renal failure, or due to medications such as steroids. Additionally the tendon may be abnormal due to prior degenerative changes in the knee extensor mechanism. Patients who sustain a quadriceps rupture typically present with acute knee pain, swelling, and functional loss of knee motion. Early diagnosis and repair of complete quadriceps ruptures is essential to ensure restoration of function. If intervention is delayed, repair is more difficult and results may be compromised. The diagnosis may be made by plain x-ray, ultrasonography or MRI. MRI is the imaging study of choice if there is any doubt about the diagnosis.


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