Quadriceps Injury Workup

Updated: Dec 14, 2022
  • Author: Thomas M DeBerardino, MD, FAAOS, FAOA; Chief Editor: Craig C Young, MD  more...
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Laboratory Studies

Blood studies are not generally indicated when the patient's history is that of overuse or sudden trauma. However, if the history and physical examination findings are suggestive of renal disease, hyperparathyroidism, soft tissue tumor, or diabetes mellitus, the appropriate studies should be sent.

The following are indicated for severe contusions and ill-appearing patients:

  • Creatine kinase

  • Hematocrit

  • Coagulation studies - If patient develops spontaneous edema or is taking anticoagulants


Imaging Studies

Initially, imaging studies may not be indicated in patients with partial rectus tears, minimally symptomatic quadriceps contusions, and mild quadriceps tendinitis. These patients have a history of acute or repetitive trauma, and the history and physical examination findings are consistent with these working diagnoses. For patients in whom the history and physical examination findings are not consistent, for patients with night pain, patients with suspected complete quadriceps rupture, those with significant quadriceps contusion, and in patients where fracture (femur or patellar), metabolic disease, or tumor is suspected, radiography is indicated on the first visit.

For patients with mild tendinitis, mild contusions, and partial rectus tears who do not respond to activity modification, rest, and physical therapy, radiography is indicated on follow-up examination.

In patients with quadriceps contusion, plain radiography may show evidence of myositis ossificans at the site of the contusion several weeks to months after injury.

Patients who have quadriceps tendinitis or partial tears of the rectus tendon may have the radiographic findings of the so-called saw tooth patella along the proximal border of the patella.

Patients with complete rupture of the tendon may have an associated patellar fracture, particularly if the patient fell on the flexed knee at the time of the injury. The radiographs in patients with complete rupture show obliteration of the quadriceps tendon shadow, patella baja, and a large effusion. A suprapatellar mass (the retracted quadriceps muscle) or a suprapatellar calcific density may also be present.

If quadriceps tendon rupture is diagnosed clinically, anteroposterior (AP) and lateral views of the knee are the minimum views required. The lateral view shows a low-riding patella, patella baja, due to the unopposed pull of the patellar tendon.

CT scanning is not usually as helpful as MRI.

Ultrasonography is less expensive than the MRI and has a high sensitivity and specificity for complete tears. Its accuracy and predictive value in partial tears is not as good.

MRI has the highest sensitivity and specificity for disorders of the quadriceps. It shows both complete and partial ruptures, soft tissue hematomas, tendinopathies, soft tissue tumors, myositis ossificans, and fascial defects. Incomplete intrasubstance tears of the rectus femoris and complete tears of the rectus femoris and quadriceps tendon are visible as increased signal intensity on the T2 images. Incomplete intrasubstance ruptures of the rectus tendon and the quadriceps tendon image as focal disruptions of the normal laminated appearance of the tendon.

An MRI study by Falkowski et al found that quadriceps femoris tendon tears most often involve the rectus femoris or vastus lateralis/medialis layers, usually in proximity to the patella. Bony avulsion of the patella is correlated with a more extensive tear of the superficial and middle layers of the tendon. [4]


Other Tests

Compartment pressure measurements should be taken if compartment syndrome is suspected in the anterior thigh.