1061 - Ultrasound in Diagnosis of Pathological Musculoskeletal Injuries

Case Diagnosis: Quadriceps tendon rupture with patellar avulsion fracture

Case Description: A 27-year-old female with PMH of osteosarcoma of the right distal femur status-post chemotherapy and fractures of the patella, femur, and tibia, presents with acute right knee pain. She slipped getting off a bus and felt her knee pop after hyperflexion. At baseline, her right knee range of motion is limited to 0-90 degrees of flexion.

On exam, her superior right patella had tenderness, swelling, and ecchymosis with limited range. Radiographs revealed superior patella fracture, with a suspicious vertical line posterior to the patella, concerning for concomitant quadriceps tear. The patient deferred MRI due to surgical hardware and elected for ultrasound, which showed 5cm proximal retraction of the quadriceps tendon from the patella with distal end retracted.

Discussions: Clinical assessment of quadriceps tendon injuries is often inaccurate and delays early operative repair, increasing risk of tendon retraction, fibrosis, and atrophy. Palpation of defects can be limited due to edema, hematomas, and underlying pain. X-rays frequently miss tendon injuries and accessibility of MRI is limited by cost and contraindications, like implanted devices and retained metal.

Ultrasound has been shown to be sensitive and specific in diagnosis of quadriceps tendon tears. It also provides the advantage of low cost, portability, and dynamic evaluation of soft tissues that MRI cannot detect. A complete rupture is diagnosed when tendon fibers are completely separated by a hypoechoic gap. Lack of tendon movement with joint range of motion is another indication of full thickness tear. Patellar avulsion fractures can also be identified as an echogenic structure in the distal retracted tendon.

Conclusions: Point of care ultrasound facilitates the diagnosis of fractures and tendon tears to expedite time to surgery. Sonography is valuable and even advantageous in detecting musculoskeletal injuries, especially when MRI is contraindicated due to medical conditions, devices, or hardware.