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Figure 1: Anteroposterior radiograph of the knee. Figure 2: Lateral image of the knee.
A 57-year-old man presents to the emergency department (ED) with right knee pain after slipping on ice earlier in the day. During the fall, the patient’s knee went into flexion and he felt a pop as he fell. Since the fall, he has not been able to put weight on or extend the leg. He reports that he has never injured the knee before. Anteroposterior and lateral radiographs of the right knee demonstrate a low-riding patella with a superior pole avulsion (Figures 1 and 2). On physical examination, there is mild swelling of the right knee area without obvious deformity and he is unable to perform a straight leg raise.
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The patient has disrupted the extensor mechanism of his knee, demonstrated by his inability to perform a straight leg raise. The radiographs show a low-riding patella (patella baja), which indicates a complete quadriceps tendon rupture.
Quadriceps tendon ruptures occur almost exclusively in men older than 40 years of age.1 Quadriceps tendon ruptures are usually obvious clinically. The presence of a palpable defect in the tendon near the patella insertion (suprapatellar gap), the inability to perform a straight leg raise, and the presence of patella baja on radiographs are all features of a quadriceps tendon rupture.1
Ordering additional imaging studies, such as an MRI, is only necessary if the diagnosis remains unclear or to differentiate between a partial and complete tear.2
Acute complete quadriceps tears are treated surgically with repair and reattachment of the tendon to the patella. Patients should be treated surgically within a week of injury, and ideally within 72 hours.1 After 72 hours, tendon retraction may occur, making the repair more difficult; a graft may be needed to fill the suprapatellar gap.1,2
The most appropriate initial treatment in the ED is to place the injured extremity in a knee immobilizer with instructions for the patient to put weight on the leg as tolerated with crutches.2 Incomplete ruptures can be managed with the knee immobilizer for 6 weeks followed by protected range-of-motion and strengthening exercises.1 For complete tendon tears, it is critical to instruct the patient to follow up with an orthopedic surgeon within 1 to 2 days to ensure a timely repair.1,2
References
1. Ilan DI, Tejwani N, Keschner M, Leibman M. Quadriceps tendon rupture. J Am Acad Orthop Surg. 2003;11(3):192-200. doi:10.5435/00124635-200305000-00006.
2. McKean J. Quadriceps rupture. Ortho Bullets. Accessed February 28, 2021. https://www.orthobullets.com/knee-and-sports/3023/quadriceps-tendon-rupture
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