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Atraumatic bilateral patellar tendon rupture, A case report and review of the literature.

Traumatic rupture of the patellar tendon is the result of severe overloading of the extensor mechanism of the knee in young, athletic patients. In contrast, prior injection of steroids and a variety of systemic diseases are associated with an increased tendency to rupture with little or no trauma1,2. The rarity of bilateral patellar tendon rupture and the symmetry of the findings on physical examination may cause clinicians to miss the diagnosis.

We report a case of spontaneous bilateral patellar tendon rupture in a patient with systemic lupus erythematosus. The patient was seen twice in the emergency department without the injury being recognized. This case highlights the potential difficulties in diagnosing atraumatic bilateral patellar tendon rupture.

A thirty-year-old woman with a sixteen-year history of systemic lupus erythematosus and recently diagnosed fibromyalgia was brought by ambulance to a local emergency department because of bilateral knee pain and an inability to bear weight on either leg. She was taking prednisone (20 mg/day) on an ongoing basis. She described a sharp pain in the right knee while standing still, which caused her to shift her weight to the left knee. She also reported a twisting sensation in the left knee with subsequent pain, and an inability to bear weight on either leg. Physical examination showed a left knee effusion and an inability to extend either knee, which the examining physician attributed to pain. Radiographs of the left knee showed no fracture (Fig. 1). The patient was diagnosed as having a knee sprain; she was treated with a knee immobilizer bilaterally and was given crutches for walking.



Fig. 1: 
Lateral radiograph of the knee, made at the time of initial presentation, demonstrating patella alta.



Seven days later, the patient returned to the emergency department because of continued inability to walk due to …