Figure 1. Anteroposterior radiograph of the right knee.
Figure 2. Lateral radiograph of the right knee.
A 44-year-old man presents to the office with right knee pain and weakness after sustaining a skiing injury 2 days prior. He was following his son down the slope and jumped off a ski jump. When he landed, his knee went into deep flexion and he felt a pop in his right knee. He was unable to ski down the mountain due to knee pain and weakness.
Anteroposterior and lateral radiographs of the right knee are taken at an urgent care clinic on the day of injury (Figures 1 and 2). On physical examination, he has severe anterior knee pain and is unable to extend his knee.
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The lateral radiograph demonstrates an obvious patella alta or high riding patella. This finding is consistent with a patella tendon rupture. The patella tendon can withstand significant forces during knee motion; for example, the force generated while climbing stairs is approximately 3.2 times a person’s body weight .1 Patella tendon ruptures most commonly occur in patients less than 40 years of age during an activity that causes sudden contraction of the quadriceps muscles by the flexed knee.1
Patients who are taking chronic oral corticosteroids and have a history of patella tendinitis are at increased risk for tendon rupture.1 In one study, 97% of tendon ruptures had a degenerative pathologic finding such as hypoxic tendinopathy, mucoid degeneration, tendolipomatosis, and calcifying tendinopathy.1 The tendon most commonly tears at the inferior pole of the patella.2
Most patella tendon ruptures can be diagnosed with a careful physical examination and radiographic finding; magnetic resonance imaging is only used if the diagnosis is unclear.2
Treatment of patella tendon rupture requires timely surgical repair within 2 weeks of injury. Physical rehabilitation after primary repair includes touch-down weight-bearing for 6 weeks with a gradual increase in weight-bearing when quadriceps strength returns.1 The prognosis after a timely surgical repair is excellent; most patients have a complete return of knee range of motion and strength.2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Matava MJ. Patellar tendon ruptures. J Am Acad Orthop Surg. 1996;4(6):287-296. doi:10.5435/00124635-199611000-00001
2. Watts E. Patella tendon rupture. OrthoBullets. Updated September 28, 2018. Accessed March 23, 2021. https://www.orthobullets.com/knee-and-sports/3024/patella-tendon-rupture.