Patella Alta
A 61-year-old man presented with a 2-hour history of left knee pain and inability to walk after having fallen onto the knee while it was flexed. On physical examination, there was swelling of the left knee and a high-riding patella, a finding known as patella alta (Panel A). The patient was unable to extend the knee. A radiograph of the left knee showed no fractures and confirmed superior displacement of the patella (Panel B; dotted line indicates normal patella position). Patella alta occurs when the patellar tendon ruptures. In contrast, patella baja — a low-lying patella — occurs as a result of a quadriceps tendon rupture. T2-weighted magnetic resonance imaging of the left knee showed discontinuity of the patellar tendon (Panel C, asterisks). The patient underwent surgical repair of a complete proximal patellar tendon rupture. After surgery, the patient completed a physical therapy program. At 6-month follow-up, he was able to walk with some limitation in the range of motion in flexing and extending the left knee.