| Introduction |
 Rare phenomenon only seen in posterior stabilized TKAs
- caused by a fibrous nodule that forms on posterior surface of quadriceps tendon above the superior pole of patella
- Epidemiology
- cause of scar tissue is unknown
- may be cause by direct trauma to quadriceps tendon during patella resection during TKA
- another possible cause is impingement of the quadriceps tendon on the femoral component due to a patellar component that is too small
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| Presentation |
- Symptoms
- patellofemoral knee pain
- complaints of knee "popping" and "catching"
- Physical exam
- painful "pop" or "catch" as knee extends (~40° of flexion)
- suprapatellar fibrous nodule gets stuck in trochlear groove box of femoral component
- with further extension, the fibrous nodule can escape and again cause a palpable or audible clunking
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| Imaging |
- US
- shows suprapatellar fibrous tissue
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| Treatment |
- Operative
- arthroscopic vs open resection of fibrous nodule
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