Differential Diagnosis of Localized Anterior Knee Pain
| Condition | Typical Findings | Diagnostic Testing |
|---|---|---|
| Bipartite or multipartite patella | Usually asymptomatic | Radiographs, including contralateral for comparison |
| Infrapatellar fat pad syndrome (Hoffa syndrome) | Tenderness below inferior patellar pole, worse with resisted knee extension | Rarely indicated |
| Osgood-Schlatter disease | Localized tibial tubercle tenderness in an adolescent or young adult | Radiographs, compare with contralateral knee |
| Patellar fracture | Localized patellar tenderness or swelling over the anterior knee | Radiographs, including contralateral to rule out multipartite patella |
| Patellar subluxation/dislocation | Apprehension with lateral patellar pressure, abnormal medial/lateral patellar glide | Radiographs if conservative therapy fails or patella is nonreducible |
| Patellar tendonitis (jumper’s knee) | Localized patellar tendon tenderness, worse with resisted knee extension | Rarely, consider MRI for chronic symptoms |
| Patellofemoral pain syndrome (Anterior knee pain syndrome) | Tenderness over patellar body or facets; abnormal patellar tracking, medial/lateral glide, or tilt; increased Q-angle* | Radiographs uncommon; consider if conservative therapy fails |
| Prepatellar bursitis (housemaid’s knee) | Tenderness, erythema, or superficial swelling over patella | Rarely indicated |
| Sinding-Larsen-Johansson disease | Localized inferior patellar pole tenderness in an adolescent or young adult | Radiographs, compare with contralateral knee |
| Tumor | Insidious pain, swelling, or mass over anterior knee; night pain or systemic symptoms | Radiographs; consider MRI or bone scan if radiographs are negative and clinical suspicion is high |
* Q-angle: An approximate measure of patellofemoral alignment. The angle is formed by the intersection of a line from the anterior superior iliac spine to the center of the patella and a line from the tibial tubercle to the center of the patella. A normal q-angle is less than 10° in men and 15° in women.