Physical Examination Findings in Patellofemoral Syndrome
On examination for patellofemoral syndrome, you will typically find diffuse retropatellar and/or peripatellar tenderness on palpation, pain with resisted knee muscle contraction, pain during squatting, and patellofemoral crepitus 1, 2.
Key Positive Examination Findings
Most Sensitive Individual Tests
The following examination maneuvers demonstrate the highest sensitivity for identifying patellofemoral pain syndrome:
- Eccentric step test (sensitivity 82%): Pain provoked during controlled descent from a step 2
- Patellar palpation (sensitivity 81%): Tenderness along the medial and lateral patellar facets and retinaculum 2, 3
- Prolonged sitting test (sensitivity 73%): Pain after sustained knee flexion (the "theater sign") 2
- Resisted muscle contraction: Pain during isometric quadriceps contraction (positive predictive value 82%) 4
Additional Supportive Findings
Physical examination commonly reveals:
- Patellofemoral crepitus: Grinding sensation with knee flexion/extension 3
- Pain with squatting and stair descent: Particularly descending stairs 2, 4
- Increased Q-angle: Though measurement must follow standardized protocol 5, 6
- Lateral retinacular tenderness: Palpable tightness or pain along lateral patella 3, 6
- Hip muscle weakness: Reduced strength in hip abductors and external rotators 5, 6
- Quadriceps weakness: Particularly vastus medialis obliquus 5
Optimal Diagnostic Approach
The most diagnostically powerful approach combines multiple findings rather than relying on single tests. The strongest combination includes:
- Pain severity 3-10/10 during stair descending test, AND
- Pain severity 6-10/10 during prolonged sitting test
This combination yields a positive likelihood ratio of 19.47 and 95% post-test probability 2.
Alternatively, any two of these three positive findings provides excellent diagnostic accuracy (positive predictive value 89%, LR+ 4.0):
- Pain with resisted muscle contraction
- Pain during squatting
- Pain with palpation 4
Tests with Lower Diagnostic Value
The following tests show low sensitivity (<50%) and should not be relied upon for diagnosis:
Important Clinical Caveats
No single examination maneuver serves as a gold standard for patellofemoral syndrome 6. The reliability of most individual physical examination tests remains low 5, 6, which is why clustering findings is essential for accurate diagnosis.
Plain radiography adds minimal diagnostic value beyond physical examination. While increased patellar subluxation may be present, other radiographic measures (sulcus angle, Laurin angle, Merchant angle, Insall-Salvati index) typically show no significant differences from controls 3.
The diagnosis remains primarily clinical, based on the characteristic presentation of gradual onset diffuse retropatellar/peripatellar pain during patellofemoral joint loading activities (squatting, stair ambulation, running) combined with the examination findings described above 1, 7.