Focused examination of the patellofemoral joint including assessment of patellar tracking, instability testing, and differentiation of anterior knee pain causes.
Patellofemoral examination assesses tracking, instability, and anterior knee pain. Examiners expect you to recognize the J-sign, perform the apprehension test correctly, and understand the factors contributing to patellar instability (Q-angle, trochlear dysplasia, patella alta).
High-Yield Exam Summary
Patellofemoral Joint:
Stability Factors:
Q-Angle:
With Patient Standing:
With Patient Seated (Legs Over Edge):
Active Range of Motion:
J-Sign: The patella suddenly moves laterally as the knee reaches terminal extension. This indicates:
Bony Landmarks:
Soft Tissues:
Patellofemoral instability
Apprehension (anxiety, grabbing examiner's hand, visible distress) - NOT just pain
History of patellar instability (patient feels patella will dislocate)
Ability to detect true positives
Ability to exclude false positives
Quantify patellar mobility
Lateral translation greater than 3 quadrants = hypermobile. Less than 1 quadrant medially = tight lateral structures
Greater than 3 quadrants lateral = instability risk. Less than 1 medially = tight lateral retinaculum
Ability to detect true positives
Ability to exclude false positives
Confirm patellofemoral instability
Apprehension resolves when patella is stabilized medially
Patellofemoral instability (analogous to shoulder relocation test)
Ability to detect true positives
Ability to exclude false positives
Patellofemoral instability
Apprehension or visible lateral patellar subluxation near terminal extension
Patellofemoral instability
Ability to detect true positives
Ability to exclude false positives
Patellofemoral pain syndrome
Pain with quadriceps contraction
Patellofemoral pathology (articular cartilage damage, chondromalacia). Note: High false positive rate
Ability to detect true positives
Ability to exclude false positives
Clarke's Test Limitations:
Patellofemoral articular pathology
Pain with direct compression
Patellofemoral chondral pathology, osteoarthritis
Ability to detect true positives
Ability to exclude false positives
Functional patellofemoral pain assessment
Anterior knee pain reproduced, dynamic valgus (knee medial to foot)
Patellofemoral pain syndrome, dynamic instability
Ability to detect true positives
Ability to exclude false positives
Q-Angle Measurement:
Patella Alta (High-Riding Patella):
Tibial Tubercle-Trochlear Groove (TT-TG) Distance:
Why Higher Risk:
First-Time Dislocation Assessment:
| condition | presentation | tests | xray |
|---|---|---|---|
| Patellofemoral Instability | Giving way, apprehension | Apprehension +, J-sign | Lateral tilt, subluxation |
| PFPS (Patellofemoral Pain) | Anterior knee pain, stairs | Clarke's may be + | Often normal |
| Chondromalacia Patella | Anterior pain, crepitus | Compression + | May show changes |
| Patella Tendinopathy | Inferior pole pain | Tender at inferior pole | Usually normal |
| Osgood-Schlatter | Tibial tubercle pain (adolescent) | Tender, prominent TT | Fragmented TT |
| Sinding-Larsen-Johansson | Inferior patellar pole pain (adolescent) | Tender inferior pole | Fragmented inferior pole |
"17-year-old female dancer with recurrent left knee giving way and one previous patellar dislocation."
Theatre Sign:
Stair Descent Pain:
Squatting Pain:
High-Yield Exam Summary