Patellofemoral Movement in Patellofemoral Pain Syndrome
Yes, the kneecap (patella) moves in patients with patellofemoral pain syndrome (PFPS), but the movement pattern itself is typically normal—the problem lies in the forces and tracking mechanics, not the absence of movement.
Understanding Patellar Movement in PFPS
The patella moves through its normal range of motion during knee flexion and extension in PFPS patients 1, 2. The syndrome results from imbalanced forces acting on the patellofemoral joint rather than restricted patellar mobility 1. Research demonstrates that:
- Patellar motion patterns (spin, tilt, and lateral translation) do not reliably distinguish PFPS patients from healthy controls 3
- The patella may be positioned slightly more laterally (approximately 2.25 mm at 19° of knee flexion) in some PFPS patients with clinical malalignment, but this finding has substantial overlap with normal individuals 3
- Movement dysfunction in PFPS involves abnormal tracking mechanics and force distribution, not absence of movement 1, 4
Clinical Implications for Assessment
When evaluating patellar movement in PFPS:
- Patellar mobility ranges from limited to hypermobile depending on the individual patient 5
- Some patients demonstrate patellar hypermobility as a risk factor 5
- Others show tight lateral restraints that alter tracking mechanics 5
- Weight-bearing axial radiographs demonstrate the degree of patellar tilt or subluxation and provide superior assessment of patellofemoral kinematics compared to clinical examination alone 6
Key Pathophysiological Mechanism
The core problem in PFPS is not that the patella fails to move, but rather how it moves:
- Imbalanced forces during knee flexion and extension lead to increased strain on peripatellar soft tissues and elevated patellofemoral joint stress 1
- Quadriceps weakness, particularly vastus medialis oblique dysfunction, contributes to abnormal patellar tracking 1, 4
- Soft-tissue tightness (especially lateral structures) alters the force vectors acting on the patella 1, 5
Common Clinical Pitfall
Do not assume that pain indicates the patella is "stuck" or immobile. The patella maintains its mobility in PFPS; the issue is the quality and mechanics of that movement, not its presence 3. Treatment focuses on correcting force imbalances through quadriceps strengthening, manual stretching of lateral patellar soft tissues, and patellar taping—all interventions that modify movement quality rather than restore absent movement 1, 7.