Function
The patella improves the extensor mechanism by increasing the quadriceps moment arm and transmits large reaction forces across the patellofemoral articulation.
Stability
Patellar stability depends on:
- Trochlear morphology
- MPFL and soft-tissue restraints
- Limb alignment and Q-angle
- Patellar height
- Dynamic quadriceps control
Clinical relevance
- Anterior knee pain
- Patellar instability
- Chondral lesions
- Patellofemoral arthritis
Examination
- Alignment and patellar tracking
- Apprehension test
- Crepitus and grind test
- Assess VMO control and lower-limb alignment
Diagram
