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Patellofemoral joint kinetics while squatting with and without an external load
David A Wallace1, George J Salem, Ruben Salinas
1Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles 90089-9006, USA.
The Journal of Orthopaedic and Sports Physical Therapy
|April 13, 2002
Summary
Squatting increases patellofemoral joint stress with deeper knee flexion and external loads. Clinicians should limit flexion angles and loads to reduce stress during rehabilitation exercises.
Area of Science:
- Biomechanics
- Orthopedics
- Sports Medicine
Background:
- Squatting depth in rehabilitation is often limited to avoid high joint forces.
- Objective criteria for safe squatting ranges of motion are lacking.
Purpose of the Study:
- To quantify patellofemoral joint reaction forces and stress during squatting.
- To compare forces and stress with and without external loads.
Main Methods:
- Fifteen healthy adults performed squats to 90 degrees knee flexion with and without 35% body weight load.
- Knee extensor moments, patellofemoral forces, and stress were calculated using 3D kinematics and ground reaction forces.
Main Results:
- Patellofemoral joint forces and stress increased significantly with knee flexion angle in both loaded and unloaded conditions.
- Peak forces and stress occurred at 90 degrees of knee flexion.
- External loads significantly increased patellofemoral joint stress at various flexion angles.
Conclusions:
- Squatting increases patellofemoral joint stress with greater knee flexion and external loads.
- Limiting terminal flexion angles and resistance loads may reduce patellofemoral joint stress.