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What causes patellofemoral pain syndrome (PFPS)?

Scott D. Martin, MD
Orthopedic Surgery
Patellofemoral pain (runner's knee) often results from alterations in patellar tracking. Three major factors are involved, although their relative contributions can differ greatly from person to person:

Malalignment. People with a high Q-angle (angle formed by the femur and the line extending from the ankle through the kneecap) are at higher risk, as are people whose arches flatten with each step.

Muscle imbalance and tightness. Tight hamstrings, calves, and hip muscles increase the pressure between the kneecap and the thighbone. Of the four muscles that make up the quadriceps, three pull the kneecap toward the outside; if the innermost quadriceps muscle is relatively weak, this can create tracking problems.

Overuse. Bending the knee moves the patella tighter against the femur. Patellofemoral pain syndrome worsens with activities that put weight on the knee while it is bent, such as squatting or running on steps and hills.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.