Due to degeneration of the cartilage underneath the patella
Patients often present with:
A grinding sensation when the knee is extended
Pain in the front of the knee that typically worsens after sitting for a long period of time
Knee pain that worsens with using stairs, running or when needing to bend the knee deeply (i.e.: squats)
Commonly thought to be due to overuse (i.e.: new running program, or marching as in military recruits), but can also be due to anatomic abnormalities like pes planus or a large Q angle. Ultimate cause is likely to be multifactorial
Can be treated with NSAIDs, and limiting activity
Physical Therapy that helps to strengthen the quadriceps can help prevent the patella from grinding on the femoral condyles.
References
Juhn MS et al. Patellofemoral pain syndrome: a review and guidelines for treatment. Am Fam Physician. (1999)
