Description

• Pain in or around the patella that increases after prolonged sitting, squatting, kneeling, or ascending/descending stairs
• Synonyms: anterior knee or retropatellar pain syndrome, chondromalacia patella, runner’s knee
• System(s) affected: musculoskeletal

Epidemiology

• Annual prevalence of 29% in adolescents and 23% in adults (1)
• In a military population, prevalence of 12% in males and 15% in females (2)

Etiology and Pathophysiology

Multifactorial etiology, including:

• Weakness and incorrect firing of knee extensors (3)
• Impaired gluteal muscle function resulting in increased hip joint adduction and internal rotation (3)
• Decreased strength and altered recruitment patterns of core muscles during movement (3)
• Decreased muscle length, particularly of the quadriceps, may also contribute (3).

Genetics
Unknown

Risk Factors

• Recent research has found that age, height, weight, body mass index, body fat, Q angle, and hip weakness are no longer considered risk factors for patellofemoral pain syndrome (PFPS) (4).
• In a military population: quadriceps weakness (4)
• In adolescents: increased hip adduction strength, although this may represent increased activity level (4)

General Prevention

Strengthening and stretching exercises, particularly hip abductors and terminal extension of the quadriceps

Commonly Associated Conditions

• Overuse
• Knee ligament injury/surgery
• Patellar tendinopathy
• Prolonged synovitis
• IT band friction syndrome