Can Patellofemoral Pain Syndrome Be Bilateral?
Yes, patellofemoral pain syndrome (PFPS) can absolutely be bilateral, and this presentation is common enough that recent research specifically examines bilateral versus unilateral cases as distinct clinical entities. 1
Evidence for Bilateral Presentation
Bilateral PFPS is well-recognized in the literature, with recent studies directly comparing outcomes between patients with unilateral versus bilateral presentations, confirming this is a standard clinical pattern rather than an exception. 1
The pathophysiology supports bilateral involvement, as PFPS results from imbalances in forces acting on the patellofemoral joint, and the underlying risk factors—including quadriceps weakness, soft-tissue tightness, and biomechanical abnormalities—frequently affect both limbs simultaneously. 2
Muscle volume deficits occur bilaterally even in unilateral PFPS, suggesting systemic rather than purely localized pathology. Women with both unilateral and bilateral PFPS demonstrate bilaterally smaller volumes of multiple hip and knee muscles compared to pain-free controls, including the iliacus, adductor muscles, hip rotators, rectus femoris, and biceps femoris. 1
Clinical Presentation Characteristics
The cardinal symptoms remain consistent whether unilateral or bilateral: gradual onset diffuse retropatellar and/or peripatellar pain during activities such as squatting, stair ambulation, and running. 3, 4
Pain typically worsens with prolonged sitting with the knee flexed (the "theater sign") and when descending stairs, regardless of whether one or both knees are affected. 5
The most sensitive physical examination finding is pain with squatting, which should be assessed bilaterally during evaluation. 5
Important Clinical Implications
Treatment should address both limbs even in unilateral presentations, as bilateral muscle deficits exist regardless of symptom laterality. Interventions should bilaterally target lower limb muscles, with knee-targeted exercise therapy combined with hip strengthening forming the foundation of treatment. 1, 4
Hip abductor and extensor weakness is a consistent predictor and should be assessed and addressed bilaterally using progressive resistance exercises including side-lying leg raises and clamshells. 6, 4
Bilateral stretching of lateral retinacular structures and iliotibial band is recommended as part of the comprehensive treatment program, performed twice daily until symptoms subside. 7, 4
Common Pitfalls to Avoid
Do not assume unilateral symptoms indicate unilateral pathology—the underlying biomechanical and muscular deficits are typically bilateral, requiring bilateral assessment and treatment. 1
Avoid focusing only on the symptomatic knee without addressing hip strength and bilateral lower extremity mechanics, as this commonly leads to treatment failure. 4