Comparison of Active Knee Flexion Angles With and Without Tibiofemoral Joint Rotation Control Between Individuals With and Without Patellofemoral Pain Syndrome

BACKGROUND Patellofemoral pain (PFP) syndrome is a common cause of anterior knee pain. Excessive tibial external rotation during knee flexion increases patellofemoral stress, and uncontrolled tibiofemoral rotation is associated with PFP syndrome. Assessing knee flexion with and without tibiofemoral joint rotation control (TFRC) may help clinicians detect impaired rotational control and guide interventions. However, few studies have compared knee flexion angles under both conditions between individuals with and without PFP syndrome. This study compared active knee flexion angles with and without TFRC and evaluated tibial external rotation using the distance between the examination table and the lateral malleolus (DBTL). MATERIAL AND METHODS A total of 24 male participants (12 with PFP and 12 without PFP) underwent knee flexion angle assessments under both TFRC and non-TFRC conditions. To minimize hip movement, the examiner manually stabilized the femoral epicondyle of the test leg to keep the patella facing forward. DBTL was measured during knee flexion without TFRC to assess tibial external rotation. Data were analyzed using a 2-way repeated-measures analysis of variance (ANOVA) for knee flexion angles and independent t-tests for DBTL comparisons. RESULTS No significant differences in knee flexion angles were observed without TFRC. However, with TFRC, the PFP group exhibited significantly reduced knee flexion angles (P<0.01). The PFP group also showed significantly higher DBTL (P<0.01), indicating greater tibial external rotation. CONCLUSIONS These results suggest that uncontrolled tibiofemoral joint rotation may represent a characteristic movement pattern in individuals with PFP and underscore the importance of considering TFRC in clinical assessments in PFP syndrome.