Fear of movement is associated with biomechanical variables in women with patellofemoral pain

BACKGROUND: Understanding whether biopsychosocial and biomechanical factors are related in patellofemoral pain (PFP) could help to clarify the underlying mechanisms of this dysfunction. OBJECTIVE: To investigate whether fear of movement is associated with hip and knee muscle strength; trunk and lower limb frontal kinematics; plantar pressure, and stabilometric measures in women with and without PFP. METHOD: PFP (n = 18) and asymptomatic (n = 18) women answered the Tampa Scale for Kinesiophobia; underwent strength tests of knee extensors, hip abductors, and hip extensors; and performed the single-leg squat test to determine trunk, pelvis, and knee frontal angles, and baropodometric measurements. Correlation and multiple linear regression analyses were performed (p < 0.05). RESULTS: In the PFP group, fear of movement correlated with knee extensor (r = -0.529, p = 0.024) and hip abductor torque (r = -0.534, p = 0.023); ipsilateral trunk inclination (r = 0.505, p = 0.033); amplitude (r = 0.545, p = 0.019), velocity (r = 0.713, p = 0.001), and standard deviation of anteroposterior oscillation (r = 0.714, p = 0.001), standard deviation of mediolateral oscillation (r = 0.579, p = 0.012), and total displacement of the center of pressure (CoP) (r = 0.637, p = 0.004). It was predicted (p = 0.000, R<sup>2</sup> = 0.82) by ipsilateral trunk inclination (B = 0.40, p = 0.040); amplitude of anteroposterior oscillation (B = -0.13, p = 0.013), and standard deviation of anteroposterior (B = 0.78, p = 0.001) and mediolateral CoP oscillation (B = 1.33, p = 0.001). In the control group, there was no significant correlation. CONCLUSION: Fear of movement is related to decreased knee extensor and hip abductor strength, increased ipsilateral trunk inclination, and postural instability in women with PFP.