Background & Aims
Patellofemoral pain syndrome (PFPS) is one of the most common causes of anterior knee pain. PFPS occurs in females more than males and in athletic people more than sedentary people. Several factors can contribute to the development of PFPS such as pelvic alignment, knee and patellar alignment, hip muscle strength, and knee muscle strength. Several studies have extensively investigated the role of knee and patellar alignment and knee muscle strength in PFPS, with limited research on the role of hip and pelvic alignment and hip muscle strength. Thus, this cross-section study aims to investigate the relationship between lower limb function investigated by triple hop distance test (THD) and pain intensity investigated by visual analogue scale (VAS) with hip muscle strength, range of hip internal and external rotation, hip alignment represented by femoral neck anteversion angle (FNA), pelvic alignment represented by pelvic tilt angle, and self-reported disability represented by Kujala score
Methods
Based on sample size calculation, forty-two female patients with unilateral PFPS were recruited through posted flyers and announcements. This study has been approved by the Faculty of Physical Therapy Ethical Committee. Informed consent was signed by the participants. All Participants completed the Kujala scale and VAS, to evaluate self-reported functional limitations and subjective pain intensity. An isokinetic dynamometer was used to assess hip muscle strength, a universal goniometer was used to assess the range of hip internal and external rotation as well as FNA, and an inclinometer was used to assess pelvic tilting. Descriptive statistics were represented as mean and standard deviation and the Shapiro-Wilk test was used to assess the normality of data. Pearson correlation coefficient was used to assess the relationship between the investigated variables and paired t-test was used to assess the differences between the measured variables in the affected and non-affected lower limb.
Results
Patients showed a mean pain intensity of 4.48 (1.62), with mean self-reported disability of 73.95 (10.67) and a mean anterior pelvic tilt of 4.75 (3 degrees). Patients showed more internal hip rotation (P<0.001) and FNA (P=0.016) and less THD and external hip rotation (P<0.001) on the affected side. Significant moderate to good correlations (r = -0.7) were found between the VAS score and the Kujala score. Also, significant fair correlations (r = 0.4) were found between the VAS score and pelvic tilting angle. Moreover, significant fair correlations were found between THD and concentric hip abductor torque (r= 0.4; P= 0.01), eccentric hip abductor torque (r= 0.4; P= 0.02), and concentric hip external rotators torque (r= 0.3; P= 0.03). Based on the regression model, the Kujala score explained 31% of variations in pain severity (R=0.56, R2=0.31, F=18.33, P=0.000), while concentric hip abductor torque explained 15% of variations in THD (R= 0.39, R2=0.15, F=6.98, P=0.012).
Conclusions
Pain intensity was significantly correlated with self-reported disability and anterior pelvic tilting, with self-reported disability explaining 31% of variations in pain intensity. Moreover, lower extremity function was significantly correlated with hip muscle strength, with concentric hip abductor torque explaining 15% of variations in lower extremity function.
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