| Summary: | 碩士 === 國立陽明大學 === 物理治療暨輔助科技學系 === 97 === Background and Purpose: Patellofemoral pain syndrome (PFPS) is one of the most common orthopedic knee complaints among young and physically active females. The etiology of PFPS is speculative. A well-accepted pathomechanism of PFPS is based on patellar mal-alignment or mal-tracking phenomenon. Patellar alignment could be influenced by the rotational position of the femur. Changes of the femoral motion in the transverse or frontal plane have been shown to increase the patellofemoral joint stress by altering the patellofemoral joint contact area. Weakness of the hip abductors or extensors or altered muscular control of hip abductor/rotators (tensor fascia lata, gluteus medius, and gluteus maximus) has been hypothesized to cause excessive hip adduction or internal rotation during unilateral weight-bearing activities. However, results of previous studies which had investigated hip kinematics in females with PFPS during functional activities were inconsistent in whether differences existed in hip motion, muscle activation, or strength of hip abductors and extensors in subjects with PFPS as compared to those without PFPS. Moreover, there has been no study to simultaneously investigate the hip kinematics and muscle activity of all the hip abduct/rotators during unilateral weight-bearing activities. The purpose of the study was to investigate the hip motion and muscular control on the frontal and transverse planes during step down tests in females with and without PFPS. Method: Twenty six females with PFPS and 26 age, gender, and height matched healthy controls participated in the study. Kinematic variable of peak angle and range of hip adduction and internal rotation during anterior and lateral step down tests were collected with an electromagnetic motion tracking system while muscle activity of the hip abductors/rotators was simultaneously recorded with surface electromyography. Additionally, maximum strength of hip abductors and extensors was measured isometrically with a hand-held dynamometer. Results: Females with PFPS displayed a greater hip adduction range during both step down tests, a larger peak hip adduction angle during the anterior step down test, and greater activation intensity of the gluteus medius during the ascending phase of the lateral step down task as compared to the control subjects. No difference was found in the maximum strength of the hip abductors or extensors. Correlations of hip kinematic variables with strength or muscle activation intensity of the hip abductor/rotators were low to moderate. Conclusion: Female subjects with PFPS displayed increased hip adduction during the step down tests. However, no between-group difference in strength and electromyographic control of the hip abductor/rotators could be found to explain the kinematic difference. Further studies may employ other measurements of muscle performance or examine movement patterns of other body segment to best understand how hip kinematics was affected in patellofemoral pain syndrome.
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