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The Influence of Vastus Muscle and Patella Alignment in Subjects With Patellofemoral Pain. Reporter: Chao-jung Hsieh Supervisor : Sai-wei Yang Date: 2007/5/10. Introduction. Patellofemoral pain syndrome (PFPS)
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The Influence of Vastus Muscle and Patella Alignment in Subjects With Patellofemoral Pain Reporter: Chao-jung Hsieh Supervisor : Sai-wei Yang Date: 2007/5/10
Introduction • Patellofemoral pain syndrome (PFPS) • Peripatellar or retropatellar pain results from physical and biomechanical changes in the patellofemoral joint • Subjects with PFPS have more symptoms and pain during the last 30° of maximal sitting knee extension Thomee et al 1995
Pathomechanics Bony Alignment Soft Tissue Increased Q angle Patella malalignment Femoral anteversion Insufficient flexibility Strength deficit Abnormal biomechanics Abnormal patella tracking Excessive pressure on patellofemoral joint Patellofemoral pain syndrome
Literature review • The EMG activity of the VMO is pronounced at the end-range of extension which emphasizes the function of the structure in providing medial patella stability Fulkerson 1990 • Slow eccentric quadriceps open chain activity PFPS sufferers experienced a break in eccentric torque Anderson 2003
Purpose • To investigate the influence of vastus muscle and patella alignment in subjects with PFPS Hypothesis • Lateral patella tracking would be associated with • Decreased vastus medialis oblique muscle fatigue rate and muscle activity relative to vastus lateralis • The break phenomenon in eccentric torque curve and the level of pain
Methods • Subjects: 30 subjects diagnosed with PFPS • Preliminary examination: • Postural alignment • Leg length • Femoral anteversion • Tibial torsion • Q angle • Muscle flexibility test
Methods • Condition: during muscle isokinetic contraction • Variables: • Patella alignment • Lateral patella angle • Lateral patella displacement • Vastus medialis oblique and vastus lateralis • Electrical activity (EA)-muscle activity • Median frequency (MDF)-muscle fatigue Measured at 30°.45° and 60° of knee flexion
Methods • Joint analysis of spectra and amplitude Slope of MDF Adaptation Force increase Slope of EA Force decrease Fatigue
Methods • Equipments • Electromyography • Isokinetic dynamometer
Pilot study • 1 female • Age: 23 yrs • BMI: 18.5
Lateral patella angle 13.7° 15.3° 17°
Patella lateral displacement Bisect offset method
Joint analysis of spectra and amplitude VL 120° VMO 60° VL 60° VMO 120°
Isokinetic knee flexion/extension 60° 120°
References • Christopher MP(2000) Patellar kinematics, part I: The influence of vastus muscle activity in subjects with and without patellofemoral pain. Physical therapy. 10:956-964 • Davies AP, Bayer J(2004) The optimum knee flexion angle for skyline radiography is thirty degrees. Clinical orthopaedics and related research. 423:166-171 • Goran MH, Alwin L, Matthias J(2000) Methodologies for evaluating electromyographic field data in ergonomics. Journal of electromyography and kinesiology. 10:301-312