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The Influence of Vastus Muscle on Patella Alignment and Balance in Subjects With

Patellofemoral Pain Syndrome

Reporter: Chao-jung HsiehSupervisor: Sai-wei Yang

Date: 2007/6/11

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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

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PathomechanicsBony Alignment Soft Tissue

Femoral

anteversion

Patella

malalignment

Increased

Q angle

Abnormal biomechanics

Abnormal patella tracking

Insufficient flexibility

Strength deficit

Excessive pressure on patellofemoral joint

Patellofemoral pain syndrome

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Literature review

• The EMG activity of the vastus medialis oblique is pronounced at the end-range of extension which emphasizes the function of the structure in providing

medial patella stability Fulkerson 1990

• Effective control of balance also relies on a timely response of strong muscles

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Purpose• To investigate the influence of vastus muscle and

patella alignment in subjects with PFPS

• To evaluate the relationship of impairment of balance

and muscle strength of the knee

Hypothesis• Vastus medialis oblique and vastus lateralis muscle

imbalance would be associated with Lateral patella tracking

Poor balance

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Methods

• Subjects: 30 subjects diagnosed with PFPS• Preliminary examination:

Postural alignment Leg length Femoral anteversion Tibial torsion Q angle Muscle flexibility test

Estimating the pain intensity: visual-analog scale

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Methods

• Condition: during muscle isokinetic contraction

• Variables: Patella alignment

Lateral patella angleLateral patella displacement

Vastus medialis oblique and vastus lateralis Electrical activity (EA)-muscle activity

Measured at 30°.45° and 60° of knee flexion

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Methods Equipments

Electromyography Isokinetic dynamometerStewart platform

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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

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