Download Labmeeting0510

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
Femoral
Patella
Increased
anteversion
malalignment
Q angle
Insufficient
flexibility
Abnormal biomechanics
Abnormal patella tracking
Excessive pressure on patellofemoral joint
Patellofemoral pain syndrome
Strength
deficit
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
Measured at 30°.45° and
60° of knee flexion
Vastus medialis oblique and vastus lateralis
 Electrical activity (EA)-muscle activity
 Median frequency (MDF)-muscle fatigue
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
Right side
Left side
Leg length
87.5cm
87cm
Femoral
anteversion
Tibial torsion
9°
12°
13°
16°
Q angle
15°
18°
Lateral patella angle
13.7°
15.3°
17°
Patella lateral displacement
Angle
Ratio
0.472024
30°
45°
0.516143
Bisect offset method
60°
0.561106
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
Thanks for your listening