1. Reporter: Chao-jung Hsieh Supervisor : Sai-wei Yang Date: 2007/5/10
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

2. 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

3. 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

4. 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

5. 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

6. Methods Subjects: 30 subjects diagnosed with PFPS
Preliminary examination:
Postural alignment
Leg length
Femoral anteversion
Tibial torsion
Q angle
Muscle flexibility test

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

8. Methods Joint analysis of spectra and amplitude Slope of MDF
Adaptation
Force increase
Slope of EA
Force decrease
Fatigue

9. Methods
Equipments
Electromyography
Isokinetic dynamometer

10. Pilot study 1 female Age: 23 yrs BMI: 18.5 Right side Left side
Leg length
87.5cm
87cm
Femoral anteversion 9°
12°
Tibial torsion
13°
16°
Q angle
15°
18°

11. Lateral patella angle
13.7°
15.3°
17°

12. Patella lateral displacement
Angle
Ratio
30°
45°
60°
Bisect offset method

13. Joint analysis of spectra and amplitude
VL 120°
VMO 60°
VL 60°
VMO 120°

14. Isokinetic knee flexion/extension
60° °

15. References
Christopher MP(2000) Patellar kinematics, part I: The influence of vastus muscle activity in subjects with and without patellofemoral pain. Physical therapy. 10:
Davies AP, Bayer J(2004) The optimum knee flexion angle for skyline radiography is thirty degrees. Clinical orthopaedics and related research. 423:
Goran MH, Alwin L, Matthias J(2000) Methodologies for evaluating electromyographic field data in ergonomics. Journal of electromyography and kinesiology. 10:

16. Thanks for your listening