Patellafemoral Knee Pain Syndrome (PFPS) is one of the most common lower limb musculoskeletal kinematic dysfunction which relates to pain in the peripatellar or retropatellar region of the knee. Irish, Millward, Wride, Bernhard, & Haas (2010), discussed the effects of closed-kinetic and open-kinetic chain exercises in this quantitative, level 3 evidence research study that affects 25% of the general population and as much as 60% of the athletic population. Irish et al, (2010), studied the relationship of the strength of the Vastus Medialis Oblique and the Vastus Lateralis to the alignment of the patella in the trochlear groove during knee extension activities. Ideally, an equal strength balance between the VMO and VL would provide optimal tracking of the patella helping to reduce symptoms of PFPS. It has been reported that subjects with PFPS show a ratio much lower than an equal VMO:VL relationship providing a lateral pull to the patella.
Twenty-two subjects that were between the ages of 18 and 40, and had no prior history of knee or lower limb injury took part in this study to show a cause and effect relationship between two closed kinetic chain exercises (double leg squat with isometric hip adduction and the lunge) and one open chain kinetic exercise (knee extension) and measure the muscle activity using surface electromyography on both the Vastus Medialis Oblique (VMO) and the Vastus Lateralis (VL). Statistics were recorded on the activation of VMO and VL during the open and closed kinetic chain exercises. Recording a number closest to 1 provided information that there was equal output between the VMO and VL. A recording larger than 1, showed that the VMO produced more output and pulled the patella medially on the leg. Irish et al. (2010) findings of this study showed that the double leg squat with hip adduction and the lunge produced the greatest activation of both the VMO and VL, creating the closest activation ratio of the two muscles. The knee extension exercise created the greatest activation of the Vastus Lateralis. In regards to rehabilitation programs, creating an equal balance among the VMO and VL helps reduce the symptoms of PFPS. Results of the study showed the double leg squat with hip adduction and the lunge would produce the most benefit in the alignment of the patella during knee exercises. The single leg knee extension created the greatest activation of the VL which helps provide results that the leg extension may not be an appropriate leg exercise for people with PFPS.
The research by Irish et al. (2010) provides beneficial insight to the exercise procedures that would be beneficial to post PFPS therapy. Having an equal strength relationship between the VMO and the VL has been an important component in the treatment and prevention of PFPS, and this study helped provide evidence to the exercises that therapists can prescribe to maintain an equal strength balance to assist in proper patellar tracking.
Irish, Sian E., Adam J. Millward, James Wride, Bernhard M. Haas & Gary L.K. Shum, 2010. The Effect of Closed-Kinetic Chain Exercises and Open-Kinetic Chain Exercises on the Muscle Activity of Vastus Medialis Oblique and Vastus Lateralis. J Strength Conditioning Research 24(5): 1256-1262.