Doctor of Philosophy (PhD)
First Committee Member
Second Committee Member
Third Committee Member
Fourth Committee Member
Patellofemoral pain (PFP) is the most common knee injury among runners, military personnel, adolescents and recreationally active persons. PFP commonly presents as diffuse pain across the anterior knee that increases with activities such as running, squatting, and walking up and down stairs. Nearly 75% of patients with PFP either alter or completely stop physical activity as a result of the pain. There are numerous mechanisms that contribute to PFP symptoms; such as muscle weakness, abnormal joint mechanics and abnormal joint stress, which make it difficult to successfully treat. In addition, PFP may lead to patellofemoral joint (PFJ) osteoarthritis, a debilitating degenerative joint disease, further compromising engagement in physical activity. Evidence suggests a causal link between PFP and patellofemoral osteoarthritis.In persons with PFP, altered knee and hip kinematics have been identified to occur during weight bearing activities. These include excessive adduction and internal rotation of the femur under a relatively stable patella. This abnormal kinematic change is thought to be the result of weak hip abductors and external rotators. These weak muscles can result in a shift of the knee joint center, relative to the foot, causing dynamic knee valgus. As a result, PFJ stress increases due to a reduction in the articular surface contact area between the femur and patella. For this reason, one approach to preventing or delaying the progression of PFP and PFJ osteoarthritis is to correct the dysfunctional hip musculature and altered PFJ mechanics. However, patients with PFP who undergo standard hip strengthening have been shown to continue to have persistent pain, and restrictions in daily and physical activities up to 8 years after diagnosis. One possible explanation is that the regular strengthening program does not specifically address neuromuscular control deficits of the gluteal muscles that may contribute to excessive dynamic knee valgus during weight-bearing. It would be clinically relevant to determine if muscle inhibition is affecting the gluteal muscles in the PFP population contributing to abnormal kinematics. The overall purpose of this dissertation was to determine the neurophysiology, lower extremity kinematics and overall knee function factors that are associated with PFP. To meet this purpose three studies were designed: 1) To compare the gluteus medius central activation ratio of healthy participants to participants with PFP; 2) To determine the relationship between gluteus medius activation, kinematics, and strength between people with and without PFP; 3) To compare the results of a subjective questionnaire, Anterior Knee Pain Scale (AKPS), to gluteus medius activation for participants with patellofemoral pain to see if lower AKPS scores are correlated with lower activation. The purpose of the first study was to compare the central activation ratio (CAR), which could provide critical information about neuromuscular control deficits, of patients with PFP, to the CAR of healthy individuals. The study was conducted to determine if participants with PFP have different gluteus medius CAR than healthy controls. 28 female participants volunteered for this study. The results of this study showed a statistically significant difference of CAR between groups, after controlling for participant age, mass and gluteus medius MVIC. Participants with PFP had a lower CAR when compared to healthy controls. The purpose of study two was to investigate movement patterns of a dynamic task to determine if relationships exist between gluteus medius activation, strength, and lower extremity kinematics. Impaired pelvic-femoral control due to weakness of the gluteus medius is a common impairment seen in individual with PFP, usually observed as dynamic knee valgus. 21 female participants volunteered for this study. Participants were evaluated completing a step-down task with two-dimensional kinematic analyses. The results of this study suggest that there were no relationships between gluteus medius CAR, strength, and lower extremity kinematics in either group. Since nearly 75% of patients with PFP either alter or completely stop physical activity as a result of the pain, the third study was developed to determine if a relationship exists between a patient-reported outcome measures and CAR. Fifteen female participants volunteered for this study. Participants completed the Anterior Knee Pain Scale (AKPS), which assesses how PFP affects the participant’s activities of daily living and their ability to be physically active. The results of this study suggest that there were no significant associations between gluteus medius CAR and gluteus medius MVIC to individual scores on the AKPS.
anterior knee pain; inhibition; kinematics; outcome meaurers
Physical Therapy | Physiotherapy
University of Nevada, Las Vegas
Samuel, Michelle, "Effects of Patellofemoral Pain on Central Activation and Function of the Gluteus Medius Muscle in Physically Active Females" (2022). UNLV Theses, Dissertations, Professional Papers, and Capstones. 4617.
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