Comparison of Lumbopelvic Hip Muscle Activity Between Individuals With and Without Patellofemoral Pain Katbamna RY, Mangum LC, Hart JM, Saliba SA: University of Virginia, Charlottesville, VA Context: Patellofemoral pain (PFP) is one of the most common knee conditions in the physically active population Its etiology remains unknown; however, there may be a contribution from proximal musculature in the lumbopelvic hip complex, including: transverse abdominis (TrA), gluteus maximus (GMax), and gluteus medius (GMed) Although strength and muscle activation are often assessed, ultrasound imaging can also be used to evaluate the function of these muscles between healthy and PFP patients Objective: To compare muscle thickness changes of the TrA, GMax, and GMed using ultrasound imaging between participants with and without patellofemoral pain in multiple unloaded and loaded positions Design: Descriptive laboratory study Setting: Laboratory Patients or Other Participants: 24 total participants (12 PFP: Age = 24.0 ± 5.5 years, Height = 167.2 ± 7.6 cm, Mass = 71.9 ± 18.9 kg; 12 healthy: Age = 20.3 ± 1.7 years, Height = 174.8 ± 11.6 cm, Mass = 72.5 ± 14.4 kg) volunteered for the study Interventions: Ultrasound imaging with a wireless linear transducer was used to visualize muscle thickness of the abdominal wall muscles (TrA) and gluteals (GMax, GMed) Main Outcome Measures: Static ultrasound images were captured in resting and contracted states with participants placed in multiple positions (tabletop, bipedal standing, single leg stance, and single leg squat) The abdominal draw-in maneuver was used as the contraction for TrA in tabletop and standing, while side-lying hip abduction was used for gluteal contraction in tabletop and a gluteal squeeze as contraction during standing Muscle thickness during the single leg stance and single leg squat was normalized to a bipedal quiet standing Journal of Athletic Training thickness to identify percent activation beyond quiet standing 95% confidence intervals (CI) were also calculated for each mean difference Cohen’s d effect sizes were used to represent the magnitude of difference between groups Results: Compared to the healthy individuals, the participants with PFP had a 27% (0.27; CI: 0.25, 0.30) increase in activation of the TrA during standing (P = 04, d = 87 [CI: 0.03, 1.71]) and a 10% (0.10; CI: 0.07, 0.12) decrease in GMax activation (P = 008, d = -1.37 [CI: -2.26, -0.48]) in the same position During the single leg squat, healthy participants had a 21% (0.21; CI: 0.17, 0.24) increase in GMed activity (P = 003, d = -1.47 [CI: -2.37, -0.57]) There were no other significant differences between groups found in any of the muscles or positions Conclusions: Individuals with PFP had a large difference in lumbopelvic hip muscle activation compared to the healthy controls while standing and performing a single leg squat, as measured via ultrasound imaging The increase in TrA activity found in those with PFP may indicate a protective mechanism while standing in a loaded position due to dysfunction distally at the knee Muscle imbalances in the PFP group may also be responsible for the altered gluteal activation during standing and during the single leg squat Volume 52 • Number (Supplement) June 2017 S-134 Reproduced with permission of copyright owner Further reproduction prohibited without permission ...Reproduced with permission of copyright owner Further reproduction prohibited without permission