A Combination of Ultrasound and CT for Investigation of Muscle and Functional Changes in Hip OA Across the Disease Spectrum

Hip osteoarthritis (OA) is one of the most common causes of disability in older adults, with pain, stiffness, and weakness the most frequently reported symptoms. Weakness is a major concern as decreased lower extremity strength is a contributor to balance and other mobility limitations that increase fall risk in the aging population. Weakness in the primary hip muscles in particular have been shown to contribute to gait variability and altered mechanics of stepping when recovering from a balance perturbation. Contributing factors for these strength deficits are multifactorial and may include decreased muscle mass/size, changes in muscle composition, and/or a decreased ability to activate the muscle. Intramuscular fat infiltration (IMAT), has been reported in several conditions affecting older adults, and has been shown to be more modifiable at lower levels, suggesting that earlier detection and intervention may be important. CT and MRI are both commonly used to measure these relevant muscle properties, but ultrasound imaging may be valid alternative, and has the advantage of being more accessible to clinicians in many settings. The investigators hypothesize that cross-sectional area (CSA) and IMAT of the hip and lumbar musculature will be significantly altered in individuals with hip OA (affected limb) compared to that seen in similar-aged control participants, and that larger differences in CSA and IMAT will be positively correlated with OA severity, increased impairment, pain, and disability.