Background

• Hip OA and subsequent hip replacement has significant impact on the adult population, and it is essential to translate some of these methods to characterize hip OA.
• The initial stages of hip OA are manifested in alterations in hip loading patterns, which can be investigated using motion analysis tools.
• Previous studies have reported altered loading patterns in subjects with varying levels of hip OA. Changes in kinematics, kinetics, spatio-temporal gait characteristics and functional activities have been reported in patients with early hip OA. While these parameters have not been linked with radiographic markers of OA, their relationship with early cartilage degeneration remains to be determined.
• Femoroacetabular Impingement (FAI), including pincer and cam types, has emerged as a probable cause of OA of the hip associated with demonstrable kinematic changes in the hip joint.
• Preliminary studies from our group and others have shown promising results demonstrating altered biomechanics and cartilage biochemistry in patients with hip OA.

Aims

• To investigate early hip OA by integrating motion analysis and MRI techniques, thereby assessing the relationship between biomechanical loading and functional kinematics to cartilage degeneration and progression of hip OA.
• To characterize hip cartilage biochemistry (measured by MRI T1ρ and T2 relaxation time) in patients with hip OA compared to controls and to determine the changes in cartilage T2 and T1ρ relaxation time over 4 years; and the cross-sectional and longitudinal relationship between hip cartilage biochemistry (measured by MRI T1ρ and T2 relaxation time) and cartilage morphology, patient function (kinematics, kinetics, spatio-temporal gait characteristics, functional tests) and pain (WOMAC).
• To test the central hypothesis that imaging-based measures of hip cartilage biochemistry and bone structure differ between patients with hip OA and controls and are related to cartilage morphology, pain, function, and severity of disease.

Significance and Translational Aspects

• The results of the proposed study will help determine whether or not early biochemical degeneration in cartilage, as quantified by T2 and T1ρ mapping parameters, is associated with the progression of hip OA manifested by altered hip loading patterns, changes in bone and cartilage morphology, and to the detriment of patient function.
• This study translates the previously established MR and quantitative analysis methodologies for knee osteoarthritis by addressing early detection and quantification of degeneration at the hip joint, the second most common site of OA.
• The results of this project (relating the MR imaging-based biomarkers to function, pain, and measures of biomechanics of the joint) will assist researchers in understanding the pathogenesis of hip OA and in designing future interventions.