Hip Osteoarthritis: Effects of Exercise Programs on Pain and Disability

Osteoarthritis is the most common form of arthritis in the United States. It is estimated that 20 million Americans have arthritis, and the annual societal cost is $95 billion. Several exercise studies have shown modest improvements in disability, physical performance, and pain in subjects with knee osteoarthritis. While similar results have been suggested in hip osteoarthritis, well-designed randomized clinical trials have not been conducted. Exercise programs appear beneficial but without adherence, the beneficial effects of exercise for knee and hip osteoarthritis decline over time. A well-designed, evidence-based, arthritis-specific study controlling for exercise duration, frequency and adherence is needed. The objective of this study is to determine the effects of structured exercise programs on self-reported pain and disability in adults with hip osteoarthritis. This prospective, randomized study with a wait-list control is designed to develop preliminary data to support an R01 funding request for a large, randomized clinical trial. All exercise interventions and outcome assessments will take place at OHSU in the Orthopaedics and Rehabilitation Clinics, Rehabilitation Services physical therapy gym, and the General Clinical Research Center. Subjects will be selected to include individuals representative of the larger population with documented hip osteoarthritis. This three-month study will evaluate the effects of an aerobic and resistance exercise program on pain and disability in individuals with hip osteoarthritis. Outcome assessment will follow the Outcome Measures in Rheumatology (OMERACT) recommendations for a core set of outcome measures for clinical trials in arthritis and assess pain, physical function, patient global assessment, and joint imaging. Data analysis will focus on comparing pre- and post-intervention endpoints using conventional statistical analyses such as repeated-measure analysis of variance for repeated continuous measures (e.g. walking distance), and non-parametric methods such as Chi-square or frequency analysis for proportions (e.g. visual pain scores).

Exercise intervention will consist of a three-month, supervised, facility-based, hip-specific strengthening, flexibility, and endurance exercise program. The intervention will consist of two phases and take place at OHSU rehabilitation services. Phase 1 will be a two-week orientation and general conditioning program. Phase 2 will be a ten-week progressive workload program. Subjects in both Phase 1 and Phase 2 will meet two to three times per week for 45 minutes per session. Phase 1 will be group sessions with more individualized orientation and attention by the exercise instructors. Phase 2 will begin progressive conditioning and utilize exercise groups of four to six subjects.

Due to limited space in exercise intervention classes, subjects may be placed on a waitlist for 3 months. When an opening becomes available, the subject will begin the exercise program identical to that of Group 2

Evaluated using a 100mm pain VAS (range 0-100), with higher scores indicating worse pain. Calculated as change from baseline to 3 months.

Change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Physical Function Subscale

The WOMAC Physical Function Subscale has a range of 0-68, with higher scores indicating worse functional limitations. Calculated as change from baseline to 3 months.

Inclusion Criteria: Age 21 years or more Pain at least once a week in one or both hips Difficulty with at least one of the following secondary to hip pain: walking 1/4 mile, climbing stairs, getting in and out of a car, rising from a chair, lifting and carrying groceries, getting out or bed, getting out of the bathtub, or performing shopping, cleaning or self-care activities Radiographic evidence of femoral and/or acetabular osteophytes on radiograph -OR- radiographic evidence of axial joint space narrowing and active hip flexion </= 115 degrees Primary care physician's written consent to participate in the exercise-based protocol. If te subject does not have a primary care physician, the subject will complete a screening questionnaire for coronary artery disease. If the subject screens as "high risk", te subject will be excluded from the study Exclusion Criteria: A medical condition that precludes safe participation in an exercise program including active cardiac disease, angina, class III heart failure, myocardial infarction in the past year Screening as "high risk" for coronary artery disease Inflammatory arthritis (e.g. psoriatic or rheumatoid) Collecting workers' compensation Involved in litigation regarding pain and/or disability Unable to walk six minutes without cane or assistive device Participating in a conflicting research study Significant, symptomatic knee or ankle osteoarthritis Other lower extremity pathology including peripheral vascular disease that would preclude participation in an exercise program Pregnancy

Thompson AR, Christopherson Z, Marshall LM, Carlson HL, Carlson NL. A Pilot Randomized Controlled Trial for Aerobic and Strengthening Exercises on Physical Function and Pain for Hip Osteoarthritis. PM R. 2020 Mar;12(3):229-237. doi: 10.1002/pmrj.12262. Epub 2019 Dec 12.