Mechanisms of a Dynamic Stability Approach

Background. Arthritis is the leading cause of disability in the United States and osteoarthritis (OA) of the hand affects an estimated 25.6 US residents. OA of the thumb carpometacarpal (CMC) joint is the most disabling form of hand OA. Rehabilitation for persons with thumb CMC OA is recommended as the initial treatment and often involves instruction on joint protection and fitting of a splint to reduce joint stress and pain. More recently, evidence has suggested that specialized exercise may impact a factor linked to this condition, altered joint mechanics. Health records data also suggests that these exercises reduce pain and disability more than what would be experienced by those receiving standard care (SOC) rehabilitation. However, there has not yet been a prospective investigation on how these dynamic stability (DS) exercises alter joint mechanics, improve function, and reduce pain relative to standard treatment. Relatedly, thumb CMC mechanics are most often assessed by physicians through CAT scan and although rehabilitation therapists are not licensed to conduct such assessments, they could benefit from 'real-time' imaging to inform and evaluate the mechanical effects of treatment. Sonography might afford therapists the precision to evaluate mechanical response to treatment yet it is not yet known if thumb CMC sonography corresponds with the gold standard, CAT scan. Goal and Specific Aims. The long term goal this line of study is to reduce the effects of thumb CMC OA on activity performance and participation through non-invasive and non- pharmacological interventions. We expect to achieve our goals by pursuit of the following two specific aims: 1). Determine if a novel exercise regimen reduces radiographic thumb CMC joint misalignment among persons with thumb carpometacarpal osteoarthritis and 2) Evaluate the accuracy of ultrasound compared with CAT scan (reference standard) for quantifying thumb CMC subluxation Design and Methods. Specific aim 1 will be addressed through a prospective pre-post interventional study of a 8-week clinic-based dynamic stability program and will undergo a CAT scan before treatment and upon completion of the program (9 weeks) and specific aim 3 will be addressed through a psychometric 'concurrent validity' design.