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.

Arthritis, Exercise, Thumb, Treatment, Intervention, Dynamic stability, Hand, Therapy, Occupational, Physical

Involves four 60-minute occupational therapy visits as well as a daily home program across a 8-week period. Clinic visits focus primarily on home program coaching, and progression of the exercise regimen. Home programs involve daily exercises which follow the intensity and duration recommended for older adults. The intervention focuses on enhancing mobility and strength of the thumb for use during daily activities.

The thumb CMC DS intervention involves four 60-minute occupational therapy visits as well as a daily home program across a 8-week period. Clinic visits focus primarily on home program coaching, and progression of the exercise regimen. Home programs involve daily exercises which follow the intensity and duration recommended for older adults.

CAT scan will be used at baseline and 9 weeks to obtain measurements as per the American College of Radiology's 2013 Technical Standards. A validated positioning jig reproduced by our lab will be used to maintain standardized joint positioning and standardize stress to the thumb metacarpal during fluoroscopic examination. "Joint subluxation" is a measure of thumb CMC instability and will be measured in centimeters.

CAT scan will be used at baseline and 9 weeks to obtain measurements as per the American College of Radiology's 2013 Technical Standards. A validated positioning jig reproduced by our lab will be used to maintain standardized joint positioning and standardize stress to the thumb metacarpal during fluoroscopic examination. "Joint subluxation" is a measure of thumb CMC instability and will be measured in centimeters.

Sonographic assessment of thumb carpometacarpal subluxation will occur at the time of participants' baseline CAT scan. The same views, position jig and standardized upper limb postures used for the fluoroscopic assessments will again be employed. The thumb CMC joint sonographic procedures described by Oo et al. and the general guidelines put forth by American Institute of Ultrasound in Medicine will be followed. Long axis views of the dorsal and radial borders of the thumb CMC joint will be visualized via use of the Philips Lumify Portable Sonography Device. In these views, the amount of translation of metacarpal base with respect to trapezium will be quantified in millimeters

Inclusion Criteria: adults with radiographically-confirmed thumb CMC OA Exclusion Criteria: Persons who have had cortisone treatments to the affected thumb within the prior three months, thumb CMC joint replacement, inflammatory arthritis, Ehlers Danlos Syndrome, Marfan's disease, pregnancy or questionable pregnancy, cognitive disorders which would preclude a client from following the testing commands and home program participation, concomitant conditions affecting the arthritic thumb, grade 4 arthritis staging, no ongoing hand rehabilitation (i.e., within prior 6 months), non-English Speaking, and pain which precludes participants from completing testing