Strengthening of the First Dorsal Interosseous for Thumb Carpometacarpal Osteoarthritis

To determine the effect of first dorsal interosseus (FDI) strengthening in patients with thumb carpometacarpal (CMC) osteoarthritis.

Thumb CMC osteoarthritis is a normal part of aging. Most patients are able to adapt to symptoms of pain and disability, other patients might benefit from non-operative interventions; e.g. splinting, corticosteroid injections, pain medication, and multiple hand exercises. The dorsal ligament complex is one of the components for stability of the thumb CMC joint. These ligaments specifically create stability for pinch and grip during the final phase of opposition. Both, the opponens pollicis (OP) and the first dorsal interosseous (FDI) play a key role in centralizing the metacarpal on the trapezium. A retrospective study showed that a dynamic stability modeled approach, including targeting the FDI, reduced pain and improved function in patients with thumb CMC osteoarthritis. Recently, another study demonstrated that reduction of radial subluxation - the thumb metacarpal versus the trapezium CMC joint - was achieved by contraction of the dynamic stabilizers of the healthy hand, specifically with the focus on the FDI. More clinical research is needed to determine if there are efficacious (effective and low-cost) evidence-based exercise programs for pain reduction and functional improvement in patients with thumb CMC osteoarthritis. The investigators are interested in the effect of FDI strengthening in patients with thumb CMC osteoarthritis. Therefore, the investigators hypothesized that there is no difference in the change of lateral pinch strength at 12 weeks between patients treated with a splint versus patients treated with a splint and FDI strengthening for thumb CMC osteoarthritis. We also tested the same hypothesis for 3-point chuck strength, VAS for pain, and PROMIS Upper Extremity CAT.

Subjects with carpometacarpal (CMC) osteoarthritis treated by splinting of their thumb combined with first dorsal interosseous (FDI) strengthening stabilization exercises.

Subjects will use a splint custom-made by Massachusetts General Hospital Occupational Therapists as part of standard care for treatment of carpometacarpal (CMC) osteoarthritis.

Subjects will use a splint custom-made by Massachusetts General Hospital Occupational Therapists as part of standard care for treatment of carpometacarpal (CMC) osteoarthritis and will also be taught two first dorsal interosseous (FDI) strengthening exercises.

Investigators will measure the pinch strength by placing a pinch meter between the pad of the thumb and pad of the index and middle finger. The investigators will compare the change in 3 point chuck strength between the two cohorts after 12 weeks of treatment.

The investigators will measure lateral pinch strength by placing a pinch meter between the pad of the thumb and lateral surface of the index finger. The investigators will compare the change in lateral pinch strength between the two cohorts after 12 weeks of treatment.

The Visual Analog Scale for Pain measures the amount of pain on a scale from 0, no pain, to 10, worst possible pain. The investigators will compare the change in pain between the two cohorts after 12 weeks of treatment.

Change in Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity Computer Adaptive Test (CAT) at 12 weeks

A computerized assessment of depression measured at enrollment. The average T score of the U.S. population is 50, so the T score reported compares the study population to the U.S. population, where a T score greater than 50 is worse than the average and a T score less than 50 is better than the average. The investigators will compare the change in PROMIS Upper Extremity between the two cohorts after 12 weeks of treatment.

Inclusion Criteria: At least 18 years old English-speaking Splint treatment for thumb carpometacarpal (CMC) osteoarthritis Exclusion Criteria: Less than 18 years old Rheumatoid Arthritis or post-traumatic carpometacarpal (CMC) osteoarthritis Patients that received a corticosteroid injection during the appointment for treatment of thumb carpometacarpal (CMC) osteoarthritis

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