Association Between Orthotic Wear Duration and Pain Reduction in Thumb Carpometacarpal Osteoarthritis.

BACKGROUND: Orthotic stabilization is a recommended first-line conservative option for thumb carpometacarpal (CMC) osteoarthritis, and randomized controlled trials have shown that it relieves pain. Because its effect depends on actual exposure, however, the benefit hinges on patient adherence, commonly expressed as daily wear duration. It remains unclear whether wear time is independently related to changes in pain over time. METHODS: This retrospective study included 63 orthosis-treated thumbs from 56 consecutive patients with thumb CMC osteoarthritis. Pain severity was assessed using a 100-mm visual analog scale (VAS) at baseline and 3 months. At 3 months, patients retrospectively reported their average daily orthotic wear time. Linear mixed-effects models examined the relationship between wear duration and pain change over time, incorporating a prespecified time-by-wear-duration interaction and adjusting for age, sex, and radiographic severity. RESULTS: Median VAS scores improved from 65 at baseline to 30 at 3 months (P < .001). HAND20 scores improved significantly, whereas pinch strength did not. However, time-by-wear-duration interactions were not significant for VAS or HAND20, indicating no evidence that longitudinal improvements varied according to orthotic wear duration. CONCLUSIONS: In thumb CMC osteoarthritis, orthotic management was associated with meaningful short-term gains in pain and function. Across the range of use commonly seen in practice, daily wear duration showed no independent association with longitudinal pain reduction. These findings suggest that therapeutic benefit may depend more on appropriate, activity-specific use than on maximizing daily wear time.