This study examines which of three splint designs most effectively improved hand function in a patient with radial nerve palsy, and demonstrates the application of a single-subject experimental design. The static volar wrist cock-up splint (splint 1), dynamic tenodesis suspension splint (splint 2), and dorsal wrist cock-up with dynamic finger extension splint (splint 3) were evaluated. Each splint was worn for 3 weeks, and hand function was assessed by means of standardized measures of function and disability. Statistical significance was calculated using the minimal level of detectable change (MDC) at the 95% confidence level. Only with splints 2 and 3 did a true change in function occur, compared with baseline scores (no splint). In addition, the patient completed all tasks while using splints 2 and 3 but did not complete three tasks while using splint 1. The hand therapists' goal is to fabricate a splint that improves function and that the patient will wear. Only splint 3 met these criteria. This experiment highlights the need to evaluate both the statistical and the clinical significance of treatment interventions.