Driving with an arm immobilized in a splint: a randomized higher-order crossover trial

Background: The aim of this study was to determine whether immobilization of an arm has detrimental effects on driving performance. Methods: Thirty-six healthy officers-in-training were assigned a sequence of fiberglass splints (left and right-sided above-the-elbow thumb spica and below-the-elbow splints) with use of a randomized higher-order crossover design. Runs were scored on a cone-marked driving course used for officer certification with predetermined passing requirements. Driving time, the number of cones hit per course section, and the cone-adjusted total time (a five-second penalty per hit cone) were recorded. A linear mixed-effect model with random environmental and learning effects for cone-adjusted time analysis was used. Participants rated perceived driving difficulty and safety with each splint, and ratings were compared with the Wilcoxon signed-rank test. Results: Thirty participants completed the entire set of runs. Analysis of total cone-adjusted time revealed a significant performance decrease with the left arm in an above-the-elbow thumb spica splint (average, 22.2 seconds; p < 0.001) and with the left arm in a below-the-elbow splint (average, 16.2; p = 0.007). Analysis of forward-only course sections revealed poorer performance trends with all splints, with the worst performance with the left arm in an above-the-elbow thumb spica splint. Driving with the left arm in an above-the-elbow thumb spica splint had the highest perceived difficulty (median, 8.0) and lowest perceived safety (median, 3.0). Conclusions: Driving performance as measured with a standardized track and scoring system was significantly degraded with splint immobilization of the left arm. Further studies are required to determine the effect of arm immobilization on normal driving conditions.