Effects of Right Lower Limb Orthopedic Immobilization on Braking Function: An On-The-Road Experimental Study With Healthy Volunteers.

Little is known about how immobilization of the right lower limb might affect driving. The purpose of the present study was to evaluate the effect of 2 types of immobilization on the emergency braking time of healthy subjects during actual driving conditions. The emergency braking times of 14 healthy volunteers were assessed in a closed circuit under 3 conditions: wearing running shoes, wearing an Aircast Walker(®), or wearing a walking cast on their right lower limb. An instrumented car was used to measure the emergency braking times during braking tests with and without a distractor. The foot movement times were significantly increased with both immobilization devices compared with the running shoe (p < .01). The median total braking time with the running shoe during emergency braking without a distractor was 0.452 (interquartile range, 25th to 75th [IQR], 0.413 to 0.472) second. The results obtained with the Aircast Walker(®) or the walking cast were significantly longer (p < .01), at 0.480 (IQR, 0.431 to 0.537) second and 0.512 (IQR, 0.451 to 0.535) second, respectively. When a distractor was added, the total braking time with the running shoe, Aircast Walker(®), and walking cast was 0.489 (IQR, 0.429 to 0.575), 0.516 (IQR, 0.459 to 0.586), and 0.510 (IQR, 0.469 to 0.570) second, respectively, with no statistically significant differences among these 3 conditions. Wearing an immobilization device on the right lower limb minimally lengthens the emergency braking time in healthy drivers under actual driving conditions. Clinicians must nonetheless exercise caution when advising a driver wearing an orthopedic immobilization, because driving a motor vehicle is a complex psychomotor task that goes well beyond the emergency braking time.

Effects of orthopaedic immobilization of the right lower limb on driving performance: an experimental study during simulated driving by healthy volunteers.

BACKGROUND: The effects of immobilization of the right lower limb on driving performance are unknown. Therefore, clinicians and legislators cannot put forth recommendations for road safety for patients requiring such immobilization. The objective of the present study was to evaluate the effect of two orthopaedic immobilization devices on the braking performances of healthy volunteers under simulated driving conditions. METHODS: The braking performances of forty-eight healthy volunteers were evaluated under three conditions: wearing a running shoe, wearing a walking cast, and wearing an Aircast Walker on the right lower limb. A computerized driving simulator was used to measure the maximum force applied on the brake pedal during braking as well as the braking reaction time and the total braking time during emergency braking with and without a distractor. RESULTS: The mean braking forces applied with the shoe, the walking cast, and the Aircast Walker were 293.8, 275.4, and 287.2 lb (133.3, 124.9, and 130.3 kg), respectively. The value with the walking cast was significantly lower than that with the shoe or Aircast Walker (p < 0.0001); there was no difference between the shoe and the Aircast Walker. The adjusted mean braking reaction times during emergency braking without a distractor were 0.580 second (shoe), 0.609 second (cast), and 0.619 second (Aircast Walker). The value with the running shoe was significantly lower than that with either type of immobilization (p < or = 0.0001). With a distractor, the mean braking reaction time was shorter with the running shoe than it was with either form of immobilization (p < or = 0.0001); the mean time was also shorter with the walking cast than it was with the Aircast Walker (p = 0.003). During both emergency braking tasks (with and without a distractor), the mean total braking time was shorter with the shoe than it was with either type of immobilization (p < 0.0001). With a distractor, the adjusted mean total braking time was shorter with the walking cast than it was with the Aircast Walker (p = 0.035). CONCLUSIONS: Immobilization of the right lower limb affects the braking force as well as the braking reaction time and total braking time during emergency braking by healthy volunteers. While these changes are significant, their impact on the ability to drive safely during emergency braking situations is questionable. Future research into the impact of such immobilization on the emergency braking performances of patients is warranted to confirm these observations.