Immobilization Following Ankle Surgery Reduces Driver Response Time

Total driving brake-response time while wearing an ankle immobilization device such as a splint or brace is significantly increased when compared with the response time when wearing normal footwear.

Researchers at Brooke Army Medical Center (BAMC, San Antonio, TX, USA) and William Beaumont Army Medical Center (El Paso, TX, USA) conducted a prospective observational study to assess the effect of immobilization devices on braking times. A driving simulator was used to assess total brake-response time, reaction time, and braking time in 35 volunteers, who were assessed while wearing normal footwear (control group), wearing a controlled-ankle-motion boot, wearing a removable short leg cast, and employing a left-foot driving adapter. All subjects were healthy adults who had not recently undergone surgery or sustained an injury.

The results showed that when compared with an individual wearing normal footwear, an individual traveling at a highway speed of 96.6 km/h would travel an additional 2.8 meters during emergency braking when wearing a right lower-extremity controlled-ankle-motion boot. A driver wearing a right lower-extremity short leg cast would travel an additional 1.9 meters before coming to an emergency stop, while a driver using a left-foot braking adapter would travel an additional 1.8 meters.

At a community-driving speed of 56.3 km/h, these same individuals would travel an additional 1.6 meters, 1.1 meters, and 1.1 meters, respectively. These changes in distance traveled might represent the difference between being involved in or avoiding a collision in an emergency setting. The effect of immobilization devices on fine braking scenarios such as navigating a curve or driving in stop-and-go traffic is unknown, according to the researchers, but it is likely to be even greater. The study was published in the December 1, 2010, issue of the Journal of Bone and Joint Surgery (JBJS).

"Based on our findings we cannot recommend that any patient return to driving using a brake adapter or wearing an immobilization device on the right foot,” said study coauthor orthopedic surgeon Captain Thomas Dowd, MD, of the department of orthopedics and rehabilitation at BAMC. "We only tested emergency braking situations, but it's reasonable to assume that if a person cannot stop quickly in an emergency, it may not be safe for that person to be driving.”

Related Links:
Brooke Army Medical Center
William Beaumont Army Medical Center