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The Effect of Immobilization Devices and Left-Foot Adapter on Brake-Response Time

Orr, MAJ Justin, MD1; Dowd, CPT Thomas, MD2; Rush, CPT Jeremy K., MD2; Hsu, LTC Joseph, MD2; Ficke, COL James, MD2; Kirk, LTC Kevin, DO2

doi: 10.2106/JBJS.J.00225
Scientific Articles

Background: The ability to perform an emergency stop is essential for safe driving and can be represented by total brake-response time, reaction time, and braking time. Immobilization of the lower extremities is routinely performed for a variety of musculoskeletal conditions. This study sought to investigate the effect of immobilization with a left-foot driving adapter, a controlled-ankle-motion device, and a short leg cast on braking times. Our hypothesis was that there would be a significant difference in braking-time values between individuals utilizing a left-foot driving adapter or immobilization device and control individuals wearing normal footwear.

Methods: A prospective, observational study was conducted to assess the effect of the immobilization devices on braking times. A driving simulator was used to assess total brake-response time, reaction time, and braking time in thirty-five volunteers. Volunteers were assessed while (1) wearing normal footwear (control group), (2) wearing a controlled-ankle-motion boot, (3) wearing a removable short leg cast, and (4) employing a left-foot driving adapter.

Results: The mean total brake-response time was significantly increased as compared with that of the control group in all three study groups. The mean reaction time was significantly increased for the short leg cast and controlled-ankle-motion groups as compared with reaction time in the control group. The mean braking time was significantly increased in the controlled-ankle-motion and left-foot driving-adapter groups as compared with braking time in the control group.

Conclusions: Total brake-response time while wearing a controlled-ankle-motion boot or a short leg cast or while utilizing a left-foot driving adapter is significantly increased, or worsened, as compared with the response time while wearing normal footwear. This information may prove valuable to physicians when counseling patients on when it may be safe to return to driving.

Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.

1William Beaumont Army Medical Center, 5005 North Piedras Street, El Paso, TX 79920

2Department of Orthopedics and Rehabilitation (T.D., J.K.R., J.F., and K.K.), United States Army Institute of Surgical Research (J.H.), Brooke Army Medical Center, 3851 Roger Brooke Drive, Fort Sam Houston, TX 78234. E-mail address for T. Dowd:

A commentary by Edward K. Rodriguez, MD, PhD, is available at and is linked to the online version of this article.

Copyright © 2010 by The Journal of Bone and Joint Surgery, Incorporated
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