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The Effect of Immobilization Devices and Left-Foot Adapter on Brake-Response Time
MAJ Justin Orr, MD1; CPT Thomas Dowd, MD2; CPT Jeremy K. Rush, MD2; LTC Joseph Hsu, MD2; COL James Ficke, MD2; LTC Kevin Kirk, DO2
1 William Beaumont Army Medical Center, 5005 North Piedras Street, El Paso, TX 79920
2 Department 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: tcdowd@gmail.com
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Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

A commentary by Edward K. Rodriguez, MD, PhD, is available at www.jbjs.org/commentary and is linked to the online version of this article.
Investigation performed at the Brooke Army Medical Center and the United States Army Institute of Surgical Research, Fort Sam Houston, Texas
Disclaimer: The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of Defense or the United States government. The authors are employees of the United States government. This work was prepared as part of their official duties and, as such, there is no copyright to be transferred.

Copyright © 2010 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2010 Dec 15;92(18):2871-2877. doi: 10.2106/JBJS.J.00225
A commentary by Edward K. Rodriguez, MD, PhD, is available here
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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.


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.


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.


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.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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    Charles Kenny, MD
    Posted on January 14, 2011
    Surgeons Should Not Give Driving Advice
    Orthopaedic Surgeon, Stockbridge Orthopaedic Clinic, Stockbridge, Massachusetts

    To the Editor:

    The article entitled "The Effect of Immobilization Devices and Left-Foot Adapter on Brake-Response Time" by Orr et al. (2010;92:2871-7) adds scientific evidence to better answer patient questions about driving, but raises significant concerns as well.

    After surgery or injury, should surgeons really answer such questions as, "Can I drive safely now?" Has surgery or injury imparted the surgeon with a special insight? Could the surgeon have reliably answered the question in the absence of injury?

    I have routinely fielded such questions by telling my patients that I can advise them about driving safety related specifically and only to the affected limb; if they have any doubt about their ability to drive, they should consult a certified driving instructor. Such instructors are generally available on a consultative basis to take the patient out on the road for a driving test and are licensed by the state to make the decisions that are discussed in the study. This may not be the most convenient answer for the patient, but judging from the questions left unanswered by the study, it is the safest and most reliable for patient, doctor, and the general public. I find that this approach is entirely consistent with the strategy that I use in affairs regarding my patients: if the area of concern is beyond my expertise, I ask for a consultant.

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