Lower Extremity Immobilization Negatively Impacts Braking Response Time

SAN DIEGO — Practitioners should consider counseling their patients
against driving when they wear or have been prescribed certain lower-extremity
immobilization devices, according to the results of a prospective observational
study presented at the 2011 Annual Meeting of the American Academy of
Orthopaedic Surgeons, which took place Feb. 15-19 in San Diego.

  Jeremy K. Rush
  Jeremy K. Rush

In addition, patients who have their right foot immobilized should
considering not using a left foot adaptor for the purposes of braking the
vehicle. The study showed that using the adaptor or wearing immobilization
devices significantly increased total brake response time among participants.

Jeremy K. Rush, MD, of Fort Sam, Houston, Texas, and colleagues
conducted the study.

“Based on the findings from our study, we recommend that no patient
should be allowed to drive while immobilized in either a right lower-extremity
cast or a controlled-ankle- motion (CAM) boot,” Rush explained to the
audience during his presentation.

Investigators examined 35 healthy volunteers’ braking response
times in a driving simulator experiment. The investigators hypothesized that
wearing a controlled-ankle-motion boot or a prefabricated removable short-leg
cast on the right leg or using a left-foot driving adaptor would negatively
impact drivers’ ability to stop.

Investigators measured braking times to within thousandths of a second.
Controls for the study consisted of participants performing the same driving
and braking routines, but in normal footwear.

The investigators found that the controls consistently outperformed the
immobilization group thus proving their hypothesis true.

“The ability to perform a safe stop is critical to safe
driving,” but it is not the only aspect of safe driving, Rush explained.

For more information:

  • Rush JK, Orr JD, Dowd TC, et al. The effect of immobilization
    devices and the left foot driving adaptor on brake response time. Paper #52.
    Presented at the 2011 Annual Meeting of the American Academy of Orthopaedic
    Surgeons. Feb. 15-19, 2011. San Diego.


I think that is a great paper. We want to hear a paper like that because
we want to tell our patients the same thing, but we have no data to back it up.
When you did this, you basically gave the patients three trials, and they had
to do it 10 times. So, the question is, is three trials enough?

— Steven L. Haddad, MD
Glenview, Ill. AAOS
session moderator

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