Device wear delays braking response
By Lori Roniger
A recently published study from the Temple University School of Podiatric Medicine in Philadelphia bolsters previous research suggesting that wearing a lower extremity immobilization device on the right foot could negatively affect driving performance.
The driving-simulator study, which was published in the September-October issue of The Journal of Foot & Ankle Surgery (JFAS), found that mean braking response times were significantly slower in 25 healthy individuals while wearing a surgical shoe (.611 sec) or walking boot (.736 sec) on the right foot than while wearing their normal footwear (.575 sec).
“It’s a very common question we get from our patients,” said Laura E. Sansosti, DPM, chief resident at Temple’s podiatric surgical residency program and one of the study’s authors, about whether it’s safe to drive while wearing an immobilization device on the right foot. “We typically advise that it’s not safe to drive with any type of device on.”
Braking response time while wearing a surgical shoe was still faster than the previously published threshold for normal reaction time of .7 seconds, but abnormally delayed brake responses were significantly more common with both the surgical shoe (18.5%) and the walking boot (55.5%) than with regular shoes (2.5%).
Although the study was conducted in healthy individuals, Sansosti said the results indicate that patients should not drive with a walking boot or surgical shoe on the right foot. The findings are consistent with those of previous studies on lower extremity immobilization and braking response (see “Driving safety: The effects of lower extremity impairment,” LER, July 2015, page 18).
Notable because of its inclusion of a surgical shoe, the JFAS study is also the first of six the Temple researchers have in the works on driving and lower extremity immobilization. Three of the studies focus on diabetes, Sansosti said, while another looks at driving restrictions and guidelines for wearing lower extremity immobilization devices by state. The final study summarizes the results of the others.
In the recently published study, participants were instructed to brake when red lights appeared on the monitor of the driving simulator. The researchers also monitored for inaccurate brake responses, defined as the patient inadvertently pressing the accelerator along with the brake pedal. This occurred in 4% of cases with the surgical shoe and 18% with walking boot; only the walking boot condition differed significantly from the regular shoe condition (2% of cases).
Driving restrictions can present logistical and socioeconomic challenges for patients, Sansosti noted. However, public transportation in cities like Philadelphia can be an option, and many postoperative patients are accompanied to visits by a family member or friend, she said.
“I feel like most of our patients do listen to our recommendation about not driving,” Sansosti said.
Good compliance may be easier to come by in cases involving planned surgeries than in patients who end up with a lower extremity immobilization device after a traumatic accident. Geoffrey S. Maracek, MD, assistant professor of orthopaedic surgery at University of Southern California Keck School of Medicine in Los Angeles, works with such trauma patients and coauthored a 2013 review article in the Journal of the American Academy of Orthopaedic Surgeons on driving after orthopedic surgery.
In his clinic, he has handouts about the issue for patients.
“I try to talk to them about why they shouldn’t drive,” Maracek said. “I say, ‘It’s not about you. It’s about everyone else in the road. If the neighbor’s kid runs into the street after a ball, do you think you can stop?’”
Maracek agreed with the Temple authors that, if a patient can’t wear a regular shoe because of surgery or injury, it’s probably not a great idea for them to drive. Such patients are likely to have more impaired neuromuscular control than the healthy volunteers in the JFAS study and others, he noted.
“I think it’s pretty clear that, if you’re wearing an immobilization device, you shouldn’t be driving,” Maracek said. “You don’t have tactile feedback or motion.”
However, he added, a device could potentially be removed for driving in specific situations not involving a recent surgery or fracture—in the case of a patient with posterior tibial tendinitis, for example.
The brake response findings in the Temple study are particularly interesting, Maracek said.
“It’s one thing to say that reaction time is impaired, but even your ability to step on the gas is impaired,” he said. “That highlights the idea that even more people shouldn’t be driving.”
Lori Roniger is a freelance writer based in San Francisco.
Sansosti LE, Rocha ZM, Lawrence MW, Meyr AJ. Effect of variable lower extremity immobilization devices on emergency brake response driving outcomes. J Foot Ankle Surg 2016;55(5):199-1002.
Sohn SY, Stepleman R. Meta-analysis on total braking time. Ergonomics 1998;41(8):1129-1140.
Green M. How long does it take to stop? Methodological analysis of driver perception-brake times. Transport Hum Factors 2000;2:195-216.
Marecek GF, Schafer MF. Driving after orthopaedic surgery. J Am Acad Orthop Surg 2013;21(11):