New York—March 11, 2014
The study, titled, “A Novel Assessment of Driving Reaction Time Following THR Using a New Fully Interactive Driving Simulator,” was presented at the annual meeting of the American Academy of Orthopaedic Surgeons in New Orleans on March 11, 2014.
“One of the most common questions patients ask after hip replacement is when they can start driving again, and this is the first study of its kind to test their reaction time after the procedure,” said Dr. Westrich, who came up with the idea for the driving simulator while watching his children play video games.
But the interactive simulator used in his study is more intricate than a Wii game. “It’s a very sophisticated machine made by a company that makes driving simulators for the automobile industry,” Dr. Westrich said.
More than 330,000 hip replacements are performed in the United States each year. People exhibit decreased reaction time after the surgery, making it unsafe to drive in the immediate post-operative period. Most doctors recommend patients wait about six weeks before they resume driving, but many don’t want to wait that long.
“Over the past five or 10 years, we’ve seen advances such as minimally invasive hip replacement and newer implants that are advantageous to patients and may improve recovery time. Our study set out to obtain good, objective data to determine if it would be safe for people to return to driving sooner,” Dr. Westrich said.
One-hundred patients from three orthopedic surgeons at Hospital for Special Surgery were enrolled in the study to assess their driving reaction times using a fully-interactive driving simulator with an automatic brake reaction timer from the American Automobile Association.
All of the participants had a total hip replacement on the right side, and they all took the driving test prior to having surgery. They were then randomly selected to repeat the test TWO, THREE or FOUR weeks after hip replacement. Reaction time was measured by the computerized driving simulator.
The reaction timer, equipped with an accelerator and brake pedal, simulates driving. Patients were instructed to place their foot on the accelerator, which activated a green light, and to keep their foot on the accelerator until a Stop sign appeared. When the Stop sign popped up, they were supposed to move their foot to the brake pedal. The amount of time it took for the subject to switch from the gas to the brake pedal was measured by the machine.
The study defined a return to safe driving reaction time as a return to a reaction time that was either the same as or better than the preoperative driving reaction time. Observing reaction times at different intervals revealed that two and three weeks after surgery patients had not yet made a full recovery to their respective baseline reaction time and generally were not ready to drive.
However, at four weeks following hip replacement, patients had actually improved their reaction time compared to what it was before the surgery and therefore could be cleared to drive. It was also observed that patients under the age of 70 reached an improved reaction time earlier than those over 70.
“By using a standardized, driving simulator to measure reaction times, our study will be reproducible and we can apply our model to other surgical procedures that may affect one’s ability to drive safely postoperatively,” Dr. Westrich noted. He will soon begin enrolling patients in another study to determine when it is safe to drive after total knee replacement.
About HSS | Hospital for Special Surgery
HSS is the world’s leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the ninth consecutive year) and No. 3 in rheumatology by U.S.News & World Report (2018-2019). Founded in 1863, the Hospital has one of the lowest infection rates in the country and was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center four consecutive times. The global standard total knee replacement was developed at HSS in 1969. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State. In 2017 HSS provided care to 135,000 patients and performed more than 32,000 surgical procedures. People from all 50 U.S. states and 80 countries travelled to receive care at HSS. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. The HSS Global Innovation Institute was formed in 2016 to realize the potential of new drugs, therapeutics and devices. The culture of innovation is accelerating at HSS as 130 new idea submissions were made to the Global Innovation Institute in 2017 (almost 3x the submissions in 2015). The HSS Education Institute is the world’s leading provider of education on the topic on musculoskeletal health, with its online learning platform offering more than 600 courses to more than 21,000 medical professional members worldwide. Through HSS Global Ventures, the institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally.