The current recommendation on how soon it is safe to return to driving following hip replacement surgery is six weeks. However, a new study has found that patients are able to return to driving two weeks sooner than this.
The research was carried out by Dr. Geoffrey Westrich, Director of Research, Adult Reconstruction and Joint Replacement at the Hospital for Special Surgery in New York City, using an interactive driving simulator
"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.
He came up with the idea for the driving simulator while watching his children play video games, although the interactive simulator used in his study is more intricate. "It's a very sophisticated machine made by a company that makes driving simulators for the automobile industry," Dr. Westrich said.
People exhibit decreased reaction time after hip replacement surgery, making it unsafe to drive in the immediate post-operative period. Most doctors recommend that 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 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 computerised 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 they were to break. The amount of time it took for the subject to switch from the accelerator to the brake pedal was measured by the machine.
Observed reaction times
The study defined a return to safe driving reaction time as a return to a time that was either the same as or better than the pre-operative driving reaction time. Observing reaction times at different intervals revealed that at two and three weeks following 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 pre-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 standardised, 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.
The study, entitled, "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.
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