Driving After Knee Replacement

Adults who have a total knee replacement often ask their surgeons, "How soon before I can drive?" Even more than the patient who has a total knee replacement, concerned family members want to know, "Is it safe to drive?" The usual guideline for return-to-driving is six to eight weeks after surgery. Driving restrictions primarily apply to patients who have had a right knee replacement (assuming they drive an automatic vehicle).

But the question has come up about getting back behind the wheel sooner with the new and improved procedures. With less soft tissue disruption, muscle strength and motor control should come back even faster than with traditional procedures.

To find out if this theory is correct, occupational therapists measured brake time response before and after right total knee replacements in 29 patients. Patients were allowed to return to driving when the postop braking time was equal to (or faster than) the preop braking level.

Patients enrolled in the study were between the ages of 47 and 81, still driving, and had a diagnosis of osteoarthritis. Surgery was done by one surgeon for all 29 patients using the same surgical technique, anesthesia, and implant. Likewise, everyone was given the same preop procedures and postop care (including intense rehab).

All but three of the patients were discharged from the hospital directly to home by day three following the procedure. The remaining three patients went to an inpatient rehab center for a few extra days but were home by day eight. Brake time was tested at regular intervals after the replacement surgery (at four weeks, six weeks, and eight weeks postop).

Occupational therapists specialize in assessing function and ability to complete daily tasks and activities. As such, they are the health care professionals who test for ability to drive. In this study, a testing device (Vericom stationary reaction timer) was used. The set up included a computer monitor with video of driving down the road, steering wheel attached to a table, and pedals on the floor.

Driving was simulated with acceleration (pushing down on the gas pedal) and stopping by pressing on the brake pedal. Red and green lights signaled the driver when to accelerate and when to brake. The computer program measured and recorded the reaction time. Reaction time included time from foot at rest to gas pedal, time to lift foot off the gas pedal (called "gas off"), transition from gas to brake, and braking.

The patient's age and gender were also factored in to see if either of these variables made a difference in reaction time. The results showed that neither one made any difference in ability to react in a braking situation. And everyone in the study was back to their preoperative braking reaction time by the end of four weeks.

The improved surgical techniques, better pain control, and advanced rehab protocols have now put patients back in the driver's seat so-to-speak. With less pain, faster return of knee motion and mobility, patients experience better function sooner. Many patients feel ready to quickly regain the social independence driving provides.

The authors of this study were not quite ready to say all total knee patients can be released and return-to-driving after four weeks. This is just the first study they designed to address the question. There are other factors to be considered that weren't tested for such as vision, overall reaction time, effect of narcotics or other medications, and other health concerns.

They did check a smaller group of eight patients from the original 29 to see how they did after just two or three weeks compared to their brake reaction times at four weeks. They found that six of the eight patients in the subgroup passed at the two-week mark. Another patient passed at week three, and the final one passed at week four. This information suggests that many patients may be ready even before the four week cut-off.

Future studies will be needed to continue investigating this topic and forming guidelines for return-to-driving after right knee replacement. Separate testing should be done for automatic versus standard transmission vehicles. Any one who passes the brake test but who might need additional testing can be evaluated more completely with an on-the-road test.

Reference: David F. Dalury, MD, et al. When Can I Drive? Brake Response Times After Contemporary Total Knee Arthroplasty. In Clinical Orthopedics and Related Research. January 2011. Vol. 469. Pp. 82-86.

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