July 2015

Driving safety: The effects of lower extremity impairment

shutterstock_269757611-APBy Hank Black

The question of when or if it’s safe for patients to drive after surgery or while wearing a lower extremity orthotic device is one practitioners should address. But, in the absence of formal guide­lines, clinicians’ advice is often inconsistent.

There’s a point, said Douglas H. Richie Jr, DPM, when most clinicians realize they should have a talk with their patients about when it will be safe again to drive after their lower extremity movement or response time has been impaired as a result of surgery or an existing condition. His own such aha! moment came several years ago after a patient with diabetic neuropathy, who Richie had just fitted with a short leg walking cast, drove away from Richie’s Seal Beach Podiatry Group in California, and shortly afterward crashed through several patio tables at a fast food restaurant.

“Thankfully, no one was outside eating at the time, or there would have been injuries or even fatalities, but that was when it became clear to me that I had a responsibility to warn people of dangers I assumed they should know intuitively,” Richie said. “When you are wearing a cast or tight ankle brace and can’t plantar flex the ankle, or have loss of feeling and lose some fine motor coordination, you likely can’t feel the difference between the brake and gas pedals.”

The ability to drive is vitally important to many patients.1 All practitioners interviewed for this article said the when-to-drive question is ubiquitous in almost all practices, and recommended that a relevant conversation should definitely take place. They also said, however, that this often does not happen, or that advice is inconsistent.

Studies back them up. For example, Lewis et al surveyed 100 patients after knee arthroscopy and found only 65% of those responding said their surgeon talked about postoperative driving. In addition, patients reported that the time before patients were allowed to drive varied from two days to four weeks.2 Argintar et al surveyed sports medicine-trained physicians about driving instructions given before patients underwent uncomplicated arthroscopy and found that fewer than 30% said they always had the conversation.3 Fifty-seven percent of physicians reported they brought up the subject half the time or less.

Studies have not provided the clarity and consistency required to spur adoption of formal practice guidelines by medical, transportation, government, or other professional groups.3 However, recent advances in technology and surgical management may help answer the question.

For modern automobiles with automatic transmissions, the leg in question is almost always the one that controls the brake and accelerator, which in the US is the right limb. Impairment of the left leg is not problematic once flexibility is regained and narcotic pain medication is not a factor, so most research deals with the right leg.4,5

Medicolegal landscape

The question of when it’s safe to drive following surgery is fraught with legal and safety considerations.6 Insurance companies put the responsibility for safe driving on the patient, as do law enforcement agencies. Practitioners in the US have not yet been successfully sued for providing improper return-to-driving instructions,7 but a 2007 Massachusetts case produced a precedent for litigation stemming from poor advice allegedly given about operating a vehicle while using a prescribed narcotic.8 The same state passed legislation in 2010 that extends liability protection to physicians who breach patient privacy to report impaired drivers.9

A Swiss report10 by Fleury et al noted physicians in that country are not obligated to report a patient who is unfit to drive, but they also are not bound to medical professional secrecy in case they choose to notify the authorities. Current UK law states that, when a patient operates a vehicle against a doctor’s advice, the doctor has a professional obligation to notify authorities.11

Clinician awareness of the difficulty in deciding when a patient can return to driving is driven by the belief that the medicolegal environment is more uncertain today than in the past, the fact that laws impacting the issue vary greatly from state to state, the decreased time available for practitioners to interact with patients in a clinic visit, and the growing population of aging patients, many of whom already are anxious about the prospect of having to stop driving.6

“I believe this patient-driving question absolutely must be covered and noted in the medical record with every patient whose condition may impair driving. Rather than just a legal issue, it’s primarily my moral responsibility to the general society,” Richie said.

Geoffrey S. Marecek, MD, assistant professor of orthopedic surgery at the Keck School of Medicine at the University of Southern California in Los Angeles, was one of several who agreed.

“Physicians always should have this conversation, even if the patient doesn’t raise the question,” Marecek said. “It definitely doesn’t happen enough.”

He tells patients he can’t write a note that clears them to drive, and he provides a handout that includes his general guidelines, including the statement (which he also provides verbally): “Remember, there is no such thing as ‘clearance’ to drive. Law enforcement and insurance agencies consider it to be YOUR responsibility to ensure you can drive safely.”

Marecek coauthor­ed a 2013 literature review on the subject published in the Journal of the American Academy of Orthopaedic Surgeons.12 In it he encouraged practitioners to talk with patients about how long to wait before they might safely drive.

“We generally found that, as baseline prerequisites, patients should not drive before they are fully weight bearing, off of narcotic medications, and no longer wearing a protective
device, such as a cast or boot,” he said.

Figure  1. A patient poses with the driving simulator used in a Hospital for Special Surgery study of brake re- sponse times after total hip replace- ment.16 Inset shows a schematic of the simulator. (Photo by Robin Frank, courtesy of the Hospital for Special Surgery.)

Figure 1. A patient poses with the driving simulator used in a Hospital for Special Surgery study of brake response times after total hip replacement.16 Inset shows a schematic of the simulator. (Photo by Robin Frank, courtesy of the Hospital for Special Surgery.)

The National Highway Transportation and Safety Board recommends not driving with a splint or immobilization device and states in its physician guide, “Physicians have an ethical responsibility to assess patients’ physical or mental impairments that might adversely affect driving abilities.”13 The American Medical Association also notes in its code of medical ethics that physicians have a responsibility to assess impairments that can affect driving ability and safety.14

The importance of driving for patients, particularly those who have no other way to get to follow-up clinic appointments, increases the risk of noncompliance with restrictions related to driving and devices and narcotic medications. Orthopedic surgeons in urban practices surveyed their patients and found that up to 25% were still taking their prescribed medication when they returned to driving.1

Fortunate is the patient who lives where public transportation is adequate or who has the resources to pay a taxi or neighbor for this service.

“In major urban centers like mine, it’s convenient for a large number of people to get where they need to go by subway or bus, but elsewhere it presents a problem,” said Erika Schwartz, DPM, of Foot and Ankle Specialists of the Mid-Atlantic in Washington, DC.

Technological advances are helping to bring transportation to others, or at least minimizing the inconvenience of not driving, she noted.

“Increasing use of Uber, Lyft, and other ride-sharing apps for smartphones might make essential travel cheaper and more widespread in some areas, but the biggest beneficial change I’ve seen in recent years is the growing ability of many people to work from home via computer,” she said.

Many researchers and clinicians interviewed by LER look forward to the day when drivers can depend on their vehicle to do the “driving” itself.

“Self-driving cars are coming at some point in the future, although it may be further off than some think,” Marecek said. And those futuristic expectations, he added, wouldn’t directly benefit people who might not drive due to choice, physical condition, or lack of resources.

Geoffrey H. Westrich, MD, director of research for adult reconstruction and joint replacement at the Hospital for Special Surgery in New York City, said he looked forward to a car that actively brakes and keeps itself in the correct lane.

“No doubt, cars are getting smarter,” he said.

Driving simulators

7coverstory-shutterstock_242216164-copyA spate of recent studies is helping bring clarity to this issue. Most research uses bespoke or commercial driving simulators to determine how quickly a driver can move the right leg from the accelerator to the brake pedal and apply enough force to stop a vehicle.6 Others use simpler but somewhat equivalent evaluative methods, such as how often in a defined timeframe a patient can perform a sit-to-stand task or lift the right foot over a block of wood and back.15

Driving simulators cannot take into account all the factors that go into driving on the road, and they are not uniform in their complexity, according to David Goodwin, MD, a sports medicine fellow at New York University in New York City who coauthored a recent literature review on driving after orthopedic surgery.6

“They may measure the total braking time and distance from stimulus to full stop, but there are many other distracting factors involved when you’re on the road, such as noise,” Goodwin said.

Goodwin and colleagues noted in their 2013 review of postsurgical driving recommendations6 that suggested guidelines based on individual studies vary significantly.

“When to drive may differ for individual patients, so it’s difficult to issue a blanket recommendation for safety,” he said. “In my sports medicine practice, for example, it’s hard to rein in younger, more active patients. And, depending on the type and location of surgery, who performed it and where, individual differences show up.”

Researchers hope better driving simulation equipment, in tandem with more modern surgical techniques, can reduce driver downtime and provide support for the development of official rather than suggested recommendations. Total hip arthroplasty (THA) is one procedure that has benefited from such studies. The suggested guidelines for return to driving following right THA historically have ranged from six to eight weeks, but results of two recent studies using advanced driving simulators purport to show that driving may start earlier.

Westrich used a fully interactive driving simulator with an American Automobile Association automatic brake reaction timer (Figure 1) in a study of 100 patients undergoing modern THA.16 The participants all took a brake reaction-time test before surgery to establish a baseline, then were randomly selected to repeat the test two, three, or four weeks after the operation; the average return to preoperative baseline timing was about four weeks.

“There are some physically fit or less pain-sensitive patients who recover more quickly and may drive sooner than four weeks, and some are a bit older and not in as good physical shape who may not be able to drive that quickly,” he said. “Of course, it’s always good to err on the side of caution for driving issues.”

Advances in operative technique and materials might reduce the time a patient needs to wait before driving after some surgeries. A group led by Victor H. Hernandez, MD, MS, found patients might drive as soon as two weeks postoperatively. Using an advanced driving simulator to evaluate braking time in 38 patients before surgery and at two, four, and six weeks after modern muscle-sparing THA, Hernandez et al determined that 33 reached their baseline target by two weeks. The other five (13%) took four weeks to reach baseline, but even so were under the nationally recommended safe brake time standard.17

“With advanced techniques, we avoid cutting the muscles unless necessary and spend time repairing them if we do. Our contemporary protocol also includes multimodal pain management with minimal use of narcotics, an early mobilization physical therapy protocol, and more stable hip [implants] and other materials,” said Hernandez, an assistant professor in the Department of Orthopedic Surgery at the University of Miami in Florida.

Immobilizing and adaptive devices

Most practitioners interviewed said they do not allow driving if a patient is still wearing an immobilizing device on the lower extremity, which is routine for many procedures. Their conclusions were based primarily on a report by Orr et al.18 Using a driving simulator, Orr et al found total brake response time was significantly slower when volunteers wore a short leg cast or controlled ankle-motion boot and when they used a driving adapter that allows the left foot to press the accelerator or brake, compared with response times when they wore normal footwear.

Several other studies came to similar conclusions regarding immobilization appliances.19-21 Murray et al evaluated the emergency braking times in healthy volunteers wearing a walking cast, a walking boot, or a running shoe on the right limb.19 Total braking time as assessed with an instrumented car was significantly shorter for the running shoe condition than for either of the immobilizing devices.

Dammerer et al20 assessed brake response time in 64 healthy volunteers with commonly used knee braces using a custom driving simulator. They found that knee braces that restricted range of flexion-extension motion were associated with significantly slower braking response time than the no-brace condition, but a patellofemoral realignment brace, a ligament instability brace, an offloading osteoarthritis brace, and an elastic knee bandage had no significant effect on response time.

In a UK study of 23 healthy volunteers and a driving simulator, immobilization of the knee and ankle increased the time it took to move the foot from the accelerator to the brake pedal.21 An above-knee plaster cast, a below-knee cast, and a knee brace fixed at 0° of flexion were all associated with significantly longer total braking reaction time than unrestricted braking. The group wearing an above-knee cast performed worst, with the stopping distance at 30 miles per hour increased by almost three meters on average. The analysis also showed, unexpectedly, that driver “thinking time” increased with the level of restriction. And, in the case of a car accident, Goodwin noted, a driver wearing a brace or cast is less likely to be given the benefit of the doubt by law enforcement or insurance personnel.

“If a patient has had surgery and is seen wearing a restrictive device when getting out of the car following a collision, they can expect that fact to be noted by investigators as well as other parties and likely will be listed as a contributing cause of the wreck,” he said.

Even forefoot dressings are too restrictive for driving, Richie said.

“I don’t let patients drive after bunionectomy while there’s a dressing on the foot,” he said. “When the dressing is off and the surgical site is stable, I let them drive wearing a surgical shoe. If they are ambulating with the more restrictive walking boot, I get them to remove it and wear a surgical shoe when driving, which protects the surgery fairly well.”

Although orthotists are often involved in providing braces and other immobilizing devices, they generally do not consider the question of driving when they make clinical decisions on the type of bracing recommended for an individual, said Phillip Stevens, MEd, CPO, FAAOP, president of the American Academy of Orthotists & Prosthetists, who practices in Salt Lake City, UT.

7coverstory-iStock1141631-copy“We are viewing the orthotic device in the context of affecting the kinematics of ambulation, sit-to-stand transfers, or navigation of uneven terrain,” Stevens said. “It is rare that a device is designed specifically with driving in mind, so patients should always be made aware of that limitation. When patients ask me if they can safely drive with an orthosis, I will always defer to their physician for that broader discussion of whether they are competent to drive. Many of the deficits that might bring patients to us are such that, whether due to weakness, paralysis or neuropathy, they would affect driving with or without the use of an orthosis.”

Research to guide clinicians is sketchy in some areas. The usual recommendation for bunionectomy is primarily based on a study by Holt et al of patients who had undergone hallux valgus surgery with a first metatarsal osteotomy.22 The researchers tested 28 such patients preoperatively and at two and six weeks after surgery and compared them with a control group of healthy volunteers. Only 25% of operated patients could perform emergency stops at the two-week mark. At six weeks, brake reaction time had improved significantly but still was slower than that of the controls.

General guidelines from recent literature reviews3,6,10 include the following: simple knee arthroscopy, four weeks; anterior cruciate ligament repair, four to six weeks; bunionectomy, six weeks; diaphyseal fracture, 12 weeks; periarticular fracture, 16 weeks; ankle fracture, nine weeks; total knee arthroplasty, four to eight weeks; and total hip arthroplasty, six to eight weeks.

Clinicians should also keep in mind that, if a condition is dire enough to warrant possible surgical intervention, it might already be compromising the ability to conduct an emergency stop even before surgery has been performed. In a cross-sectional survey, Hofmann et al found that osteoarthritis of the right knee or hip could preoperatively prolong time to make an emergency stop of a vehicle.23 Unexpectedly, while osteoarthritis of the left hip did not prolong braking time significantly, osteoarthritis of the left knee did impair this capability.

Driver evaluation programs

Driver evaluation programs are a resource that many clinicians and patients may not be aware of.1 Elin Schold Davis, OTR/L, CDRS, a driving rehabilitation specialist with the American Occupational Therapy Association (AOTA), said, “Any individual with strong cognitive abilities can compensate for physical impairment with training, adaptive devices, or vehicular modification. Driver rehabilitation assistance is offered by trained specialists, including occupational therapists, who have a clinical background, engineers, and driver education experts.”

Schold Davis, coordinator of the AOTA’s Older Driver Initiative in Chicago, said that no single test, including driving simulation, can determine whether a driver needs intervention.

“We seek to work with surgeons and physicians to tailor programs for the specific needs of their clinic population,” she said. “Currently there are people driving scared because they have a medical condition that threatens to take away their ability to drive, and we could help them. Before a driving evaluation, I even saw someone relying on a cane to press on the accelerator.”

The AOTA works with a broad range of groups to help educate drivers who may be impaired. CarFit (car-fit.org), for example, was started by the AOTA, the American Automobile Association, and the American Association of Retired People to help older adults adapt to the myriad features of modern automobiles, from bucket seats to back-up camera displays. Schold Davis met recently with the Transportation Research Board to discuss what will be necessary to help people use self-driving features and, eventually, self-driving cars. The board’s membership includes appointees from the Institute of Medicine and the National Academy of Science.

Because of expense and the learning curves involved, vehicular modifications and driver adaptations may not be the answer for patients who are surgically impaired for only a few weeks. Longer-lasting or permanent problems may call for such interventions, however. Richie cited patients with a long-term drop-foot diagnosis who found that hand controls for the brake and accelerator allowed safer driving. “There are too many patients with neuromuscular or other conditions who are not aware they can safely drive if they take a course and learn to manage with such adaptations,” he said.

Individual recommendations

Studies give a structure for decision-making, but individualized approaches and patients’ awareness of their own responsibility should go into their choices, Marecek said.

“Guidelines today are not official rules,” he said, “so when I talk with patients about this, I try to make it personal and give them the grandkid test: ‘How will you feel if your grandchild chases a ball in front of the car you’re driving—do you feel comfortable being behind the wheel with that child’s life in your hands?’”

Hank Black is a medical writer in Birmingham, AL.

REFERENCES
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