Driving safely following total hip arthroplasty through an direct anterior approach: investigating brake force and brake response time.

After total hip arthroplasty, a rapid recovery protocol is applied, aiming for
optimization of joint function and minimization of morbidity and complications.
According to Alrijne hospital protocol, patients return to the Orthopedics
outpatient six to eight weeks after hip arthroplasty. A frequently discussed
topic at the follow-up appointment is the return to driving. Most patients have
long since resumed their daily activities and are eager to return to driving,
thereby regaining their independence. An important competency to drive safely,
which may be impaired after hip arthroplasty, is the ability to perform an
emergency stop. Essential factors influencing an emergency stop are response
time and brake force. According to CBR guidelines, based on European
directives for vehicles, the brake pedal must be depressed with at least a
force of 500 Newton to make an emergency stop. No explicit threshold is
suggested, concerning response time, since it shows a large amount of
interindividual variability.

The time to resume driving after total hip arthroplasty, described in the
current literature, varies. Based on response time, results range from two days
to six weeks after surgery. A few studies examined brake force after THA, in
which results ranged from recovery after four weeks to twelve weeks.
Additionally, for hip arthroplasties through an anterior approach, currently
the standard protocol at Alrijne Hospital and other hospitals, response time
and brake force have not been investigated before. Since this approach leads to
less muscle damage and less postoperative pain in the short term, preoperative
values may be achieved earlier and thus patients will be able to return to
driving earlier than described by the current literature. Literature shows how
quickly patients mobilize and achieve good short term functional outcomes, but
also clinical experience teaches us that many patients stop using their
crutches and start riding a bike within four weeks, which suggests that pain
experience has evidently diminished and that patients regained sufficient power
and confidence at that point.

In conclusion, there is no explicit, scientifically substantiated answer to the
question when patients can resume driving after total hip arthroplasty yet. For
that reason, patients wait until the six- to eight-week follow-up appointment
for approval from the orthopedic surgeon. This study will investigate when
patients will be able to return to driving following total hip arthroplasty
through an anterior approach. We will measure brake force, brake response time
and patient reported driving ability in two cohorts: left side THA and right
side THA. Also, brake response time and brake force of the left leg on the
clutch pedal will be measured and compared. Furthermore, opioid consumption
will be registered at all measurement moments, since opioid use may adversely
affect driving abilities. This study will use a driving simulator to measure
the brake force and the brake response time. The repeatability of the driving
simulator is measured to ensure data consistency. This will be investigated by
examining healthy subjects. After objectifying recovery after THA, with regards
to driving abilities, we aspire to further investigate how fitness to drive can
be tested and demonstrated in practice. A practically feasible test can offer
patients the opportunity to determine fitness to drive, independently of the
orthopedic surgeon, and can ensure that patients can return to driving more
quickly. It is hypothesized that patients can safely return to driving four
weeks after right sided THA through DAA and two weeks after left sided THA
through DAA.

The primary objective is to study the prevalence of subjects that reach their
preoperative median level of brake force following THA through DAA. Results
will not be used for decision making.

Driving ability of patients undergoing THA through DAA will be investigated in
this prospective, observational cohort study by assessing brake force and brake
response time by the use of a driving simulator. Brake force and brake response
time will be measured preoperatively and at four moments postoperatively,
namely one day, two weeks, four weeks and six weeks after surgery. Brake
response time and brake force on the clutch pedal will also be measured.
Postoperative measurements on one day, two weeks, four weeks and six weeks
after surgery will be compared to the median preoperative value. In addition,
patients will be asked if they feel confident to drive, which will be compared
to brake force and brake response time at each timepoint. The healthy subjects
will be measured two times. The measurements will take approximately 30
minutes. The measurements will be repeated the next day under the same
conditions.

Subjects will be requested to make two additional hospital visits for
measurements and a short questionnaire, each taking a half- to one hour, travel
time excluded. The extra visits will take place two weeks and four weeks after
surgery.
The design of the driving simulator takes into account safety and comfort for
the subjects. The chair position will be comparable to a normal chair, on which
patients are allowed to sit the same day after surgery. The seat height will be
normal to high and the chair will be in upright position, comparable to e.g. an
SUV. This position limits wound pressure and prevents pain and discomfort.
There are no expected risks for the healthy subjects. Concluding, no problems
are expected.