Driving after total knee and hip arthroplasty - an observational study from the perspective of rehabilitative orthopaedic therapy

Abstract


Background
For a large proportion of the population, especially those residing in the countryside, the use of a car for daily activities is indispensable. Following a TKA or THA procedure, the overseeing physician will usually recommend refraining from driving, sometimes up to 12 weeks after surgery with a major social and economical impact on patient's life.
Methods 92 eligible participants, contained within the frame of a prospective experimental observational study, were contacted via telephone 12 weeks after surgery and interviewed using a structured questionnaire.
The answers were statistically analysed using SPSS®.

Discussion
There were statistically signi cant differences regarding operated side, gender and place of residence.
Male patients drove in the 6th and 7th postoperative week, while female patients drove in the 8th and 9th postoperative week. For 58.6% of patients the reasoning for the rst post-operative drive was medical: the journey to physiotherapy or to a doctor's appointment. TKA impaired patients the most. Patients recovering from a TKA drive considerably later. Patients recovering from a right sided TKA have an increased risk by a factor of nine, not to become an "early driver". Female patients who underwent TKA had an increased risk by a factor of 21, of becoming a "late driver".

Conclusions
The rehabilitation following a right sided TKA proved a challenge with regard to the reuptake of driving.
This should be taken into account when planning the course of therapy for patients who are regular drivers. Female patients could bene t from special training. Background Arthrosis of the knee and hip joints is a common arthritic condition worldwide. In the GEDA 2014/2015-EHIS study conducted by the Robert-Koch-Institute of Germany, 17.9% of adults above the age of 18 report having suffered from arthritis in the last 12 months. [1] Replacement of the knee or hip joint (arthroplasty) following progressive joint destruction and function loss due to Osteoarthritis, has a major social and economical impact on patient's life. According to the Endoprosthesis Register in Germany (ERPD), approximately 450.000 endoprosthetic procedures (primary and revision arthroplasty) were carried out in 2018. [2] Also a search was run using the database of the German federal o ce of statistics (DESTATIS) on 24 January 2020 using the following string: "Koxarthrose/Gonarthrose" as a discharge diagnosis from hospital in 2018. It identi ed 178.329 patients with osteoarthrosis of the hip and 185.439 patients with osteoarthrosis of the knee.
Driving a car is important for people in general because it provides the opportunity for personal control and autonomy, especially for those residing in the countryside, due to a lack of public transport. For people having more di culties walking or riding a bike due to health issues, driving a car is more than often the only option for a independent mobility, is often necessary to make doctor's and physiotherapy appointments and sometimes it is a requirement to resume working, not just in the remote countryside.
One of the most frequently asked questions, especially during the postoperative rehabilitation phase, by patients following a TKA or THA is "When can I start driving again?" In Germany, health care insurance providers are legally mandated (SGB IX, § 42) to nance a three-week in-patient postoperative rehabilitation (bedridden or ambulatory) following TKA or THA. Because most of the patients with a TKA or THA undergo a bedridden rehabilitation and they will be discharged between the 4th and 5th week after surgery, there is no reason to drive a motor vehicle before their discharge date. Also the legal stipulations in Germany require that every driver must evaluate whether they view themselves t to drive prior to starting their engine. The driver must evaluate to what extent ful ls the requirement for roadworthiness.
Doctor's recommendations should guide and support the patients in their evaluation. The decision to get behind the wheel of a motor vehicle, however, is made by the patient -that is what the legislation stipulates.
When driving, the ability to brake in time to avoid an obstacle is key. Both the cognitive and the motor skills are important. The interaction of these skills constitutes the brake reaction time, which represents a signi cant parameter of safe driving. That is why a large number of studies [6,7,8,11,18] rightfully make use of this parameter. A brake reaction time within the normal range offers a decision-making tool for postoperatively reuptake of driving. The measured brake reaction time is a parameter of safe driving, however not the main criterion for postoperative roadworthiness.
Regarding recommendations when to reuptake driving after TKA or THA, there have been a lot of studies published. The authors of this paper have focused on the more recent published works and were able to nd that there is a very large bandwidth of recommendations when to reuptake driving after TKA or THA, ranging from two days up to 8 weeks after surgery. [4,5,11,12,13,14,15,16,17,18] In Germany, in some cases the recommendation to restrain from driving after TKA or THA procedures is 12 weeks after surgery. We've decided to take the 12 weeks timeframe as the maximum amount of recovery time after a TKA or THA procedure, with no further complications, and set out to nd to what extent patients take said recommendations into account when returning to motor vehicle driving after surgery.
Considering the legal stipulations in Germany regarding tness to drive a motor vehicle, the aim of this study is to nd out when patients with a TKA or THA actually take up driving again after surgery; how the replaced joint, side, gender, place of residence and physician's recommendations, in uences the patient in making the decision when to start driving again.

Methods
The study design was that of a prospective experimental observational study, as a single center study in a orthopedic rehabilitation clinic in Germany.
For the statistical analysis the signi cance level was set for 5%, while the con dence interval was set for 95%. Pursuant to the concept of W. Viechtbauer et al., the ideal sample size was calculated to be of 90 participants. [3] The study was approved by the ethics committee of Sachsen-Anhalt's medical board on the 11th of November 2019. Number 18/19. Inclusion criteria: primary TKA or THA, age between 20 and 90 years, a valid driver's license, and regular driving practice. Exclusion criterion: total hip joint replacement surgery following trauma. Patient comorbidities were not taken into account.
In all, 100 participants consented, verbally and in written form, to the participation in the study, all of whom had been assigned to the Celenus Fachklinik "Teufelsbad" Blankenburg for in-patient rehabilitation from ve surrounding hospitals. Recruitment occurred between the 17th of July 2019 and the 3rd of November 2019. In this time frame the authors oversaw the rehabilitation of 167 patients following TKA or THA. Of these, 59% were recruited into the study. This sample size ful ls criterion number 3 of the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. [9] The questionnaire used to collect the data was created speci cally for this study and was based on the aim of this study. It included data about participants driving licence, age, sex, place of residence, operated joint and side, date of the operation, use of walking aids, driving practice, timeframe of postoperative driving resumption (weeks), pain level, car's transmission type and the reason for st drive after surgery.
From the 13. post-operative week patients were contacted via telephone and the questionnaire was lled out by the caller, subject to the answers given by the participant. Hand written modi cations were made in addition (placed of residence).
One participant revoked his consent, three other participants were no longer contactable via telephone.
Four participants were wrongfully recruited (three participants with uni-compartmental knee replacement and one participant with total hip arthroplasties on both sides) and were excluded from the study. Finally, one participant had to be excluded as the data recording his place of residence was missing. Of the 100 original participants 92 remained who ful lled the criteria and were included in the study. The drop-out rate was 4,1%. (Flowchart patient enrolment) The study sample (Table 1) consisted of 56 male and 36 female participants with an age range of between 34 and 81 years of age. The Mean age for male participants was 64.2 years of age, for female participants it was 60.6 years of age. Results 92.4% (n = 85) of the participants drove within the rst 12 weeks of recovery following surgery. Seven participants refrained from driving -one participant suffered an apoplexy in the rst 12 weeks post operation. Six participants answered the question "Did you resume driving after your operation?" with "I have not felt t enough to drive (yet)". None of the participants who drove reported any accidents in the rst 12 weeks of recovery.
29.3% (n = 27) of the participants resumed driving within the rst 6 weeks after surgery. The earliest resumption of driving was within the 3rd postoperative week.
For 58.6% of the participants (n = 54) the rst reason for driving was medical: driving to physiotherapy or a doctor's appointment.
The gender analysis of the postoperative resumption of driving showed that male participants resumed driving earlier than female participants (p = 0.0015). (Fig. 1) The analysis of the operated side (left vs. right) showed a signi cant side preference (p = 0.019) in the postoperative resumption of driving. Participants who underwent a TKA or THA on the left side resumed driving earlier than participants who underwent a TKA or THA on the right side. (Fig. 2) The Mode for the left side was 4th + 5th postoperative week, while the Mode for the right side was 8th + 9th postoperative week, with 17 and 14 participants, respectively.
The location of residence also had a statistically signi cant effect on the timeframe in which the participant resumed driving (p = 0.0299). Participants who lived in the countryside drove earlier than participants who lived in cities. (Fig. 3) The Mode for participants who resided in the countryside is in the 4th + 5th week post-surgery, while the Mode for participants who resided in cities is in the 6th + 7th week post-surgery, with 13 and 19 participants, respectively.
In our statistical analyses we were unable to nd a signi cant difference (p = 0.053) between TKA and THA regarding the time frame in which the participants resumed driving.
The interaction between the operated side and operated joint was also analysed, the result of which showed a signi cance regarding TKA (p = 0.020) but no signi cance regarding THA (p = 0.304). Participants with left-sided TKA resumed driving earlier than participants with right-sided TKA. (Fig. 4) Additionally, we conducted two risk analyses. The risk analysis for side and joint presented statistical signi cance for TKA (p = 0.031). Regarding the Odds Ratio analysis for operated side, participants who were operated on the right side were 9.00 times less likely to be a "early driver" (resumption of driving before the 6th + 7th week post-surgery; 95% CI 1.01-79.54). The risk analysis for gender and joint had also statistical signi cance (p = 0.00015); female participants who had undergone a TKA were 21.08 times more likely to be "late drivers" (resumption of driving 10th + 11th weeks post-surgery; 95% CI 3.64-121.83). Therefore, female patients and patients who underwent a right-sided TKA can be considered high risk groups with regard to being a "late driver".
Our assumption, that there would be a correlation between place of residence and reason for the rst drive post-surgery could not be statistically supported (p = 0.927).

Discussion
This study showed that the recommendations for postoperative resumption of driving given by doctors and physical therapists were not heeded by patients. Rather, the participants resumed driving considerably earlier than recommended. On average male participants resumed driving between the 6th and 7th week post-surgery, female participants resumed driving between the 8th and 9th week postsurgery. This study aided in the veri cation of the fact that different study groups in part showcase drastically different results. For this reason, recommendations should be individualised as "one size ts all" recommendations are not helpful in this context.
A signi cant goal of regular driver who underwent a TKA or THA is the swift resumption of driving postsurgery. From a therapeutic perspective, this means that patients who wish to drive again shortly after surgery should receive individualised counsel and precise support so far as they are part of one of the risk groups mentioned above. By way of providing tailormade recommendations, the patient satisfaction can be positively in uenced. This is important since the patient's subjective interpretation of success after knee or hip replacement surgery is heavily impacted by the ful lment of the therapeutic expectations held by the patient.
A striking result of the gender analysis of postoperative driving was the binomial distribution of female participants. (Fig. 1) Male participants and a proportion of female participants behave similarly. A smaller proportion of female participants resumes driving later, in the 10th -12th week post-surgery.
Another result of the study was the discrepancy between participants who resided in the countryside and participants who resided in the city with regard to the timing of resumption following surgery. (Fig. 3) The authors de ned "city" with a population of ≥ 30.000 and "countryside" with a population of < 30.000.
This distinction is arbitrary, however, statistically, it showed signi cant differences with regard to when patients resumed driving post-surgery. The assumption is that "cities" boast a better transport infrastructure, which can be made use of and thus reduces the need for a car. Participants who reside in the "countryside" resumed driving considerably earlier (the Mode in the "countryside" was 13 participants in the 4th + 5th week post-surgery) than participants who reside in the "cities" (the Mode was 19 participants in the 6th + 7th week post-surgery). 58.6% of the participants gave a medical reasoning for the rst post-operative drive: a journey to a physical therapy appointment or a doctor's appointment. A hypothesised correlation between size of residential location and reason for the rst post-operative drive could not be statistically con rmed (p = 0.927).
In a number of studies [4,6,11,12,13,14] the operated side did not in uence the postoperative resumption of driving. Our results showcase a different picture: there was no trend in patients who had undergone a THA (p = 0.304), in patients who had undergone a TKA, however, there was a trend of patients with a right-side arthroplasty driving signi cantly later (p = 0.020). A possible explanation for this is that driving requires little hip movement, whereas the right knee has the key function of pressing the gas and brake pedals. Thus, roadworthiness largely depends on the functionality and performance of the right knee. Clearly, this aspect is very central to the decision of roadworthiness the patient must make prior to driving.
In a study by Rondon et al. 98.2% of the study participants resumed driving within the rst 12 weeks postsurgery. [5] We were able to deliver similar results, 92.4% of our study participants resumed driving in the rst 12 weeks post-surgery.
In our study, the average time frame in which participants resumed driving following a TKA or THA was between the 6th and 7th week post-surgery. We were not able to nd a signi cant difference between TKA and THA (p = 0.053). By contrast, Rondon et al. discovered a statistically signi cant difference between knee and hip arthroplasties (TKA = 4.4 weeks, THA = 3.7 weeks). [5] This discrepancies could be explained by two possible reasons. In Germany, health insurance providers are legally mandated to nance a three-week in-patient postoperative rehabilitation following knee or hip arthroplasty. Our participants were recruited from the patient population in the rehabilitation facility and were therefore all undergoing a three-week in-patient rehabilitation, they were discharged between the 4th and 5th week post-surgery. For our study participants there was therefore no reason to drive before their discharge date. In addition to this, the sample size in this study was considerably smaller (n = 92) than the sample size in the study conducted by Rondon et al. (n = 1044). [5] This could explain why we were unable to nd a statistically signi cant difference between total knee and hip arthroplasties with regard to the resumption of driving post-surgery. Rondon et al. identi ed the implementation of postoperative rehabilitation as a reason for later resumption of driving. [5] We identi ed a higher risk of being a "late driver" if the participant underwent a right-side procedure or if the participant was female. Rondon et al. delivered similar results, there, too, patients whose right side was operated, and female patients drove later. [5] In addition, we conducted an Odds Ratio test with regard to the risk of resuming driving later post-surgery. An "early driver" was de ned as a participant who resumed driving in the 4th + 5th week post-surgery. A "late driver" was de ned as a participant who resumed driving in the 10th + 11th week post-surgery. There was a signi cantly (p = 0.031) 9.00-fold (95% CI 1.01-79,54) increased risk for patients who had undergone a right-sided TKA not to resume driving in the 4th + 5th week post-surgery. The risk analysis for gender and joint revealed a signi cant (p = 0.00015) 21.08-fold increased risk (95% CI 3.64-121.83) of female patients who had undergone TKA resuming driving in the11th + 12th week post-surgery. It therefore appears that female participants heed the recommendation given by doctors more than male participants. Consequently, this implies that female patients who have undergone a TKA should receive special guidance and a more intensive rehabilitation program if they intend to drive post-surgery. Of the female participants 13.9% (n = 5) did not drive by the 13th week pot-surgery compared to 1.8% (n = 1) of the male participants.
Davis et al. (2018) showed that both male and female participants (n = 32) achieve their preoperative brake reaction time after the 2nd postoperative week. [6] Most of the participants drove with an automatic transmission. The operated side did not have an impact on how fast the preoperative brake reaction time was achieved. Gender, however, did: male participants reached their preoperative brake reaction earlier than female participants. [6] In Germany, a driver must evaluate his own roadworthiness before he can start his engine. Roadworthiness is de ned as the ability to operate the vehicle safely, regardless of situation. Limitations of roadworthiness, for example drug or alcohol consumption are prosecuted by the legislator, however there are no legislative speci cations regarding temporary physical limitations. The driver must evaluate himself in this regard and, provided he decides he is not roadworthy, refrain from driving. This selfevaluation is therefore crucial from a judicial standpoint. The present prospective study precisely examines this self-evaluation with regard to roadworthiness. was not feasible since the accident rate was not elevated in drivers who had undergone TKA or THA when compared to the general age population. Our participants did not report any accidents. From this we can conclude that the self-evaluation of roadworthiness following TKA and THA was adequate and the individual time frame chosen by the participants was responsibly chosen.
After TKA or THA patients experience considerable limitations of the function of their affected leg for an uncertain period of time. This is why they turn to their overseeing doctor or physical therapist, for recommendations regarding post-op resumption of driving. A glance at the current research literature as an anchor or orientation regarding this recommendations, does not deliver consistent evidence.
The available studies can be categorised into two groups: studies which record when patients drive postsurgery and respect their participants' self-evaluations and studies which use measurable parameters, most often brake reaction time, to recommend when patients can resume driving post-surgery.
In a review study by Latz et al. [14] a recommendation of 2 to 4 weeks of rest is made before resumption of driving after a TKA or THA. Goodwin et al. [15], on the other hand, recommend 10 days to 8 weeks of rest following a right-sided TKA and 6 to 8 weeks of rest following a right-sided THA before resumption of driving. When it comes to the brake reaction time a similar picture is painted: Marques et al. [16] recorded 44 ± 19 days for the patients to reach their preoperative brake reaction time following a right-sided TKA and 20 ± 15 days following a left-sided TKA. Nizam et al. [17], however, recorded a Median of 3 weeks following a TKA, regardless of side. Van der Velden et al. [12] and Huang et al. [18] saw a return to the preoperative brake reaction time 4 weeks following a TKA and was able to show an inverse correlation between brake reaction time and the "step-test" by Marmon et al. [19].
To our knowledge, this study is one of the few that provides a unique point of view regarding the reuptake of driving after TKA or THA procedures, from the perspective of rehabilitative orthopaedic therapy. It showcases that the patient self-evaluation after a TKA or THA procedure is actually, at least in Germany, the main criterion for making the decision to reuptake driving again.
There were several limitations related to our study. Because most patients with a TKA or THA undergo a three week bedridden rehabilitation in Germany, there is until the end of the 5th postop week, no reason to reuptake driving again. It could be considered that the bedridden rehabilitation impairs the patient to reuptake driving earlier than they actually do. This is a particularity of the German health care system and could be considered a limitation of this study, when compared with other national health care systems, where a bedridden rehabilitation after a TKA or THA is not a common practice. Also the fact that this is a single center study and although the study sample size was calculated, with the help of a statistician, prior to study begin, it is too small to upscale this study results at the national level and only re ects the postoperative driving practices after TKA or THA of one region of Germany.
The large bandwidth of results across the board and the resulting variance of recommendations likely leave the patient at a loss. An operational approach which would examine the skills required for safe driving and base recommendations on these parameters would be more practical. A low pain level, su cient range of motion (ROM) of the affected joint, unaided walking, safe entrance and exit from the vehicle, a preferably high score in the "step-test" and an acceptable brake reaction time seem to be the most crucial parameters to develop individual recommendations for patients. What role these parameters play in the decision-making process for the postoperative resumption of driving following a TKA or THA is unclear. Further research is required to examine the signi cance of these parameters in recommendations.

Conclusions
The key results of the present study are the signi cant differences of resumption of driving after surgery with regard to gender, place of residence, affected side and identi cation of high-risk groups.
When making the decision of when to resume driving following a TKA or THA patients should be advised individually. During the three-week in-patient rehabilitation program mandated in Germany patients should be supported and prepared, speci cally female patients who have undergone TKA. The authors aim to develop a training program which can be implemented during the in-patient rehabilitation stay, with which the right knee can be trained to prepare for driving following a TKA.