When is it Safe to Drive After Total Ankle Arthroplasty?

Background: With the increase in the number of total ankle arthroplasties (TAA), guidelines on when physicians should begin to consider patients' return to driving are valuable. Further, due to sagittal motion strength, the ankle is the most important mover in braking motions over the knee and hip.
Questions/purposes: (1) Does brake-reaction time return to a safe value within 6 weeks of TAA? (2) Are there factors associated with a delay of return of brake-reaction time to safe values after TAA?
Methods: After obtaining institutional review board approval for the study, we prospectively recruited 60 patients undergoing right TAA. A large proportion of the patients undergoing TAA during the period were recruited. Patients who had extensive concomitant surgery, such as triple arthrodesis or tibial osteotomy, were excluded from the study. Patients were between 43 and 83 years old (median, 63 years), and 35 (59%) were men. Brake-reaction time was tested at 6 weeks postoperatively and repeated weekly until patients achieved a passing brake-reaction time. A control group of 20 volunteer participants matched for age and sex who did not have right lower-extremity pathology or pain were used to establish a passing brake-reaction time of 0.850 seconds. Patients were given a novel driver-readiness survey to complete; a score of 10 of 15 points or higher was considered a passing score. The following factors were explored for their association with brake-reaction time: age, American Orthopaedic Foot and Ankle Society (AOFAS)-Hindfoot assessment and VAS for pain via a patient-reported survey, and ankle plantarflexion and dorsiflexion via dedicated weightbearing lateral radiographs made with the ankle in maximum plantarflexion and dorsiflexion.
Results: At 6 weeks postoperatively, 92% of patients (54 of 59) achieved a passing brake-reaction time and were considered able to drive safely, and the mean brake-reaction time of the patients with a passing brake-reaction time was 0.626 seconds (± 0.111). At 9 weeks, all patients who completed the study achieved a passing brake-reaction time. Patients with a failed brake-reaction time at 6 weeks had greater median VAS scores for pain (3 [interquartile range 2 to 7] versus 1 [IQR 0 to 3]; p = 0.022) and diminished ankle plantarflexion (14° [± 5°] versus 24° [± 10°]; p = 0.037) compared with those with a passing brake-reaction time at that time point. All five patients with a failed brake-reaction time also had a failing score for the driver-readiness survey.
Conclusions: More than 90% of patients in this series achieved a safe brake-reaction time within 6 weeks of TAA, and those who did not were more likely to have had more pain and a stiffer ankle. Surgeons might counsel patients with persistent pain and stiffness at 6 weeks to delay driving for an additional 3 weeks, since by 9 weeks after TAA, all patients in this series had a brake-reaction time comparable with patients who had not undergone surgery. Future studies might elucidate what key gaps in knowledge remain and determine a practical way to answer these questions.
Level of Evidence: Level II, therapeutic study.