SLR - July 2015 - Lonny Nodelman
Reference: Yousri T, Jackson M. Ankle fractures: When can I drive doctor? A simulation study, Injury. 2015 Feb;46(2):399-404.Scientific Literature Review
Reviewed By: Lonny Nodelman, DPM
Residency Program: Cambridge Health Alliance
Podiatric Relevance: A common question posed by patients following ankle fractures, whether they are treated non-operatively or operatively, is when it is safe to drive. Previous studies have examined this question but tested brake response time instead of focusing on ability to apply a certain force to the brake. Although reaction time is of importance, being able to apply a certain force and sustaining this force is equally important to bring a vehicle to a stop.
Methods: Patients recruited to this study sustained right-sided ankle fractures that were treated conservatively or with open reduction internal fixation. It was required that the fracture be radiographically united and that the patient was fully weight bearing. The Drive Test Station (DTS) is a simulator used in the UK for assessment of a disabled patient’s ability to drive and was used in this pilot study. A brake power test and visual reaction time test was performed for each study subject and the contralateral non-injured limb was utilized as a control. A worst-case scenario was tested with the subject having to perform an emergency stop of a vehicle traveling 70 mph. The authors performed a validation test to confirm that the non-operative left limb could be used as a control. To assess this, 26 normal subjects were recruited and visual reaction times were tested using both the right and left limb.
Results: A total of 12 patients with right ankle fractures were tested with a mean age of 40 and with an average driving experience of 21.7 years (or 10,000 miles on average per annum). Five patients were treated in plaster and the other seven underwent open reduction with internal fixation. Patients were tested within 3 weeks of coming out of immobilization and being cleared for full weight bearing without restriction. The average time in plaster immobilization was 52 days. The average maximum brake pedal force was 34.4 kg. All subjects were able to hold this force for at least 5 seconds and with minimal discomfort. The average total visual reaction time (the time from visual stimulus to the time of task completion with a force of 35 kg applied to the brake pedal) of the injured and control limb was 0.79 seconds and 0.86 seconds, respectively. The visual pathway reaction time for the injured and control limb was 0.41 seconds and 0.39 seconds, respectively. Paired t-test demonstrated no statistical difference between the injured and non-injured limb. To assess validity of using the non-injured limb as a control, 26 normal subjects were recruited and a paired sample t-test demonstrated no significant difference between the right and left limb.
Conclusions: Current literature does not provide guidance for physicians treating ankle fractures as to when it is safe to clear a patient to drive. As described by the current investigators of this pilot study, most reports focus on reaction time. This is important; however, equally important is ability to administer and to sustain a certain force to the brake to ensure that a vehicle can come to a stop. In this particular study with a limited sample size, subjects were able to sustain a force of 350 N for 5 seconds, which is likely more than necessary for most modern cars. Rehabilitation following traumatic injury to the distal extremity is complex and there is no objective testing that dictates when it is safe to return to driving. In addition to this, it is difficult to apply the knowledge ascertained from this particular study to other populations. The study did not mention the nature of ankle injury sustained (isolated malleolar, bimalleolar, trimalleolar, syndesmosis involvement, etc…) which adds an additional level of complexity to the analysis and requires further study. The DTS may be of benefit in the podiatric surgical clinic to assess a patient’s ability to safely return to the wheel but clearly further study validation is necessary.