Session III - Injury Prevention
Purpose: The purpose of this IRB-approved study was to determine when brake reaction time returns to baseline following long bone or intra-articular fracture of the right lower extremity.
Background: The results of a recently completed pilot study looking at braking times after surgical fixation of right-sided ankle fractures revealed impaired function at 6 weeks with total brake time (TBT) returning to baseline 9 weeks postoperatively. This OTA-granted study continues our work with respect to other lower extremity fractures that may impact driving performance.
Methods: A validated computerized driving simulator was used. The Labview software (National Instruments, TX) was used to collect and display data. Three groups of subjects were tested. First, healthy volunteers (n=12) were tested once to establish normal mean values for variables tested (group 1). Group 2 consisted of 19 patients who underwent repair of a diaphyseal femoral (9) or tibia (10) fracture who were tested at 6, 9, and 12 weeks following surgery. Group 3 consisted of 26 patients who sustained an articular fracture of the tibia (3 acetabulum, 10 plateau, 8 pilon, and 5 calcaneus); they were tested at 12, 15, and 18 weeks after surgery. All patients were tested with a series of driving scenarios (city, suburban, highway) with reaction and response times to various stimuli recorded. SMFA's scores were recorded at each test session and compared to results of the driving test. Descriptive statistics (mean + SD) of the subjects' demographic data and results of clinical and functional outcome measures are reported. In addition, repeated analysis of variance was used to investigate effect of visit and testing condition on brake reaction time. A p value <0.05 was considered significant.
Results: Total brake time was 1,114 msec for the control group. For femoral shaft fractures, TBT was 1,392 msec, 1,137 msec, and 1,163 msec at 6, 9, and 12 weeks postoperatively. For tibial shaft fractures, TBT was 2,100 msec, 1,329 msec, and 1,397 msec at 6, 9, and 12 weeks after surgery. For tibial plateau fractures, TBT was 1,349 msec, 1,225 msec, and 1,261 msec at 12, 15, and 18 weeks postoperatively. For Pilon fractures, TBT was 2,214, 1,694 msec, and 1,671 msec at 12, 15, and 18 weeks after surgery. TBT consistently improved for each of the driving scenarios between the first and second test date. (p=0.05) No correlation was seen between functional testing and computer-generated data.
Conclusion: By 9 weeks, driving performance in patients who have undergone fixation of femoral and tibial shaft fractures returns to normal baseline. The return to baseline is seen at 15 weeks for articular fractures of the lower extremity. In all cases it appears that braking function follows return of ambulation by 3 weeks. Patients may be allowed to drive early in their postoperative course if weight bearing is begun early.