Driving reaction times in patients with foot and ankle pathology before and after image-guided injection: pain relief without improved function.

BACKGROUND: Foot and ankle pathology is common in the driving population. Local anesthetic steroid injections are frequent ambulatory treatments. Brake reaction time (BRT) has validated importance in motor vehicle safety. There are no prior studies examining the effect of foot and ankle pathology and injection treatment on the safe operation of motor vehicles. We studied BRT in patients with foot and ankle musculoskeletal disease before and after image-guided injection treatment.

METHODS: A total of 37 participants were enrolled. Image-guided injections of local anesthetic and steroid were placed into the pathological anatomical location of the right or left foot and ankles. A driving reaction timer was used to measure BRTs before and after injection. Patients suffering right "driving" and left "nondriving" pathology as well as a healthy control group were studied.

RESULTS: All patients reported >90% pain relief postinjection. All injections were confirmed to be accurate by imaging. Post hoc Bonferonni analysis demonstrated significant difference between the healthy group and the right-sided injection group (P = .008). Mean BRT for healthy controls was 0.57 ± 0.11 s. Patients suffering right foot and ankle disease displayed surprisingly high BRTs (0.80 ± 0.23 s preinjection and 0.78 ± 0.16 s postinjection, P > .99). Left nondriving foot and ankle pathology presented a driving hazard as well (BRT of 0.75 ± 0.12 s preinjection and 0.77 ± 0.12 s postinjection, P > .99). Injections relieved pain but did not significantly alter BRT (P > .99 for all).

CONCLUSION: Patients suffering chronic foot and ankle pathology involving either the driving or nondriving side have impaired BRTs. This preexisting driving impairment has not previously been reported and exceeds recommended cutoff safety values in the United States. Despite symptom improvement, there was no statistically significant change in BRT following image-guided injection in either foot and ankle.

LEVELS OF EVIDENCE: Therapeutic, Level II: Prospective Comparative Study.