Measurement of brake response time after right anterior cruciate ligament reconstruction.

Recommendations on safe driving after anterior cruciate ligament (ACL) reconstruction have been largely intuitive. This study evaluated 12 male patients who underwent ACL reconstruction with subsequent outpatient rehabilitation and compared them with 10 subjects who had no knee dysfunction. The following clinical measures were assessed every 2 weeks for 10 weeks: brake response time (BRT), 6-meter walk time (6MWT), knee range of motion (ROM), pain (visual analog scale), and joint effusion. Statistical testing was completed using analysis of covariance with repeated measures. The results from treatment group were compared with norms from the AAA Traffic Safety and Engineering Department. BRT showed significant differences over 10 weeks (P =.043) in the study group. There were no significant differences between the study and control group based on condition (ACL reconstruction v control) (P =.586). Pain and effusion were found to have no significant interaction effect on BRT. The treatment group's BRT increased from the 25th percentile (AAA normals) to the 87th percentile after 10 weeks of rehabilitation. Although treatment group BRT was equal to AAA normal population BRT at week 4, the large improvement from week 2 to week 4 meant that learning effects could not be ruled out until week 6. Significant differences were found for 6MWT between week 2 and all other weeks (P <.0001). The results suggest brake reaction time matches control times at 4 to 6 weeks. Thus, BRT might be used to establish return to driving criteria (in part) after ACL reconstruction if other driving impediments do not exist.