Effect of total hip arthroplasty on brake reaction time and braking force

The correct moment for return to driving after total hip arthroplasty (THA) remains unclear. Until today no uniform recommendation exists on the ability to perform an emergency brake.The aim of this prospective study was to investigate the braking ability of patients before and after THA implantation based on brake reaction time in milliseconds (BRT) and braking force in N (BF).

In total, 25 patients (15 men, 10 women, mean age 51.3 ± 10.1 years) were treated with THA on the right side. Inclusion criteria consisted of a valid driving licence, frequent road participation and at least 2 years of driving experience. Exclusion criteria were underlying neurological disorders as well as severe complaints in the lumbar spine and the right knee joint. The brake ability was evaluated for emergency braking with a car simulator and a measuring sole. Measurements were performed preoperatively, 6 days, 2, 4 and 6 weeks after surgery.

Preoperatively, the mean BRT was 671.3 ± 123.5 ms and the BF 455.4 ± 185.0 N. Significant differences were observed at 6 days and 2 weeks after surgery, (BRT 836.4 ± 219.7 ms, respectively, BRT 735.0 ± 186.7 ms, and BF 302.6 ± 154.9 N, respectively, BF 375.5 ± 149.3 N, p < 0.05). Only 4 weeks after, no significant differences were seen compared to pre-operative with a BRT of 647.0 ± 91.9ms (p = 0.354) and BF of 435.9 ± 177.4 (p = 0.843). Furthermore, the BRT improved significantly after 6 weeks (607.4 ± 87.6; p = 0.005).

The braking force is significantly reduced, and the brake reaction time is prolonged directly after surgery for at least 2 weeks. After 4 weeks, no statistically significant differences were measured, although special care should still be taken during return to activity.