Objective: This study aims to develop and evaluate a simple tool for daily practice that might allow a rough estimate of individual braking performance (brake response time, BRT) of patients with osteoarthritis or those with arthroplasty of the knee or hip.
Methods: In this cross-sectional study, we examined 162 patients (72 men, 90 women; mean age = 64±12.8 years) who suffered from osteoarthritis of the knee (n=45) or hip (n=64) or who underwent a total hip (n=37) or knee (n=16) arthroplasty. BRT of each patient was measured in a brake simulator. The results were compared to demographic data, various clinical tests, and pain surveys. From these data, a multiple linear regression model was developed.
Results: From the observed correlations, the regression model consisted of age (correlation with BRT τ=0.176, p=0.001), sex (τ=0.361, p<0.001), Hau's step test (τ=-0.345, p<0.001), and the pain dimension of the Hip disability/Knee injury and Osteoarthritis Outcome Score (τ=-0.265, p<0.001). We, therefore, suggested the following formula: BRTest = 634.8 - (8.8 x Hau) + 119.2 (for women) + (3.0 x age) - (1.3 x H/KOOS Pain). The above-mentioned variables contributed significantly to the prediction of BRT and could achieve a multiple R² adj of 0.31. The model leaves a residual standard error (i.e., SD of the residuals) of 158.4 ms, which is superior to a model without predictors; F (4.140)=16.8, p<0.001.
Conclusion: Our evaluated regression model offers an uncertainty which is comparable to the one based on a fixed time period after surgery or a defined pathologic condition. The high variability even within a single patient over several brake simulator measurements makes it unlikely for a model to be generated solely based on clinical testing. Taking the available data in literature into account, we advise caution when formulating a real-time- or condition-based recommendation. We rather suggest being aware of risk factors that might lead to impaired BRT to sensitize patients to their impaired ability to drive. We identify such risk factors, namely old age, female sex, impaired musculoskeletal function, as tested in Hau's step test, and high levels of pain.
Level of evidence: Level III, Therapeutic Study.