Development of a Lower Extremity Mobility Assessment Methodology for Motor Vehicle Operation and Initial Validation

Limited quantifiable data exists on lower extremity mobility and function during driving. To date, the most appropriate existing measures of successful driving function are assessed by a driving rehabilitation specialist during an on-road evaluation. Establishing the kinematic chain- or the order and magnitude in which joints are moved- during driving may prove to be a useful tool in lower extremity function assessment in drivers. To this end, a study was conducted instrumenting both the left and right legs of healthy licensed male drivers (18-26 years old) with a system of angle measuring goniometers (Biometrics, Ltd.) in a driving simulator (DriveSafety CDS-250). The motions across the hip, knee and AFC joints were measured during active driving simulator scenarios, performing pedal tasks with both the right and left leg. Subjects completed 3 trials for each leg in which they were required to respond to braking tasks and peripheral queuing, and comparisons between left versus right leg driving over time were conducted for measuring brake response time, return to gas movement time, and joint angle minimums, maximums, and ranges of motion. Kinematic chain joint angles were also correlated against each other so as to yield a slope and strength of correlation, allowing the development of a numerical assessment of the kinematic chain. Results of this work indicate that left leg driving requires characteristically different kinematic chain in lower extremity motions, primarily with respect to the altered use of AFC inversion/eversion. Left limb correlation values were found, in general, to have a higher value, indicating a greater degree of repeatable gross motor movement. Right leg motions showed a greater range of fine motor control, which could be characteristic of dominant leg driving in general. Similar movement patterns were found in both phases of pedal transition, both the brake application and the return from brake to gas. This study showed that the distinctive motions seen in right versus left-footed driving can indeed be characterized by goniometric application. Further studies should explore the effects of left leg driver training in a longitudinal manner, testing this driving task over the period of several weeks. If these future studies show a development and improvement of left leg driver performance, patients undergoing right leg orthopedic procedures could be taught to drive effectively with the left leg during rehabilitation for extended periods of time, thereby allowing those patients to maintain their independence.