Anthropometry of Wheeled Mobility Project: Final Report

3.3.6 Knee Clearance Height, minimum

Knee clearance heights for the four sets of standards range from 650 mm (25.6 in.) (Australia) to 700 mm (27.6 in.) (U.K.) (Figure 3‒6). The U.S. standard for knee clearance height is 685 mm (27 in.). The U.K. BS8300 results for knee clearance height suggest that current U.K. standard generally accommodates most wheelchair users in that country. In the case of the U.S. and Canadian standards, however, the level of accommodation drops to 80% in relation to measured knee heights among wheelchair users in their respective countries.

A review of photographs of participants in the IDeA sample indicated that the largest individuals are not always the ones who need the greatest knee clearances. Smaller individuals who have large thighs, those with high seats and scooter users also have high lap heights. Individuals with extended footrests and scooter users have deep knee clearances but not necessarily high knee clearances.

* Indicates data plotted in the graph.

** Does not include individuals with an above-knee right leg amputation (n=6) or with the right leg constrained in fully extended position (n=3) such as in an orthopedic cast.

Figure 3-6. Knee clearance height: research findings versus the standards.