Anthropometry of Wheeled Mobility Project: Final Report

3.3.8 Knee Clearance Depth, minimum

Knee clearance depths for the four sets of standards range from 200 mm (8 in.) in Canada to 280 mm (11 in.) in the U.S. (Figure 3‒8). None of the comparison studies used for this report provided anthropometric information about knee clearance depth. The results of our study suggest that a large percentage of WhMD users are not accommodated by the standards. The U.S. standard on knee clearance depth accommodated just over 50% of our overall sample, and was well below the 80th percentile values of maximum knee height for manual wheelchair users (369 mm or 14.5 in.) and power chair users (345 mm or 13.5 in.). Even fewer would be accommodated by the standards of the U.K., Australia and Canada. A knee clearance depth of over 400 mm (16 in.) is needed to accommodate close to 95% of our sample’s manual and powered wheelchair users.

* indicates data plotted in the graph

** does not include individuals with an above-knee right leg amputation (n=7) or with the right leg constrained in fully extended position (n=3) such as in an orthopedic cast.

Figure 3-8. Knee clearance depth: research findings versus the standards