Slipping cane and crutch tips. Part I--static performance of current devices.

A variety of commercially available cane and crutch tips were tested on surfaces of ice and soapy tile under varying axial (thrust) loads. The output measurement consisted of the angle between the vertical and the cane axis at which slip occurred. It was learned that: 1. From the viewpoint of a user, a minimal slip angle of roughly 25 deg is desirable. 2. On ice-rink ice, a number of cane tips approach the desired slip angle under conditions of low temperature; fewer appear safe at elevated air temperatures. Only one of the tested devices appears truly safe under any ice condition. 3. On rough tile flooded with soapy water, some cane tips offer adequate performance. However, no tested cane tip offers acceptable performance on slick tile flooded with soapy water. 4. There appears to be no simple relationship between the slip performance of a cane tip on ice-rink ice and that developed on soapy wet tiles. 5. No simple relationship between thrust load and slip angle emerged. Similarly, no simple relationship between contact area and slip appeared in the data.