Relation between form and function in the sacroiliac joint. Part II: Biomechanical aspects.

The amount of friction between the articular surfaces of sacroiliac (SI) joints was determined and related to the degree of macroscopic roughening. Results show that articular surfaces with both coarse texture and ridges and depressions have high friction coefficients. The influence of ridges and depressions appears to be greater than that of coarse texture. The data are compatible with the view that roughening of the SI joint concerns a physiologic process.