HUMAN ULNAR BENDING STIFFNESS, MINERAL-CONTENT, GEOMETRY AND STRENGTH

Predictability of ulnar strength in three point bending by measurements of bending stiffness, mineral content, and geometry was studied in 45 embalmed human ulnae. All bones were tested wet. Mineral content, width (mediolateral), and depth (anteroposterior) were determined 1/3 of the ulnar length proximal to the head. The correlation coefficient between breaking strength and bending stiffness was 0. 958. The correlation coefficient between strength and mineral content was 0. 947. The highest correlation between strength and a geometrical parameter was with cross-sectional area estimated from width and depth: r equals 0. 754. Use of a regression function relating strength to stiffness and width together improved the strength estimate. The correlation coefficient between predicted and actual strength was 0. 962 (standard error of estimate of 37 lb or 11% of the mean value). It is concluded that ulnar strength can best be estimated noninvasively from measurements of bending stiffness or mineral content.