Proposed Provisional Reference Values for the Humerus for Evaluation of Injury Potential

A humerus provisional reference value (PRV) based on human surrogate data was developed to help evaluate upper arm injury potential. The proposed PRV is based on humerus bone bending moments generated by testing pairs of cadaver arms to fracture in three-point bending on an Instron testing machine in either lateral-medial (L-M) or anterior-posterior (A-P) loading, at 218 mm/s and 0.635 mm/s loading rates. The results were then normalized and scaled to 50^th and 5^th percentile sized occupants.

The normalized average L-M bending moment at failure test result was 6 percent more than the normalized average A-P bending moment. The normalized average L-M shear force at failure was 23 percent higher than the normalized average A-P shear force. The faster rate of loading resulted in a higher average bending moment overall - 8 percent in the L-M and 14 percent in the A-P loading directions. The faster rate of loading gave 3 percent higher and 11 percent higher shear forces in the L-M and A-P directions respectively.

The differences between the two loading rates and L-M and A-P directions however were not statistically significant. The proposed PRV for the 50^th percentile occupant is F_x = F_y = 2.5 kN and M_x = M_y = 230 N·m. The proposed PRV for the 5^th percentile occupant is F_x = F_y = 1.7 kN and M_x = M_y = 130 N·m.