A mechanical comparison between conventional and modified angular plates for proximal humeral fractures.

The objective of this study is to present a modified angular blade plate for fixing 2-part and even 3-part fractures of the proximal humerus, as well as the results of the comparative mechanical test between the conventional angular blade plate and this new modified plate. The plates were tested in flexion and rotational trials in a wooden model that simulated a 2-part humeral fracture of the proximal extremity. The results (mean +/- SD) of bending strength and stiffness obtained after testing showed findings of 601 +/- 349 N and 0.5 +/- 0.2 N/mm, respectively, for the conventional plate and 4005 +/- 164 N and 3.9 +/- 0.7 N/mm, respectively, for the modified plate. The torsional stiffness test showed findings of 1.26 +/- 0.09 KN.mm degrees for the conventional plate and 1.74 +/- 0.21 KN.mm degrees for the modified plate. The test of torsional moment showed findings of 57.0 +/- 7.6 KN.mm for the conventional plate and 115.2 +/- 9.3 KN.mm for the modified plate. The test of angular displacement at the torsional moment showed findings of 50.8 degrees +/- 7.2 degrees for the conventional plate and 70.2 degrees +/- 2.6 degrees for the modified plate. The results of the mechanical trials of flexion and rotation were superior for the modified angular blade plate compared with the conventional angular blade plate.