Finite element analysis, mechanical assessment and material comparison of two volar slab constructs.

Abstract

In order to help prevent joint stiffness, the injured or postoperative hand is splinted in the intrinsic-plus position. We aimed to determine the strongest type of volar slab construct that would be appropriate in this treatment. Two constructs were compared, a double-ridged and a non-ridged slab. Two materials were used, plaster of Paris (POP) and resin. We performed finite element analysis (FEA) and mechanical assessment to establish which combination of construct and material resulted in the strongest volar slab. We were unable to form ridges on the resin slab, and therefore this construct was not tested. Finite element analysis showed that most stress occurred at the wrist region, where all the slabs failed. The double-ridged POP slab was found to be 5.3 times stronger than the non-ridged POP slab and 1.4 times stronger than the non-ridged resin slab (p<0.001). To improve strength of the conventional POP volar slab, we suggest forming two anterior ridges in the plaster.