An In Vitro Evaluation of Plate Luting Using Osteotomized Equine Third Metacarpal Bones with a Limited Contact‐Dynamic Compression Plate

Abstract

To evaluate the effects of plate luting on the biomechanical properties of a broad limited contact-dynamic compression plate (LC-DCP) fixation to repair osteotomized equine 3rd metacarpal (MC3) bones. In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by LC-DCP fixation, with 1 of the pair luted with polymethylmethacrylate (PMMA). Ten pairs of adult equine cadaveric MC3 bones. Ten pairs of equine MC3 were divided into 2 test groups (5 pairs each) for (1) palmarodorsal 4-point bending single cycle to failure testing and (2) palmarodorsal 4-point bending cyclic fatigue testing. The LC-DCP (8 hole, 4.5 mm) was applied to the dorsal surface of each pair of MC3 bones. All plates and screws were applied using standard AO/ASIF techniques. All MC3 bones had mid-diaphyseal osteotomies. One of the matched pairs of LC-DCP-MC3 constructs were randomly chosen to be luted with PMMA. Mean test variable values for each method were compared using a paired t-test within each group; significance was set at P<.05. Mean palmarodorsal 4-point bending yield bending moment, failure bending moment of the LC-DCP fixation with luting was not significantly different (P>.05) than those of the LC-DCP fixation without luting. Mean cycles to failure for palmarodorsal 4-point bending was significantly (P<.0003) greater, with a 7.2-fold increase, for the LC-DCP fixation with luting compared with the LC-DCP fixation without luting. Luting the broad LC-DCP with PMMA in the fixation osteotomized equine MC3 bones increases the fatigue life of cyclic loading for palmarodorsal 4-point bending under the in vitro conditions studied. The cyclic fatigue data supports the conclusion that luted broad LC-DCP fixation is biomechanically superior to the non-luted broad LC-DCP fixation in osteotomized equine MC3 bones.