A biomechanical evaluation of different plates for fixation of canine radial osteotomies.

BACKGROUND AND METHODS

The biomechanical properties of plates depend on their geometries and elastic moduli. The low contact-dynamic compression plate (LC-DCP) with relieved undersurfaces is a modification of the dynamic compression plate (DCP). Little attention has been directed toward comparison of the biomechanical properties of the LC-DCP and the DCP. This study compared the stiffness and strength of bone-plate constructs using plates of various designs and materials for fixation of radial osteotomies. In 20 matched pairs of canine radii, midshaft transverse osteotomies were created and fixed with 3.5-mm eight-hole plates on the volar surface. In 10 pairs, stainless-steel LC-DCPs and stainless-steel DCPs were applied. In the other 10 pairs, stainless-steel LC-DCPs and titanium LC-DCPs were placed. Bending and torsional stiffness were determined. The plates were removed, and a 5-mm gap was created at the osteotomy site. The plates were reapplied to the bones with the interfragmental gap. Stiffness and yield point in the anteroposterior direction were determined.

RESULTS

In the absence of a bone gap, no statistically significant differences in construct stiffness were seen between the paired groups. In the presence of a gap, the stainless-steel LC-DCP construct was stiffer than the titanium LC-DCP construct (p = 0.02), and the DCP construct was stiffer than the LC-DCP construct (p = 0.002). The yield point of the DCP-bone construct was 59% greater than that of the stainless-steel LC-DCP construct (p = 0.02). However, the yield points of the titanium and stainless-steel LC-DCP-constructs were similar (p = 0.35).

CONCLUSION

The similar results between constructs in the absence of a gap indicate that plate design and material properties may be less significant for achieving adequate stability after plate fixation of simple fractures. The use of the stiffer dynamic compression plate may be advantageous when maximum stability is required, such as with comminution or bone loss.