In vitro mechanical evaluation of a limited contact dynamic compression plate and hybrid carpal arthrodesis plate for canine pancarpal arthrodesis

Abstract

The mechanical advantages of the HP over the LC-DCP make it a viable alternative for PCA. Smaller CC, MAD and PSS of the HP may reduce the risk of implant failure and postoperative morbidity following PCA.

The effect of external coaptation on plate deformation in an ex vivo model of canine pancarpal arthrodesis

“…The maximum strain recorded during testing to 60% of body mass in the present study was -310 με. This magnitude is in broad agreement with that documented in a recent study where cadaver PCA constructs stabilised with a hybrid plate and loaded to 40% of body mass experienced strains of 269 με ±100 με, and when loaded to 80% of body mass, strains of 646 με ± 259 με were experienced (23). The hybrid PCA plates used in that study were contoured to provide an additional 20° of extension, by introducing an acute bend centered over the solid region of the plate between the R4 and RCB screw holes, and subsequent strain recordings were made from a site equivalent to the INT site in this study.…”

“…To accurately replicate the manner of loading experienced by a PCA construct in vivo would be extremely difficult, and a simplified system using axial loading has been used in previous biomechanical studies of distal limb arthrodesis (16,17). In common with other mechanical studies of canine PCA, we elected to leave the articular cartilage and palmar supporting structures to the carpus intact (17,23). Although this does not precisely replicate the clinical situation, in which these structures are variably disrupted, the contribution of the palmar support to the overall construct stability remained uncertain, and it was therefore left intact to minimise the variation between specimens.…”

Mechanical Evaluation of Two Hybrid Locking Plate Designs for Canine Pancarpal Arthrodesis

“…Six RH and OH hybrid locking pancarpal arthrodesis plates accepting 3.5 mm and 2.7 mm screws were manufactured from implant-grade stainless steel (316L) by DePuy Synthes (Paoli, PA). The implants were consistently prebent for 20° joint fusion angle using a custom-made bending press ( Figure 2 ) [ 17 ]. The press was designed to consistently and accurately bend the plates at a point centered at the solid plate section between the distal radial and radiocarpal holes ( Figure 1 ).…”

“…Whereas the latter plate design may facilitate plate application, it could diminish its mechanical strength by lowering the area moment of inertia near the point of maximum stress. While the mechanical superiority of hybrid compression plates over standard limited contact compression plates has been demonstrated in a recent study [ 17 ], comparisons between the two novel designs are lacking. Furthermore, the effect of an oval radiocarpal hole on the structural parameters of the plate has not been tested.…”

Progress in Articular Surgery

“…This is despite the potential biomechanical limitations of application of the bone plate on the non-tension surface. Guillou and colleagues in their very elegant study published in this issue compared standard bone plates and tapered hybrid plates under conditions of cyclic axial loading, to mimic loading conditions at the stance, walk and trot (5). Although these in vitro tests have limitations, they more closely replicate the clinical situation than acute quasi-static loading to failure.…”