A biomechanical comparison of 3.5 locking compression plate fixation to 3.5 limited contact dynamic compression plate fixation in a canine cadaveric distal humeral metaphyseal gap model

Abstract

Objective-To compare the biomechanical properties of 3.5 locking compression plate (LCP) fixation to 3.5 limited contact dynamic compression plate (LC-DCP) fixation in a canine cadaveric, distal humeral metaphyseal gap model in static axial compression and cyclic axial compression and torsion.Study Design-Biomechanical in vitro study.Sample Population-30 paired humeri from adult, medium to large breed dogs.Methods-Testing was performed monotonically to failure in axial compression on ten pairs of humeri, cyclically in axial compression for 10,000 cycles on ten pairs and cyclically in torsion for 500 cycles on the last ten pairs.Results-Humeral constructs stabilized with LCPs were significantly stiffer than those plated with LC-DCPs when loaded in axial compression (P=0.0004). When cyclically loaded in axial compression over 10,000 cycles, the LC-DCP constructs were significantly stiffer than those constructs stabilized with LCPs (P=0.0029). Constructs plated with LC-DCPs were significantly more resistant to torsion over 500 cycles than those plated with LCPs (P<0.0001), though no difference was detected during the first 280 cycles.iii Conclusions-The increased stiffness of LCP constructs in monotonic loading compared to constructs stabilized with non-locking plates may be attributed to the stability afforded by the plate-screw interface of locking plates. The LCP constructs demonstrated less stiffness in dynamic testing in this model, likely due to plate-bone offset secondary to non-anatomic contouring and occasional incomplete seating of the locking screws when using the torque-limiting screw driver.Clinical Relevance-LCPs yield less stiff fixation under dynamic loading than conventional LC-DCPs when applied to severely comminuted, metaphyseal fractures.Improving anatomical contouring of the plate and insuring complete screw insertion into the locking plate hole may improve stiffness when using LCPs in comminuted fractures.iv ACKNOWLEDGEMENTS

Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices

“…Many previous studies have used clamped loading conditions. 9 , 10 , 12 – 14 , 16 , 21 – 25 This study showed that clamped loading conditions were relatively insensitive to the positioning of screws. In our experimental tests, some motion was seen from the digital image correlation, which revealed that the clamp was not completely restraining movement.…”

Radiographic Assessment of Implant Failures of Titanium 3.5 LCP vs. 4.5 LCP Used for Flexible Bridging Osteosynthesis of Large Segmental Femoral Diaphyseal Defects in a Miniature Pig Model

“…In spite of increasing knowledge on bone healing in fractures and associated biomechanical aspects (Perren and Cordey 1980;Rahn 1982;O'Sullivan et al 1989;Hulse et al 1997;Hulse et al 2000;Gautier and Sommer 2003;Wagner 2003;Aguila et al 2005;Koch 2005;Tyler et al 2008;Zahn et al 2008;Filipowicz et al 2009;Goh et al 2009) and the increasing quality of bone implants, bone nonunion remains a frequent problem both in human and veterinary medicine (Lambiris et al 2007). It is presumed that bone regeneration and successful bone defect healing may be supported by transplantation of mesenchymal stem cells in combination with biomaterials Nečas et al 2009).…”

Mathematical Modelling of Crack Fractography after Implant Failure of Titanium 4.5 LCP Used for Flexible Bridging Osteosynthesis in a Miniature Pig

“…The testing of mechanical properties of some types of fracture fixations and verification and comparison of their strength and resistance ability to various types of acting forces are currently of significant scientific interest as evidenced by some studies (Hulse et al 1997;Zahn et al 2008;Filipowicz et al 2009, Urbanová et al 2010). However, in these studies, it is not clearly defined which acting force causes eventual implant failure.…”