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Vet Comp Orthop Traumatol 2025; 38(04): 178-185
DOI: 10.1055/s-0044-1800973
Original Research

The Effect of Locking Head Inserts on the Biomechanical Properties of a 3.5-mm Broad Locking Compression Plate When Used in an Open Fracture-Gap Model

William T. G. Hawker
1   Department of Clinical Studies, The Ontario Veterinary College, Guelph, Canada
,
Noel Moens
1   Department of Clinical Studies, The Ontario Veterinary College, Guelph, Canada
,
Bruce Guest
2   School of Engineering, University of Guelph, Guelph, Ontario, Canada
,
Michelle Oblak
1   Department of Clinical Studies, The Ontario Veterinary College, Guelph, Canada
,
Melissa MacIver
1   Department of Clinical Studies, The Ontario Veterinary College, Guelph, Canada
,
John Runciman
2   School of Engineering, University of Guelph, Guelph, Ontario, Canada
› Author Affiliations
Funding Funding for this research was provided by the Ontario Veterinary College Pet Trust Fund. The research funder had no additional involvement in research design or manuscript preparation.
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Abstract

Objective To determine the effect of locking head inserts (LHI) on plate strain, stiffness, and deformation when applied to a 3.5-mm broad locking compression plate (LCP) in an open fracture-gap model.

Study Design Six, 13-hole, 3.5-mm broad LCP were secured to epoxy bone models with a 10 mm central defect and 1 mm plate offset. Two peripheral locking screws were placed in each segment, with the remaining screw holes left unfilled. Three strain gauges were glued to each LCP at anticipated regions of maximum strain. Constructs underwent cyclic uniaxial loading at a rate of 20 mm/min to 400 N in three different configurations (Configuration 1: no LHI, Configuration 2: 3 LHI, Configuration 3: 9 LHI). LHI were tightened to 4 Nm of torque. A data acquisition system was used to collect implant strain during testing. Construct stiffness and deformation were recorded by the biomechanical testing machine.

Results Maximum implant strain was recorded at the central screw hole directly over the simulated fracture gap in all configurations (Mdn 1,837.3 µε [interquartile range: 1,805.1–1,862.0]). There was no difference in implant peak-to-peak strain with addition of LHI at all three gauges (Gauge 1 [p = 0.847], Gauge 2 [p = 0.847], Gauge 3 [p = 0.311]). Similarly, peak-to-peak displacement (p = 0.069) and axial construct stiffness (p = 0.311) did not change with the addition of LHI.

Conclusion The addition of LHI to a 3.5-mm broad LCP construct was not shown to have an effect on plate strain, stiffness, or deformation.

Keywords

biomechanics - implants - locking plates - MIPO - locking head inserts

Authors' Contribution

W.T.G.H. contributed to the design of the study, compiled the data, analyzed the data for statistical significance, interpreted the data, and drafted and revised the manuscript. N.M. contributed to the design of the study, assisted with data interpretation, and provided scientific in-line editing of the manuscript. B.G. contributed to the design of the study; assisted in biomechanical analysis, instrumentation, and experimental design. M.O. contributed to the design of the study; critical revisions of the final manuscript. M.M. contributed to the design of the study; critical revisions of the final manuscript. J.R. contributed to the design of the study; assisted in biomechanical analysis, instrumentation, and experimental design. All authors provided a critical review of the manuscript and endorse the final version. All authors are aware of their respective contributions and have confidence in the integrity of all contributions.


Supplementary Material



Publication History

Received: 22 May 2024

Accepted: 19 November 2024

Article published online:
21 January 2025

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