Vet Comp Orthop Traumatol 2020; 33(06): 458-460
DOI: 10.1055/s-0040-1718727
Letter to the Editor

Reply to Plate Stress Does Not Decrease When Working Length is Increased

MacArthur L. Sandra
1  Pitt County Animal Services/Spay Today, Greenville, North Carolina, United States
,
Matthew D. Johnson
2  Department of Small Animal Clinical Sciences, American College of Veterinary Surgeons-Small Animal, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States
,
Lewis D. Daniel
2  Department of Small Animal Clinical Sciences, American College of Veterinary Surgeons-Small Animal, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States
› Author Affiliations

We would like to thank Dr Roe for his insightful comments regarding plate working length and plate strain.[1] The effects of varying plate working length on plate strain are somewhat of a Pandora's box and are a contentious issue in orthopaedics. Studies evaluating this relationship have reported variable results which, in part, can be ascribed to differences in study design and methodology; did the study utilize non-locking or locking plates, were the plates in direct contact or positioned remote to the cortical surface, what was the plate bridging ratio and plate span ratio and, as astutely pointed out by Dr Roe, what was the simulated fracture gap?[1] [2] [3] [4] [5] [6] [7] [8] [9] When employing the concept of elastic osteosynthesis, increasing plate working length is considered advantageous.[10] [11] Increasing working length decreases construct stiffness and disperses stress over a greater area of the plate and may be protective against plastic deformation in cyclic loading. Plates having open screw holes appear particularly susceptible to fatigue failure as mentioned by Dr Roe; however, keeping plate working length to a minimum has also been cited as a source of complications in human patients[2] [5] [12] [13] [14] as increased construct stiffness has been incriminated in the development of non-union or stress concentration precipitating implant failure.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] While the lion's share of human patients is reasonably compliant, dogs and cats will consistently challenge implants in the postoperative convalescent period and erroring on the side of having stiffer constructs is probably the lesser of two evils. The interaction between locking plate systems, fracture configuration and bone healing is complex with many factors ultimately affecting outcome. We did not intend to further convolute the issue with our wording and thank Dr Roe for his insights on this issue.



Publication History

Received: 28 September 2020

Accepted: 29 September 2020

Publication Date:
12 November 2020 (online)

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