Effect of Intramedullary Rod Diameter on a String of Pearls Plate‐Rod Construct in Mediolateral Bending: An <i>In Vitro</i> Mechanical Study

Rutherford, Scott; Demianiuk, Ryan M.; Benamou, Jérôme; Beckett, Clifford; Ness, Malcolm G.; Déjardin, Loïc M.

doi:10.1111/vsu.12348

Cited by 9 publications

(7 citation statements)

References 25 publications

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“…Without any data for clinical comparison, this study concluded that small diameter IM pin may prove beneficial in clinical cases where a locking SOP-rod construct is used. 60 That study also supported the use of monocortical screws in locking plate-rod constructs. Despite finding significant differences in deformation and compliance between mono and bicortical SOP fixation without a pin, these differences were eliminated by adding a 24% IM pin to the monocortical SOP constructs.…”

Section: (C) Locking Plate-rod Studiessupporting

confidence: 58%

The effect of intramedullary pin size and monocortical screw configuration on locking compression plate-rod constructs in an in vitro fracture gap model

Pearson¹,

Glyde²,

Hosgood³

et al. 2015

Vet Comp Orthop Traumatol

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Objective: To investigate the effect of intramedullary (IM) pin size in combination with various monocortical screw configurations on construct stiffness and strength as well as plate stain in locking compression plate-rod (LCPR) constructs. Methods:A synthetic bone model with a 40mm fracture gap was used. LCPs with monocortical locking screws were tested with no pin (LCPMono) and IM pins of 20% (LCPR20), 30% (LCPR30) and 40% (LCPR40) of IM diameter. LCPs with bicortical screws (LCPBi) were also tested in the first paper.The first paper used screw configurations with 2 or 3 screws per fragment modelling long (8 hole), intermediate (6 hole) and short (4 hole) plate working lengths. Responses to axial compression, biplanar four point bending and axial load to failure were recorded. The second paper used 2 screws per fragment to model a long (8 hole) and short (4 hole) plate working length and strain responses to axial compression were recorded at 6 regions of the plate via 3D digital image correlation. Results:In the first paper, LCPBi were not significantly different from LCPMono control for any of the outcome variables measured. In bending, LCPR20 were not significantly different from LCPBi and LCPMono. LCPR30 were stiffer than LCPR20 and the controls. LCPR40 constructs were stiffer than all other constructs. The addition of an IM pin of any size provided a significant increase in axial stiffness and load to failure. This effect was incremental with increasing IM pin diameter. As plate working length decreased there was a significant increase in stiffness across all constructs.The addition of an IM pin of any size provided a significant decrease in plate strain. For the long working length, LCPR30 and LCPR40 had significantly lower strain than the LCPR20 and plate strain was significantly higher adjacent to the screw closest to the fracture site. For the short working length, there was no significant difference in strain across any LCPR constructs or at any region of the plate. Plate strain was significantly lower for the short working length compared to the long working length for LCPMono and LCPR20 but not LCPR30 and LCPR40. Conclusions:A pin of any size increases resistance to axial loads whereas a pin of at least 30% IM diameter is required to increase bending stiffness. Short plate working lengths provide maximum stiffness. However, the overwhelming effect of IM pin size obviates the effect of changing plate working length on construct stiffness.The increase in plate strain encountered with a long working length can be overcome by the use of a pin of 30-40% IM diameter. Where placement of a large diameter IM pin is not possible, screws should be placed as close to the fracture gap as possible to minimize plate strain and distribute it more evenly over the plate.Both studies showed a consistent effect of increasing IM pin diameter and using a short plate working length. However, a significant interaction effect between these variables was only detected on plate strain with the IM pin largely negating...

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Section: (C) Locking Plate-rod Studiessupporting

confidence: 58%

The effect of intramedullary pin size and monocortical screw configuration on locking compression plate-rod constructs in an in vitro fracture gap model

Pearson¹,

Glyde²,

Hosgood³

et al. 2015

Vet Comp Orthop Traumatol

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“…17,37,38 If CCP are to be used in tibial fractures that are unable to be reconstructed, supplemental fixation in the form of an intramedullary pin or orthogonal plate may be advisable. 39,40 Further clinical investigation of both plating systems is warranted to determine optimal applications when stabilizing tibial fractures in cats.…”

Section: Discussionmentioning

confidence: 99%

Biomechanical Comparison of Two Locking Plate Constructs for the Stabilization of Feline Tibial Fractures

Hottmann

Johnson

Banks

et al. 2019

Vet Comp Orthop Traumatol

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Objectives The aim of this study was to compare the biomechanical characteristics of locking compression plate (LCP) and conical coupling plate (CCP) constructs for the stabilization of experimentally induced gap fractures in cat tibiae. Materials and Methods Pelvic limbs were harvested from eight cat cadavers. Paired tibiae were stripped of all soft tissues, and randomly assigned to the LCP or CCP stabilization group. An eight-hole 2.7 mm LCP or a six-hole 2.5 mm CCP was applied to the medial surface of each tibia. A 1-cm segment of the tibia was excised centrally beneath the plate. The specimens were potted, then tested in non-destructive four-point craniocaudal and mediolateral bending, followed by non-destructive axial compression. Each construct was subsequently loaded to failure in axial compression. Bending and axial stiffness, yield load and failure load were calculated for each specimen. Results The LCP constructs were significantly stiffer than the CCP constructs when subjected to non-destructive bending and axial loading. Craniocaudal bending stiffness was significantly greater than mediolateral bending stiffness for both constructs. Yield load and failure load were significantly greater for LCP constructs compared with CCP constructs. Clinical Significance LCP may be a more suitable implant for stabilizing complex diaphyseal tibial fractures in cats. Additional supplemental fixation should be considered when using CCP to stabilize unreconstructed diaphyseal tibial fractures in cats. Further clinical investigation of both implants is recommended.

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“…A generic femoral bone model was designed by using the morphometric measurements of the native feline femurs obtained in the first phase of the study. The overall shape of this symmetrical model was similar to that of a canine bone model previously used in our laboratory . The model featured a 20‐mm outer diameter segment used for linkage to custom holding fixtures at each extremity.…”

Section: Methodsmentioning

confidence: 99%

Characterization of the torsional structural properties of feline femurs and surrogate bone models for mechanical testing of orthopedic implants

2018

Self Cite

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Objective: To characterize the torsional structural properties of the feline femur and design a bone model surrogate for mechanical testing of feline orthopedic implants. Study design: Experimental. Sample population: Paired feline femurs (n = 30) and bone models (8 materials, n = 4/group).Methods: Femurs were cyclically tested nondestructively in torsion and then loaded to failure. A generic femoral model was then designed from native femur dimensions and tested similarly by using 1 of 8 materials that were 3-dimensionally printed or machined. Outcome measures consisting of torsional compliance, angular deformation (AD), and torque to failure were compared by using Student's t test (P < .05). Failure modes are reported as descriptive statistics. Results: Torsional compliance (1.6 AE 0.3 /Nm, 2.0 AE 0.1 /Nm), AD (3.1 AE 0.6 , 3.8 AE 0.2 ) and torque to failure (7.8 AE1.2 Nm, 8.1 AE 1.3 Nm) did not differ between feline femurs and short-fiber epoxy (SFE) models. Conversely, most printed materials displayed excessive TC and failed by plastic deformation (AD > 15-fold that of native femurs) rather than by fracture. Feline bone and SFE both failed by spiral fractures. Conclusion: None of the outcome measures differed between the 4th generation SFE model and cadaveric femurs, but differences were identified between feline bone and printed materials. Clinical impact: Machined SFE can be used to create a surrogate bone model with torsional structural properties similar to those of feline femurs. In contrast, common printable materials appear unsuitable to produce a realistic feline bone surrogate.

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Effect of Intramedullary Rod Diameter on a String of Pearls Plate‐Rod Construct in Mediolateral Bending: An In Vitro Mechanical Study

Cited by 9 publications

References 25 publications

The effect of intramedullary pin size and monocortical screw configuration on locking compression plate-rod constructs in an in vitro fracture gap model

The effect of intramedullary pin size and monocortical screw configuration on locking compression plate-rod constructs in an in vitro fracture gap model

Biomechanical Comparison of Two Locking Plate Constructs for the Stabilization of Feline Tibial Fractures

Characterization of the torsional structural properties of feline femurs and surrogate bone models for mechanical testing of orthopedic implants

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