Time-elapsed screw insertion with microCT imaging

Ryan, Melissa; Mohtar, Aaron; Cleek, Tammy M.; Reynolds, Karen

doi:10.1016/j.jbiomech.2015.12.021

Cited by 10 publications

(8 citation statements)

References 13 publications

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“…Second, the width of unloaded fracture gaps was not correlated with the type of repair at every measurement site. Had previous compression resulted in permanent bone volume reduction, this would have been most apparent at the mid P1 site because any change in trabecular bone volume is typically restricted to within a few millimeters of the implant . Had this effect been present, the triangular repair should have been associated with a smaller fracture gap grade at this site; however, this was not the case.…”

Section: Discussionmentioning

confidence: 98%

In vitro comparison of linear vs triangular screw configuration to stabilize complete uniarticular parasagittal fractures of the proximal phalanx in horses

et al. 2018

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Objective To assess fracture gap reduction and stability of linear vs triangular 4.5‐mm lag screw repair of experimental, uniarticular, and complete forelimb proximal phalanx (P1) fractures. Study design Experimental. Sample population Fourteen equine cadaver limbs/horses. Methods Simulated fractures were repaired with 2 lag screws under 4‐Nm insertion torque (linear repair). Computed tomography (CT) imaging was performed with the leg unloaded and loaded to forces generated while walking. The fracture repair was revised to include 3 lag screws placed with the same insertion torque (triangular repair) prior to CT. The width of the fracture gap was assessed qualitatively by 2 observers and graded on the basis of gap measurements relative to the average voxel size at dorsal, mid, and palmar P1 sites. Interobserver agreement was assessed with Cohen's κ. The effect of repair type, loading condition, and measurement site on fracture gap grades was evaluated by using Kendall's τ‐b correlation coefficients and paired nonparametric tests. Significance was set at P ≤ .05. Results Agreement between loading and fracture gap widening was fair in triangular (κ = 0.53) and excellent in linear (κ = 0.81) repairs. Loading resulted in fracture gap distraction in linear repairs (Plinear = .008). Triangular repairs reduced fractures better irrespective of loading (Punloaded = .003; Ploaded < .001). The type of repair was not correlated with fracture gap grades at unloaded mid and loaded dorsal P1 sites. Conclusion Repair of uniarticular complete parasagittal fractures with a triangular screw configuration improved in vitro fracture gap reduction and stability. Clinical significance Triangular lag screw repair likely improves biomechanical conditions during postoperative weight bearing.

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Section: Discussionmentioning

confidence: 98%

In vitro comparison of linear vs triangular screw configuration to stabilize complete uniarticular parasagittal fractures of the proximal phalanx in horses

et al. 2018

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“…All D values were zeroed at a starting F value of 5 N to eliminate the initial "slack" effect in tests. Relaxation of bone material during microCT scans was shown in similar axial loading studies 32,34 to produce local dips in force values but to not affect the overall shape or maximum values of the F-D curve. These findings were confirmed in a pilot study (Supplementary Materials).…”

Section: Discussionmentioning

confidence: 81%

“…Indenters were fabricated from 5.0 mm diameter rods of 6061‐T6 aluminum, selected for its radiolucency. A review of the literature indicated that the yield strength and elastic modulus of the material (250 MPa and 70 GPa, respectively) would provide satisfactory rigidity given the stresses anticipated during the experiment. Rods were cut into 40 mm segments, and one end of each segment was precision lathed to add either a flat or sharp/conical tip (55° vertex angle) (Fig.…”

Section: Methodsmentioning

confidence: 99%

Development and initial validation of a novel smoothed‐particle hydrodynamics‐based simulation model of trabecular bone penetration by metallic implants

Kulper

Fang

Ren

et al. 2017

Journal Orthopaedic Research

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A novel computational model of implant migration in trabecular bone was developed using smoothed-particle hydrodynamics (SPH), and an initial validation was performed via correlation with experimental data. Six fresh-frozen human cadaveric specimens measuring 10 × 10 × 20 mm were extracted from the proximal femurs of female donors (mean age of 82 years, range 75-90, BV/TV ratios between 17.88% and 30.49%). These specimens were then penetrated under axial loading to a depth of 10 mm with 5 mm diameter cylindrical indenters bearing either flat or sharp/conical tip designs similar to blunt and self-tapping cancellous screws, assigned in a random manner. SPH models were constructed based on microCT scans (17.33 µm) of the cadaveric specimens. Two initial specimens were used for calibration of material model parameters. The remaining four specimens were then simulated in silico using identical material model parameters. Peak forces varied between 92.0 and 365.0 N in the experiments, and 115.5-352.2 N in the SPH simulations. The concordance correlation coefficient between experimental and simulated pairs was 0.888, with a 95%CI of 0.8832-0.8926, a Pearson ρ (precision) value of 0.9396, and a bias correction factor Cb (accuracy) value of 0.945. Patterns of bone compaction were qualitatively similar; both experimental and simulated flat-tipped indenters produced dense regions of compacted material adjacent to the advancing face of the indenter, while sharp-tipped indenters deposited compacted material along their peripheries. Simulations based on SPH can produce accurate predictions of trabecular bone penetration that are useful for characterizing implant performance under high-strain loading conditions. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1114-1123, 2018.

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“…This may be related to the very limited area over which trabecular deformation occurs with screw tightening. 10 There were a number of limitations in this study. First, the cadaveric simulated arthrodesis used in this study only models the behavior of bone at the time of surgery.…”

Section: Discussionmentioning

confidence: 92%

Mechanical Effects of Lag Screw Retightening in a Simulated Hindfoot Arthrodesis Model

Rugg

Requist

Johnson

et al. 2021

Foot & Ankle Orthopaedics

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Background: Nonunion following hindfoot arthrodesis may be caused by failure to maintain compression at the arthrodesis site. The ability of lag screws, commonly used in arthrodesis, to maintain compression in hindfoot bones has not been well characterized. The aim of this work was to quantify the stress relaxation response of hindfoot bone with initial and repeated compression with a lag screw. Methods: Ten sets of 25-mm-diameter bone cylinders were cut from the talus and calcaneus in fresh-thawed cadaveric feet. A load cell was compressed between cylinders with an 8.0-mm partially threaded cannulated lag screw simulating arthrodesis. For 7 sets, screws were tightened by 3 quarter-turns, rested for 3 minutes, retightened 1 quarter-turn, and rested for 30 minutes. Three sets served as controls in which screws were not retightened. Results: Maximum compression after initial screw tightening and retightening averaged 275 and 337 N ( P = .07), respectively. Compression 3 minutes after initial screw tightening and retightening averaged 199 and 278 N ( P = .027), respectively. The compression recorded 3 minutes after screw retightening was an average of 40% higher than that recorded 3 minutes after initial tightening. The average compression 30 minutes after screw retightening was 255 N, a compression loss of 25% from the average maximum compression after retightening. Eighty percent of this compression loss happened in an average of 5.5 minutes. Conclusion: Hindfoot bones exhibit compression loss over time during simulated arthrodesis. Compression maintenance in bone is improved with screw retightening. Further work is needed to understand the mechanism of action and determine optimum time for recompression. Clinical Relevance: Retightening lag screws before wound closure may improve compression at the arthrodesis site and thereby decrease the chance of nonunion. Level of Evidence: N/A, laboratory experiment.

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Time-elapsed screw insertion with microCT imaging

Abstract: 'This is the peer reviewed version of the following article: Ryan MK, Mohtar AA, Cleek TM, Reynolds KJ. Time-elapsed screw insertion with microCT imaging. Journal of Biomechanics. pii: S0021-9290(15)00727-7.

Cited by 10 publications

References 13 publications

In vitro comparison of linear vs triangular screw configuration to stabilize complete uniarticular parasagittal fractures of the proximal phalanx in horses

In vitro comparison of linear vs triangular screw configuration to stabilize complete uniarticular parasagittal fractures of the proximal phalanx in horses

Development and initial validation of a novel smoothed‐particle hydrodynamics‐based simulation model of trabecular bone penetration by metallic implants

Mechanical Effects of Lag Screw Retightening in a Simulated Hindfoot Arthrodesis Model

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