Single cycle to failure in bending of three titanium polyaxial locking plates

Eid, Chadi; Martini, Filippo Maria; Bonardi, Andrea; Lusetti, Filippo; Belesini, Anna Brandstetter de; Nicoletto, Gianni

doi:10.3415/vcot-16-07-0111

Cited by 6 publications

(1 citation statement)

References 25 publications

(40 reference statements)

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“…This seems to be a weak point in polyaxial designs, as the engagement between components is limited and multiple insertions can further compromise it. Surprisingly, most studies only investigated the interface between the screw head and the plate hole using destructive tests [11][12][13][14]. Consequently, little is known about the engagement of the screw head and the plate hole components in cases of single and multiple insertions of the screws.…”

Section: Introductionmentioning

confidence: 99%

Effect of screw angulation and multiple insertions on load-to-failure of polyaxial locking system

Glowacki,

Bartkowiak,

Paczos

et al. 2023

PLoS ONE

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Purpose Polyaxial locking plates rely on the alignment between the thread-to-thread connections of the screw head and the plate hole. These implants have provided substantial support for surgeons. In particular, extended screw positioning have proven to be beneficial in the fixation of challenging fractures. This study aimed to investigate the mechanical properties of ChM 5.0 ChLP polyaxial screws inserted in off-axis trajectories, including multiple insertions and to correlate these parameters with the screw head and the plate hole thread-to-thread engagement. Methods Polyaxial locking screws were inserted into the plates at various angles (0°,10°,15°, -15° off-axis). Multiple time inserted screws were placed firstly at 15°, then 0° and finally -15° off-axis in the same plate hole. A microCT scan of the plate-hole and screw-head interface was conducted before destructive tests. Representative screws from each group were also examined by Scanning Electron Microscope. Results The standard insertion at 0° sustained the greatest maximum bending strength without relocation in the screw hole. Screws inserted at 10° and 15° (one time) showed a significant reduction in load-to-failure of up to 36% and 55%, (p = 0.001) (p = 0.001) respectively. Screws inserted at -15° after a maximum of three multiple insertions with angle shift, showed a total reduction in force of up to 70% (p = 0.001). A microCT analysis of thread engagement showed significant correlations. However, the results obtained for multiple insertions were highly variable. Conclusions ChM 5.0 ChLP polyaxial locking system has valuable properties that foster fracture fixation, providing various surgical options. Nevertheless, the freedom of off-axis placement and multiple insertions of the screws comes at the price of reduced force. When possible surgeons should minimize the angles of insertions.

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Section: Introductionmentioning

confidence: 99%

Effect of screw angulation and multiple insertions on load-to-failure of polyaxial locking system

Glowacki,

Bartkowiak,

Paczos

et al. 2023

PLoS ONE

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Design for Additive Manufacturing and Finite Element Analysis of Fe-Mn Biodegradable Fracture Fixation Plate with Varying Porosity Levels

Shaikh,

Kahwash,

et al. 2023

Industrializing Additive Manufacturing

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How Do the Locking Screws Lock? A Micro-CT Study of 3.5-mm Locking Screw Mechanism

Kaczmarek¹,

Bartkowiak

Paczos

et al. 2020

Vet Comp Orthop Traumatol

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Objective To quantify the amount of the screw head thread and the plate hole thread connection in two 3.5 mm locking plates: Locking Compression Plate (LCP) and Polyaxial Locking System (PLS). Materials and Methods A micro - CT scan of a screw head - plate hole connection was performed pre- and post destructive tests. Tests were performed on bone surrogates in a fracture gap model. The 3.5 LCP and 3.5 PLS plates, with 3 perpendicular screws per segment were used in a destructive static test. The 3.5 PLS plates with mono- and polyaxial screws were compared in a cyclic fatigue tests in two orthogonal directions. Pre - and post - test scan datasets were compared. Each dataset was converted into serial images depicting sections cut orthogonally to locking screw axis. The amount of engagement was detected through automated image postprocessing. Results The mean amount of the thread connection for the LCP was 28.85% before and 18.55% after destructive static test. The mean amount of the connection for the PLS was 16.20% before and 14.55% after destructive static test. When inserted monoaxially, the mean amount of the connection for the PLS screws was 14.4% before and 19.24% after destructive cyclic test. The mean amount of the connection for the polyaxial inserted PLS screws when loaded against plate thickness was 2.99% before and 2.08% after destructive cyclic test. The mean amount of the connection for the polyaxial inserted PLS screws when loaded against plate width was 3.36% before and 3.93% after destructive cyclic test. The 3D visualization of the thread connection showed that the initial interface points between screw head and plate hole are different for both LCP and PLS after the destructive testing. Depending on the type of applied force, there was either loss or increase of the contact. Clinical Relevance Micro-CT offers news possibilities in locking implant investigation. It might be helpful in better understanding the nature of locking mechanism and prediction of possible mode of failure in different systems.

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Single cycle to failure in bending of three titanium polyaxial locking plates

Abstract: The PAX RP and VetLOX reconstruction plates are much more likely to fail when used as bridging implants, thus adjunct support is needed. The lower bending strength of the VetLOX reconstruction plates suggests it should not be used in fractures under high loads.

Cited by 6 publications

References 25 publications

Effect of screw angulation and multiple insertions on load-to-failure of polyaxial locking system

Effect of screw angulation and multiple insertions on load-to-failure of polyaxial locking system

Design for Additive Manufacturing and Finite Element Analysis of Fe-Mn Biodegradable Fracture Fixation Plate with Varying Porosity Levels

How Do the Locking Screws Lock? A Micro-CT Study of 3.5-mm Locking Screw Mechanism

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