In vitro biomechanical analysis of three anterior thoracolumbar implants

Abstract

<jats:p content-type="fine-print"><jats:italic>Object.</jats:italic> The goal of this study was to evaluate the comparative efficacy of three commonly used anterior thoracolumbar implants: the anterior thoracolumbar locking plate (ATLP), the smooth-rod Kaneda (SRK), and the Z-plate.</jats:p> <jats:p content-type="fine-print"><jats:italic>Methods.</jats:italic> In vitro testing was performed using the T9—L3 segments of human cadaver spines. An L-1 corpectomy was performed, and stabilization was achieved using one of three anterior devices: the ATLP in nine spines, the SRK in 10, and the Z-plate in 10. Specimens were load tested with 1.5-, 3-, 4.5-, and 6-Nm in flexion and extension, right and left lateral bending, and right and left axial rotation. Angular motion was monitored using two video cameras that tracked light-emitting diodes attached to the vertebral bodies. Testing was performed in the intact state in spines stabilized with one of the three aforementioned devices after the devices had been fatigued to 5000 cycles at ± 3 Nm and after bilateral facetectomy.</jats:p> <jats:p content-type="fine-print">There was no difference in the stability of the intact spines with use of the three devices. There were no differences between the SRK- and Z-plate—instrumented spines in any state. In extension testing, the mean angular rotation (± standard deviation) of spines instrumented with the SRK (4.7 ± 3.2°) and Z-plate devices (3.3 ± 2.3°) was more rigid than that observed in the ATLP-stabilized spines (9 ± 4.8°). In flexion testing after induction of fatigue, however, only the SRK (4.2 ± 3.2°) was stiffer than the ATLP (8.9 ± 4.9°). Also, in extension postfatigue, only the SRK (2.4 ± 3.4°) provided more rigid fixation than the ATLP (6.4 ± 2.9°). All three devices were equally unstable after bilateral facetectomy. The SRK and Z-plate anterior thoracolumbar implants were both more rigid than the ATLP, and of the former two the SRK was stiffer.</jats:p> <jats:p content-type="fine-print"><jats:italic>Conclusions.</jats:italic> The authors' results suggest that in cases in which profile and ease of application are not of paramount importance, the SRK has an advantage over the other two tested implants in achieving rigid fixation immediately postoperatively.</jats:p>

Solvent-preserved, bovine cancellous bone blocks used for reconstruction of thoracolumbar fractures in minimally invasive spinal surgery?first clinical results

“…However, these are expensive alternatives, and there is a lack of long-term results considering the osseointegration of these spacers with mounted cancellous bone, sintering and loosening. For the most part, only primary stability tests have been presented [1,7,11,12,20,23,28]. Good long-term results with strut grafting and anterior stabilization were published only by Kaneda [15].…”

“…The search for an alternative reconstruction material is still under way and ranges from the use of fibula via rib segments to titanium bodies for vertebral body replacement [7,9,11,12,17,18,20,28,30]. Problems include cost, lack of long-term results concerning osseointegration and sintering, loosening and mechanical failure of spacers.…”

In vitro biomechanical effects of reconstruction on adjacent motion segment: comparison of aligned/kyphotic posterolateral fusion with aligned posterior lumbar interbody fusion/posterolateral fusion

“…The maximum loading levels were within the range of those reported in previous biomechanical studies involving lumbar reconstruction models. 1,11,13,14,23 Because pilot studies demonstrated that load-displacement and load-strain or pressure data after the second load-unload cycle were almost identical, the loading procedure involved the application of three load-unload cycles. The third loading cycle was used to allow for data analysis of all biomechanical parameters.…”

“…The specimen was allowed to "creep" for 30 seconds between load application and data collection. 13,14,23 Two-level fusion was simulated at L5-6 and L6-S1. The L4-5 level was defined as the superior adjacent segment.…”

Biomechanical analysis of anterior versus posterior instrumentation following a thoracolumbar corpectomy

“…1,5,14,15 Biomechanical studies have compared anterior with posterior instrumentation in the bovine spine, 3 as well as compared various anterior instrumentation systems, with the anterior 2-rod system being the most stable. 2,4,[6][7][8] In recent years expandable cages have become an increasingly common method of reconstructing the anterior column. Advantages include ease of deployment, induction of an axial loading force on the bodies above and below theoretically enhancing fusion rates, and ability to better preserve the adjacent endplates.…”