Hybrid Instrumentation in Lumbar Spinal Fusion

Abstract

Study DesignEx vivo human cadaveric study.ObjectiveThe development or progression of adjacent segment disease (ASD) after spine stabilization and fusion is a major problem in spine surgery. Apart from optimal balancing of the sagittal profile, dynamic instrumentation is often suggested to prevent or impede ASD. Hybrid instrumentation is used to gain stabilization while allowing motion to avoid hypermobility in the adjacent segment. In this biomechanical study, the effects of two different hybrid instrumentations on human cadaver spines were evaluated and compared with a rigid instrumentation.MethodsEighteen human cadaver spines (T11–L5) were subdivided into three groups: rigid, dynamic, and hook comprising six spines each. Clinical parameters and initial mechanical characteristics were consistent among groups. All specimens received rigid fixation from L3–L5 followed by application of a free bending load of extension and flexion. The range of motion (ROM) for every segment was evaluated. For the rigid group, further rigid fixation from L1–L5 was applied. A dynamic Elaspine system (Spinelab AG, Winterthur, Switzerland) was applied from L1 to L3 for the dynamic group, and the hook group was instrumented with additional laminar hooks at L1–L3. ROM was then evaluated again.ResultsThere was no significant difference in ROM among the three instrumentation techniques.ConclusionBased on this data, the intended advantage of a hybrid or dynamic instrumentation might not be achieved.

Optimization of Spinal Reconstructions for Thoracolumbar Burst Fractures to Prevent Proximal Junctional Complications: A Finite Element Study

“…The T10-L3 FE model in this study was validated against previously published in vitro measurements of the ROM and intradiscal pressure. The majority of our simulation results remained compatible and within one SD compared to the literature [ 31 , 32 , 33 , 34 , 36 ]. Some differences were noted in the intradiscal pressure between our results and previous experiments by Brinckmann et al (1.24 SD) [ 35 ].…”

“…To validate the finite element model, the simulated ROM and IVD stress in the present intact T10-L3 model were compared with the literature. First, the ROM of the intact thoracolumbar model in flexion-extension, lateral bending, and axial rotation were compared with three in vitro experiments by Chin et al, Rustenburg et al, and Obid et al [ 31 , 32 , 33 ]. The global ROM of the present intact model was as follows: flexion–extension, 6.86 degrees; lateral bending, 3.04 degrees; and axial rotation, 1.54 degrees.…”

“… Validation of the present FE model. Comparisons between the ( A ) ROM and ( B ) IVD pressure of the present intact model with the literature [ 31 , 32 , 33 , 34 , 35 , 36 ] (presented in mean and standard deviation). …”