Lumbar discectomy is associated with higher rates of lumbar fusion

Study design : Biomechanical study of a nucleus replacement with a finite element model. Objective : To validate a Bionate 80A ring-shaped nucleus replacement. Methods : The ANSYS lumbar spine model made from lumbar spine X-rays and magnetic resonance images obtained from cadaveric spine specimens were used. All materials were assumed homogeneous, isotropic, and linearly elastic. We studied three options: intact spine, nucleotomy, and nucleus implant. Two loading conditions were evaluated at L 3 -L 4 , L 4 -L 5 , and L 5 -S 1 discs: a 1000 N axial compression load and this load after the addition of 8 Nm flexion moment in the sagittal plane plus 8 Nm axial rotation torque. Results : Maximum nucleus implant axial compression stresses in the range of 16–34 MPa and tensile stress in the range of 5–16 MPa, below Bionate 80A resistance were obtained. Therefore, there is little risk of permanent implant deformation or severe damage under normal loading conditions. Nucleotomy increased segment mobility, zygapophyseal joint and end plate pressures, and annulus stresses and strains. All these parameters were restored satisfactorily by nucleus replacement but never reached the intact status. In addition, annulus stresses and strains were lower with the nucleus implant than in the intact spine under axial compression and higher under complex loading conditions. Conclusions : Under normal loading conditions, there is a negligible risk of nucleus replacement, permanent deformation or severe damage. Nucleotomy increased segmental mobility, zygapophyseal joint pressures, and annulus stresses and strains. Nucleus replacement restored segmental mobility and zygapophyseal joint pressures close to the intact spine. End plate pressures were similar for the intact and nucleus implant conditions under both loading modes. Manufacturing customized nucleus implants is considered feasible, as satisfactory biomechanical performance is confirmed.

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“… 46 Physiotherapy and muscle strengthening exercises are helpful 47 until symptoms get so severe that a spinal fusion must be considered. 48 …”

Section: Discussionmentioning

confidence: 99%

Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis

Vanaclocha

Atienza

et al. 2021

ACS Appl. Bio Mater.

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“…As a matter of fact, removing part of the lumbar disc might induce a secondary complex situation that can bring spinal instability ( 10 ). And it turns out an initial lumbar discectomy for the patients with LDH is statistically associated with an increased likelihood of lumbar fusion in the future ( 11 ).…”

Section: Introductionmentioning

confidence: 99%

Emerging Issues Questioning the Current Treatment Strategies for Lumbar Disc Herniation

Wan¹,

Hua

Liu

et al. 2022

Front. Surg.

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Lumbar disc herniation is among the common phenotypes of degenerative lumbar spine diseases, significantly affecting patients' quality of life. The practice pattern is diverse. Choosing conservative measures or surgical treatments is still controversial in some areas. For those who have failed conservative treatment, surgery with or without instrumentation is recommended, causing significant expenditures and frustrating complications, that should not be ignored. In the article, we performed a literature review and summarized the evidence by subheadings to unravel the cons of surgical intervention for lumbar disc herniation. There are tetrad critical issues about surgical treatment of lumbar disc herniation, i.e., favorable natural history, insufficient evidence in a recommendation of fusion surgery for patients, metallosis, and implant removal. Firstly, accumulating evidence reveals immune privilege and auto-immunity hallmarks of human lumbar discs within the closed niche. Progenitor cells within human discs further expand the capacity with the endogenous repair. Clinical watchful follow-up studies with repeated diagnostic imaging reveal spontaneous resolution for lumbar disc herniation, even calcified tissues. Secondly, emerging evidence indicates long-term complications of lumbar fusion, such as adjacent segment disease, pseudarthrosis, implant failure, and sagittal spinal imbalance, which get increasing attention. Thirdly, systemic and local reactions (metallosis) for metal instrumentation have been noted with long-term health concerns and toxicity. Fourthly, the indications and timing for spinal implant removal have not reached a consensus. Other challenging issues include postoperative lumbar stiffness. The review provided evidence from a negative perspective for surgeons and patients who attempt to choose surgical treatment. Collectively, the emerging underlying evidence questions the benefits of traditional surgery for patients with lumbar disc herniation. Therefore, the long-term effects of surgery should be closely observed. Surgical decisions should be made prudently for each patient.

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“…However, the surgery does not restore mechanical functionality to the IVD (26,27) or seal AF defects (28)(29)(30), and thus herniation may reoccur (24,31,32). Currently, there is a clinical need for more effective methods of AF repair (30,33).…”

Section: Introductionmentioning

confidence: 99%

Biofabrication of development-inspired scaffolds for regeneration of the annulus fibrosus macro- and microarchitecture

Kluser

Sprecher

Alig

et al. 2021

Preprint

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Annulus fibrosus (AF) tissue engineering is a promising strategy for repairing the degenerated intervertebral disc (IVD) and a research area that could benefit from improved tissue models to drive translation. AF tissue is composed of concentric layers of aligned collagen bundles arranged in an angle-ply pattern, an architecture which is challenging to recapitulate with current scaffold design strategies. In response to this need, we developed a strategy to print 3D scaffolds that induce cell and tissue organization into oriented patterns mimicking the AF. Polycaprolactone (PCL) was printed in an angle-ply macroarchitecture possessing microscale aligned topographical cues. The topography was achieved by extrusion through custom-designed printer nozzles which were either round or possessing circumferential sinusoidal peaks. Whereas the round nozzle produced extruded filaments with a slight uniaxial texture, patterned nozzles with peak heights of 60 or 120 μm produced grooves, 10.87 ± 3.09 μm or 17.77 ± 4.91 μm wide, respectively. Bone marrow derived mesenchymal stem cells (BM-MSCs) cultured on the scaffolds for four weeks exhibited similar degrees of alignment within ± 10 ° of the printing direction and upregulation of outer AF markers (COL1, COL12, SFRP, MKX, MCAM, SCX and TAGLN), with no statistically significant differences as a function of topography. Interestingly, the grooves generated by the patterned nozzles induced longitudinal end-to-end alignment of cells, capturing the arrangement of cells during fibrillogenesis. In contrast, topography produced from the round nozzle induced a continuous web of elongated cells without end-to-end alignment. Extracellular collagen I, decorin and fibromodulin were detected in patterns closely following cellular organization. Taken together, we present a single-step biofabrication strategy to induce anisotropic cellular alignments in x-, y-, and z-space, with potential application as an in vitro model for studying AF tissue morphogenesis and growth.

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Lumbar discectomy is associated with higher rates of lumbar fusion

Cited by 23 publications

References 9 publications

Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis

Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis

Emerging Issues Questioning the Current Treatment Strategies for Lumbar Disc Herniation

Biofabrication of development-inspired scaffolds for regeneration of the annulus fibrosus macro- and microarchitecture

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