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Cherif H, Li L, Snuggs J, Li X, Sammon C, Li J, Beckman L, Haglund L, Le Maitre CL. Injectable hydrogel induces regeneration of naturally degenerate human intervertebral discs in a loaded organ culture model. Acta Biomater 2024; 176:201-220. [PMID: 38160855 DOI: 10.1016/j.actbio.2023.12.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/30/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
Low back pain resulting from disc degeneration is a leading cause of disability worldwide. However, to date few therapies target the cause and fail to repair the intervertebral disc (IVD). This study investigates the ability of an injectable hydrogel (NPgel), to inhibit catabolic protein expression and promote matrix expression in human nucleus pulposus (NP) cells within a tissue explant culture model isolated from degenerate discs. Furthermore, the injection capacity of NPgel into naturally degenerate whole human discs, effects on mechanical function, and resistance to extrusion during loading were investigated. Finally, the induction of potential regenerative effects in a physiologically loaded human organ culture system was investigated following injection of NPgel with or without bone marrow progenitor cells. Injection of NPgel into naturally degenerate human IVDs increased disc height and Young's modulus, and was retained during extrusion testing. Injection into cadaveric discs followed by culture under physiological loading increased MRI signal intensity, restored natural biomechanical properties and showed evidence of increased anabolism and decreased catabolism with tissue integration observed. These results provide essential proof of concept data supporting the use of NPgel as an injectable therapy for disc regeneration. STATEMENT OF SIGNIFICANCE: Low back pain resulting from disc degeneration is a leading cause of disability worldwide. However, to date few therapies target the cause and fail to repair the intervertebral disc. This study investigated the potential regenerative properties of an injectable hydrogel system (NPgel) within human tissue samples. To mimic the human in vivo conditions and the unique IVD niche, a dynamically loaded intact human disc culture system was utilised. NPgel improved the biomechanical properties, increased MRI intensity and decreased degree of degeneration. Furthermore, NPgel induced matrix production and decreased catabolic factors by the native cells of the disc. This manuscript provides evidence for the potential use of NPgel as a regenerative biomaterial for intervertebral disc degeneration.
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Affiliation(s)
- Hosni Cherif
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada
| | - Li Li
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada
| | - Joseph Snuggs
- Oncology and Metabolism Department, Medical School, & INSIGNEO Institute, University of Sheffield, Sheffield, UK; Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, UK
| | - Xuan Li
- Department of Mechanical Engineering, McGill University, Montreal, QC H3A 0C3, Canada
| | - Christopher Sammon
- Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, UK
| | - Jianyu Li
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada; Department of Mechanical Engineering, McGill University, Montreal, QC H3A 0C3, Canada; Department of Biomedical Engineering, McGill University, Montreal, QC H3A 2B4, Canada
| | - Lorne Beckman
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada
| | - Lisbet Haglund
- Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada; Shriners Hospital for Children, Montreal, QC H4A 0A9, Canada
| | - Christine L Le Maitre
- Oncology and Metabolism Department, Medical School, & INSIGNEO Institute, University of Sheffield, Sheffield, UK; Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, UK.
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Li ZL, Lu Q, Honiball JR, Wan SHT, Yeung KWK, Cheung KMC. Mechanical characterization and design of biomaterials for nucleus pulposus replacement and regeneration. J Biomed Mater Res A 2023; 111:1888-1902. [PMID: 37555381 DOI: 10.1002/jbm.a.37593] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 07/23/2023] [Indexed: 08/10/2023]
Abstract
Biomaterials for nucleus pulposus (NP) replacement and regeneration have great potential to restore normal biomechanics in degenerated intervertebral discs following nucleotomy. Mechanical characterizations are essential for assessing the efficacy of biomaterial implants for clinical applications. While traditional compression tests are crucial to quantify various modulus values, relaxation behaviors and fatigue resistance, rheological measurements should also be conducted to investigate the viscoelastic properties, injectability, and overall stability upon deformation. To recapitulate the physiological in vivo environment, the use of spinal models is necessary to evaluate the risk of implant extrusion and the restoration of biomechanics under different loading conditions. When designing devices for NP replacement, injectable materials are ideal to fully fill the nucleus cavity and prevent implant migration. In addition to achieving biocompatibility and desirable mechanical characteristics, biomaterial implants should be optimized to avoid implant extrusion or re-herniation post-operatively. This review discusses the most commonly used testing protocols for assessing mechanical properties of biomaterial implants and serves as reference material for enabling researchers to characterize NP implants through a unified approach whereby newly developed biomaterials may be compared and contrasted to existing devices.
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Affiliation(s)
- Zhuoqi Lucas Li
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - Qiuji Lu
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - John Robert Honiball
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - Sandra Hiu-Tung Wan
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
| | - Kelvin Wai-Kwok Yeung
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
- Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong Shenzhen Hospital, Shenzhen, China
| | - Kenneth Man-Chee Cheung
- Department of Orthopaedics & Traumatology, The University of Hong Kong, Hong Kong, China
- Department of Orthopaedics and Traumatology, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China
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Distefano F, Epasto G, Guglielmino E, Amata A, Mineo R. Subsidence of a partially porous titanium lumbar cage produced by electron beam melting technology. J Biomed Mater Res B Appl Biomater 2023; 111:590-598. [PMID: 36208414 PMCID: PMC10092161 DOI: 10.1002/jbm.b.35176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 07/30/2022] [Accepted: 09/25/2022] [Indexed: 01/21/2023]
Abstract
The lumbar intervertebral devices are widely used in the surgical treatment of lumbar diseases. The subsidence represents a serious clinical issue during the healing process, mainly when the interfaces between the implant and the vertebral bodies are not well designed. The aim of this study is the evaluation of subsidence risk for two different devices. The devices have the same shape, but one of them includes a filling micro lattice structure. The effect of the micro lattice structure on the subsidence behavior of the implant was evaluated by means of both experimental tests and finite element analyses. Compressive tests were carried out by using blocks made of grade 15 polyurethane, which simulate the vertebral bone. Non-linear, quasi-static finite element analyses were performed to simulate experimental and physiologic conditions. The experimental tests and the FE analyses showed that the subsidence risk is higher for the device without micro lattice structure, due to the smaller contact surface. Moreover, an overload in the central zone of the contact surface was detected in the same device and it could cause the implant failure. Thus, the micro lattice structure allows a homogenous pressure distribution at the implant-bone interface.
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Affiliation(s)
- Fabio Distefano
- Department of Engineering, University of Messina, Messina, Italy
| | - Gabriella Epasto
- Department of Engineering, University of Messina, Messina, Italy
| | | | - Aurora Amata
- ABR Srl, Zona Industriale Dittaino, Assoro, Italy
| | - Rosalia Mineo
- Mt Ortho srl, via fossa lupo sn Aci Sant'Antonio, Catania, Italy
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Vanaclocha A, Vanaclocha V, Atienza CM, Clavel P, Jordá-Gómez P, Barrios C, Saiz-Sapena N, Vanaclocha L. Bionate Lumbar Disc Nucleus Prosthesis: Biomechanical Studies in Cadaveric Human Spines. ACS OMEGA 2022; 7:46501-46514. [PMID: 36570209 PMCID: PMC9774399 DOI: 10.1021/acsomega.2c05294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
DESIGN cadaveric spine nucleus replacement study. OBJECTIVE determining Bionate 80A nucleus replacement biomechanics in cadaveric spines. METHODS in cold preserved spines, with ligaments and discs intact, and no muscles, L3-L4, L4-L5, and L5-S1 nucleus implantation was done. Differences between customized and overdimensioned implants were compared. Flexion, extension, lateral bending, and torsion were measured in the intact spine, nucleotomy, and nucleus implantation specimens. Increasing load or bending moment was applied four times at 2, 4, 6, and 8 Nm, twice in increasing mode and twice in decreasing mode. Spine motion was recorded using stereophotogrammetry. Expulsion tests: cyclic compression of 50-550 N for 50,000 cycles, increasing the load until there was extreme flexion, implant extrusion, or anatomical structure collapse. Subsidence tests were done by increasing the compression to 6000 N load. RESULTS nucleotomy increased the disc mobility, which remained unchanged for the adjacent upper level but increased for the lower adjacent one, particularly in lateral bending and torsion. Nucleus implantation, compared to nucleotomy, reduced disc mobility except in flexion-extension and torsion, but intact mobility was no longer recovered, with no effect on upper or lower adjacent segments. The overdimensioned implant, compared to the customized implant, provided equal or sometimes higher mobility. Lamina, facet joint, and annulus removal during nucleotomy caused more damaged than that restored by nucleus implantation. No implant extrusion was observed under compression loads of 925-1068 N as anatomical structures collapsed before. No subsidence or vertebral body fractures were observed under compression loads of 6697.8-6812.3 N. CONCLUSIONS nucleotomized disc and L1-S1 mobility increased moderately after cadaveric spine nucleus implantation compared to the intact status, partly due to operative anatomical damage. Our implant had shallow expulsion and subsidence risks.
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Affiliation(s)
- Amparo Vanaclocha
- Biomechanical
Engineer, Biomechanics Institute of Valencia, Valencia 46022, Spain
| | | | - Carlos M. Atienza
- Biomechanical
Engineer, Biomechanics Institute of Valencia, Valencia 46022, Spain
| | - Pablo Clavel
- Instituto
Clavel, Hospital Quironsalud Barcelona, Barcelona 08023, Spain
| | - Pablo Jordá-Gómez
- Hospital
General Universitario de Castellón, Castellón de la Plana 12004, Spain
| | - Carlos Barrios
- Catholic
University of Valencia, Saint Vincent Martyr, Valencia 46001, Spain
| | | | - Leyre Vanaclocha
- Medius
Klinik, Ostfildern-Ruit Klinik für Urologie, Hedelfinger Strasse 166, Ostfildern 73760, Germany
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Vanaclocha-Saiz A, Vanaclocha V, Atienza CM, Clavel P, Jorda-Gomez P, Barrios C, Vanaclocha L. Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis. ACS APPLIED BIO MATERIALS 2022; 5:172-182. [PMID: 35014829 PMCID: PMC8767544 DOI: 10.1021/acsabm.1c01027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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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 L3-L4, L4-L5, and L5-S1 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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Affiliation(s)
- Amparo Vanaclocha-Saiz
- Escuela de Doctorado, Universitat Politècnica de Valencia, Camí de Vera, s/n, 46022 Valencia, Spain
| | - Vicente Vanaclocha
- University of Valencia, Avenida de Blasco Ibáñez, 13, 46010 Valencia, Spain
| | - Carlos M Atienza
- Instituto de Biomecánica (IBV), Universitat Politècnica de Valencia, Camí de Vera, s/n, 46022 Valencia. Spain.,Instituto de Biomecánica de Valencia-CIBER BBN, Grupo de Tecnología Sanitaria (GTS-IBV), Camí de Vera, s/n, 46022 Valencia, Spain
| | - Pablo Clavel
- Instituto Clavel, Hospital Quironsalud Barcelona, Plaça d'Alfonso Comín, 5, 08023 Barcelona, Spain
| | - Pablo Jorda-Gomez
- Hospital Politècnic i Universitari La Fe, Avinguda de Fernando Abril Martorell, 106, 46026 Valencia, Spain
| | - Carlos Barrios
- Catholic University of Valencia, Saint Vincent Martyr, Carrer de Quevedo, 2, 46001 Valencia, Spain
| | - Leyre Vanaclocha
- University College London, London, Gower St, London WC1E 6BT, U.K
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Mihalko WM, Haider H, Kurtz S, Marcolongo M, Urish K. New materials for hip and knee joint replacement: What's hip and what's in kneed? J Orthop Res 2020; 38:1436-1444. [PMID: 32437026 DOI: 10.1002/jor.24750] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 04/24/2020] [Accepted: 05/01/2020] [Indexed: 02/04/2023]
Abstract
Over the last three decades there have been significant advancements in the knee and hip replacement technology that has been driven by an issue in the past concerning adverse local tissue reactions, aseptic and septic loosening. The implants and the materials we utilize have improved over the last two decades and in knee and hip replacement there has been a decrease in the failures attributed to wear and osteolysis. Despite these advancements there are still issues with patient satisfaction and early revisions due to septic and aseptic loosening in knee replacement patients. This article reviews the state of current implant material technology in hip and knee replacement surgery, discusses some of the unmet needs we have in biomaterials, and reviews some of the current biomaterials and technology that may be able to solve the most common issues in the knee and hip replacement surgery.
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Affiliation(s)
- William M Mihalko
- Department of Orthopaedic Surgery and Biomedical Engineering, Campbell Clinic Department of Orthopaedic Surgery and Biomedical Engineering, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Hani Haider
- Orthopaedic Biomechanics and Advanced Surgical Technologies Laboratory, Department of Orthopaedic Surgery and Rehabilitation, University of Nebraska Medical Center, Omaha, Nebraska
| | - Steven Kurtz
- Exponent Inc., Drexel University, Philadelphia, Pennsylvania
| | - Michele Marcolongo
- Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania
| | - Kenneth Urish
- Department of Orthopaedic Surgery, Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Bioengineering, Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
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Du CF, Liu CJ, Huang YP, Wang X. Effect of Spiral Nucleus Implant Parameters on the Compressive Biomechanics of Lumbar Intervertebral Disc. World Neurosurg 2019; 134:e878-e884. [PMID: 31733385 DOI: 10.1016/j.wneu.2019.11.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/04/2019] [Accepted: 11/05/2019] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To determine the effect of spiral nucleus implant parameters on the biomechanical behavior of the lumbar intervertebral disc after nucleus replacement under compressive loading. METHODS A finite element (FE) model of nucleus replacement in the L4-5 intervertebral disc was constructed. The effects of a spiral implant parameters, such as elasticity, size, and friction property, on the biomechanical behavior of the disc under a compressive load were determined. The effect of an implant with a sharp edge on disc biomechanics was also examined. The stress distribution and contact pressure on the endplate and AF, axial stiffness of disc, and annular bulge of the nucleus replacement models were investigated. RESULTS Axial stiffness, annular bulge, and contact pressure were all insensitive to friction properties. Insertion of the spiral implant reversed the changes in the AF and endplates due to the removal of the nucleus. There was a positive correlation between axial stiffness and elasticity with implant size. Annular bulge was positively correlated with size but negatively correlated with elasticity. Compared with the base model, the implant with a sharp edge caused a decrease in disc axial stiffness but an increase in contact pressure on the AF in an annular bulge in the sagittal and coronal axis, respectively. CONCLUSIONS A spiral implant may provide similar biomechanical behavior as a normal disc during compressive loading, with an optimal modulus of approximately 7 MPa. The spiral implant should fully conform to the nucleus cavity during replacement for the best biomechanical results.
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Affiliation(s)
- Cheng-Fei Du
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China; National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Chun-Jie Liu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China; National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China
| | - Yun-Peng Huang
- Department of Orthopedics, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Xin Wang
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China; National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China.
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Wang Y, Yi XD, Li CD. The influence of artificial nucleus pulposus replacement on stress distribution in the cartilaginous endplate in a 3-dimensional finite element model of the lumbar intervertebral disc. Medicine (Baltimore) 2017; 96:e9149. [PMID: 29390319 PMCID: PMC5815731 DOI: 10.1097/md.0000000000009149] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVE This study aimed to investigate the effects involved with the artificial nucleus pulposus (NP) replacement on stress distribution of the cartilaginous endplate (CEP) in a 3-dimensional lumbar intervertebral disc (IVD) model using a finite element (FE) analysis. METHODS A healthy male volunteer was recruited for the purposes of the study and a spiral computed tomography scan was subsequently conducted to obtain the data information in relation to the L4/5 motion segment. An FE model of the L4/5 motion segment constructed, on the basis of which degenerative IVD, IVD with NP removal, and IVD with NP replacement were in turn built. The stress distribution of the CEP and bulging of IVD were estimated using various motion states, including axial loading, forward flexion, backward extension, left axial rotation, and right axial rotation. RESULTS Under different motion states, the vertebral stress was higher in the degenerative IVD, the IVD with NP removal, and the IVD with NP replacement, in comparison to that of the normal IVD. Furthermore, a higher vertebral stress was detected in the degenerative IVD than the IVD with NP removal and the IVD with NP replacement. An even distribution of vertebral stress was observed in the IVD model with an artificial NP replacement, while the vertebral stress and bulging displacement were lower than after NP removal. Our findings provided confirmation that stress of the CEP was consistent with the vertebral stress. CONCLUSION This study provided evidence suggesting that NP replacement, vertebral stress, and bulging displacement are lower than that of degenerative IVD and IVD with NP removal under different motion states.
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Functional compressive mechanics and tissue biocompatibility of an injectable SF/PU hydrogel for nucleus pulposus replacement. Sci Rep 2017; 7:2347. [PMID: 28539658 PMCID: PMC5443820 DOI: 10.1038/s41598-017-02497-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 04/10/2017] [Indexed: 11/08/2022] Open
Abstract
In spinal degenerative disease, an injectable liquid hydrogel can fill in defect entirely, lessen the danger of implant relocation and following loss of disc height, minimizing the operative trauma. Here, we propose an injectable in-situ chemically cross-linked hydrogel by a two-component reaction of liquid silk fibroin with liquid polyurethane at physiological temperature conditions. Confined compression tests and fatigue tests were reported to assess physical properties of the hydrogel. Impact of different diameter on the biomechanical behaviours was tested to evaluate the clinical potentiality of the hydrogel for replacing nucleus pulposus. Degradation behaviours in different solutions and animal experiments were also investigated to examine the tissue biocompatibility of the hydrogel. The hydrogel modulus was affected by the hydrogel geometrical (diameter) parameters. SF/PU composite hydrogel can survive a million cycles, unconstrained fatigue resistance. More importantly, in vivo biocompatibility using New Zealand white rabbits, showed good biocompatibility over a three-month period in culture. Particularly, they showed the significant clinical merit of providing stronger axial compressive stiffness on confined compression test. Based on the outcomes of the present research, the SF/PU composite hydrogel may provide significant advantages for use in future clinical application in replacing nucleus pulposus field.
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Coogan JS, Francis WL, Eliason TD, Bredbenner TL, Stemper BD, Yoganandan N, Pintar FA, Nicolella DP. Finite Element Study of a Lumbar Intervertebral Disc Nucleus Replacement Device. Front Bioeng Biotechnol 2016; 4:93. [PMID: 27990418 PMCID: PMC5133048 DOI: 10.3389/fbioe.2016.00093] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 11/16/2016] [Indexed: 11/13/2022] Open
Abstract
Nucleus replacement technologies are a minimally invasive alternative to spinal fusion and total disc replacement that have the potential to reduce pain and restore motion for patients with degenerative disc disease. Finite element modeling can be used to determine the biomechanics associated with nucleus replacement technologies. The current study focuses on a new nucleus replacement device designed as a conforming silicone implant with an internal void. A validated finite element model of the human lumbar L3-L4 motion segment was developed and used to investigate the influence of the nucleus replacement device on spine biomechanics. In addition, the effect of device design changes on biomechanics was determined. A 3D, L3-L4 finite element model was constructed from medical imaging data. Models were created with the normal intact nucleus, the nucleus replacement device, and a solid silicone implant. Probabilistic analysis was performed on the normal model to provide quantitative validation metrics. Sensitivity analysis was performed on the silicone Shore A durometer of the device. Models were loaded under axial compression followed by flexion/extension, lateral bending, or axial rotation. Compressive displacement, endplate stresses, reaction moment, and annulus stresses were determined and compared between the different models. The novel nucleus replacement device resulted in similar compressive displacement, endplate stress, and annulus stress and slightly higher reaction moment compared with the normal nucleus. The solid implant resulted in decreased displacement, increased endplate stress, decreased annulus stress, and decreased reaction moment compared with the novel device. With increasing silicone durometer, compressive displacement decreased, endplate stress increased, reaction moment increased, and annulus stress decreased. Finite element analysis was used to show that the novel nucleus replacement device results in similar biomechanics compared with the normal intact nucleus.
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Affiliation(s)
| | | | | | | | - Brian D Stemper
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA; Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA
| | - Narayan Yoganandan
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA; Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA
| | - Frank A Pintar
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA; Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA
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Abstract
STUDY DESIGN In vitro biomechanical laboratory study. OBJECTIVES The purpose of this study is to evaluate a mechanical treatment to create a degenerative motion segment and the ability of nucleus augmentation to restore biomechanics. SUMMARY OF BACKGROUND In cases with an intact annulus fibrosus, the replacement or augmentation of the nucleus pulposus alone may provide a less invasive option to restore normal biomechanics and disk height when compared with spinal fusion or total disk replacement. Laboratory testing allows these changes to be fully characterized. However, without preexisting pathology, nucleus augmentation therapies are difficult to evaluate in vitro. METHODS The present study evaluated pure moment bending and compressive biomechanics in 3 states (n=6): (1) intact, (2) after creep loading and nucleus disruption to induce degenerative biomechanical changes, and (3) after nucleus augmentation through an injectable polymer (DiscCell). RESULTS Neutral zone and ROM were increased in all modes of bending after the degenerative treatment. The most sensitive mode of bending was lateral bending, with intact ROM (20.0±2.9 degrees) increased to 22.3±2.6 degrees after degenerative treatment and reduced to 18.4±1.6 degrees after injection of the polymer. All bending ROM and NZ changes induced by the degenerative treatment were reversed by nucleus augmentation. CONCLUSIONS This material was shown to be effective at altering motion segment biomechanics and restoring disk height during time zero tests. This technique may provide a model to examine the time zero performance of a nucleus augmentation device/material.
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Schmidt H, Bashkuev M, Galbusera F, Wilke HJ, Shirazi-Adl A. Finite element study of human lumbar disc nucleus replacements. Comput Methods Biomech Biomed Engin 2013; 17:1762-76. [PMID: 23477684 DOI: 10.1080/10255842.2013.766722] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Currently, there are a number of nucleus replacements under development. The important concern is how well these implants duplicate the mechanical function of the native nucleus. This finite element model study aimed to investigate the influence of different nucleus replacements on the mechanical response of the disc. Models included partial, full, over-sized, partially saturated, elastic and poroelastic solid replacements. Over-sized nucleus replacements up to 25% yielded results that were comparable to those in the intact state. Differences were much greater in cases with under-sized nucleus replacements. The effect was most pronounced for the 75% under-sized replacement that resembled the condition with a full nucleotomy. Nucleus implants with elastic properties substantially altered load transmission when 10% under-sized and over-sized replacements were considered. Compared to intact, the under-sized implants should be avoided when using biphasic materials with properties similar to the native nucleus, whereas for elastic replacements both under- and over-sized implants should not be used.
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Affiliation(s)
- Hendrik Schmidt
- a Julius Wolff Institut, Charité - Universitätsmedizin Berlin, CVK , Institutsgebäude Süd/Südstraße 2, Augustenburger Platz 1, 13353 Berlin , Germany
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13
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Strange DG, Oyen ML. Composite hydrogels for nucleus pulposus tissue engineering. J Mech Behav Biomed Mater 2012; 11:16-26. [DOI: 10.1016/j.jmbbm.2011.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 09/16/2011] [Accepted: 10/10/2011] [Indexed: 11/27/2022]
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Lewis G. Nucleus pulposus replacement and regeneration/repair technologies: present status and future prospects. J Biomed Mater Res B Appl Biomater 2012; 100:1702-20. [PMID: 22566484 DOI: 10.1002/jbm.b.32712] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 02/19/2012] [Accepted: 03/18/2012] [Indexed: 12/28/2022]
Abstract
Degenerative disc disease is implicated in the pathogenesis of many painful conditions of the back, chief among which is low back pain. Acute and/or chronic low back pain (A/CLBP) afflicts a large number of people, thus making it a major healthcare issue with concomitant cost ramifications. When conservative treatments for A/CLBP, such as bed rest, anti-inflammatory medications, and physical therapy, prove to be ineffectual, surgical options are recommended. The most popular of these is discectomy followed by fusion. Although there are many reports of good to excellent outcomes with this method, there are concerns, such as long-term adverse biomechanical consequences to adjacent functional spinal unit(s). A surgical option that has been attracting much attention recently is replacement or regeneration/repair of the nucleus pulposus, an approach that holds the prospect of not compromising either mobility or function and causing no adjacent-level injury. There is a sizeable body of literature highlighting this option, comprising in vitro biomechanical studies, finite element analyses, animal-model studies, and limited clinical evaluations. This work is a review of this body of literature and is organized into four parts, with the focus being on replacement technologies, regeneration/repair technologies, and detailed expositions on 14 areas for future study. This review ends with a summary of the salient points made.
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Affiliation(s)
- Gladius Lewis
- Department of Mechanical Engineering, The University of Memphis, Memphis, Tennessee 38152, USA.
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Hu J, Chen B, Guo F, Du J, Gu P, Lin X, Yang W, Zhang H, Lu M, Huang Y, Xu G. Injectable silk fibroin/polyurethane composite hydrogel for nucleus pulposus replacement. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2012; 23:711-22. [PMID: 22231270 DOI: 10.1007/s10856-011-4533-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Accepted: 12/10/2011] [Indexed: 05/07/2023]
Abstract
In degenerative disc disease, an injectable hydrogel can fill a degenerate area completely, reduce the risk of implant migration and subsequent loss of height of the intervertebral disc, and minimise surgical defects. Here, we propose a method of preparing an injectable silk fibroin/polyurethane (SF/PU) composite hydrogel by chemical cross-linking under physiological conditions. Mechanical testing was used to determine the mechanical strength of the hydrogel. The impact of hydrogel height on the biomechanical properties was discussed to estimate the working capacity of the hydrogel for further clinical application. Rheological properties were also examined to assess the practical ability of the hydrogel for clinical application. Hydrogel injection and cell assessment is also of interest for clinical application. An SF/PU composite hydrogel can be injected through a small incision. A cell proliferation assay using bone marrow stromal cells showed positive cell viability and increased proliferation over a seven-day period in culture. Importantly, the hydrogel can be monitored in real-time using X-ray fluoroscopy during and after surgery according to the results of X-ray fluoroscopy examination, and shows good visibility based on X-ray assays. In particular, the hydrogel offers the clinically important advantage of visibility in CT and T2-weighted magnetic resonance imaging. Based on the results of the current study, the SF/AU composite hydrogel may offer several advantages for future application in nucleus pulposus replacement.
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Affiliation(s)
- Jingen Hu
- Department of Orthopedics, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
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