Materials and design concepts for an intervertebral disc spacer. I. Fiber‐reinforced composite design

Langrana, Noshir A.; Parsons, J. R.; Lee, Casey K.; Vuono-Hawkins, M.; Yang, Shaojie; Alexander, Harold

doi:10.1002/jab.770050205

Cited by 36 publications

(15 citation statements)

References 14 publications

(2 reference statements)

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“…One previous report of a hydrogel type nucleus prosthesis tested in human cadavers and implanted via an experimental annulus sparing technique had similar axial stiffness to that in the present study [42]. Another prosthetic (total) disc which is non-articulating and made of fiber reinforced polymers also had an axial compressive stiffness that was similar to the device described in the current study [39]. …”

Section: Discussionsupporting

confidence: 81%

Biomechanical characterization of an annulus-sparing spinal disc prosthesis

Buttermann

Beaubien

2009

The Spine Journal

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Background Context Current spine arthroplasty devices, require disruption of the annulus fibrosus for implantation. Preliminary studies of a unique annulus sparing intervertebral prosthetic disc (IPD), found that preservation of the annulus resulted in load sharing of the annulus with the prosthesis. Purpose Determine flexibility of the IPD versus fusion constructs in normal and degenerated human spines. Study design/Setting Biomechanical comparison of motion segments in the intact, fusion and mechanical nucleus replacement states for normal and degenerated states. Patient setting Thirty lumbar motion segments. Outcomes Measures Intervertebral height; motion segment range-of-motion (ROM), neutral zone (NZ), stiffness. Methods Motion segments had multi-directional flexibility testing to 7.5 Nm for intact discs, discs reconstructed using the IPD (n=12), or after anterior/posterior fusions (n=18). Interbody height and axial compression stiffness changes were determined for the reconstructed discs by applying axial compression to 1500 N. Analysis included stratifying results to normal mobile vs. rigid degenerated intact motion segments. Results The mean interbody height increase was 1.5 mm for IPD reconstructed discs. vs 3.0 mm for fused segments. Axial compression stiffness was 3.0 ± 0.9 kN/mm for intact compared to 1.2 ± 0.4 kN/mm for IPD reconstructed segments. Reconstructed disc ROM was 9.0° ± 3.7° in flexion-extension, 10.6° ± 3.4° in lateral bending and 2.8° ± 1.4° in axial torsion which was similar to intact values and significantly greater than respective fusion values (p<0.001). Mobile intact segments exhibited significantly greater rotation after fusion vs. their more rigid counterparts (p<0.05), however, intact motion was not related to motion after IPD reconstruction. The NZ and rotational stiffness followed similar trends. Differences in NZ between mobile and rigid intact specimens tended to decrease in the IPD reconstructed state. Conclusion The annulus sparing IPD generally reproduced the intact segment biomechanics in terms of ROM, NZ, and stiffness. Furthermore, the IPD reconstructed discs imparted stability by maintaining a small neutral zone. The IPD reconstructed discs were significantly less rigid than the fusion constructs and may be an attractive alternative for the treatment of DDD.

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Section: Discussionsupporting

confidence: 81%

Biomechanical characterization of an annulus-sparing spinal disc prosthesis

Buttermann

Beaubien

2009

The Spine Journal

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“…109 Operative fusion (arthrodesis) involves placement of a bone graft within the disc space post-discectomy, with further stabilization of the joint attained using spinal instrumentation. 110 A study from The Healthcare Cost and Utilization Project 111 reported that 297,883 spinal fusions were performed in the United States in 2003. Interbody fusion has resulted in successful clinical outcomes and succeeds in alleviating pain by removing the disc and eliminating any motion through the joint.…”

Section: Interbody Fusionmentioning

confidence: 99%

Tissue-Engineering Approach to Regenerating the Intervertebral Disc

2007

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In today's world there is an ever increasing incidence of low back pain, which is generally attributed to degeneration of the intervertebral disc (IVD) in those in their second or third decade of life. The most prevalent treatment modalities involve conservative methods (physical therapy and medications) or surgical fusion of the upper and lower vertebral bodies. In the last 10 years, there has been a surge of interest in applying tissue-engineering principles to treat spinal problems associated with the IVD. Tissue engineering provides many promising advantages to treating disc degeneration; it adopts a more biological and reparative approach, whereby the main goal is to restore the properties of the disc to its pre-degenerative state. This review outlines the physiology of the IVD and the etiology of disc degeneration. Much of the research carried out in the field of tissue engineering is based on three predominant constituents: cells, scaffolds, and signals. Thus, specific attention is given to these constituents and their potential use in repairing the IVD. Some of the significant challenges involved in IVD tissue engineering are also identified, and a brief discussion regarding possible future areas of research follows.

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“…To this end, the device should allow normal, unconstrained physiologic motions; permitting the spine to regulate the device, as opposed to spinal motion adapting to the implant. Additionally, the device must adequately address the in vivo loading conditions [17,18,21,22,23,24,30], must function as a stand-alone implant in the presence of an intact posterior column, and must resist wear, cold flow and material delamination. Most importantly and most challenging is for the device to encourage osseointegration at the bone-metal interface while preserving the biomechanical properties of motion.…”

Section: Discussionmentioning

confidence: 99%

Total disc replacement arthroplasty using the AcroFlex lumbar disc: a non-human primate model

Cunningham

Lowery²,

Serhan³

et al. 2002

Eur Spine J

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Using a non-human primate model, the current study was undertaken to investigate the efficacy of the AcroFlex lumbar disc as an intervertebral disc prosthesis, based on biomechanical, histopathologic and histomorphometric analyses. A total of 20 mature male baboons (Papio cynocephalus, mean weight 30 kg) were randomized into two equal groups based on post-operative time periods of 6 (n=10) and 12 months (n=10). Each animal underwent an anterior transperitoneal surgical approach to the lumbar spine, with intervertebral reconstructions performed at L3-L4 and L5-L6 using the following techniques: (1) tricortical iliac autograft and (2) AcroFlex lumbar disc. The two treatments were equally randomized between the non-contiguous operative lumbar levels. Post-mortem analysis included histopathologic assessment of the systemic reticuloendothelial tissues, multi-directional flexibility testing of the operative functional spinal units and quantitative histological analysis of trabecular bone coverage at the prosthesis endplates. Data were statistically compared using a one-way ANOVA with the Student-Newman-Keuls test. All animals survived the operative procedure and post-operative interval without significant intraor peri-operative complications. Histopathologic analysis of the paraffin-embedded systemic reticuloendothelial tissues indicated no significant pathologic changes at the 6-or 12-month intervals. Plain film radiographic analysis showed no lucencies or loosening of any prosthetic vertebral endplate. Biomechanical testing of the 6-month autograft, reconstructions with AcroFlex lumbar disc and non-operative control (n=10) intact motion segments indicated no significant differences in peak range of motion (ROM) in axial compression. However, axial rotation produced significantly lower ROM for the autograft treatment compared to the intact and AcroFlex groups (P<0.05). The most significant differences in peak ROM were noted between all treatment groups under flexion/extension and lateral bending loading modalities (P<0.05). By 12 months, the intact condition indicated significantly more motion in all bending modes compared to the AcroFlex and autograft treatments, which were not statistically different from each other (P>0.05). Gross histopathologic analysis of the AcroFlex disc prosthesis demonstrated excellent ingrowth at the level of the implant-bone interface, without evidence of fibrous tissue or synovium. BioQuant histomorphometric analysis at the metal-bone interface (bone contact area/total endplate area) indicated the mean ingrowth was 54.59± 13.24% at 6 months and 56.79± 5.85% at 12 months. Radiographic analysis showed no lucencies or loosening of the AcroFlex vertebral

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Materials and design concepts for an intervertebral disc spacer. I. Fiber‐reinforced composite design

Cited by 36 publications

References 14 publications

Biomechanical characterization of an annulus-sparing spinal disc prosthesis

Biomechanical characterization of an annulus-sparing spinal disc prosthesis

Tissue-Engineering Approach to Regenerating the Intervertebral Disc

Total disc replacement arthroplasty using the AcroFlex lumbar disc: a non-human primate model

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