A Biomechanical Study of Regional Endplate Strength and Cage Morphology as It Relates to Structural Interbody Support

Lowe, Thomas G.; Hashim, Shukor; Wilson, Lucas A.; O’Brien, Michael F.; Smith, David A.; Diekmann, Molly J.; Trommeter, Julie M.

doi:10.1097/01.brs.0000143623.18098.e5

Cited by 195 publications

(122 citation statements)

References 8 publications

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“…Oxland et al (2003) found a significant decrease in failure load and stiffness for endplate removal. Lowe et al (2004) found that mean failure loads for complete removal were significantly lower than partially removed or intact endplates. Using full and peripheral support devices, Steffen et al (2000) found no difference in failure loads with intact endplates and removed (device sitting on periphery) endplates.…”

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confidence: 90%

“…Removal of the stiffer cortical endplate exposes a host bed of bleeding trabecular bone (potentially osteogenic cells) which is advantageous from a biological point of view allowing bone fusion with the graft material. A number of in vitro investigations of the effect of endplate removal on the vertebral subsidence force have provided conflicting recommendations including: endplate preservation (Lim et al 2001;Oxland et al 2003); partial endplate removal (Steffen et al 2000;Lowe et al 2004); complete endplate removal (Hollowell et al 1996;Closkey et al 1993). Regardless of the endplate preparation technique, the insertion of a stiff metallic IFD will induce significant stress concentrations in the surrounding bone.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental studies on subsidence have predominantly focused on endplate preparation and implant geometry with the maximum failure load being measured to evaluate subsidence resistance (Lim et al 2001;Oxland et al 2003;Steffen et al 2000;Lowe et al 2004;Hollowell et al 1996;Closkey et al 1993). Oxland et al (2003) found a significant decrease in failure load and stiffness for endplate removal.…”

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confidence: 99%

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An experimental and computational investigation of the post-yield behaviour of trabecular bone during vertebral device subsidence

Kelly

Harrison

McDonnell

et al. 2012

Biomech Model Mechanobiol

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PublisherSpringer-Verlag AbstractInterbody fusion device subsidence has been reported clinically. An enhanced understanding of the mechanical behaviour of the surrounding bone would allow for accurate predictions of vertebral subsidence. The multiaxial inelastic behaviour of trabecular bone is investigated at a microscale and macroscale level. The post-yield behaviour of trabecular bone under hydrostatic and confined compression is investigated using micro-computed tomography derived microstructural models, elucidating a mechanism of pressure dependent yielding at the macroscopic level. Specifically, microstructural trabecular simulations predict a distinctive yield point in the apparent stress-strain curve under uniaxial, confined and hydrostatic compression. Such distinctive apparent stress-strain behaviour results from localised stress concentrations and material yielding in the trabecular microstructure. This phenomenon is shown to be independent of the plasticity formulation employed at a trabecular level. The distinctive response can be accurately captured by a continuum model using a crushable foam plasticity formulation in which pressure dependent yielding occurs.Vertebral device subsidence experiments are also performed, providing measurements of the trabecular plastic zone. It is demonstrated that a pressure dependent plasticity formulation must be used for continuum level macroscale models of trabecular bone in order to replicate the experimental observations, further supporting the microscale investigations. Using a crushable foam plasticity formulation in the simulation of vertebral subsidence, it is shown that the predicted subsidence force and plastic zone size correspond closely with the experimental measurements. In contrast the use of von Mises, Drucker-Prager and Hill plasticity formulations for continuum trabecular bone models lead to over prediction of the subsidence force and plastic zone.

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confidence: 90%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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An experimental and computational investigation of the post-yield behaviour of trabecular bone during vertebral device subsidence

Kelly

Harrison

McDonnell

et al. 2012

Biomech Model Mechanobiol

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“…The importance of normal sagittal alignment has been increasingly recognised in multi-segmental fusions for spinal deformity [1][2][3]. With increasing focus on patient-related outcomes, there is mounting evidence that optimum sagittal alignment in lumbar fusion is associated with improved outcomes across differing pathologies [1,[4][5][6][7][8][9], reduced post-surgical pain [1-3, 5-8, 10-13], reduced adjacent segment degeneration [4,5,7,[9][10][11][12][13][14], and reduced revision rates [1-5, 7, 9-11, 13, 15-18].…”

Section: Introductionmentioning

confidence: 99%

Do position and size matter? An analysis of cage and placement variables for optimum lordosis in PLIF reconstruction

2017

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Purpose To examine monosegmental lordosis after posterior lumbar interbody fusion (PLIF) surgery and relate lordosis to cage size, shape, and placement. Methods Eighty-three consecutive patients underwent single-level PLIF with paired identical lordotic cages involving a wide decompression and bilateral facetectomies. Cage parameters relating to size (height, lordosis, and length) and placement (expressed as a ratio relative to the length of the inferior vertebral endplate) were recorded. Centre point ratio (CPR) was the distance to the centre of both cages and indicated mean position of both cages. Posterior gap ratio (PGR) was the distance to the most posterior cage and indicated position and cage length indirectly. Relationships between lordosis and cage parameters were explored. Results Mean lordosis increased by 5.98°(SD 6.86°). The cages used varied in length from 20 to 27 mm, in lordosis from 10°to 18°, and in anterior cage height from 10 to 17 mm. The mean cage placement as determined by CPR was 0.54 and by PGR was 0.16. The significant correlations were: both CPR and PGR with lordosis gain at surgery (r = 0.597 and 0.537, respectively, p \ 0.001 both), cage lordosis with the final lordosis (r = 0.234, p \ 0.05), and anterior cage height was negatively correlated with a change in lordosis (r = -0.297, p \ 0.01).Conclusion Cage size, shape, and position, in addition to surgical technique, determine lordosis during PLIF surgery. Anterior placement with sufficient ''clear space'' behind the cages is recommended. In addition, cages should be of moderate height and length, so that they act as an effective pivot for lordosis.

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“…Li et al [9] showed that nucleus pulposis mixed with bone graft slows down the rate of bony growth, possibly through inflammatory mediators. Lowe et al [10] asserted that total area of discectomy and endplate preparation play a role in fusion rate. Thus, the goals of disc space preparation when performing lumbar interbody fusion are to thoroughly remove the disc and endplate cartilage, expose the underlying bleeding endplate bone, and avoid gross violation of the endplate.…”

Section: Introductionmentioning

confidence: 99%

Disc Space Preparation in Transforaminal Lumbar Interbody Fusion: A Comparison of Minimally Invasive and Open Approaches

Rihn

Gandhi

Sheehan

et al. 2014

Clinical Orthopaedics &Amp; Related Research

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Background Minimally invasive surgical (MIS) approaches to transforaminal lumbar interbody fusion (TLIF) have been developed as an alternative to the open approach. However, concerns remain regarding the adequacy of disc space preparation that can be achieved through a minimally invasive approach to TLIF.Questions/purposes The purpose of this cadaver study is to compare the adequacy of disc space preparation through MIS and open approaches to TLIF. Specifically we sought to compare the two approaches with respect to (1) the time required to perform a discectomy and the number of endplate violations; (2) the percentage of disc removed; and (3) the anatomic location where residual disc would remain after discectomy. Methods Forty lumbar levels (ie, L1-2 to L5-S1 in eight fresh cadaver specimens) were randomly assigned to open and MIS groups. Both surgeons were fellowship-trained spine surgeons proficient in the assigned approach used. Time required for discectomy, endplate violations, and percentage of disc removed by volume and mass were recorded for each level. A digital imaging software program (ImageJ; US National Institutes of Health, Bethesda, MD, USA) was used to measure the percent disc removed by area for the total disc and for each quadrant of the endplate. Results The open approach was associated with a shorter discectomy time (9 versus 12 minutes, p = 0.01) and fewer endplate violations (one versus three, p = 0.04) when compared with an MIS approach, percent disc removed by volume (80% versus 77%, p = 0.41), percent disc removed by mass (77% versus 75%, p = 0.55), and percent total disc removed by area (73% versus 71%, p = 0.63) between the open and MIS approaches, respectively. The posterior contralateral quadrant was associated with the lowest percent of disc removed compared with the other three quadrants in both open and MIS groups (50% and 60%, respectively). Conclusions When performed by a surgeon experienced with MIS TLIF, MIS and open approaches are similar in regard to the adequacy of disc space preparation. The least amount of disc by percentage is removed from the posterior

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A Biomechanical Study of Regional Endplate Strength and Cage Morphology as It Relates to Structural Interbody Support

Cited by 195 publications

References 8 publications

An experimental and computational investigation of the post-yield behaviour of trabecular bone during vertebral device subsidence

An experimental and computational investigation of the post-yield behaviour of trabecular bone during vertebral device subsidence

Do position and size matter? An analysis of cage and placement variables for optimum lordosis in PLIF reconstruction

Disc Space Preparation in Transforaminal Lumbar Interbody Fusion: A Comparison of Minimally Invasive and Open Approaches

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