Failure of Human Cervical Endplates: A Cadaveric Experimental Model

Truumees, Eeric; Yang, King H.; Herkowitz, Harry N.

doi:10.1097/01.brs.0000084881.11695.50

Cited by 52 publications

(25 citation statements)

References 15 publications

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“…Link [16] suggested using a rectangular footprint size in cervical arthroplasty in order to cover as much as possible of the cervical endplate, because bending forces are much stronger in the lateral aspect of cervical vertebrae than in thoracic or lumbar vertebrae. In addition, cervical endplates fail at loads lower than those typically measured for compressive failure of cervical grafts [21]. Due to the large range of lateral flexion in the cervical spine, the lateral portion surrounded by the uncinate process is also one of the strongest parts of the endplate [22].…”

Section: Discussionmentioning

confidence: 99%

Footprint mismatch in total cervical disc arthroplasty

et al. 2012

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Purpose Cervical disc arthroplasty has become a commonplace surgery for the treatment of cervical radiculopathy and myelopathy. Most manufacturers derive their implant dimensions from early published cadaver studies. Ideal footprint match of the prosthesis is essential for good surgical outcome. Methods We measured the dimensions of cervical vertebrae from computed tomography (CT) scans and to assess the accuracy of match achieved with the most common cervical disc prostheses [Bryan (Medtronic), Prestige LP (Medtronic), Discover (DePuy) Prodisc-C (Synthes)]. A total of 192 endplates in 24 patients (56.3 years) were assessed. The anterior-posterior and mediolateral diameters of the superior and inferior endplates were measured with a digital measuring system. Results Overall, 53.5 % of the largest device footprints were smaller in the anterior-posterior diameter and 51.1 % in the mediolateral diameter were smaller than cervical endplate diameters. For levels C5/C6 and C6/C7 an inappropriate size match was noted in 61.9 % as calculated from the anteroposterior diameter. Mismatch at the center mediolateral diameter was noted in 56.8 %. Of the endplates in the current study up to 58.1 % of C5/C6 and C6/ C7, and up to 45.3 % of C3/C4 and C4/C5 were larger than the most frequently implanted cervical disc devices. Conclusion Surgeons and manufacturers should be aware of the size mismatch in currently available cervical disc prostheses, which may endanger the safety and efficacy of the procedure. Undersizing the prosthetic device may lead to subsidence, loosening, heterotopic ossification and biomechanical failure caused by an incorrect center of rotation and load distribution, affecting the facet joints.

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Section: Discussionmentioning

confidence: 99%

Footprint mismatch in total cervical disc arthroplasty

et al. 2012

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“…19,42 The two-part resin was viscous when mixed and therefore did not leach or interdigitate with the endplate. The intention was to level the superior surface prior to biomechanical testing to provide a uniform interface with the materials testing machine without affecting the internal structure of the vertebra.…”

Section: Specimen Preparation and Bone Density Measurementmentioning

confidence: 99%

“…Factors influencing the limits included the weight of a human head ($50 N) for the minimum limit and the published failure load of the implant-endplate interface for the maximum limit (range: 754-2,238 N). 17,19,42 Since the intent was to examine the implant-endplate interface under cyclic loading, a maximum limit of 250 N was selected to allow a factor of safety with respect to the published ultimate failure loads.…”

Section: Specimen Preparation and Bone Density Measurementmentioning

confidence: 99%

“…[9][10][11] Extensive work has been directed to studying the graft-endplate or implant-endplate interface. The effect of graft or device-endplate surface contact [12][13][14] and that of endplate removal 12,[14][15][16][17][18][19] on the biomechanical properties of anterior cervical construct are well described. Endplate failure is also affected by bone quality.…”

mentioning

confidence: 99%

“…Endplate failure is also affected by bone quality. 13,14,16,[19][20][21][22][23] These studies utilized a failure model that is clinically consistent with acute endplate fracture, and has little correlation with the more common clinical presentation of gradual subsidence seen post-operatively.Gradual subsidence can eventually lead to failure of the spinal construct in vivo, most often due to fatigue failure. 24 Recreation of fatigue failure in vitro is difficult and is limited by assumptions involving the in vivo loading pattern and the potential for specimen degradation during testing.…”

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confidence: 99%

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Anterior cervical interbody constructs: effect of a repetitive compressive force on the endplate

Ordway

Rim²,

Tan

et al. 2011

Journal Orthopaedic Research

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Graft subsidence following anterior cervical reconstruction can result in the loss of sagittal balance and recurring foraminal stenosis. This study examined the implant-endplate interface using a cyclic fatigue loading protocol in an attempt to model the subsidence seen in vivo. The superior endplate from 30 cervical vertebrae (C3 to T1) were harvested and biomechanically tested in axial compression with one of three implants: Fibular allograft; titanium mesh cage packed with cancellous chips; and trabecular metal. Each construct was cyclically loaded from 50 to 250 N for 10,000 cycles. Nondestructive cyclic loading of the cervical endplate-implant construct resulted in a stiffer construct independent of the type of the interbody implant tested. The trabecular metal construct demonstrated significantly more axial stability and significantly less subsidence in comparison to the titanium mesh construct. Although the allograft construct resulted in more subsidence than the trabecular metal construct, the difference was not significant and no difference was found when comparing axial stability. For all constructs, the majority of the subsidence during the cyclic testing occurred during the first 500 cycles and was followed by a more gradual settling in the remaining 9,500 cycles. Keywords: cervical endplate; fatigue; cyclic testing; biomechanics; subsidence Anterior cervical fusion has traditionally been a predictable and reliable surgical technique for treatment of multiple spinal pathologies. [1][2][3] The success has been due to factors that are addressed by the surgical procedure: the removal of the pathologic process; the decompression of the neural elements; the correction of sagittal balance; and the stabilization of the motion segment. Maintenance of sagittal balance and continued stabilization of the motion segment following anterior reconstruction is essential in obtaining a successful clinical outcome. Subsidence of an interbody graft or construct prior to bony fusion can be detrimental to sagittal balance and/or stabilization of the motion segment resulting in recurrent foraminal stenosis.Options available for reconstructing the anterior cervical column include a structural autograft, a structural allograft, a carbon fiber cage, a PEEK cage, a titanium mesh cage, or a trabecular metal spacer. Material properties and interface geometries vary, but the devices function similarly by providing mechanical integrity and stability to the construct while bony fusion takes place. Independent of the device, settling occurs following anterior interbody fusion, 4-6 the amount of which is affected by intraoperative endplate injury or removal, osteoporosis, and the cross-sectional area of the implant. 7,8 Obtaining contact between the endplate and implant surfaces is technically challenging, and a certain amount of settling occurs early post-operatively. With bony implants, additional settling occurs as the graft is resorbed prior to bone fusion. The amount of settling is often <1 mm. Other causes of post-op...

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The cervical spine demonstrates less postoperative bone loss than the lumbar spine

Salzmann

Okano

Miller

et al. 2021

Journal Orthopaedic Research

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The objective of this study is to determine the bone mineral density (BMD) changes in adjacent vertebra following anterior cervical discectomy and fusion (ACDF).Consecutive patients undergoing ACDF with available preoperative and postoperative computed tomography (CT) imaging were included. Quantitative CT measurements of screw-free cervical and first thoracic vertebra were performed.Comparisons between pre-and postoperative BMD in the vertebrae one or two levels above the upper instrumented vertebra (UIV + 1, UIV + 2) and one level below the lowest instrumented vertebra (LIV + 1) were assessed. Seventy-two patients (men, 66.7%) met the inclusion criteria. The patient population was 91.7% Caucasian with a mean age of 55.0 years. The mean interval (±SD) between surgery and secondary CT was 157 ± 23 days. Preoperative BMD (±SD) in UIV + 1 was 300.6 ± 66.2 mg/cm 3 . There was a significant BMD loss of 1.5% at UIV + 1 after surgery, resulting in a postoperative BMD of 296.2 ± 64.8 mg/cm 3 (p = .029). At UIV + 2 and LIV + 1, no significant differences between pre-and postoperative BMD (304.7 ± 75.7 mg/cm 3 vs. 299.8 ± 74.3 mg/cm 3 , 197.3 ± 50.4 mg/cm 3 vs. 200.8 ± 48.7 mg/cm 3 , p = .113 and p = .078, respectively) were observed.

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Failure of Human Cervical Endplates: A Cadaveric Experimental Model

Abstract: Bone quality was predictive of endplate compressive failure loads. Intact endplates failed at significantly higher loads than their perforated or burred counterparts.

Cited by 52 publications

References 15 publications

Footprint mismatch in total cervical disc arthroplasty

Footprint mismatch in total cervical disc arthroplasty

Anterior cervical interbody constructs: effect of a repetitive compressive force on the endplate

The cervical spine demonstrates less postoperative bone loss than the lumbar spine

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