Biomechanical Study of Cervical Disc Arthroplasty Devices Using Finite Element Models

2020 ◽  
Author(s):  
Yuvaraj Purushothaman ◽  
Hoon Choi ◽  
Narayan Yoganandan ◽  
Jamie Baisden ◽  
Deepak Rajasekaran ◽  
...  
Keyword(s):  
Intradiscal Pressure ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Lateral Bending ◽  
Disc Arthroplasty ◽  
Bryan Disc ◽  
Metal On Metal ◽  
Flexion Extension ◽  
Metal Design ◽  
Index Level

Abstract Various types and designs of artificial discs for cervical disc arthroplasty (CDA) have been introduced to overcome the disadvantages of the conventional anterior cervical discectomy and fusion (ACDF). The purpose of this study was to evaluate the effects of different CDA designs on the range of motion (ROM), intradiscal pressure (IDP), and facet force variables with different types of FDA-approved CDA devices under normal physiological loading conditions. A validated three-dimensional finite element model (FEM) of the intact cervical spinal column (C2-T1) was used in the present study. The intact spine model was modified and used for postoperative FE models simulating CDAs implanted at the C5-C6 intervertebral disc space. The normal surgical procedures were used in the simulations. The hybrid loading protocol (intact spine loading: 2 Nm) with a compressive follower force of 75 N was applied at the superior end of the spine. The inferior endplate of C7 vertebra was constrained in all directions. Flexion, extension, and lateral bending loading conditions were simulated in all models: intact spine and models with different CDA devices. At the index level, all CDAs except the Bryan disc showed an increase in motion, and the range of motions at the adjacent levels decreased in flexion, extension, and lateral bending modes. The largest increase in motion occurred during lateral bending. The Bryan disc reduced the segmental motion at the index level under flexion, extension, and lateral bending, and had compensatory increases in motion at the adjacent levels. The intradiscal pressure reduced at the adjacent levels with Mobi-C and Secure-C devices. The Bryan and Prestige LP devices showed increases in the intradiscal pressure at the adjacent levels due to the reduced index level motion (Bryan disc) and the metal-on-metal design (Prestige LP). The facet force increased at the index level in all CDAs, with the highest force with Mobi-C, and this was attributed to its unrestrained design. The facet force generally decreased at the adjacent levels with CDAs, except for the Bryan disc, due to reduced index level motion, and the Prestige LP in lateral bending, likely due to its metal-on-metal design. The present study demonstrates the influence of different CDA designs on the anterior and posterior loading patterns at the index and adjacent levels. In addition, the study validates key clinical observations: CDA procedure is contraindicated in cases of facet arthropathy; and CDA may be protective against adjacent segment degeneration.

scholarly journals Biomechanical Study of Cervical Disc Arthroplasty Devices Using Finite Element Modeling

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Narayan Yoganandan ◽  
Yuvaraj Purushothaman ◽  
Hoon Choi ◽  
Jamie Baisden ◽  
Deepak Rajasekaran ◽  
...  
Keyword(s):  
Finite Element ◽  
Intradiscal Pressure ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Adjacent Segment ◽  
Lateral Bending ◽  
Disc Arthroplasty ◽  
Bryan Disc ◽  
Flexion Extension ◽  
Index Level

Abstract Many artificial discs for have been introduced to overcome the disadvantages of conventional anterior discectomy and fusion. The purpose of this study was to evaluate the performance of different U.S. Food and Drug Administration (FDA)-approved cervical disc arthroplasty (CDA) on the range of motion (ROM), intradiscal pressure, and facet force variables under physiological loading. A validated three-dimensional finite element model of the human intact cervical spine (C2-T1) was used. The intact spine was modified to simulate CDAs at C5-C6. Hybrid loading with a follower load of 75 N and moments under flexion, extension, and lateral bending of 2 N·m each were applied to intact and CDA spines. From this work, it was found that at the index level, all CDAs except the Bryan disc increased ROM, and at the adjacent levels, motion decreased in all modes. The largest increase occurred under the lateral bending mode. The Bryan disc had compensatory motion increases at the adjacent levels. Intradiscal pressure reduced at the adjacent levels with Mobi-C and Secure-C. Facet force increased at the index level in all CDAs, with the highest force with the Mobi-C. The force generally decreased at the adjacent levels, except for the Bryan disc and Prestige LP in lateral bending. This study demonstrates the influence of different CDA designs on the anterior and posterior loading patterns at the index and adjacent levels with head supported mass type loadings. The study validates key clinical observations: CDA procedure is contraindicated in cases of facet arthroplasty and may be protective against adjacent segment degeneration.

Analysis of load sharing on uncovertebral and facet joints at the C5–6 level with implantation of the Bryan, Prestige LP, or ProDisc-C cervical disc prosthesis: an in vivo image-based finite element study

2010 ◽  
Vol 28 (6) ◽  
pp. E9 ◽  
Author(s):  
Heesuk Kang ◽  
Paul Park ◽  
Frank La Marca ◽  
Scott J. Hollister ◽  
Chia-Ying Lin
Keyword(s):  
Finite Element ◽  
Normal Load ◽  
Load Sharing ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Lateral Bending ◽  
Disc Arthroplasty ◽  
Bryan Disc ◽  
Flexion Extension ◽  
Cervical Disc Prosthesis

Object The goal of this study was to evaluate and compare load sharing of the facet and uncovertebral joints after total cervical disc arthroplasty using 3 different implant designs. Methods Three-dimensional voxel finite element models were built for the C5–6 spine unit based on CT images acquired from a candidate patient for cervical disc arthroplasty. Models of facet and uncovertebral joints were added and artificial discs were placed in the intervertebral disc space. Finite element analyses were conducted under normal physiological loads for flexion, extension, and lateral bending to evaluate von Mises stresses and strain energy density (SED) levels at the joints. Results The Bryan disc imposed the greatest average stress and SED levels at facet and uncovertebral joints with flexion-extension and lateral bending, while the ProDisc-C and Prestige LP discs transferred less load due to their rigid cores. However, all artificial discs showed increased loads at the joints in lateral bending, which may be attributed to direct impinging contact force. Conclusions In unconstrained/semiconstrained prostheses with different core rigidity, the shared loads at the joints differ, and greater flexibility may result in greater joint loads. With respect to the 3 artificial discs studied, load sharing of the Bryan disc was highest and was closest to normal load sharing with the facet and uncovertebral joints. The Prestige LP and ProDisc-C carried more load through their rigid core, resulting in decreased load transmission to the facet and uncovertebral joints.

scholarly journals Comparative Finite Element Modeling Study of Anterior Cervical Arthrodesis Versus Cervical Arthroplasty With Bryan Disc or Prodisc C

2021 ◽  
Vol 186 (Supplement_1) ◽  
pp. 737-744
Author(s):  
Hoon Choi ◽  
Yuvaraj Purushothaman ◽  
Jamie L Baisden ◽  
Deepak Rajasekaran ◽  
Davidson Jebaseelan ◽  
...  
Keyword(s):  
Finite Element ◽  
Intradiscal Pressure ◽  
Implant Design ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Pathological State ◽  
Cervical Arthroplasty ◽  
Bryan Disc ◽  
Flexion Extension ◽  
Index Level

ABSTRACT Introduction Cervical disc arthroplasty (CDA), a motion-preserving alternative to anterior cervical discectomy and fusion (ACDF), is used in military patients for the treatment of disorders such as spondylosis. Since 2007, the FDA has approved eight artificial discs. The objective of this study is to compare the biomechanics after ACDF and CDA with two FDA-approved devices of differing designs under head and head supported mass loadings. Materials and Methods A previously validated osteoligamentous C2-T1 finite element model was used to simulate ACDF and two types of CDA (Bryan and Prodisc C) at the C5-C6 level. The hybrid loading protocol associated with in vivo head and head supported mass was used to apply flexion and extension loading. First, intact spine was subjected to 2 Nm of flexion extension and the range of motion (ROM) was measured. Next, for each surgical option, flexion-extension moments duplicating the same ROM as the intact spine were determined. Under these surgery-specific moments, ROM and facet force were obtained at the index level, and ROM, facet force, and intradiscal pressure at the rostral and caudal adjacent levels. Results ACDF led to increased motion, force and pressures at the adjacent levels. Prodisc C led to increased motion and facet force at the index level, and decreased motion, facet force, and intradiscal pressure at both adjacent levels. Bryan produced less dramatic biomechanical alterations compared with ACDF and Prodisc C. Numerical results are given in the article. Conclusions Recognizing that ROM is a clinical measure of spine stability/performance, CDA demonstrates a more physiological biomechanical response than ACDF, although the exact pattern depends on the implant design. Anterior and posterior column load-sharing patterns were different between the two implants and may affect implant selection based on the anatomical and pathological state at the index and adjacent levels.

Cervical disc arthroplasty for less-mobile discs

2019 ◽  
Vol 31 (3) ◽  
pp. 310-316 ◽  
Author(s):  
Tsung-Hsi Tu ◽  
Chu-Yi Lee ◽  
Chao-Hung Kuo ◽  
Jau-Ching Wu ◽  
Hsuan-Kan Chang ◽  
...  
Keyword(s):  
Clinical Outcomes ◽  
Japanese Orthopaedic Association ◽  
Neck Disability Index ◽  
Cervical Radiculopathy ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Segmental Mobility ◽  
Disc Arthroplasty ◽  
Flexion Extension ◽  
Index Level

OBJECTIVEThe published clinical trials of cervical disc arthroplasty (CDA) have unanimously demonstrated the success of preservation of motion (average 7°–9°) at the index level for up to 10 years postoperatively. The inclusion criteria in these trials usually required patients to have evident mobility at the level to be treated (≥ 2° on lateral flexion-extension radiographs) prior to the surgery. Although the mean range of motion (ROM) remained similar after CDA, it was unclear in these trials if patients with less preoperative ROM would have different outcomes than patients with more ROM.METHODSA series of consecutive patients who underwent CDA at the level of C5–6 were followed up and retrospectively reviewed. The indications for surgery were medically refractory cervical radiculopathy, myelopathy, or both, caused by cervical disc herniation or spondylosis. All patients were assigned to 1 of 2 groups: a less-mobile group, which consisted of those patients who had an ROM of ≤ 5° at C5–6 preoperatively, or a more-mobile group, which consisted of patients whose ROM at C5–6 was > 5° preoperatively. Clinical outcomes, including visual analog scale, Neck Disability Index, and Japanese Orthopaedic Association Scale scores, were evaluated at each time point. Radiological outcomes were also assessed.RESULTSA total of 60 patients who had follow-up for more than 2 years were analyzed. There were 27 patients in the less-mobile group (mean preoperative ROM 3.0°) and 33 in the more-mobile group (mean ROM 11.7°). The 2 groups were similar in demographics, including age, sex, diabetes, and cigarette smoking. Both groups had significant improvements in clinical outcomes, with no significant differences between the 2 groups. However, the radiological evaluations demonstrated remarkable differences. The less-mobile group had a greater increase in ΔROM than the more-mobile group (ΔROM 5.5° vs 0.1°, p = 0.001), though the less-mobile group still had less segmental mobility (ROM 8.5° vs 11.7°, p = 0.04). The rates of complications were similar in both groups.CONCLUSIONSPreoperative segmental mobility did not alter the clinical outcomes of CDA. The preoperatively less-mobile (ROM ≤ 5°) discs had similar clinical improvements and greater increase of segmental mobility (ΔROM), but remained less mobile, than the preoperatively more-mobile (ROM > 5°) discs at 2 years postoperatively.

Myelopathy after cervical disc arthroplasty due to progression of spondylosis at the index level: case report

2018 ◽  
Vol 28 (5) ◽  
pp. 467-471
Author(s):  
Anita Bhansali ◽  
Michael Musacchio ◽  
Noam Stadlan
Keyword(s):  
Case Report ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Artificial Disc ◽  
Rare Occurrence ◽  
Disc Disease ◽  
Disc Arthroplasty ◽  
Low Incidence ◽  
Index Level ◽  
Better Than

Cervical disc arthroplasty (CDA) has emerged as a popular alternative to anterior cervical discectomy and fusion (ACDF) for the surgical treatment of cervical degenerative disc disease. CDA has been well studied, with efficacy reported to be equivalent to or better than that seen with ACDF, and it is associated with a consistently low incidence of adverse events. The development or progression of myelopathy after CDA is a particularly rare occurrence. In this report, the authors describe the first known case of recurrence of myelopathy at the index level of surgery after CDA implantation due the continuation of the spondylitic process after placement of the artificial disc.

In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant

2004 ◽  
Vol 17 (3) ◽  
pp. 44-54 ◽  
Author(s):  
Denis J. DiAngelo ◽  
Kevin T. Foley ◽  
Brian R. Morrow ◽  
John S. Schwab ◽  
Jung Song ◽  
...  
Keyword(s):  
Axial Rotation ◽  
Biomechanical Study ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Disc Arthroplasty ◽  
Single Level ◽  
Flexion Extension ◽  
Adjacent Segments ◽  
Treated Site

An in vitro biomechanical study was conducted to compare the effects of disc arthroplasty and anterior cervical fusion on cervical spine biomechanics in a multilevel human cadaveric model. Three spine conditions were studied: harvested, single-level cervical disc arthroplasty, and single-level fusion. A programmable testing apparatus was used that replicated physiological flexion/extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending moments. Relative rotations at the superior, treated, and inferior motion segment units (MSUs) were normalized with respect to the overall rotation of those three MSUs and compared using a one-way analysis of variance with Student–Newman–Keuls test (p < 0.05). Simulated fusion decreased motion across the treated site relative to the harvested and disc arthroplasty conditions. The reduced motion at the treated site was compensated at the adjacent segments by an increase in motion. For all modes of testing, use of an artificial disc prosthesis did not alter the motion patterns at either the instrumented level or adjacent segments compared with the harvested condition, except in extension.

The Effect of T1-Slope in Spinal Parameters After Cervical Disc Arthroplasty

Neurosurgery ◽  
2020 ◽  
Author(s):  
Yi-Hsuan Kuo ◽  
Chao-Hung Kuo ◽  
Hsuan-Kan Chang ◽  
Li-Yu Fay ◽  
Tsung-Hsi Tu ◽  
...  
Keyword(s):  
Cobb Angle ◽  
Clinical Outcomes ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Cervical Lordosis ◽  
Segmental Mobility ◽  
Disc Arthroplasty ◽  
T1 Slope ◽  
Index Level ◽  
Cervical Spinal Alignment

Abstract BACKGROUND Although patients with cervical kyphosis are not ideal candidates for cervical disc arthroplasty (CDA), there is a paucity of data on patients with a straight or slightly lordotic neck. OBJECTIVE To correlate cervical lordosis, T1-slope, and clinical outcomes of CDA. METHODS The study retrospectively analyzed 95 patients who underwent 1-level CDA and had 2-yr follow-up. They were divided into a high T1-slope (≥28°) group (HTSG, n = 45) and a low T1-slope (&lt;28°) group (LTSG, n = 50). Cervical spinal alignment parameters, including T1-slope, cervical lordosis (C2-7 Cobb angle), and segmental mobility (range of motion [ROM]) at the indexed level, were compared. The clinical outcomes were also assessed. RESULTS The mean T1-slope was 28.1 ± 7.0°. After CDA, the pre- and postoperative segmental motility remained similar and cervical lordosis was preserved. All the clinical outcomes improved after CDA. The HTSG were similar to the LTSG in age, sex, segmental mobility, and clinical outcomes. However, the HTSG had higher cervical lordosis than the LTSG. Furthermore, the LTSG had increased cervical lordosis (ΔC2-7 Cobb angle), whereas the HTSG had decreased lordosis after CDA. Patients of the LTSG, who had more improvement in cervical lordosis, had a trend toward increasing segmental mobility at the index level (ΔROM) than the HTSG. CONCLUSION In this series, T1-slope correlated well with global cervical lordosis but did not affect the segmental mobility. After CDA, the changes in cervical lordosis correlated with changes in segmental mobility. Therefore, segmental lordosis should be cautiously preserved during CDA as it could determine the mobility of the disc.

scholarly journals Effect of preoperative segmental range of motion on patient outcomes in cervical disc arthroplasty

2020 ◽  
Author(s):  
Tingkui Wu ◽  
Hao Liu ◽  
Chen Ding ◽  
Xin Rong ◽  
Jun-bo He ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Clinical Outcomes ◽  
Neck Disability Index ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Cervical Lordosis ◽  
Disc Arthroplasty ◽  
Wide Range ◽  
Vas Scores ◽  
Index Level

Abstract BackgroundCervical disc arthroplasty (CDA) has been demonstrated in clinical trials as an effective and safe treatment for patients diagnosed with radiculopathy and/or myelopathy. However, the current CDA indication criteria based on the preoperative segmental range of motion (ROM), comprise a wide range of variability. Although the arthroplasty level preserved ROM averaged 7°-9° after CDA, there are no clear guidelines on preoperatively limited or excessive ROM at the index level, that could be considered as suitable for CDA in any given trials.MethodsPatients who underwent CDA between January 2008 to October 2018 using Prestige-LP discs in our hospital, were reviewed retrospectively. They were divided into the small-ROM (≤5.5°) and the large-ROM (> 12.5°) groups according to preoperatively index-level ROM. Clinical outcomes, including the Japanese Orthopedics Association (JOA), Neck Disability Index (NDI), and Visual Analogue Scale (VAS) scores, were evaluated. Radiological parameters, including cervical lordosis, disc angle (DA), global and segmental ROM, disc height (DH), and complications were measured.ResultsOne hundred and twenty-six patients, with a total of 132 arthroplasty segments were analyzed. There were 64 patients in the small-ROM and 62 in the large-ROM group. There are more patients diagnosed with cervical spondylosis in the small-ROM than in the large-ROM group (P=0.046). Patients in both groups had significantly improved in JOA, NDI, and VAS scores after surgery, but the intergroup difference was not significant. Patients in the small-ROM group increased dramatically in cervical lordosis, global and segmental ROM postoperatively (P < 0.001). However, global and segmental ROM paradoxically decreased in the large-ROM group postoperatively (P < 0.001). Patients in the small-ROM group had lower DH preoperatively (P=0.012), and a higher rate of heterotopic ossification (HO) postoperatively (P=0.037).ConclusionPatients with preoperatively limited or excessive segmental ROM could achieve satisfactory clinical outcomes at 3 years postoperatively. Patients with limited segmental ROM had more, and severe HO and significantly increased segmental mobility, which decreased in patients with excessive segmental ROM after surgery.

Heterotopic ossification and radiographic adjacent-segment disease after cervical disc arthroplasty

2019 ◽  
Vol 31 (5) ◽  
pp. 660-669 ◽  
Author(s):  
Michael M. H. Yang ◽  
Won Hyung A. Ryu ◽  
Steven Casha ◽  
Stephan DuPlessis ◽  
W. Bradley Jacobs ◽  
...  
Keyword(s):  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Adjacent Segment ◽  
Low Grade ◽  
High Grade ◽  
Artificial Disc ◽  
Disc Arthroplasty ◽  
The Mean ◽  
Index Level

OBJECTIVECervical disc arthroplasty (CDA) is an accepted motion-sparing technique associated with favorable patient outcomes. However, heterotopic ossification (HO) and adjacent-segment degeneration are poorly understood adverse events that can be observed after CDA. The purpose of this study was to retrospectively examine 1) the effect of the residual exposed endplate (REE) on HO, and 2) identify risk factors predicting radiographic adjacent-segment disease (rASD) in a consecutive cohort of CDA patients.METHODSA retrospective cohort study was performed on consecutive adult patients (≥ 18 years) who underwent 1- or 2-level CDA at the University of Calgary between 2002 and 2015 with > 1-year follow-up. REE was calculated by subtracting the anteroposterior (AP) diameter of the arthroplasty device from the native AP endplate diameter measured on lateral radiographs. HO was graded using the McAfee classification (low grade, 0–2; high grade, 3 and 4). Change in AP endplate diameter over time was measured at the index and adjacent levels to indicate progressive rASD.RESULTSForty-five patients (58 levels) underwent CDA during the study period. The mean age was 46 years (SD 10 years). Twenty-six patients (58%) were male. The median follow-up was 29 months (IQR 42 months). Thirty-three patients (73%) underwent 1-level CDA. High-grade HO developed at 19 levels (33%). The mean REE was 2.4 mm in the high-grade HO group and 1.6 mm in the low-grade HO group (p = 0.02). On multivariable analysis, patients with REE > 2 mm had a 4.5-times-higher odds of developing high-grade HO (p = 0.02) than patients with REE ≤ 2 mm. No significant relationship was observed between the type of artificial disc and the development of high-grade HO (p = 0.1). RASD was more likely to develop in the lower cervical spine (p = 0.001) and increased with time (p < 0.001). The presence of an artificial disc was highly protective against degenerative changes at the index level of operation (p < 0.001) but did not influence degeneration in the adjacent segments.CONCLUSIONSIn patients undergoing CDA, high-grade HO was predicted by REE. Therefore, maximizing the implant-endplate interface may help to reduce high-grade HO and preserve motion. RASD increases in an obligatory manner following CDA and is highly linked to specific levels (e.g., C6–7) rather than the presence or absence of an adjacent arthroplasty device. The presence of an artificial disc is, however, protective against further degenerative change at the index level of operation.

scholarly journals Mechanical Stability of the Prodisc-C Vivo Cervical Disc Arthroplasty: A Preliminary, Observational Study Using Radiostereometric Analysis

2019 ◽  
Vol 10 (3) ◽  
pp. 294-302
Author(s):  
Miranda L. van Hooff ◽  
Petra J. C. Heesterbeek ◽  
Maarten Spruit
Keyword(s):  
Adverse Events ◽  
Clinical Outcomes ◽  
Small Sample ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Radiostereometric Analysis ◽  
Disc Arthroplasty ◽  
Arm Pain ◽  
Flexion Extension ◽  
Over Time

Study Design: Prospective cohort study. Objective: To investigate the primary stability of the Prodisc-C Vivo cervical disc arthroplasty with regard to the adjacent cervical vertebrae using radiostereometric analysis (RSA), and to monitor its clinical performance. Methods: Sixteen patients with degenerative cervical disc disease were included. RSA radiographs were obtained at the first postoperative day, at 6 weeks, 3 months, and 6 months postoperatively. Migration (translation [mm]) of the superior and inferior implant components were measured with model-based RSA, expressed along the 3 orthogonal axes, and calculated as total translation. Clinical outcomes were Neck Disability Index, numeric rating scales for neck and arm pain, Likert-type scales for satisfaction, and adverse events. Range of motion was reported as C2-C7 flexion-extension mobility (ROM). Results: At final follow-up, no significant increase over time in median total translation was found. One inferior and 3 superior components subsided but were asymptomatic. ROM remained stable and clinical outcomes improved over time. Although 3 patients were unsatisfied and 3 adverse events occurred, this was not related to translation of the components. Conclusions: On a group level, both components of the Prodisc-C Vivo cervical disc arthroplasty remained stable over time and below the clinical threshold of 1 mm. Individual outliers for translation were not clinically relevant and probably related to settling of the components into the vertebral endplates. RSA allowed us to perform a preliminary but accurate study on the micromotion of a new cervical disc replacement in a small sample size, without putting large numbers of patients at risk.

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