Bryan Disc Prosthesis Research Articles

Heterotopic ossification associated with myelopathy following cervical disc prosthesis implantation

This case report presents a 37-year-old man with clinical signs of myelopathy almost 9years after implantation of a Bryan disc prosthesis (Medtronic Sofamor Danek, Memphis, TN, USA) for C5/C6 soft disc herniation. As demonstrated on MRI and CT scan, spinal cord compression was caused by bony spurs due to heterotopic ossification posterior to the still moving prosthesis. The device, as well as the ectopic bone deposits, had to be removed because of myelopathy and its imminent aggravation. Conversion to anterior spondylodesis was performed.

In Vitro Biomechanics of Cervical Arthroplasty with Bryan Disc Prosthesis or ProDisc-C Prosthesis: A Cadaveric Study

Introduction The purpose of this study is to compare the biomechanical performances of ProDisc-C arthroplasty and Bryan disc arthroplasty. Materials and Methods Six human cadaveric cervical spines were used in this study. After testing in the intact condition, all the specimens were reconstructed at C45 level with the following procedures: (1) cervical arthroplasty with ProDisc-C prosthesis; (2) cervical arthroplasty with Bryan disc prosthesis; (3) allograft and cervical plate. Range of motion and intradiscal pressures (IDPs) were recorded under flexion/extension, lateral bending, and rotations. Results (1) Comparing to normal model, both Bryan disc and ProDisc-C prosthesis maintained the motion of the operative segment. The ROM was also similar between the ProDisc-C group and Bryan group under all six directional motions. (2) In the ProDisc-C group, the IDPs of adjacent segments trended to decrease; The IDPs of C34 under right bending and left rotation reached a statistical significance. In the Bryan group, the IDPs of adjacent segments also trended to decrease and the IDPs of C34 under left bending reached a statistical significance. Conclusion ProDisc-C prosthesis and Bryan disc prosthesis maintained the ROM in all modes of motion. The adjacent segment IDPs both trended to decrease after ProDisc-C arthroplasty and Bryan disc arthroplasty. Disclosure of Interest None declared References Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 1999;81(4):519–528 Goffin J, Casey A, Kehr P, et al. Preliminary clinical experience with the Bryan Cervical Disc Prosthesis. Neurosurgery 2002;51(3):840-845, discussion 845–847 Walraevens J, Demaerel P, Suetens P, et al. Longitudinal prospective long-term radiographic follow-up after treatment of single-level cervical disk disease with the Bryan Cervical Disc. Neurosurgery 2010;67(3):679-687, discussion 687 Zhao YB, Sun Y, Chen ZQ, Liu ZJ. Application of cervical arthroplasty with Bryan cervical disc: long-term X-ray and magnetic resonance imaging follow-up results. Chin Med J (Engl) 2010;123(21):2999–3002 Sasso RC, Anderson PA, Riew KD, Heller JG. Results of cervical arthroplasty compared with anterior discectomy and fusion: four-year clinical outcomes in a prospective, randomized controlled trial. J Bone Joint Surg Am 2011;93(18):1684–1692 Murrey D, Janssen M, Delamarter R, et al. Results of the prospective, randomized, controlled multicenter Food and Drug Administration investigational device exemption study of the ProDisc-C total disc replacement versus anterior discectomy and fusion for the treatment of 1-level symptomatic cervical disc disease. Spine J 2009;9(4):275–286 Zigler JE, Delamarter R, Murrey D, Spivak J, Janssen M. ProDisc-C and anterior cervical discectomy and fusion as surgical treatment for single-level cervical symptomatic degenerative disc disease: five-year results of a Food and Drug Administration study. Spine 2013;38(3):203–209 Anderson PA, Sasso RC, Hipp J, Norvell DC, Raich A, Hashimoto R. Kinematics of the cervical adjacent segments after disc arthroplasty compared with anterior discectomy and fusion: a systematic review and meta-analysis. Spine 2012;37(22, Suppl)S85-S95 McAfee PC, Cunningham BW, Devine J, Williams E, Yu-Yahiro J. Classification of heterotopic ossification (HO) in artificial disk replacement. J Spinal Disord Tech 2003;16(4):384–389 Sun Y, Zhao YB, Pan SF, Zhou FF, Chen ZQ, Liu ZJ. Comparison of adjacent segment degeneration five years after single level cervical fusion and cervical arthroplasty: a retrospective controlled study. Chin Med J (Engl) 2012;125(22):3939–3941 Zhao YB, Sun Y, Zhou FF, Liu ZJ. Cervical disc arthroplasty with ProDisc-C artificial disc: 5-year radiographic follow-up results. Chin Med J (Engl) 2013;126(20):3809–3811 Helgeson MD, Bevevino AJ, Hilibrand AS. Update on the evidence for adjacent segment degeneration and disease. Spine J 2013;13(3):342–351 Delamarter RB, Zigler J. Five-year reoperation rates, cervical total disc replacement versus fusion, results of a prospective randomized clinical trial. Spine 2013;38(9):711–717 Dmitriev AE, Cunningham BW, Hu N, Sell G, Vigna F, McAfee PC. Adjacent level intradiscal pressure and segmental kinematics following a cervical total disc arthroplasty: an in vitro human cadaveric model. Spine 2005;30(10):1165–1172 Chang UK, Kim DH, Lee MC, Willenberg R, Kim SH, Lim J. Changes in adjacent-level disc pressure and facet joint force after cervical arthroplasty compared with cervical discectomy and fusion. J Neurosurg Spine 2007;7(1):33–39

The biomechanical research on the changes of pressures in the C7/T1 intervertebral space after C5/6 cervical artificial disc replacement

Objective To explore the stress changes of C7/T1 intervertebral space pre-and post C5/6 discectomy and artificial disc replacement.Method Eleven healthy adult fresh muhisegmental cadaveric cervical spine segments were utilized in this investigation and biomechanically evaluated under the following C5/6 conditions:intact spine,discectomy,and Bryan Disc prosthesis implantation.The load,of neutrality and pure moments of axial,flexion,extension,and lateral bending were applied on each group.The stress changes of the inferior (C7/T1)interverlebral space was detected by modified cyclo-shaped miniature transducer.Result Under axial,anteflexion,and lateral bending loading,the discectomy indicated a significant increase in the stress of the inferiorer(C7/T1)intervertebral space,compared to intact condition and CADR(P＜0.05).Under extension loading,the discectomy indicated an increase in the stress of the inferiorer(C7/T1)intervertebral space,compared to intact condition(P＞0.05).Under axial,flexion,extension and lateral bending loading,the Bryan Disc prosthesis implantation indicate minor increase of the stress in the inferior(C7/T1)intervertebral space to intact condition(P＞0.05).Conclusion There was no difference between the C5/6 ADR and intact spine group.The discectomy of the Cs/6 can increase the stress of the C7/T1 intervertebral spaoe. Key words: Intervertebral disk/SU; Cervical spondylosis/SU; Cervical vertebrae/SU; Biomechanics

Cervical spine biomechanics following implantation of a disc prosthesis

This study presents a finite element model of the C4–C7 segment in healthy conditions and after implantation of a disc prosthesis at a single level, in order to investigate of the influence of disc arthroplasty on the biomechanics of the cervical spine. A nonlinear finite element model of the C4–C7 segment in intact conditions was developed and run in flexion and extension. A detailed model of the Bryan disc prosthesis, including contacts between the different components of the device, was built and positioned at C5–C6. The calculated segmental motion resulted preserved after disc arthroplasty, with respect to the model of the intact spine, in both flexion and extension. A general preservation of the forces transmitted through the facet joints was obtained; a minor force increase at the implanted level was detected. The analysis of the instantaneous centers of rotation (ICR) in flexion–extension showed the preservation of a physiological kinematics. The mechanical behaviour showed an asymmetry between flexion and extension, probably due to the removal of the anterior longitudinal ligament and the anterior part of the annulus fibrosus, and the preservation of the posterior structures. In general, the disc prosthesis showed to be able to reproduce a nearly physiological motion. However, other important mechanical aspects, such as the possible micromotion at the bone–implant interface and the possible degenerative conditions of the spine, need to be evaluated before drawing a conclusion about total disc arthroplasty from an engineering point of view.

TRAUMATIC LOADING OF THE BRYAN CERVICAL DISC PROSTHESIS

The Bryan disc prosthesis (Medtronic Sofamor Danek, Memphis, TN) relies on a precise fit between the device and the vertebral endplates to provide immediate stability after cervical arthroplasty. The safety of the cervical arthroplasty in the setting of trauma is unknown. We compare the segmental strength of the normal cervical spine and the cervical spine after single-level arthroplasty. Fifteen cadaveric cervical spines with arthroplasty placed at the C5-C6 level were compared with 16 intact cadaveric controls. A pure moment was applied to induce flexion, extension, or axial rotation until the segment failed. The prosthesis provided 63, 45, and 69% of the strength of a normal spine during flexion, extension, and rotation, respectively. There were no cases of prosthesis expulsion. After insertion of the Bryan disc, the remaining ligamentous tissues provide adequate acute stability to the spine.

Clinical report of cervical arthroplasty in management of spondylotic myelopathy in Chinese.

ObjectivesTo investigate clinical effects and manual operational point of Bryan cervical disc prosthesis in Chinese, to observe the stability and range of movement (ROM) post-operatively.Methods and materialsFrom 2003,12 to 2005,12, Bryan disc prosthesis replacement applied in 83 cases (102 levels) of cervical spondylotic myelopathy (CSM) after anterior decompression in our hospital. Clinical (JOA grade and Odom's scale) and radiological (X-ray of flexion, extension; left and right bending position) follow-up was performed. Systemic radiographic study about stability and ROM of replaced level post operationally were measured. CT or MRI scans were applied in all cases to evaluate the signs of the prosthesis deflexion and hetero-ossification in the replaced levels.ResultsAt least 12 months follow-up were done in 65/83 of these paients. All of 83 patients were improved according to Odsm's scale. JOA score increased from average 8.7 to 15.5. There was no prosthesis subsidence. Replaced segment achieved stability and restored partial of normal ROM 4.73°(3.7°–5.9°) early postoperation and 8.12°(5.8°–13.6°) more than 12 months postoperation in flex and extension position. No obvious loss of lordosis was found. CT or MRI follow-up shows position deflexion of the prosthesis metal endplates (<1.5 mm) in 14/77 levels and (1.5~3 mm) in 4/77. heter-ossification was found in the replaced levels only in 2 cases.ConclusionByran cervical disc prosthesis restored motion to the level of the intact segment in flexion-extension and lateral bending in post-operative images. At the same time, it can achieve good anterior decompression treatment effect and immediate stability in replaced 1 or 2 levels, and which is a new choice for the treatment of CSM.

Clinical and radiological results following cervical arthroplasty

This was a retrospective study of clinical and radiological results of cervical arthroplasty using the Bryan cervical disc prosthesis to evaluate the efficacy of arthroplasty in clinical applications. A total of 46 patients underwent arthroplasty of a single level using the Bryan disc prosthesis. Clinical outcome was assessed using the visual analogue scale (VAS) and the neck disability index (NDI). All patients were evaluated using preoperative and postoperative static cervical spine radiographs to compare cervical sagittal balance. Dynamic cervical spine radiographs were used to compare movement at the level of the procedure, movement at the adjacent level and movement of the whole cervical spine. With the exception of four patients with aggravated neck pain, the NDI and VAS scores decreased significantly in late follow-up evaluations. The range of movement of the whole cervical spine, the functional segmental unit, and the adjacent segments were preserved after arthroplasty. The sagittal alignment of the cervical spine showed kyphosis after surgery but restored lordosis at a later time. The postulated cause of kyphotic changes include "over-milling" at the dorsal endplate, inappropriate angle of disc insertion, structural absence of lordosis in the Bryan disc, removal of posterior longitudinal ligament, and pre-existing kyphosis. Arthroplasty using the Bryan disc appears to be safe and provided a favorable preliminary clinical and radiological outcome. Postoperative kyphosis can be prevented by understanding the biomechanical properties of the Bryan disc. Future studies will need to address the association between postoperative kyphosis, clinical outcome and adjacent segment disease.

Biomechanics of the C5-C6 Spinal Unit Before and After Placement of a disc prosthesis

The study consists of a biomechanical comparison between the intact C5-C6 spinal segment and the same segment implanted with the Bryan artificial disc prosthesis (Medtronic Ltd., Memphis, TN, USA), by the use of the finite element (FE) method. Our target is the prediction of the influence of prosthesis placement on the resulting mechanics of the C5-C6 spine unit. A FE model of the intact C5-C6 segment was built, employing realistic models of the vertebrae, disc and ligaments. Simulations were conducted imposing a compression preload combined to a flexion/extension moment, a pure lateral bending moment and a pure torsion moment, and the calculated results were compared to data from literature. The model was then modified to include the Bryan cervical disc prosthesis, and the simulations were repeated. The location of the instantaneous center of rotation (ICR) of C5 with respect to C6 throughout flexion/extension was calculated in both models. In general, the moment-rotation curves obtained from the disc prosthesis-implanted model were comparable to the curves obtained from the intact model, except for a slightly greater stiffness induced by the artificial disc. The position of the calculated ICRs was rather stable throughout flexion-extension and was generally confined to a small area, qualitatively matching the corresponding physiological region, in both models. These results imply that the Bryan disc prosthesis allows to correctly reproduce a physiological flexion/extension at the implanted level. The results of this study have quantified aspects that may assist in optimizing cervical disc replacement primarily from a biomechanical point of view.

Fusion around Cervical Disc Prosthesis: Case Report

Cervical arthroplasty is a relatively new method to maintain motion after cervical anterior discectomy. Two cases are presented in which bony fusion occurred around a cervical disc prosthesis. A 30-year-old man and a 49-year-old woman underwent a right-sided anterior cervical discectomy because of pain in the right arm resulting from a herniated disc (C5-C6). A cervical disc prosthesis (Bryan disc prosthesis) was implanted. Postoperatively, the patients were completely free of pain. At the regular 1- and 2-year follow-up examinations, bony fusion was seen on plain x-rays of the cervical spine. The patients were still completely free of signs and symptoms. This is the first report in the literature of bony fusion after cervical arthroplasty with the Bryan disc prosthesis.

Cervical arthroplasty complicated by delayed spontaneous fusion

The authors describe the case of a 55-year-old woman who presented with a left C-6 radiculopathy and neck pain and in whom there was evidence of disc/osteophyte compression of the left C-6 nerve root. The patient underwent a C5-6 anterior cervical decompression and placement of a Bryan disc prosthesis. More than 7000 cervical discs have been inserted worldwide. Postoperatively, dynamic imaging demonstrated loss of motion at the instrumented level. The patient suffered persistent neck and arm pain that was slow to resolve. Seventeen months after the initial surgery osseous fusion was observed across the interspace and posterior surface of the prosthesis. This is the first documented case of fusion occurring at the level at which cervical arthroplasty had been performed. The precise reason for this phenomenon is unclear, but potential contributing factors include patient-related issues, poor motion due to neck pain, or possibly implant-related issues. To date, this is an exceedingly rare complication and warrants careful and prolonged follow up of all arthroplasty-treated cases.

Two-level artificial disc placement for spondylotic cervical myelopathy

This report describes a 49-year-old woman who presented with a myeloradiculopathy with two-level spinal cord compression. She underwent C5-6 and C6-7 anterior cervical decompressions and placement of two Bryan disc (Medtronic Sofamor-Danek. Memphis, TN) prostheses. Whilst single-level cervical arthroplasty using the Bryan disc prosthesis has been described before, this is the first two-level case reported in the literature and opens the way for the possible future management of multilevel cervical cord compression in a way that maintains cervical motion, avoids donor site bone graft problems, and may reduce the incidence of adjacent segment disease.