In vitro evaluation of a ball-and-socket cervical disc prosthesis with cranial geometric center

Barrey, Cédric; Mosnier, T.; Jund, J.; Perrin, Gilles; Skalli, Wafa

doi:10.3171/2009.6.spine0949

Cited by 19 publications

(8 citation statements)

References 33 publications

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“…7 Stress distribution in the implants segment unit, and the previous studies concluded that TDR could maintain kinematic motion [23,24]. In the present study, TDR with the ball-in-socket sliding articulationdesigned artificial disc of Prodisc-C had well demonstrated its function as reflected by the maintained spinal kinematic motion in the operative site.…”

Section: Discussionsupporting

confidence: 48%

Biomechanical effects of cervical arthroplasty with U-shaped disc implant on segmental range of motion and loading of surrounding soft tissue

Zhao

Wang

et al. 2013

Eur Spine J

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Purpose Various design concepts have been adopted in cervical disc prostheses, including sliding articulation and standalone configuration. This study aimed to evaluate the biomechanical effects of the standalone U-shaped configuration on the cervical spine. Methods Based on an intact finite element model of C3-C7, a standalone U-shaped implant (DCI) was installed at C5-C6 and compared with a sliding articulation design (Prodisc-C) and an anterior fusion system. The range of motion (ROM), adjacent intradiscal pressure (IDP) and capsular ligament strain were calculated under different spinal motions. Results Compared to the intact configuration, the ROM at C5-C6 was reduced by 90 % after fusion, but increased by 70 % in the Prodisc-C model, while the maximum percentage change in the DCI model was 30 % decrease. At the adjacent segments, up to 32 % increase in ROM happened after fusion, while up to 34 % decrease occurred in Prodisc-C model and 17 % decrease in DCI model. The IDP increased by 11.6 % after fusion, but decreased by 5.6 and 6.3 % in the DCI and Prodisc-C model, respectively. The capsular ligament strain increased by 147 % in Prodisc-C and by 13 % in the DCI model. The DCI implant exhibited a high stress distribution. Conclusions Spinal fusion resulted in compensatory increase of ROM at the adjacent sites, thereby elevating the IDP. Prodisc-C resulted in hyper-mobility at the operative site that led to an increase of ligament force and strain. The U-shaped implant could maintain the spinal kinematics and impose minimum influence on the adjacent soft tissues, despite the standalone configuration encountering the disadvantages of high stress distribution.

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Section: Discussionsupporting

confidence: 48%

Biomechanical effects of cervical arthroplasty with U-shaped disc implant on segmental range of motion and loading of surrounding soft tissue

Zhao

Wang

et al. 2013

Eur Spine J

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“…Accordingly, due to conflicting information, surgeons face difficulties with the selection of appropriate indications and the type and size of implants [20,21]. Ex vivo motion studies and finite element studies have provided insight into the function of different CDR designs [4,38]. Unfortunately, laboratory studies are limited and cannot completely simulate the complex coupled in vivo motions during cervical spine activities, so patient-based research is required.…”

Section: Introductionmentioning

confidence: 99%

“…CDRs offer a varying degree of mobility and can be further stratified into constrained, semi-constrained and minimally/non-constrained ( Fig. 1) [4,20,21,25,30,31]. With constrained devices motion is less than that seen physiologically and may theoretically cause high-stress concentrations at the implant-vertebra interface.…”

Section: Introductionmentioning

confidence: 99%

In vivo analysis of cervical kinematics after implantation of a minimally constrained cervical artificial disc replacement

et al. 2012

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Introduction To better understand cervical kinematics following cervical disc replacement (CDR), the in vivo behavior of a minimally constrained CDR was assessed. Methods Radiographic analysis of 19 patients undergoing a 1-level CDR from C4-5 to C6-7 (DISCOVER, DepuySpine, USA) was performed. Neutral-lateral and flexionextension radiographs obtained at preop, postop and late follow-up were analyzed for segmental angle and global angle (GA C2-7). Flexion-extension range of motion was analyzed using validated quantitative motion analysis software (QMAÒ, Medical Metrics, USA). The FSU motion parameters measured at the index and adjacent levels were angular range of motion (ROM), translation and center of rotation (COR). Translation and COR were normalized to the AP dimension of the inferior endplate of the caudal vertebra. All motion parameters, including COR, were compared with normative reference data. Results The average patient age was 43.5 ± 7.3 years. The mean follow-up was 15.3 ± 7.2 months. C2-7 ROM was 35.9°± 15.7°at preop and 45.4°± 13.6°at follow-up (Dp\ .01). Based on the QMA at follow-up, angular ROM at the CDR level measured 9.8°± 5.9°and translation was 10.1 ± 7.8 %. Individuals with higher ROM at the CDR level had increased translation at that level (p \ .001, r = 0.97), increased translation and ROM at the supra-adjacent level (p \ .001, r = .8; p = .005, r = .6). There was a strong interrelation between angular ROM and translation at the supra-adjacent level (p \ .001, r = .9) and caudal-adjacent level (p\.001, r = .9). The location of the COR at the CDRand supra-adjacent levels was significantly different for the COR-X (p \ .001). Notably, the COR-Y at the CDR level was significantly correlated with the extent of CDR-level translation (p = .02, r = .6). Shell angle, which may be influenced by implant size and positioning had no impact on angular ROM but was correlated with COR-X (p = .05, r = -.6) and COR-Y (p = .04, r = -.5). Conclusion The COR is an important parameter for assessing the ability of non-constrained CDRs to replicate the normal kinematics of a FSU. CDR size and location, both of which can impact shell angle, may influence the amount of translation by affecting the location of the COR. Future research is needed to show how much translation is beneficial concerning clinical outcomes and facet loading.

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“…11 [34]. Restoring a more physiological COR in the frontal plane may allow for restoration of a more physiological kinematic in axial rotation and lateral bending and theoretically limiting uncovertebral and facet kinematic conflicts during these motions [35,36]. In fact, TDR with caudal centre of rotation is more suitable during FE motion, whereas TDR with cranial centre of rotation is preferred during lateral bending and axial rotations.…”

Section: Kinematicsmentioning

confidence: 99%

Sagittal alignment and kinematics at instrumented and adjacent levels after total disc replacement in the cervical spine

et al. 2012

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Background The purpose of the study was to report radiological outcomes after total disc replacement (TDR) in the cervical spine through a 24 months follow-up (FU) prospective study with a special focus on sagittal alignment and kinematics at instrumented and adjacent levels. Materials and methods Thirty-two patients, who sustained one-level TDR with a ball-and-socket arthroplasty (Discocerv TM implant, Scient'x/Alphatec Spine, USA) were consecutively included in the study. Clinical (visual analogical scale and neck disability index) and radiological parameters were measured preoperatively and postoperatively at 3/6 months, 1-year and 2-year FU. Sagittal alignment, ranges of motion (ROM) and center of rotations (CORs) were analyzed using specific motion analysis software (Spineview TM , Paris, France). Patients CORs were compared with those of a control group of 39 normal and asymptomatic subjects.Results Both local and C3-C7 lordosis significantly increased postoperatively (?8°and ?13°at 2 years, respectively). At instrumented level ROM in flexionextension (FE) was measured to 10.2°preoperatively versus 7.5°at 1 year and 6.1°at 2 years. There were no differences in ROM at adjacent levels between pre and postoperative assessments. When compared with control group and preoperative measurements, we noted postoperative cranial shift of the COR at instrumented level for patients group. In contrast, there was no difference in CORs location at adjacent levels. Conclusion Through this prospective study, we observed that cervical lordosis consistently increased after TDR. In addition, although ball-and-socket arthroplasty did not fully restore native segmental kinematics with significant reduction of motion in FE and consistent cranial shift of the COR, no significant changes in terms of ROM and CORs were observed at adjacent levels.

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In vitro evaluation of a ball-and-socket cervical disc prosthesis with cranial geometric center

Cited by 19 publications

References 33 publications

Biomechanical effects of cervical arthroplasty with U-shaped disc implant on segmental range of motion and loading of surrounding soft tissue

Biomechanical effects of cervical arthroplasty with U-shaped disc implant on segmental range of motion and loading of surrounding soft tissue

In vivo analysis of cervical kinematics after implantation of a minimally constrained cervical artificial disc replacement

Sagittal alignment and kinematics at instrumented and adjacent levels after total disc replacement in the cervical spine

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