Artificial Disc Research Articles

A comparative study of the effect of facet tropism on the index-level kinematics and biomechanics after artificial cervical disc replacement (ACDR) with Prestige LP, Prodisc-C vivo, and Mobi-C: a finite element study

IntroductionArtificial cervical disc replacement (ACDR) is a widely accepted surgical procedure in the treatment of cervical radiculopathy and myelopathy. However, some research suggests that ACDR may redistribute more load onto the facet joints, potentially leading to postoperative axial pain in certain patients. Earlier studies have indicated that facet tropism is prevalent in the lower cervical spine and can significantly increase facet joint pressure. The present study aims to investigate the changes in the biomechanical environment of the cervical spine after ACDR using different prosthese when facet tropism is present.MethodsA C2-C7 cervical spine finite element model was created. Symmetrical, moderate asymmetrical (7 degrees tropism), and severe asymmetrical (14 degrees tropism) models were created at the C5/C6 level by adjusting the left-side facet. C5/C6 ACDR with Prestige LP, Prodisc-C vivo, and Mobi-C were simulated in all models. A 75 N follower load and 1 N⋅m moment was applied to initiate flexion, extension, lateral bending, and axial rotation, and the range of motions (ROMs), facet contact forces(FCFs), and facet capsule stress were recorded.ResultsIn the presence of facet tropism, all ACDR models exhibited significantly higher FCFs and facet capsule stress compared to the intact model. In the asymmetric model, FCFs on the right side were significantly increased in neutral position, extension, left bending and right rotation, and on both sides in right bending and left rotation compared to the symmetric model. All ACDR model in the presence of facet tropism, exhibited significantly higher facet capsule stresses at all positions compared to the symmetric model. The stress distribution on the facet surface and the capsule ligament in the asymmetrical models was different from that in the symmetrical model.ConclusionsThe existence of facet tropism could considerably increase FCFs and facet capsule stress after ACDR with Prestige-LP, Prodisc-C Vivo, and Mobi-C. None of the three different designs of implants were able to effectively protect the facet joints in the presence of facet tropism. Research into designing new implants may be needed to improve this situation. Clinical trials are needed to validate the impact of facet tropism.

Fiber‐Dependent 3D Anisotropic Stiffness‐Tunable Biomimetic Intervertebral Disc via Multi‐Material Additive Manufacturing

AbstractLumbar intervertebral disc degeneration is a global musculoskeletal disorder. Total disc replacement is an effective treatment for symptomatic degeneration unresponsive to conservative care. However, current artificial discs, with their joint‐like structural design and homogeneous materials, fail to replicate the 3D anisotropic stiffness of natural discs. Inspired by the intricate structure and material gradient of the natural disc, a biomimetic intervertebral disc is designed and fabricated using multi‐material additive manufacturing. The biomimetic disc exhibits 3D anisotropic stiffness similar to natural discs. By adjusting the hardness, diameter, and arrangement of fibers in annulus fibrosus, the biomimetic disc closely matches the 3D anisotropic stiffness of the natural lumbar disc, exceeding 90% similarity and outperforming existing artificial discs. This highlights the crucial role of fiber properties in disc stiffness regulation and enhances the understanding of biomechanical functions of structures and materials in the annulus fibrosus of human discs. These insights may inspire high‐performance artificial disc designs.

Combined effect of artificial cervical disc replacement and facet tropism on the index-level facet joints: a finite element study

BackgroundArtificial Cervical Disc Replacement (ACDR) is an effective treatment for cervical degenerative disc diseases. However, clinical information regarding the facet joint alterations after ACDR was limited. Facet tropism is common in the sub-axial cervical spine. Our previous research indicated that facet tropism could lead to increased pressure on the cervical facet joints. This study aimed to assess the impact of facet tropism on the facet contact force and facet capsule stress after ACDR.MethodsA C2–T1 cervical finite element model was constructed from computed tomography (CT) scans of a 28-year-old male volunteer. Symmetrical, moderate asymmetrical (7 degrees tropism), and severe asymmetrical (14 degrees tropism) models were created at the C5/C6 level by altering the facet orientation at the C5-C6 level. The C5/C6 ACDR was simulated in the intact, moderate asymmetrical and severe asymmetrical models. A 75-N follower load with 1.0-Nm moments was applied to the top of C2 vertebra in the models to simulate flexion, extension, lateral bending, and axial rotation with the T1 vertebra fixed. The range of motions (ROMs) under all moments, facet contact forces (FCFs) and facet capsule strains were tested.ResultsIn the asymmetrical model, the right FCFs considerably increased under flexion, extension, right bending, left rotation, especially under right bending the right sided FCF of the severe asymmetrical model was about 5.44 times of the neutral position, and 3.14 times of the symmetrical model. and concentrated on the cephalad part of the facets. The facet capsule stresses on both sides remarkably increased under extension, lateral bending and right rotation. In the moderate and severe asymmetrical models, the capsule strain was greater on both sides of each position than in the symmetric model.ConclusionsThe face tropism increased facet contact force and facet capsule strain after ACDR, especially under extension, lateral bending, and rotation, and also could result in abnormal stress distribution on the facet joint surface and facet joint capsule. The results suggest that face tropism might be a risk factor for post-operative facet joint degeneration progression after ACDR. Facet tropism may be noteworthy when ACDR is considered as a surgical option.

Three dimensional-printed artificial disc replacement for single-level cervical spondylosis: a cohort study.

To compare the clinical efficacy of 3D-printed artificial discs with that of ACDF for treating cervical spondylosis. This was a retrospective analysis of 73 patients with single-level cervical spondylosis who met the inclusion criteria between January 2020 and December 2022 at XX Hospital. The patients were divided: 38 patients in the ACDF group and 35 patients in the CADR group. Patient general information, including operation time and intraoperative blood loss, was collected. The clinical effect of the combination therapy was evaluated by the VAS, JOA, and NDI. The radiological effect was evaluated using the ROM test. Ethics No. 201,606,009. The average follow-up times in the ACDF and CADR groups were 28.24 ± 4.65 and 29.11 ± 5.06 months, respectively (P = 0.443). Clinical symptoms (evaluated by VAS, NDI, and JOA) are significantly improved in both the ACDF and CADR groups with similar efficacy. The preoperative ROM of the ACDF group was 40.03 ± 8.79, while that of the CADR group was 42.11 ± 7.98 (P = 0.293). However, the postoperative ROM in the ACDF group was 35.29 ± 7.23, which was lower than that in the CADR group (40.43 ± 6.98) (P = 0.003). Furthermore, only one patient in the ACDF group experienced mild dysphagia after surgery, and the patient recovered within three days. ASD occurred in nine patients in the ACDF group and in two patients in the CADR group (Χ²=4.597, P = 0.032). Compared with ACDF, 3D-printed artificial discs for treating single-level cervical spondylosis have proven to be clinically effective; it associated with less blood loss and a lower incidence of ASD, and maintain a better cervical ROM.

Analysis of factors influencing the development of paravertebral ossification in the distant future after artificial disc replacement for cervical disc herniation

Analysis of factors influencing the development of paravertebral ossification in the distant future after artificial disc replacement for cervical disc herniation

Changes in the Centers of Rotation in Different Prosthetic Segments Following Continuous Two-Level Cervical Disc Replacement: A Retrospective Study

To observe the short-term to medium-term therapeutic effects and radiological outcomes of adjacent 2-level cervical spondylosis treated with artificial cervical disc replacement (ACDR) using Mobi-C and Bryan discs. To observe changes and discrepancies in the flexion-extension centers of rotation (FE-COR) of different ACDR segments. Twenty-four patients undergoing 2-level (C4/5 and C5/6) ACDR were analyzed retrospectively (11 patients in the Mobi-C group and 13 patients in the Bryan group). Clinical outcomes were assessed using modified Japanese Orthopedic Association score, Neck Disability Index, and visual analog scale. Preoperative and 2years' follow-up radiographs were collected to compare total cervical spine curvature (C2-C7) range of motion (ROM), upper and lower ACDR segmental ROM, and the operated adjacent segmental ROM. The FE-COR of the ACDR segment was measured using the mid-plumb line method. The degree of disc degeneration in the adjacent segment was observed. At the 2years' follow-up, in both group, the modified Japanese Orthopedic Association score increased significantly, and the Neck Disability Index and neck and upper extremity visual analog scale scores decreased significantly compared with preoperative (P<0.05). There were no significant statistical differences in postoperative scores between the 2 groups (P > 0.05). The overall cervical ROM, the upper and lower segmental ROM at the 2years' follow-up showed no significant statistical differences compared with the preoperative period (P > 0.05). There was no statistically significant difference in the adjacent segmental ROMs compared with the preoperative period (P > 0.05). Furthermore, the statistical analysis revealed no significant differences in the measurements of the ROM at each time points between the Mobi-C Group and the Bryan Group (P > 0.05). There was no significant difference in the preoperative FE-COR-X (indicating the horizontal position of the point in the coordinate system) and FE-COR-Y (indicating the vertical position of the point in the coordinate system) of upper or lower ACDR segments between the 2 groups (P > 0.05). At the 2years' follow-up, there were significant differences both in FE-COR-X and FE-COR-Y between the 2 groups (P < 0.05). For the Mobi-C group, in both the upper and lower segment, the FE-COR-X significantly increased compared with preoperative (P < 0.05), while the FE-COR-Y decreased compared with preoperative (P < 0.05). For the Bryan group, no significant changes were observed in the upper or lower segment in both FE-COR-X and FE-COR-Y compared with preoperative (P > 0.05). Fourty-eight adjacent segments (24 superior and 24 inferior segments) were included in the studies of adjacent segment disease. Four segments showed imaging adjacent segment disease (4/48, 8.33%) in 4 patients, of which 2 were mild and 2 were moderate according to the grading criteria. Among them, 2 were from the Mobi-C group and 2 were from the Bryan group. No severe imaging degeneration was observed. In continuous 2-level cervical ACDR surgery, both Mobi-C and Bryan artificial cervical discs achieved satisfactory clinical outcomes in the short to medium term postoperatively. The FE-COR exhibited different trends of change. In the Mobi-C group, the FE-COR for both upper and lower segments shifted anteriorly and inferiorly, whereas in the Bryan group, whether upper or lower, the FE-COR remained closer to the preoperative state. The changes in FE-COR did not significantly affect the short-term to medium-term clinical outcomes postoperatively.

Five-year Follow-up of a Prospective Food and Drug Administration Investigational Device Exemption Trial Evaluating a PEEK-on-Ceramic Cervical Disc Replacement.

Prospective trial comparing the investigation group to propensity matched historic control group. To evaluate 5-year results of single-level PEEK-on-ceramic cervical total disc replacement (TDR) compared to a propensity matched anterior cervical discectomy and fusion (ACDF) control group. Cervical TDR has gained acceptance as treatment for symptomatic disc degeneration. The design and materials used in these devices continue to evolve. Data were collected in the Food and Drug Administration Investigational Device Exemption trial for the PEEK-on-ceramic Simplify(®) Cervical Artificial Disc (n=150) with comparison to a propensity matched ACDF control group (n=117). All patients were treated for single-level cervical disc degeneration with radiculopathy and/or myelopathy. Clinical outcome was based on composite clinical success (CCS), Neck Disability Index (NDI), visual analog scales (VAS) assessing pain, re-operations, and satisfaction. Radiographic measures included segmental range of motion (ROM), disc space height, and heterotopic ossification (HO). Evaluations were performed pre-operatively and post-operatively within 2 and 6 weeks, and 3, 6, 12 months, and annually thereafter. At 5-year follow-up, CCS was significantly greater with TDR than ACDF (91.1% vs. 74.6%; P<0.01). In the TDR group, the mean NDI score was 63.3 pre-operatively, reduced significantly to 23.1 at 6 weeks and remained below 20 throughout 5-year follow-up. In the ACDF group, the mean pre-operative NDI score was 62.4, decreasing to 33.7 at 6 weeks, and ranged from 25.9 to 21.5 throughout follow-up. Mean NDI scores were significantly lower in TDR group at all post-operative points (P<0.05). Mean TDR ROM was 7.3o pre-operatively and 10.1o at 5 years. Bridging HO occurred in 9%. With TDR, there were 6 re-operations (4.0%) vs. 11 (9.4%) with ACDF (P>0.40). PEEK-on-ceramic TDR produced significantly improved outcomes maintained throughout 5-year follow-up, were similar or superior to ACDF, supporting TDR in appropriately selected patients.

C5 Palsy after Cervical Disc Arthroplasty: Two Case Reports and Literature Review

Cervical disc arthroplasty (CDA), also known as cervical artificial disc replacement, has become an alternative for the treatment of cervical spondylosis with radicular or myelopathic symptoms. However, there is limited literature regarding its complications and outcomes. We present two cases that developed C5 nerve palsy (C5P) following two-level CDA. Both patients presented with C5P in a delayed fashion with 2/5 and 1/5 deltoid weakness on MMT, respectively. Postoperative imaging did not demonstrate any spinal cord compression and symptoms resolved (5/5 on MMT) with conservative management in both cases. To our knowledge, these represent the first cases of delayed C5P after cervical arthroplasty reported in the literature. We performed a literature review to further enhance our knowledge regarding CDA. By understanding its pathophysiology and response to treatment, these cases can serve as a guide for spine surgeons and improve their future outcomes.

P107. Evaluation of radiographically relevant heterotopic ossification following one-level cervical disc arthroplasty with a PEEK-on-ceramic artificial disc

P107. Evaluation of radiographically relevant heterotopic ossification following one-level cervical disc arthroplasty with a PEEK-on-ceramic artificial disc

P103. Seven-year outcomes for single-level total disc replacement with a novel viscoelastic artificial cervical disc

P103. Seven-year outcomes for single-level total disc replacement with a novel viscoelastic artificial cervical disc

Expert consensus on clinical application of cervical artificial disc replacement

Cervical artificial disc replacement preserves the range of motion after the decompression, and this technology has achieved good clinical results. The indications, surgical procedures, and perioperative management of cervical disc arthroplasty are different from traditional anterior cervical decompression and fusion. The Health Management and Enhanced Recovery of Cervical Spine Disorders Committee, Chinese Research Hospital Association has established an expert group to draw up this expert consensus through literature analysis and professional discussions. The purpose of this consensus is to standardize the surgical indications and patient selection of cervical artificial disc replacement, to guide surgical procedures and perioperative management, and to improve the clinical outcomes of cervical artificial disc replacement.

Facet joint loading after 1-, 2- and 3-level cervical disc arthroplasty: a comparison of spiked versus keeled baseplates

BackgroundThe purpose of this study was to examine facet contact forces above, below, and at surgical index levels induced by artificial disc implantation and compare the results from spiked versus keeled baseplates comprising the arthroplasty device. MethodsHuman specimens from C2 to C7 were subjected to flexion, extension, and lateral bending prior to, and following random allocation to spiked or keeled cervical arthroplasty at the index (C5-C6), inferior (C6-C7), and superior (C4-C5) levels. Thin film force sensors were inserted unilaterally into the corresponding facets prior to intact testing. Force data was normalized to the minimum forces recorded during each loading mode under each condition, reported as (Max/Min) force ratio and subjected to a 1-way ANOVA with Dunnett's post-hoc tests for comparison to intact specimens. ResultsUnder flexion, compared to intact, all levels displayed a significant reduction in force ratio following a 1- and 3-level implantation for the spiked baseplate device. An increase in force ratio was observed at the index level for a 2-level implantation but was mitigated with the completion of a superior device insertion. No statistical differences were noted for keeled devices. In extension, the spiked baseplate device reduced the force ratio for 1- and 2-level implantations. A 3-level insertion did not alter facet force ratios. For the keeled device, no statistical changes were noted. Lateral bending associated with spiked devices resulted in statistically reduced or nonsignificant changes in facet loading ratios. The keeled devices did not display significant changes to facet force ratios. ConclusionsImplantation of multilevel disc devices can reduce or sustain unaltered facet loading conditions. In general, 3-level arthroplasty statistically reduced or does not increase facet force ratios compared to intact values. The use of spiked versus keel device baseplates is a clinical selection involving anterior/posterior placement and endplate degeneration conditions.

Clinical Validation of a Deep Learning-Based Software for Lumbar Bone Mineral Density and T-Score Prediction from Chest X-ray Images.

Screening for osteoporosis is crucial for early detection and prevention, yet it faces challenges due to the low accuracy of calcaneal quantitative ultrasound (QUS) and limited access to dual-energy X-ray absorptiometry (DXA) scans. Recent advances in AI offer a promising solution through opportunistic screening using existing medical images. This study aims to utilize deep learning techniques to develop a model that analyzes chest X-ray (CXR) images for osteoporosis screening. This study included the AI model development stage and the clinical validation stage. In the AI model development stage, the combined dataset of 5122 paired CXR images and DXA reports from the patients aged 20 to 98 years at a medical center was collected. The images were enhanced and filtered for hardware retention such as pedicle screws, bone cement, artificial intervertebral discs or severe deformity in target level of T12 and L1. The dataset was then separated into training, validating, and testing datasets for model training and performance validation. In the clinical validation stage, we collected 440 paired CXR images and DXA reports from both the TCVGH and Joy Clinic, including 304 pared data from TCVGH and 136 paired data from Joy Clinic. The pre-clinical test yielded an area under the curve (AUC) of 0.940, while the clinical validation showed an AUC of 0.946. Pearson's correlation coefficient was 0.88. The model demonstrated an overall accuracy, sensitivity, and specificity of 89.0%, 88.7%, and 89.4%, respectively. This study proposes an AI model for opportunistic osteoporosis screening through CXR, demonstrating good performance and suggesting its potential for broad adoption in preliminary screening among high-risk populations.

Does the novel artificial cervical joint complex resolve the conflict between stability and mobility after anterior cervical surgery? a finite element study.

Our group has developed a novel artificial cervical joint complex (ACJC) as a motion preservation instrument for cervical corpectomy procedures. Through finite element analysis (FEA), this study aims to assess this prosthesis's mobility and stability in the context of physiological reconstruction of the cervical spine. A finite element (FE)model of the subaxial cervical spine (C3-C7) was established and validated. ACJC arthroplasty, anterior cervical corpectomy and fusion (ACCF), and two-level cervical disc arthroplasty (CDA) were performed at C4-C6. Range of motion (ROM), intervertebral disc pressure (IDP), facet joint stress (FJS), and maximum von Mises stress on the prosthesis and vertebrae during loading were compared. Compared to the intact model, the ROM in all three surgical groups demonstrated a decline, with the ACCF group exhibiting the most significant mobility loss, and the highest compensatory motion in adjacent segments. ACJC and artificial cervical disc prosthesis (ACDP) well-preserved cervical mobility. In the ACCF model, IDP and FJS in adjacent segments increased notably, whereas the index segments experienced the most significant FJS elevation in the CDA model. The ROM, IDP, and FJS in both index and adjacent segments of the ACJC model were intermediate between the other two. Stress distribution of ACCF instruments and ACJC prosthesis during the loading process was more dispersed, resulting in less impact on the adjacent vertebrae than in the CDA model. The biomechanical properties of the novel ACJC were comparable to the ACCF in constructing postoperative stability and equally preserved physiological mobility of the cervical spine as CDA without much impact on adjacent segments and facet joints. Thus, the novel ACJC effectively balanced postoperative stability with cervical motion preservation.

Biomechanical analysis of single and multi-level artificial disc replacement (ADR) in cervical spine using multi-scale loadings: A finite element study.

Artificial disc replacement (ADR) is a clinical procedure used to diagnose cervical degenerative disc disease, preserving range of motion (ROM) at the fixation level and preventing adjacent segment degeneration (ASD). This study analyzed the biomechanics of ADR by examining range of motion (ROM), stress levels in bone and implants, and strain in the bone-implant interface using multi-scale loadings. The study focused on single- and double-level patients across various loading scales during physiological motions within the cervical spine. Results showed increased ROM in single-level and double-level fixations during physiological loadings, while ROM decreased at the adjacent level of fixation with the intact cervical spine model. The Prodisc-Implant metal endplate experienced a maximum von Mises stress of 432 MPa during axial rotation, confirming the long durability and biomechanical performance of the bone-implant interface.

Structural modification and biomechanical analysis of lumbar disc prosthesis: A finite element study

BackgroundMost ball-in-socket artificial lumbar disc implanted in the spine result in increased hypermobility of the operative level and overloading of the facet joint. MethodsA finite element model was established and validated for the lumbar spine (L1-L5). The structure of the Mobidisc prosthesis was modified, resulting in the development of two new intervertebral disc prostheses, Movcore and Mcopro. The prostheses were implanted into the L3/L4 level to simulate total disc replacement, and the biomechanical properties of the lumbar spine model were analyzed after the operation. FindingsFollowing the implantation of the prostheses, the mobility of operative level, peak stress of lumbar spine models, and peak stress of facet joint increased. The performance of mobility was found to be more similar between Movcore and Mobidisc. The mobility and facet joint peak stress of the Mcopro model decreased progressively with an increase in the Young's modulus of the artificial annulus during flexion, extension, and lateral bending. Among all the models, the Mcopro50 model had the mobility closest to the intact model. It showed a 3% decrease in flexion, equal range of motion in extension, a 9% increase in left lateral bending, a 7% increase in right lateral bending, and a 3% decrease in axial rotation. InterpretationThe feasibility of the new intervertebral disc prostheses, Movcore and Mcopro, has been established. The Mcopro prosthesis, which features an artificial annular structure, offers significant advantages in terms of reduced mobility of the operative level and peak stress of facet joint.

Effect of patient-specific factors on regeneration in lumbar spine at healthy disc and total disc replacement. Computer simulation

Background and ObjectiveDegenerative diseases of the spine have a negative impact on the quality of life of patients. This study presents the results of numerical modelling of the mechanical behaviour of the lumbar spine with patient-specific conditions at physiological loads. This paper aims to numerically study the influence of degenerative changes in the spine and the presence of an endoprosthesis on the creation of conditions for tissue regeneration. MethodsA numerical model of the mechanical behaviour of lumbar spine at healthy and after total disc replacement under low-energy impacts equivalent to physiological loads is presented. The model is based on the movable cellular automaton method (discrete elements), where the mechanical behaviour of bone tissue is described using the Biot poroelasticity accounting for the presence and transfer of interstitial biological fluid. The nutritional pathways of the intervertebral disc in cases of healthy and osteoporotic bone tissues were predicted based on the analysis of the simulation results according to the mechanobiological principles. ResultsSimulation of total disc replacement showed that osseointegration of the artificial disc plates occurs only in healthy bone tissue. With total disc replacement in a patient with osteoporosis, there is an area of increased risk of bone resorption in the near-contact area, approximately 1 mm wide, around the fixators. Dynamic loads may improve the osseointegration of the implant in pathological conditions of the bone tissue. ConclusionsThe results obtained in the case of healthy spine and osteoporotic bone tissues correspond to the experimental data on biomechanics and possible methods of IVD regeneration from the position of mechanobiological principles. The results obtained with an artificial disc (with keel-type fixation) showed that the use of this type of endoprosthesis in healthy bone tissues allows to reproduce the function of the natural intervertebral disc and does not contribute to the development of neoplastic processes. In the case of an artificial disc with osteoporosis of bone tissues, there is a zone with increased risk of tissue resorption and development of neoplastic processes in the area near the contact of the implant attachment. This circumstance can be compensated by increasing the loading level.

Segment selection for fusion and artificial disc replacement in the hybrid surgical treatment of noncontiguous cervical spondylosis: a finite element analysis.

Introduction: The treatment of skip-level cervical degenerative disease (CDD) with no degenerative changes observed in the intervening segment (IS) is complicated. This research aims to provide a reference basis for selecting treatment approaches for noncontiguous CDD. Methods: To establish accurate finite element models (FEMs), this study included computed tomography (CT) data from 21 patients with CDD (10 males and 11 females) for modeling. The study primarily discusses four cross-segment surgical approaches: upper (C3/4) anterior cervical discectomy and fusion (ACDF) and lower (C5/6) cervical disc arthroplasty (CDA), FA model; upper CDA (C3/4) and lower ACDF (C5/6), AF model; upper ACDF (C3/4) and lower ACDF (C5/6), FF model; upper CDA (C3/4) and lower CDA (C5/6), AA model. An initial axial load of 73.6 N was applied at the motion center using the follower load technique. A moment of 1.0Nm was applied at the center of the C2 vertebra to simulate the overall motion of the model. The statistical analysis was conducted using STATA version 14.0. Statistical significance was defined as a p value less than 0.05. Results: The AA group had significantly greater ROM in flexion and axial rotation in other segments compared to the FA group (p < 0.05). The FA group consistently exhibited higher average intervertebral disc pressure in C2/3 during all motions compared to the AF group (p < 0.001); however, the FA group displayed lower average intervertebral disc pressure in C6/7 during all motions (p < 0.05). The AA group had lower facet joint contact stresses during extension in all segments compared to the AF group (p < 0.05). The FA group exhibited significantly higher facet joint contact stresses during extension in C2/3 (p < 0.001) and C6/7 (p < 0.001) compared to the AF group. Discussion: The use of skip-level CDA is recommended for the treatment of non-contiguous CDD. The FA construct shows superior biomechanical performance compared to the AF construct.

Restoration of Range of Motion in the Cervical Spine through Single-Segment Artificial Disc Replacement Using the Baguera®C Prosthesis.

Background: Anterior cervical discectomy and fusion (ACDF) is a standard procedure for degenerative diseases of the cervical spine, providing nerve decompression and spinal stabilization. However, it limits cervical spine motility, restricts fused segment activity, and may lead to adjacent degeneration. Cervical disc arthroplasty (CDA) is an accepted alternative that preserves the structure and flexibility of the cervical spine. This study aimed to explore the dynamic changes in the range of motion (ROM) of the cervical spine after CDA using a viscoelastic artificial disc, as well as the factors affecting mobility restoration. Methods: A retrospective analysis was conducted on 132 patients who underwent single-level anterior cervical discectomy and CDA from January 2015 to June 2022. Result: Analysis of data from 132 patients revealed a significant improvement in clinical outcomes. The mean ROM of C2-C7 and functional spinal unit (FSU) segments significantly increased from 2 to 36 months post-operatively. Cervical spine flexibility was preserved and enhanced after prosthesis implantation. However, it took six months for the cervical spine motility to stabilize. In addition, sex and age were found to impact motility restoration, with female and younger patients exhibiting larger ROMs post-surgery. Additionally, CDA at the C5-C6 level resulted in the greatest increase in ROM, potentially improving overall kinematic ability. Conclusions: Single-segment artificial disc arthroplasty effectively restores the ROM in degenerative cervical spine conditions.

Could the different surgical goals of fusion and non-fusion also be achieved in combination within the same patient? Clinical and radiological outcome of hybrid cervical spine surgery.

Hybrid cervical spine surgery (HS) is a novel surgical strategy wherein an artificial disc replacement is done with a cervical fusion nearby with a stand-alone titanium cage to combine the advantages in both procedures. The aim of this study was to evaluate interactions of these devices within the same patient, and to analyze, if the different goal of each implant is accomplished. Thirty-six patients were treated surgically within a non-randomized retrospective study framework with HS. Patients were examined preoperatively followed by clinical and radiological examination at least one year postoperative. Clinical outcome was detected with NDI, VAS arm/neck, pain self-assessment questionnaires and subjective patient satisfaction. Radiological assessments included RoM, segmental lordosis, cervical lordosis of C2-C7, subsidence, ap-migration and heterotopic ossifications (HO) at the cTDR levels. Statistically significant improvement of all clinical scores was observed (NDI 37.5 to 5.76; VASarm 6.41 to 0.69; VASneck 6.78 to 1.48). Adequate RoM was achieved at cTDR levels. RoM in the ACDF levels was reduced statistically significant (p < 0.001), and solid fusion (> 2°) was achieved in all evaluated fusion level. Global lordosis (C2-C7) increased statistically significant (2.4° to 8.1°). Subsidence and HO at the cTDR levels did not occur. HS results in preservation of the segmental motion in the cTDR and fast and solid fusion in the cage cohort simultaneously. Patient safety was proven. In carefully selected cases, HS is a safe and viable treatment option by choosing the right "philosophy" level per level.