Total Disc Replacement Research Articles

Results of Total Cervical Disc Replacement with a Minimum Follow-up of 10 Years.

Objective In the present study, we present the results with at least 10 years of follow-up of the cervical disc prosthesis implanted in a single level. Methods Retrospective study of patients undergoing single-level total cervical disc replacement (TCDR). Clinical results included the neck disability index (NDI) and the visual analogue scale (VAS) in the preoperative period, one year postoperatively, and a minimum of 10 years of follow-up. The radiographic parameters included cervical mobility, segmental lordosis, C2-C7 angle, heterotopic ossification (HO), facet and joint degeneration (FJD) and adjacent segment disease (ASD). Results We identified 22 patients, 16 women and 6 men with mean age of 39.7 years old (26–51 years old), of which fifteen completed a minimum follow-up of 10 years. There was a statistically significant improvement of NDI and VAS ( p < 0.001) between the preoperative and the postoperative periods (1 year or > 10 years). At the end of 10 years, HO was observed in 59% of the cases. The mobility of the implant was preserved in 80% of the patients. Radiological evidence of ASD was recorded in 6 patients (40%). There was no correlation between the clinical parameters evaluated and the presence of ASD or the different classes of HO. Conclusion Clinical improvement in all evaluated parameters, which persists over time. Most implants maintained mobility, as has already been demonstrated in other studies with shorter follow-ups. In a significant percentage of cases, ASD was observed, questioning the concept of motion preserving technology. However, we did not have any surgical intervention for this reason, since there was no correlation with worse clinical results.

Postoperative Care Pathways Following Lumbar Total Disc Replacement: Results of a Modified Delphi Approach.

A modified Delphi method was used to establish consensus. Subject matter experts were invited to participate as the expert panel. Best practice statements were distributed to the panel. Panel members were asked to mark "agree" or "disagree" after a series of statements during several rounds until either consensus could be obtained or the practice method was deemed unable to achieve consensus. Lumbar total disc replacement (TDR) is acknowledged as an alternative to spinal fusion in appropriately selected patients. There is a lack of unanimity on the appropriate postoperative patient protocols and rehabilitation expectations for the procedure. The long-term viability of Lumbar TDR, further adoption in the community setting and specific patient outcomes are contingent on the existence of appropriate postoperative recovery programs. Currently there are no established methods for postoperative care following lumbar TDR. Establishing a postoperative clinical pathway algorithm may improve patient outcomes with respect to lumbar TDR. A lumbar TDR expert panel of 22 spine surgeons employed a modified Delphi method to drive consensus on postoperative care following single-level Lumbar TDR. The panel first reviewed literature and guidelines relevant to postoperative care following lumbar TDR. Panel members considered 21 survey questions intended to determine "standard-practice" postoperative care recommendations for patients who have undergone lumbar TDR for the initial recovery phase (0-4 wk) and rehabilitation (4-20 wk). Each panel member participated in a round of anonymous voting followed by a group discussion. Consensus was defined as 80% agreement or higher among the respondents. Consensus was achieved in 11 of the 21 survey questions. There was a high degree of consensus around the key goals for both the initial recovery and rehabilitation phases, ceased use of narcotics for pain management by 4 weeks postoperative, unrestricted walking immediately following surgery, timelines for physical therapy (within 2-4 wk) and return to work based on level of activity (as early as 1 wk postoperative). Lack of agreement included the use of back bracing and timing of postoperative visits. Generally, panel members felt that patient expectations regarding return to function were different following lumbar TDR versus fusion and warrant further study. Surgeon and patient alignment around postoperative expectations may significantly affect the long-term results of lumbar TDR. This surgeon consensus study found agreement for immediate postoperative ambulation, rapid reduction in opioids within the first month, and early return to work. When expectations are appropriately set with patients preoperatively, both provider and patient have shared goals in the return-to-function process. 5.

Impact of artificial disc height on the morphology of cervical facet joint

Objective: To investigate the impact of implant height on the morphology of cervical facet joints in artificial cervical disc replacement (ACDR). Methods: A finite element model of the cervical spine from C(2) to C(7) was constructed. The surgical processes of ACDR were simulated by insertion of 5 mm, 6 mm or 7 mm Prestige-LP artificial cervical discs. The morphological changes of cervical facet joints were recorded in terms of facet overlap distance, facet overlap area and facet angle. Results: The normal height Prestige-LP cervical disc could restore the natural status of the cervical spine. Compared with the intact condition, the model with ≥2 mm height implant would reduce the overall range of motion (ROM) by 19.2% in flexion, 19.4% in extension, 18.4% in lateral bending and 19.0% in axial rotation. Besides, the ROM at the surgical level reduced by 15.8% in flexion, 15.4% in extension and lateral bending and 19.0% in rotation. The upper and lower adjacent levels (C(4/5) and C(5/6)) showed more obvious changes in ROM, which reduced by 26.8% and 26.5% in flexion, 26.6% in extension, 26.5% and 26.4% in lateral bending, and 26.4% and 26.3% in rotation, respectively. The reduction of facet overlap distance, facet angle and facet overlap area with the ≥2 mm height artifact was 9.6%, 30.7%, and 17.9% respectively at the upper adjacent level, and 22.3%, 35.3% and 28.2% respectively at the surgical level, compared with the intact model.The morphology of facet joints at the lower adjacent level were slightly changed. Conclusion: The implant height selection in ACDR should be in accordance with the physiological intervertebral disc height. Artifact with ≥2 mm in height would obviously change the morphology of facet joints, thus should not be used in clinical practice.

Insight into the wear particles of PEEK and CFRPEEK against UHMWPE for artificial cervical disc application: Morphology and immunoreaction

Abstract Artificial cervical disc is a key device for artificial cervical disc replacement (ACDR). In our previous study, we developed PEEK-on-UHMWPE and CFRPEEK-on-UHMWPE tribo-parings for artificial cervical disc application. To further evaluate the biotribological properties and potential inflammation responses of their by-products, the size distribution and morphological characteristics of collected post-test wear particles as well as the biological response of aggregated particles were studied. Our results indicated that the majority of these wear particles were in a size range of 0.05–25 μm and the possibility of immunoreaction was small. Thus, we provide further evidence from the wear particles' point of view to suggest that CFRPEEK-on-UHMWPE can be considered as the potential paring for artificial cervical disc application.

The strategy selection of surgical approach and decompression and fusion for cervical spondylotic myelopathy

Cervical spondylotic myelopathy is a common and frequently-occurring disease in Orthopaedics, especially with multi-segmental cervical spondylotic myelopathy. There are several pathogenic factors for cervical spondylotic myelopathy. The clinical symptoms are serious, and the imaging manifestations are complex. Most of them are accompanied by serious neurological damage, which seriously affects the quality of life of patients. Furthermore, some patients have serious cervical spinal cord injury symptoms, which endanger their lives after mild trauma. Therefore, early diagnosis, early treatment and surgery are the most effective methods at present, which could effectively eliminate the factors of spinal cord compression and reconstruct the stability of cervical spine function. However, the choice of surgical approach and decompression fusion has always been the focus of debate. The primary purpose of surgery for cervical spondylotic myelopathy is to completely relieve the compression of spinal cord. According to the imaging characteristics of cervical spondylotic myelopathy, it is the key to the success of the operation to determine the decompression and reconstruction of cervical spondylotic myelopathy. Anterior approach can be adopted in patients with the compression factors located in front of the spinal cord, including disc protrusion, mild osteophyte or local ossification posterior longitudinal ligament, less lesion segments, small compression range, cervical kyphosis or local kyphosis deformity, easy resection of compression and sagittal imbalance correction. Decompression fusion can be selected through intervertebral space, subtotal vertebral body resection and mixed decompression for fusion and fixation. In order to retain the active function of cervical vertebrae, artificial disc replacement and fusion can be selected. For patients with the compression factors located in the posterior part of the spinal cord, including ligamentumflavum hypertrophy or ossification, congenital developmental spinal canal stenosis, there are many factors causing compression in front of the spinal cord. The range is larger, the lesion segment is longer. Thus, it is difficult to resect thoroughly in front of the spinal cord with higher risk of anterior surgery. Although the posterior approach is indirect decompression with the help of posterior spinal cord movement, it plays a good role in improving nerve function with fewer complications and relatively higher safety. There are absolute surgical indications and relative indications for two approaches. Combining anterior and posterior surgery has advantages of complete decompression and strong fixation. However, it has the advantages of great trauma and high risk, so it is necessary to apply it in clinical practice. Moreover, no matter how to choose the approach, we should use perfect imaging data combined with clinical symptoms and signs to clarify the pathological factors of spinal cord com pression, the severity of spinal cord injury, the scope of compression and the responsible segment, and formulate an individualized operation plan.

Biomechanical Analysis of the Cervical Spine Following Disc Degeneration, Disc Fusion, and Disc Replacement: A Finite Element Study.

Discectomy and fusion is considered the "gold standard" treatment for clinical manifestations of degenerative disc disease in the cervical spine. However, clinical and biomechanical studies suggest that fusion may lead to adjacent-segment disease. Cervical disc arthroplasty preserves the motion at the operated level and may potentially decrease the occurrence of adjacent segment degeneration. The purpose of this study was to investigate the effect of disc generation, fusion, and disc replacement on the motion, disc stresses, and facet forces on the cervical spine by using the finite element method. A validated, intact, 3-dimensional finite element model of the cervical spine (C2-T1) was modified to simulate single-level (C5-C6) and 2-level (C5-C7) degeneration. The single-level degenerative model was modified to simulate both single-level fusion and arthroplasty (total disc replacement [TDR]) using the Bryan and Prestige LP discs. The 2-level degenerative model was modified to simulate a 2-level fusion, 2-level arthroplasty, and single-level disc replacement adjacent to single-level fusion (hybrid). The intact models were loaded by applying a moment of ±2 Nm in flexion-extension, lateral bending, and axial rotation. The motion in each direction was noted and the other modified models were loaded by increasing the moment until the primary C2-T1 motion matched that of the intact (healthy) C2-T1 motion. Both Bryan and Prestige discs preserved motion at the implanted level and maintained normal motions at the adjacent nonoperative levels. A fusion resulted in a decrease in motion at the fused level and an increase in motion at the unfused levels. In the hybrid construct, the TDR (both) preserved motion adjacent to the fusion, thus reducing the demand on the other levels. The disc stresses followed the same trends as motion. Facet forces increased considerably at the index level following a TDR. The Bryan and Prestige LP TDRs both preserved motion at the implanted level and maintained normal motion and disc stresses at the adjacent levels. The motion patterns of the spine with a TDR more closely resembled that of the intact spine than those of the degenerative or fused models.

Comparison of M6-C and Mobi-C cervical total disc replacement for cervical degenerative disc disease in adults.

Cervical total disc replacement (CTDR) is complicated by adjacent segment degeneration (ASD). Since non-physiological spine kinematics after CTDR was postulated to cause ASD, M6-C prosthesis has been developed to better replicate the natural kinematics of the intervertebral disc. This retrospective cohort study aims to compare the short-term outcomes between patients receiving either the M6-C or Mobi-C prostheses. Patients who had refractory radiculopathy and/or myelopathy secondary to cervical degenerative disc disease and underwent CTDR between March 2004 and April 2017 were included. All CTDRs were performed by a single surgeon at a single institution. Self-reported clinical outcomes and radiological parameters were evaluated at baseline and final follow-up between March 2004 and April 2018. Sixty-two patients with greater than 1-year follow-up or who developed HO within 12 months of surgery, were included in the study. The mean radiological follow-up was 29.0 months (3-84 months), which includes 7 patients with less than 12 months follow-up who also developed HO. The changes in clinical and radiological measures were comparable between M6-C and Mobi-C prostheses. Thirty-seven out of 52 spinal segments (71.2%) and 10 out of 16 spinal segments (62.5%) developed HO in M6-C and Mobi-C group respectively. There was no significant difference in the rate of HO between the two groups. No short-term differences were found in clinical or radiological outcomes between patients who received either the M6-C or Mobi-C prosthesis. Further randomized trials with a long-term follow-up period are warranted to determine the safety and efficacy of M6-C prosthesis.

Treatment of Discogenic Low Back Pain: Current Treatment Strategies and Future Options-a Literature Review.

Many studies have demonstrated that discogenic low back pain is the most common type of chronic low back pain (CLBP), one of the major causes of disability, and has a major socioeconomic impact. Our aim is to review present therapeutic interventions for discogenic low back pain. There are a multitude of treatments used in clinical practice to treat CLBP, but there is continued debate and lack of consensus among clinicians and the policy makers as to which modality is the best approach. Based on controlled evaluations, lumbar intervertebral discs have been shown to be the source of chronic back pain without disc herniation in 26 to 39% of patients. Treatment modalities include noninvasive treatments such as drug therapy, multiple physical modalities, and multidisciplinary biopsychosocial rehabilitation; interventional modalities such as intradiscal therapies and epidural injections; and regenerative modalities with disc injections of various solutions; and, finally, surgical approaches such as fusion and artificial disc replacement, all of which are accompanied by significant discussion, limited evidence, and lack of consensus. The results of this evaluation show that the evidence for drug therapy in chronic discogenic low back pain is limited; for multidisciplinary biopsychosocial rehabilitation, it is moderate; and for multiple physical and behavioral therapies, the evidence is limited. For intradiscal therapies, it is poor; for epidural injections, it is moderate; and for regenerative therapies, evidence levels of 3 to 4. The evidence for surgical fusions and disc replacement is similar, without superiority when compared with multidisciplinary biopsychosocial rehabilitation, well-designed physical therapy, or epidural injections.

Accuracy and Reliability of X-ray Measurements in the Cervical Spine.

Study DesignThis study is a post hoc analysis of a multicenter prospective randomized controlled trial which compared artificial disc replacement and anterior cervical discectomy and fusion.PurposeUseful radiographic parameters for assessing cervical alignment include the Cobb angles, T1 slope (T1S), occipitocervical inclination (OCI), K-line tilt (KLT), and cervical sagittal vertical axis (cSVA). This study aimed to determine measurement accuracy and reliability for these parameters.Overview of LiteratureVarious authors have assessed repeatability by comparing different methods of measurement, but knowledge of measurement error and minimal detectable change is scarce.MethodsWe evaluated 758 lateral cervical radiographs. One medical student and one spine surgeon (i.e., measured ×2 within 4 weeks) independently measured the parameters obtaining 5,850 values. Standard error of measurement (SEm) and minimum detectable change (MDC) were calculated for each parameter. The accuracy and reliability of the Cobb angle measurements were calculated for the different types of angles: cervical lordosis, prosthesis angle, segmental angle with two bone surfaces (SABB), and segmental angle with one bone and one metal surface. Reliability was determined with intraclass correlation coefficient (ICC).ResultsSEm was 1.8° and MDC was 5.0° for the Cobb angle, with an intraobserver/interobserver ICC of 0.958/0.886. All the different subtypes of Cobb angles had an ICC higher than 0.950, except SABB (intraobserver/interobserver ICC of 0.922/0.716). The most accurate and reliable measurement was for KLT.ConclusionsThis study provides normative data on SEm and MDC for Cobb angles, T1S, KLT, OCI, and cSVA in cervical lateral radiographs. Reliability was excellent for all parameters except SABB (e.g., good).

Implant Design and the Anchoring Mechanism Influence the Incidence of Heterotopic Ossification in Cervical Total Disc Replacement at 2-year Follow-up.

A nonrandomized, prospective, and single-center clinical trial. The aim of this study was to determine whether the prosthesis design, and especially changes in the primary anchoring mechanism between the keel-based ProDisc C and the spike-based ProDisc Vivo, affects the frequency of heterotopic ossification (HO) formation over time. The occurrence of motion-restricting HO as well as underlying risk factors has so far been a widely discussed, but not well understand phenomenon. The anchoring mechanism and the opening of the anterior cortex may be possible causes of this unwanted complication. Forty consecutive patients treated with the ProDisc C and 42 consecutive patients treated with the ProDisc Vivo were compared with respect to radiological and clinical outcome, with 2 years of follow-up. Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), and arm and neck pain self-assessment questionnaires. Radiological outcomes included the segmental lordosis and range of motion (ROM) of the index-segment as well as the occurrence of HO. The clinical outcome parameters improved in both groups significantly. [ProDisc C: VAS arm and neck pain from 6.3 and 6.2 preoperatively to 0.7 and 1.3; NDI from 23.0 to 3.7; ProDisc Vivo: VAS arm and neck pain from 6.3 and 4.9 to 1.4 and 1.6, NDI from 34.1 to 8.7; 2-year follow-up (FU)]. The ProDisc Vivo cohort demonstrated a significantly lower incidence of HO than the ProDisc C group at 1-year FU (P = 0.0005) and 2-year FU (P = 0.005). Specifically, high-grade HO occurred in 9% versus 31%. These findings demonstrate that prosthesis designs that allow primary anchoring without violation of the cortical surface help to reduce the incidence of severe ossification, possibly affecting the functionality and mobility of the artificial disc device over of time. 3.

Long-term clinical outcome of two revision strategies for failed total disc replacements

PurposeTo compare the long-term clinical results and complications of two revision strategies for patients with failed total disc replacements (TDRs).MethodsIn 19 patients, the TDR was removed and the intervertebral defect was filled with a femoral head bone strut graft. In addition, instrumented posterolateral fusion was performed (removal group). In 36 patients, only a posterolateral instrumented fusion was performed (fusion group). Visual Analogue Scale (VAS) for pain and Oswestry Disability Index (ODI) were completed pre- and post-revision surgery. Intra- and post-operative complications of both revision strategies were assessed.ResultsThe median follow-up was 12.3 years (range 5.3–24.3). In both the removal and fusion groups, a similar (p = 0.515 and p = 0419, respectively) but significant decrease in VAS (p = 0.001 and p = 0.001, respectively) and ODI score (p = 0.033 and p = 0.013, respectively) at post-revision surgery compared to pre-revision surgery was seen. A clinically relevant improvement in VAS and ODI score was found in 62.5% and 43.8% in the removal group and in 43.5% and 39.1% in the fusion group (p = 0.242 and p = 0.773, respectively). Removal of the TDR was associated with substantial intra-operative complications such as major vessel bleeding and ureter lesion. The percentage of late re-operations for complications such as pseudarthrosis were comparable for both revision strategies.ConclusionsRevision of a failed TDR is clinically beneficial in about half of the patients. No clear benefits for additional TDR removal as compared to posterolateral instrumented fusion alone could be identified. In particular, when considering the substantial risks and complications, great caution is warranted with removal of the TDR.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.

Neural cell responses to wear debris from metal-on-metal total disc replacements

PurposeTotal disc replacements, comprising all-metal articulations, are compromised by wear and particle production. Metallic wear debris and ions trigger a range of biological responses including inflammation, genotoxicity, cytotoxicity, hypersensitivity and pseudotumour formation, therefore we hypothesise that, due to proximity to the spinal cord, glial cells may be adversely affected.MethodsClinically relevant cobalt chrome (CoCr) and stainless steel (SS) wear particles were generated using a six-station pin-on-plate wear simulator. The effects of metallic particles (0.5–50 μm3 debris per cell) and metal ions on glial cell viability, cellular activity (glial fibrillary acidic protein (GFAP) expression) and DNA integrity were investigated in 2D and 3D culture using live/dead, immunocytochemistry and a comet assay, respectively.ResultsCoCr wear particles and ions caused significant reductions in glial cell viability in both 2D and 3D culture systems. Stainless steel particles did not affect glial cell viability or astrocyte activation. In contrast, ions released from SS caused significant reductions in glial cell viability, an effect that was especially noticeable when astrocytes were cultured in isolation without microglia. DNA damage was observed in both cell types and with both biomaterials tested. CoCr wear particles had a dose-dependent effect on astrocyte activation, measured through expression of GFAP.ConclusionsThe results from this study suggest that microglia influence the effects that metal particles have on astrocytes, that SS ions and particles play a role in the adverse effects observed and that SS is a less toxic biomaterial than CoCr alloy for use in spinal devices.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.

Preoperative imaging differences of patients with cervical spondylosis with cervical vertigo indicate the prognosis after cervical total disc replacement.

ObjectiveTo evaluate the relationship between the preoperative imaging differences and prognosis in patients with cervical spondylosis with cervical vertigo who underwent total disc replacement (TDR).MethodsThis was a retrospective study of patients with cervical spondylosis with cervical vertigo treated with single-segment TDR. The severity of pre- and postoperative cervical vertigo was evaluated separately. Paired samples t-tests were used to compare the severity of the symptoms before and after surgery. Characteristics of plain films, computed tomography myelography and magnetic resonance imaging were compared between patients with different outcomes by analysis of variance and Fisher’s exact tests.ResultsThe severity of cervical vertigo was significantly different after single-segment TDR. Three groups with different treatment outcomes were not significantly different with regard to gender, age, type of the cervical spondylosis, follow-up time, segment of surgery, cervical curve, range of motion, T2WI high signal in the spinal cord, and location of compression. The type of compression was significantly different between the three groups.ConclusionsCervical vertigo was improved in patients with cervical spondylosis through the TDR procedure. Those in whom a herniated disc was the main source of compression may have a better prognosis following TDR.

Experimental Evaluation of Vertebral Strain in Lumbar Total Disc Replacement

Total disk replacement (TDR) has met considerable reluctance from the medical community, mainly in the United States, because the insurance companies have refused to reimburse surgeons for fear of delayed complications, revisions and unknown secondary costs. Typical long-term vertebrae-implant related structural complications include subsidence, migration, implant displacement, endplate fracture, wear and loosening. Intervertebral disc implant size, shape, position, endplate removal and compressive strength of trabecular bone further affect the risk of implant subsidence and loosening. The aim of the present study is to understand the combined effects of the different depth positioning of the ProDisc-L implant and endplate removal during surgery on the vertebral bone strain behaviour. Manufactured synthetic spinal L3-L4 segments were used to experimentally predict vertebrae cortex strain behaviour for different depth implant positioning and endplate thickness removal. In addition, validated finite element models were developed to assess the structural behaviour of cancellous-bone. Measured cortex strains showed significant differences relative to the intact vertebra for the most extreme depth implant positioning. The endplate thickness reduction tends to decrease significantly compressive cortex strains for all strain gauges. A two- to three-fold cancellous-bone strain increase occurs when more than 50% of the endplate thickness is removed, independently of the depth implant position. It is concluded that the implanted strain distribution that better fits intact vertebra strain behaviour is achieved when the depth centred implant position is combined with a partial endplate thickness removal.

Clinical and Radiographic Outcome of Patients With Cervical Spondylotic Myelopathy Undergoing Total Disc Replacement.

A nonrandomized, prospective, and single-center clinical trial. The aim of this study was to investigate the clinical and radiographic efficacy of ProDisc Vivo cervical total disc replacement (cTDR) in patients with clinical and radiographic documented cervical spondylotic myelopathy (CSM), due to degenerative changes at the index level. Decompression and fusion is still the gold standard in patients with cervical myelopathy. Very limited data are available regarding the application of cTDR in patients with clinical and radiological documented CSM in context of clinical and radiographic outcomes. Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), arm and neck pain self-assessment questionnaires as well as the Nurick grade and the Japanese Orthopaedic Association (JOA) score. The radiological outcome included the range of motion (ROM), the segmental and global (C2-C7) lordosis, and the occurrence of heterotopic ossifications. Eighteen consecutive patients (10 males, 8 females) with documented clinical and radiological signs of myelopathy were included in this investigation. The study population had a mean age of 52.4 years and a follow-up period of 20.3 months in average (range 3-48 months). The mean range ROM of the index level stayed consistent with 6.8° preoperatively and 7.2° (P = 0.578) at the last follow-up; the global lordosis in neutral position changed from 3.5° to 14.2° significantly (P = 0.005) in mean. The JOA score improved from 11.3 to 16.6 (P < 0.001) as well as the NDI 36.7 to 10.3 (P < 0.001) and the VAS score from 5.7/6.1 (arm/neck) to 1.3/2.0 (P < 0.001/P < 0.001). The mean Nurick grade was 1.33 preoperatively and dropped down in all cases to Nurick grade of 0 (P < 0.001). cTDR (with ProDisc Vivio) in patients with CSM yielded good clinical and radiographic outcomes and found as a reliable, safe, and motion-preserving surgical treatment option, although its indication is very limited due to numerous exclusion criteria. 4.

Prevalence of and Risk Factors for Heterotopic Ossification After Cervical Total Disc Replacement: A Systematic Review and Meta-Analysis.

Study Design:A systematic review and meta-analysis.Objectives:The results from previous meta-analyses are limited by the small number of included studies. Moreover, the risk factors of heterotopic ossification (HO) have not been well studied. Therefore, this study aims to estimate the prevalence of HO after cervical total disc replacement (CTDR) at different follow-up time points and explore potential risk factors for HO.Methods:We searched databases to identify eligible studies that reported the rate of HO after CTDR. The pooled prevalence of HO, according to different grades of HO, length of follow-up and types of prosthesis, and 95% confidence intervals (CIs) were calculated. Multivariable meta-regression analyses were performed to identify factors that may contribute to the heterogeneity between estimates.Results:Of the 94 studies included, 82 studies reported an overall rate of HO, encompassing a total of 5861 cervical spinal levels that underwent CTDR. The overall pooled prevalence of HO was 32.5% (95% CI 26.7% to 38.4%). Single-level CTDR was associated with a higher overall rate of HO. When the rate of HO was stratified by McAfee/Mehren classification, the pooled prevalence of range of motion (ROM)–limiting HO was 11.0% (95% CI 9.2% to 12.8%). Latest publication, single-level CTDR, longer follow-up period, and studies published outside were associated with a higher rate of ROM-limiting HO.Conclusions:We provide a comprehensive overview of the prevalence of different grades of HO. This meta-analysis also identifies and rules out some risk factors for HO after CTDR.

Analysis of Outcomes and Cost of Inpatient and Ambulatory Anterior Cervical Disk Replacement Using a State-level Database.

Outpatient cervical artificial disk replacement (ADR) is a promising candidate for cost reduction. Several studies have demonstrated low overall complications and minimal readmission in anterior cervical procedures. The objective of this study was to compare clinical outcomes and cost associated between inpatient and ambulatory setting ADR. Outcomes and cost were retrospectively analyzed for patients undergoing elective ADR in California, Florida, and New York from 2009 to 2011 in State Inpatient and Ambulatory Databases. A total of 1789 index ADR procedures were identified in the inpatient database (State Inpatient Databases) compared with 370 procedures in the ambulatory cohort (State Ambulatory Surgery and Services Databases). Ambulatory patients presented to the emergency department 19 times (5.14%) within 30 days of the index procedure compared with 4.2% of inpatients. Four unique patients underwent readmission within 30 days in the ambulatory ADR cohort (1% total) compared with 2.2% in the inpatient ADR group. No ambulatory ADR patients underwent a reoperation within 30 days. Of the inpatient ADR group, 6 unique patients underwent reoperation within 30 days (0.34%, Charlson Comorbidity Index zero=0.28%, Charlson Comorbidity Index>0=0.6%). There was no significant difference in emergency department visit rate, inpatient readmission rate, or reoperation rates within 30 days of the index procedure between outpatient or inpatient ADR. Outpatient ADR is noninferior to inpatient ADR in all clinical outcomes. The direct cost was significantly lower in the outpatient ADR group ($11,059 vs. 17,033; P<0.001). The 90-day cumulative charges were significantly lower in the outpatient ADR group (mean $46,404.03 vs. $80,055; P<0.0001). ADR can be performed in an ambulatory setting with comparable morbidity, readmission rates, and lower costs, to inpatient ADR.

Comparing 30-Day Outcomes between Orthopaedic Surgeons and Neurosurgeons Following Single-Level Cervical Total Disc Replacement

Comparing 30-Day Outcomes between Orthopaedic Surgeons and Neurosurgeons Following Single-Level Cervical Total Disc Replacement

Incidence of Fusion Across Total Disc Replacement With Heterotopic Ossification: Are Ball and Socket Disk Replacements Fusing With and Without Radiographic Evidence.

This is a level III retrospective study. The authors aim to review the outcomes and complications of ball and socket total disk replacements (TDRs). TDR is a motion-preserving technique that closely reproduces physiologic kinematics of the cervical spine. However, heterotopic ossification and spontaneous fusion after implantation of the total cervical disk have been reported in several studies to decrease the range of motion postulated by in vitro and in vivo biomechanical studies. The medical records of 117 consecutive patients undergoing cervical TDR over a 5-year period with Mobi-C, Prodisc-C, Prestige LP, and Secure-C implants were followed. Outcomes assessed included Visual Analogue Scale neck and arm and Neck Disability Index scores. The radiographic assessment looked at heterotopic ossification leading to fusion and complication rates. Of the 117 patients that underwent TDR, 56% were male with the group's mean age being 46.2±10.3 years and body mass index of 18.9±13.6 kg/m. The longest follow-up was 5 years with Prodisc-C group, with overall fusion noted in 16% of patients. One patient was also noted to have fusion which was not seen radiographically but noted intraoperatively for adjacent segment disease. There has been no demonstrable radiographic fusion seen in the Prestige LP group, however, the follow-up has only been 12-24 months for this group. In this study, we have demonstrated radiographic fusion anterior to the ball and socket TDR as well as the uncovertebral joint. We postulate that with the use of a mobile core disk there is an increased potential for fusion leading to a nonfunctional disk replacement.

Artificial disc replacement in spine surgery.

Total disc replacement (TDR) is an innovative procedure that has gained traction in spine surgery. A large amount of data in the literature report on the short-term outcomes of TDR surgery favorably. However, surgeons remain reluctant to opt for TDR surgery due to uncertainty of long-term outcomes. Recently, long term data regarding TDR surgery has become available, with some studies showing superior outcomes to fusion surgery. The goal of this review is to synthesize and clinically contextualize the recent literature on TDR surgery. This article also provides brief discussion of the biggest challenges currently facing disc arthroplasties and the ways in which they are being tackled.