Two-level Cervical Disc Arthroplasty Research Articles

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.

166. Thirty-six-month clinical outcomes of a prospective, controlled, multicenter study evaluating two-level cervical disc arthroplasty with a PEEK-on-ceramic artificial disc

166. Thirty-six-month clinical outcomes of a prospective, controlled, multicenter study evaluating two-level cervical disc arthroplasty with a PEEK-on-ceramic artificial disc

136. Relative vertebral motion after one- and two-level cervical disc arthroplasty

<h3>BACKGROUND CONTEXT</h3> While cervical disc arthroplasty has been studied for some time, few studies examined the relative motion between respective vertebral bodies. <h3>PURPOSE</h3> The purpose of this study was to examine the effects on the relative motion of the vertebral bodies above, below and at the surgical index level. <h3>STUDY DESIGN/SETTING</h3> Human cervical spines from C2-C7 were subjected to continuous loading cycles under flexion, extension, and lateral bending. Three-dimensional motion data were acquired using electromagnetic sensors at C4-C5, C5-C6 and C6-C7. <h3>PATIENT SAMPLE</h3> Eight planned cadaver cervical spines were subjected to each loading mode under intact, index (C5-C6) and inferior (C6-C7) artificial disc implantations. Specimens displayed degenerated discs with reduced intervertebral disc height. <h3>OUTCOME MEASURES</h3> The motion at C4-C5, C5-C6 and C6-C7 was computed to compare implantation vs intact conditions. Computations involved removal of induced motion by the testing apparatus and subsequently computing the relative motion between vertebral levels. <h3>METHODS</h3> Human cadaver specimens were loaded in extension, flexion and lateral bending under displacement control of 3 mm for 20 cycles at 0.1Hz. The testing configuration permitted orientation and loading of the specimen without removal from the testing apparatus. The loading modes were obtained by rotating the specimen into the loading axis of the testing apparatus. Motion data were collected continuously at 60 frames/second. Artificial discs were implanted by experienced spine surgeons for one- and two-level implantations at C5-C6 and C6-C7. Data were compared using a one-way ANOVA with Dunnett's post-hoc tests. Significance was set at P <0.05. <h3>RESULTS</h3> Based on half of the specimens analyzed, in flexion, a trend (P >0.05) toward increased motion was observed as the number of implanted levels increased. An increase in motion by 44.8% was observed with implantation at the index level relative to the intact condition. Implantation of a device inferiorly resulted in a 43% increase in motion relative to the intact level. In extension, no significant differences were seen regardless of the level of implantation. Lateral bending displayed a trend toward decreased motion though this was not statistically significant. The examination of total relative motion between vertebral bodies may be an improved consideration when evaluating the effects of disc arthroplasty. <h3>CONCLUSIONS</h3> Based on the number of specimens currently analyzed, a trend toward increased flexural motion was observed. Examination of isolated vertebral level motion may lead to unforeseen biomechanical conditions arising at adjacent levels from the index level. Further studies to include increased sample population could offer more insight toward ensuring that overall cervical motion is not unduly influenced. <h3>FDA DEVICE/DRUG STATUS</h3> prodisc C (Approved for this indication)

133. Facet joint loading after one- and two-level cervical disc arthroplasty

133. Facet joint loading after one- and two-level cervical disc arthroplasty

Cervical Alignment Analysis Comparing Two-Level Cervical Disc Arthroplasty with Anterior Cervical Discectomy and Fusion with Anterior Plate Fixation

This study assesses cervical alignments after 2-level cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) with anterior plate fixation. Eighty-two patients who underwent 2-level CDA or ACDF in 2014-2019 were identified. Cervical alignment parameters were compared between the 2 cohorts. Subgroup analyses were performed to determine factors that differentiate alignment outcomes between the 2 procedures. Although both cohorts achieved significant focal lordosis (FL) and overall cervical lordotic (CL) gains, CDA cohorts achieved significantly greater 12-month FL gain (P= 0.022). However, in a multivariate analysis controlling for preoperative variables, FL gain was no longer significant. Although the CDA cervical sagittal vertical axis (cSVA) significantly improved at 3 (P= 0.030) and 12 (P= 0.007) months, these improvements were not superior to the ACDF cSVA. Male patients undergoing CDA achieved greater 12-month CL gain. Patients undergoing CDA with body mass index >25 kg/m2 achieved greater 12-month FL gain. Patients undergoing CDA with symptom duration >12 months achieved greater FL gain at 3 and 12 months. Patients undergoing CDA with high baseline T1 slope or cSVA achieved greater 12-month cSVA reduction. Clinical outcomes were comparable between the 2 cohorts. Unlike the ACDF group, CL gain in the CDA group was significantly correlated with the cSVA reduction, which was associated with significant improvement in the Neck Disability Index, arm pain, and 12-Item Short-Form Mental Component Scores. Heterotopic ossification was not found to significantly affect patient outcome and cervical alignment in both cohorts. ACDF and CDA are viable options for 2-level degenerative disc disease in carefully selected patients. Both approaches produced equivalent postoperative alignment changes in a 2-level operation.

Classification of three-level hybrid surgery for the treatment of cervical degenerative disc disease: a retrospective study of 108 patients

IntroductionAccording to the different numbers and locations of cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF), three-level hybrid surgery (HS) has many constructs. The purpose of the present study was to introduce a classification system for three-level HS and compare the two types with each other and with ACDF.MethodsA retrospective study was conducted involving patients with three-level cervical degenerative disc disease (CDDD) who underwent ACDF or HS in our hospital between June 2012 and May 2019. According to the different numbers and locations of ACDFs and CDAs, we classified the three-level HS into two types (type I: one-level CDA and two-level ACDF, and type II: two-level CDA and one-level ACDF). The differences of clinical and radiological outcomes were compared with each other and with three-level ACDF.ResultsA total of 108 patients were analyzed. The Neck Disability Index (NDI) of the ACDF group at 3 months postoperatively was significantly higher than that in the type I and type II groups (p < 0.05). The cervical lordosis was significantly lower in the ACDF group than that in the type I and II groups at 3 days, 6, 12 months postoperatively and the final follow-up (p < 0.05). The range of motion (ROM) of the total cervical spine decreased significantly in all three groups at 3, 6, and 12 months postoperatively and at the final follow-up (p < 0.05). The ACDF group was observed with the most severe loss of ROM of the total cervical spine, followed by the type I group. The type II group could preserve the most ROM of the total cervical spine. The ROM of adjacent segments increased most in the ACDF group, followed by the type I group.ConclusionsCompared with ACDF, three-level HS may yield a faster recovery rate and superior radiological outcomes, such as a superiority in maintaining the cervical curvature and ROM of the total cervical spine and a smaller increase in the ROM of adjacent segments. The advantages were most remarkable in the type II group.

Radiological Changes in Adjacent and Index Levels after Cervical Disc Arthroplasty.

PurposeThe purpose of this retrospective study was to evaluate radiological and clinical outcomes in patients undergoing cervical disc arthroplasty (CDA) for cervical degenerative disc disease. The results may assist in surgical decision-making and enable more effective and safer implementation of cervical arthroplasty.Materials and MethodsA total of 125 patients who were treated with CDA between 2006 and 2019 were assessed. Radiological measurements and clinical outcomes included the visual analogue scale (VAS), the Neck Disability Index (NDI), and the Japanese Orthopaedic Association (JOA) myelopathy score assessment preoperatively and at ≥2 years of follow-up.ResultsThe mean follow-up period was 38 months (range, 25–114 months). Radiographic data demonstrated mobility at both the index and adjacent levels, with no signs of hypermobility at an adjacent level. There was a non-significant loss of cervical global motion and range of motion (ROM) of the functional spinal unit at the operated level, as well as the upper and lower adjacent disc levels, compared to preoperative status. The cervical global and segmental angle significantly increased. Postoperative neck VAS, NDI, and JOA scores showed meaningful improvements after one- and two-level CDA. We experienced a 29.60% incidence of heterotrophic ossification and a 3.20% reoperation rate due to cervical instability, implant subsidence, or osteolysis.ConclusionCDA is an effective surgical technique for optimizing clinical outcomes and radiological results. In particular, the preservation of cervical ROM with an artificial prosthesis at adjacent and index levels and improvement in cervical global alignment could reduce revision rates due to adjacent segment degeneration.

Outcome of Cervical Disc Arthroplasty in Degenerative Disc Disorder

AbstractBackground: Cervical Disc Arthroplasty (CDA) has beenconsidered as an alternative to cervical arthrodesis in thetreatment of Cervical Degenerative Disc Diseases (CDDD).Aim of Study: The aim of this study was to assess thelong-term clinical and radiographic outcomes of CDA.Patients and Methods: A total of 17 patients who under-went single-or two-level CDA with Prestige-LP Disc wereretrospectively investigated at a minimum of 4-year follow-up. Clinical assessments included Visual Analogue Scale (VAS) for neck and arm pain, Neck Disability Index (NDI),and Japanese Orthopedic Association (JOA) score. Radiologicalevaluations included Range of Motion (ROM) of the indexand adjacent levels, segmental angle, cervical sagittal align-ment, Heterotopic Ossification (HO) and Adjacent SegmentDegeneration (ASD).Results: Significant and maintained improvement in VASfor neck and arm, NDI and JOA were observed after a meanfollow-up of 54.7 months (p < 0.001). The preoperative ROMof the index level was 9.7o, which was maintained at 1-and2-year follow-up (9.3o, and 9.2o), but was decreased to 8.0oat final follow-up. Mobility was maintained in 84.2% (16/19)of the implanted prostheses at final follow-up. ROM of thesuperior and inferior adjacent segments, cervical sagittalalignment and cervical angel were all maintained. The inci-dence of HO was 36.8% at final follow-up, but it did notinfluence the clinical outcome. Radiographic ASD weredetected in 26.3% of the patients. However, the incidence ofsymptomatic ASD was only 5.2%.Conclusion: Cervical disc arthroplasty demonstrated amaintained and satisfactory clinical outcome at a minimal of4-year follow-up, with majority of the prostheses remainedmobile. Cervical disc arthroplasty can be considered as aneffective surgical method in treating CDDD.

Implant complications after one-level or two-level cervical disc arthroplasty: A retrospective single-centre study of 105 patients.

The aim of study was to investigate the complications of cervical disc arthroplasty (CDA) and to discuss the factors affecting the mobility of the prosthesis and the measures to prevent these complications. Hundred and five patients who underwent CDA between 2009 and 2016 were enrolled. The clinical and radiographic outcomes were used to assess and the complications were recorded as well.All the patients were followed-up with an average of 41.30 ± 16.90 months with an average age of 47.90 ± 9.22 years. The visual analogue scale (VAS), neck disability index (NDI), and Japanese Orthopaedic Association (JOA) scores improved significantly at the final follow-up (FU) compared with the preoperative values. At the final FU, the overall incidence of heterotopic ossification (HO) was 51.42%. The distribution of different grades of HO was low-level HO (53.7%) and high-level HO (46.3%). No significant differences were found in the NDI, VAS, or JOA scores between patients with HO and those without HO (P > .05). In the high-level HO patients, the range of mobility (ROM) was significantly reduced compared with the low-level HO patients and those without HO (P < .05). The anterior displacement, subsidence, and instability were observed in 1 patient respectively and the segmental kyphosis, adjacent segment degeneration in 3 patients respectively. The patient of CDA instability also suffered severe neck pain and the revision surgery was performed.Postoperative complications in CDA such as HO, segmental kyphosis, and prosthesis displacement are prone to occur, affecting prosthesis mobility. Surgical indications should be strictly controlled, and intraoperative and postoperative treatments should be given great attention in order to reduce prosthesis-related complications.

Two-Level Anterior Cervical Discectomy and Fusion Versus Cervical Disc Arthroplasty-Long-Term Evidence Update.

Multiple studies have highlighted the motion-sparing benefits of single-level cervical disc arthroplasty (CDA) compared with anterior cervical discectomy and fusion (ACDF). However, few studies have reviewed multilevel ACDF versus CDA. Several recent studies have midterm and even long-term data available comparing 2-level ACDF versus CDA. We reviewed 3 reports from 2 large randomized, prospective Food and Drug Administration investigational drug exemption trials looking at 2-level CDA versus ACDF, which provide the bulk of the available midterm to long-term, high-level evidence for the topic. We also present several smaller and/or shorter-term studies. One 5-year study showed that, while both CDA and ACDF showed significant improvement in patient-reported outcome scores, CDA demonstrated greater improvement in Neck Disability Index (NDI) scores than ACDF (mean = -37 versus mean = -28, P = .0003), were more likely to be satisfied (96.4% versus 89.5%, P = .04), had fewer secondary surgeries (4% versus 16.2%, P = .0003), had fewer adjacent level reoperations (3.1% versus 11.4%), and developed less adjacent segment degeneration (50.7% versus 90.5%, P < .0001). Adverse events occurred more frequently with ACDF (8.6% versus 4.4%).Similarly, Lanman et al [Lanman TH, Burkus JK, Dryer RG, Gornet MF, McConnell J, Hodges SD. Long-term clinical and radiographic outcomes of the Prestige LP artificial cervical disc replacement at 2 levels: results from a prospective randomized controlled clinical trial. J Neurosurg Spine. 2017;27(1):7-19] showed that, at 7 years, while both groups demonstrated improvement in patient-reported outcomes, CDA had greater improvement in regard to NDI, neck pain, and Short Form (36) Physical Component Summary scores (each P < .001), had higher rates of satisfaction (94.8% versus 92.6%), had lower rate of secondary surgery at treated levels (4.2% versus 14.7%), and had a lower, albeit not statistically significant, rate of secondary surgeries at adjacent levels (6.5% versus 12.5%). Adverse events were more common with ACDF (7.2% versus 3.2%).More recently, Gornet et al [Gornet MF, Lanman TH, Burkus JK, et al. Two-level cervical disc arthroplasty versus anterior cervical discectomy and fusion: 10-year outcomes of a prospective, randomized investigational device exemption clinical trial. J Neurosurg Spine. 2019;31:508-518.] in 2019 reported 10-year data from the same clinical trial as the Lanman et al report comparing 2-level CDA (209 patients) versus ACDF (188 patients). With >84% follow-up for both groups at 10 years, they found that CDA demonstrated a statistically significantly improved rate of overall success (84% versus 62%) as compared with ACDF. Greater improvements were seen in several other outcome measures for CDA, including NDI, neurological success, and neck pain scores. The CDA group had a lower rate of serious implant-related adverse events and demonstrated a lower rate of needing a secondary surgery at an adjacent level, 9% versus 18% in the ACDF group. Results of 2 large randomized trials suggest similar-to-improved patient reported outcomes for multilevel CDA versus ACDF maintained out to midterm to long-term follow-up of 5-10 years, with lower rates of revision surgery at index and adjacent levels and lower rates of serious adverse device-related events. 5. Comparison of the safety and efficacy of multi-level cervical disc arthroplasty and cervical discectomy and fusion.

Incidence of bone loss after Prestige-LP cervical disc arthroplasty: a single-center retrospective study of 396 cases

BACKGROUND CONTEXTThe development of bone loss (BL) at the operated level after cervical disc arthroplasty (CDA) has not been well recognized. The incidence of BL may be correlated with the prosthesis type. Currently, no study has reported the incidence of BL after CDA with the Prestige-LP disc, and this remains an active area of research. PURPOSETo determine the incidence of BL after Prestige-LP CDA and evaluate the impact of BL on clinical and radiological outcomes. STUDY DESIGNThis is an observational study. PATIENT SAMPLEA total of 396 patients were reviewed. OUTCOME MEASURESThe Japanese Orthopedics Association (JOA), Visual Analogue Scale (VAS), and Neck Disability Index (NDI) scores were evaluated. Cervical lordosis, disc angle, global and segmental range of motion (ROM), heterotopic ossification (HO), and BL were measured. METHODSWe retrospectively reviewed patients who underwent Prestige-LP disc from January 2008 to October 2018 at our institution. Clinical outcomes were evaluated using JOA, VAS, and NDI scores. Radiological variables, including cervical lordosis, disc angle, global and segmental ROM, HO, and BL, were retrieved. RESULTSA total of 396 patients and 483 CDAs were evaluated. BL occurred in 56.6% of patients and 52.8% of CDA segments. Mild BL occurred in 30.2%, moderate BL in 37.3%, and severe BL in 32.5% of CDA segments. Notably, 88.2% of CDA segments developed BL within the first 3 months, and 19.1% of them progressed at 6 months. However, no progressive BL after 12 months was seen. About 50.2% of CDAs showed superior and inferior endplates involvement. The incidence of BL was associated with age, surgery type, level distribution, and incidence and grade of HO. Patients with BL had a better segmental ROM, but no relationships between patients with or without BL were found in clinical outcomes. CONCLUSIONSBL was a common but self-limited phenomenon after CDA at the early postoperative stage. It occurred more often in relatively young age patients, two-level CDA, and C5/6 segment. However, patients suffering from BL showed no deterioration of the clinical outcomes, more exceptional motion preservation at the arthroplasty level, and lower incidence with a lower grade of HO.

Cervical disc arthroplasty versus anterior cervical discectomy and fusion: a meta-analysis of rates of adjacent-level surgery to 7-year follow-up.

Anterior cervical discectomy and fusion (ACDF) is an effective treatment for cervical spondylosis. A limitation of ACDF is the risk of adjacent-segment degeneration (ASD), owing to arthrodesis of a motion segment. Cervical disc arthroplasty (CDA) has hence garnered significant attention; yet, compelling evidence of reduction in ASD requiring surgery is lacking. This systematic review and meta-analysis sought to compare long-term longitudinal adjacent-level operation rates with CDA versus ACDF. An electronic literature search was conducted. Eligible studies were multi-center randomized controlled trials (RCTs) comparing CDA with ACDF for one- or two-level symptomatic cervical spondylosis. The primary outcome was adjacent-level operation. Index-level reoperation was a secondary outcome. Outcomes were evaluated at 1-year intervals from the index operation to last reported follow-up by random-effects meta-analyses. Eleven RCTs met criteria. For one-level spondylosis, there was no difference in the rate of adjacent-level operation between CDA (2.3%) and ACDF (3.6%) at 2 years. However, a large difference favoring CDA became evident at 5 years and persisted at 7 years (4.3% vs. 10.8%, P<0.001). Significantly fewer patients who underwent CDA required index-level reoperation at all time points out to 7 years (5.2% vs. 12.7%, P<0.001). Similar to one-level operations, there was no significant difference in adjacent-level operations with two-level CDA (1.7%) versus two-level ACDF (3.4%) at 2 years. At 7 years, a significant difference favoring CDA became apparent (5.1% vs. 10.0%, P=0.014). Two-level CDA resulted in fewer index-level reoperations out to 7 years (4.2% vs. 13.5%, P<0.001). In this meta-analysis, the short-term rate of adjacent-level operation was similar with CDA or ACDF. However, around 5 years, a statistically significant divergence emerged, where the rate of adjacent-level surgery rose steeply for ACDF. Index-level reoperations were less frequent with CDA in both the short- and long-term. These data indicate CDA may have a superior longevity to ACDF with regard to need for subsequent adjacent-level operation.

Cervical disk arthroplasty

Anterior cervical discectomy and fusion (ACDF) is a well-established surgical intervention for degenerative cervical spine pathology. Concerns over pseudarthrosis and adjacent segment degeneration (ASD), however, have led to an increased interest in motion-preserving alternatives. Cervical disc arthroplasty (CDA) may reduce ASD through preservation of cervical biomechanics and has demonstrated non-inferiority when compared to ACDF in medium-term studies with indications for single- and two-level cervical disease. This chapter describes the indications, biomechanical properties of common designs, and complications of CDA. Additionally, we describe a two-level CDA case study and highlight some pearls and pitfalls associated with CDA implantation as it is more technically demanding than ACDF. While CDA may represent a viable alternative to ACDF with fewer complications, studies are needed to establish its long-term safety.

Radiological and clinical outcomes of 3-level cervical disc arthroplasty.

One- and two-level cervical disc arthroplasty (CDA) has been compared to anterior cervical discectomy and fusion (ACDF) in several large-scale, prospective, randomized trials that have demonstrated similar clinical outcomes. However, whether these results would be similar when treating 3-level disc herniation and/or spondylosis has remained unanswered. This study aimed to investigate the differences between 3-level CDA and ACDF. A series of 50 patients who underwent 3-level CDA at C3-7 was retrospectively reviewed and compared with another series of 50 patients (age- and sex-matched controls) who underwent ACDF at C3-7. Clinical outcomes were measured using the visual analog scale (VAS) for neck and arm pain, the modified Japanese Orthopaedic Association (mJOA) scale, and the Neck Disability Index (NDI). Radiological outcomes included range of motion (ROM) at the index levels. Every patient was evaluated by CT for the presence of fusion in the ACDF group. Also, complication profiles were investigated. The demographics and levels of distribution in both groups were very similar. During the follow-up period of 24 months, clinical outcomes improved (overall and respectively in each group) for both the CDA and ACDF patients when compared with the patients' preoperative condition. There were essentially few differences between the two groups in terms of neck and arm pain VAS scores, mJOA scores, and NDI scores preoperatively and at 3, 6, 12, and 24 months postoperatively. After the 3-level surgery, the CDA group had an increased mean ROM of approximately 3.4°, at 25.2° ± 8.84°, compared to their preoperative ROM (21.8° ± 7.20°) (p = 0.001), whereas the ACDF group had little mobility (22.8° ± 5.90° before and 1.0° ± 1.28° after surgery; p < 0.001). The mean operative time, estimated blood loss, and complication profiles were similar for both groups. In this selectively matched retrospective study, clinical outcomes after 3-level CDA and ACDF were similar during the 2-year follow-up period. CDA not only successfully preserved but slightly increased the mobility at the 3 index levels. However, the safety and efficacy of 3-level CDA requires more long-term data for validatation.

119. Ten-year outcomes of one- and two-level cervical disc arthroplasty: results from a US multicenter study

BACKGROUND CONTEXT Short- and mid-term studies have shown the effectiveness of cervical disc arthroplasty (CDA) to treat cervical disc degeneration. Upon completion of the 7-year Mobi-C FDA study, follow-up continued on a subset of CDA patients in the FDA study. PURPOSE The purpose of this study is to report the 10-year outcomes of a multicenter experience with cervical arthroplasty for 1- and 2-level pathology. STUDY DESIGN/SETTING This was a prospective cohort study of patients treated with cervical disc replacement at one or two contiguous levels using the Mobi-C® Cervical Disc. PATIENT SAMPLE Following completion of the 7-year FDA post approval study, follow-up continued to 10 years for consenting patients at 9 high-enrolling centers. The primary inclusion criteria were cervical degenerative disc at one or two contiguous levels and no prior cervical operations. OUTCOME MEASURES Outcome measures included NDI, VAS neck and arm pain, patient satisfaction, secondary surgical procedures (removals, revisions, reoperations, or additional fixation) and adverse events. Radiographic end points included segmental and global range of motion, sagittal alignment, adjacent level degeneration (ALD) and heterotopic ossification (HO). Radiographic ALD was defined with the Kellgren-Lawrence scale. HO was classified by the system adapted from McAfee and Mehren. Independent radiologists (Medical Metrics, Inc., Houston, TX) conducted radiographic evaluations. METHODS From the original enrollment of 257 CDA patients at 9 sites, 231 patients were eligible for follow-up after 7 years. Ten-year follow-up was obtained from 187 patients (81% follow-up). The longest follow-up was 11.2 years. Radiographs were obtained from 170 patients at 10 years. There were no significant differences in preoperative characteristics between these patients and the original FDA cohort. RESULTS Ten years after CDA, patients continued to show significant improvement from baseline NDI, VAS neck and arm pain, and neurologic function. Outcomes at 10 years were improved from results at 7 years for NDI at one (14.2 vs 18.7; p=0.12) and two levels (15.6 vs 19.7; p=0.02). Comparable results were observed for neck and arm pain. These improvements were less than the MCID for NDI and pain. There were no significant differences in outcomes between 1- and 2-level CDA at 10 years. Segmental flexion-extension range of motion remained significantly higher (p 0.05). The incidence of clinically relevant HO at 10 years was not significantly different from the 7-year incidence for 1-level (30.7% vs 29.6%; p=0.88) or 2-level (41.7% vs 39.2%; p=0.70) CDA patients. Only 2 subsequent surgeries were reported after 7 years. One patient underwent supplemental fixation at the index level 9.5 years after CDA. The other case was ACDF at a nonadjacent level unrelated to the CDA. Total incidence of subsequent surgery after 10 years was 4.7% (12/257) at the index level and 3.5% (9/257) at an adjacent level. CONCLUSIONS At 10-years, both 1- and 2-level CDA demonstrate sustained improvement of NDI, pain scores, range of motion and sagittal alignment compared to baseline. Progression of ALD and HO from 7 to 10 years was minimal. Our results through 10 years demonstrate that CDA with Mobi-C continues to be a safe and effective surgical treatment for patients with 1- or 2-level cervical degenerative disc disease. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.

Two-level cervical disc arthroplasty versus anterior cervical discectomy and fusion: 10-year outcomes of a prospective, randomized investigational device exemption clinical trial.

The authors assessed the 10-year clinical safety and effectiveness of cervical disc arthroplasty (CDA) to treat degenerative cervical spine disease at 2 adjacent levels compared to anterior cervical discectomy and fusion (ACDF). A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted comparing the low-profile titanium ceramic composite-based Prestige LP Cervical Disc (n = 209) at two levels with ACDF (n = 188). Ten-year follow-up data from a postapproval study were available on 148 CDA and 118 ACDF patients and are reported here. Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative follow-up intervals for up to 10 years. The primary endpoint was overall success, a composite variable that included key safety and efficacy considerations. Ten-year follow-up rates were 86.0% for CDA and 84.9% for ACDF. From 2 to 10 years, CDA demonstrated statistical superiority over ACDF for overall success, with rates at 10 years of 80.4% versus 62.2%, respectively (posterior probability of superiority [PPS] = 99.9%). Neck Disability Index (NDI) success was also superior, with rates at 10 years of 88.4% versus 76.5% (PPS = 99.5%), as was neurological success (92.6% vs 86.1%; PPS = 95.6%). Improvements from preoperative results in NDI and neck pain scores were consistently statistically superior for CDA compared to ACDF. All other study effectiveness measures were at least noninferior for CDA compared to ACDF through the 10-year follow-up period, including disc height. Mean angular ranges of motion at treated levels were maintained in the CDA group for up to 10 years. The rates of grade IV heterotopic ossification (HO) at the superior and inferior levels were 8.2% and 10.3%, respectively. The rate of severe HO (grade III or IV) did not increase significantly from 7 years (42.4%) to 10 years (39.0%). The CDA group had fewer serious (grade 3-4) implant-related or implant/surgical procedure-related adverse events (3.8% vs 8.1%; posterior mean 95% Bayesian credible interval [BCI] of the log hazard ratio [LHR] -0.92 [-1.88, -0.01]). The CDA group also had statistically fewer secondary surgical procedures at the index levels (4.7%) than the ACDF group (17.6%) (LHR [95% BCI] -1.39 [-2.15, -0.61]) as well as at adjacent levels (9.0% vs 17.9%). The Prestige LP Cervical Disc, implanted at two adjacent levels, maintains improved clinical outcomes and segmental motion 10 years after surgery and is a safe and effective alternative to fusion.Clinical trial registration no.: NCT00637156 (clinicaltrials.gov).

Radiological and clinical outcomes of cervical disc arthroplasty for the elderly: a comparison with young patients

BackgroundThis study aimed to investigate whether cervical disc arthroplasty (CDA) would be equally effective in elderly patients as in the young. The inclusion criteria of published clinical trials for CDA-enrolled patients covered the ages from 18 to 78 years. However, there was a paucity of data addressing the differences of outcomes between older and the younger patients.MethodsA series of consecutive patients who underwent one- or two-level CDA were retrospectively reviewed. Patients at the two extreme ends of the age distribution (≥65 and ≤ 40 years) were selected for comparison. Clinical outcome parameters included visual analog scale (VAS) of neck and arm pain, neck disability index (NDI), and Japanese Orthopaedic Association (JOA) scores. Radiographic outcomes included range of motion (ROM) at the indexed level and evaluation of heterotopic ossification (HO) by computed tomography (CT). Complication profiles were also investigated.ResultsThere were 24 patients in the elderly group (≥65 years old) and 47 patients in the young group (≤40 years old) with an overall mean follow-up of 28.0 ± 21.97 months. The elderly group had more two-level CDA, and thus the mean operative time was longer (239 vs. 179 min, p < 0.05) than the young group. Both groups had similarly significant improvement in clinical outcomes at the final follow-up. All the replaced disc segments remained mobile on post-operative lateral flexion and extension radiographs. However, the elderly group had a slight decrease in mean ROM (− 0.32° ± 3.93°) at the index level after CDA when compared to that of pre-operation. In contrast, the young group had an increase in mean ROM (+ 0.68° ± 3.60°). The complication profiles were not different, though a trend toward dysphagia was noted in the elderly group (p = 0.073). The incidence or severity (grading) of HO was similar between the two groups.ConclusionsDuring the follow-up of two years, CDA was equally effective for patients over 65 years old and those under 40 years in clinical improvement. Although the elderly group demonstrated a small reduction of mean ROM after CDA, in contrast to the young group which had a small increase, the segmental mobility was well preserved at every indexed level for each group.

Thursday, September 27, 2018 3:35 PM–5:05 PM Section on Motion Technology Abstract Presentations: 134. Ten-year radiographic analysis of one- and two-level cervical disc arthroplasty in a U multicenter study

BACKGROUND CONTEXT Short- and mid-term studies have demonstrated that cervical disc arthroplasty (CDA) can maintain or restore range of motion and sagittal alignment in select patients with cervical disc degeneration. Upon completion of the 7-year Mobi-C FDA study, follow-up continued out to 10 years on a subset of CDA patients from high-enrolling centers in the FDA study. This is an analysis of the radiographic outcomes of the first 98 CDA patients with 10-years follow-up. PURPOSE The purpose of this study is to present preliminary radiographic outcomes of the first 98 (approximately 50%) patients followed for 10-years in a multicenter study of cervical arthroplasty for one- and two-level pathology. STUDY DESIGN/SETTING This was a prospective cohort study of patients treated with cervical disc replacement at one or two contiguous levels using the Mobi-C Cervical Disc. Following completion of the 7-year FDA post approval study, follow-up was extended to 10 years for consenting patients at seven high-enrolling centers. PATIENT SAMPLE The inclusion criteria for this study was adult patients (>18 years) with radiculopathy or myelopathy and cervical spondylosis at one or two contiguous levels and no prior cervical operations. OUTCOME MEASURES All radiographic evaluations were conducted by independent radiologists (Medical Metrics, Inc., Houston, TX, USA). Radiographic endpoints included segmental and global range of motion, sagittal alignment, adjacent level degeneration (ALD) and heterotopic ossification (HO). The Kellgren-Lawrence scale of disc degeneration was used to define radiographic ALD. HO was classified using the system adapted from McAfee and Mehren. HO grades 3 and 4 were classified as clinically relevant due to restricted ROM. METHODS Ten-year radiographic follow-up was obtained from 98 CDA patients (53 2-level; 45 1-level) at seven centers. All radiological endpoints for the study cohort including HO were evaluated at 10 years, and were compared to the 7-year data for the group using statistical tests that were 2-sided, with p values RESULTS There were no significant differences in demographic factors or preoperative patient-reported outcomes between these patients and the original FDA cohort. Both segmental flexion-extension (FE) and lateral bending (LB) range of motion remained significantly greater (p .05). Global (C2-C6) flexion-extension and sagittal alignment also were maintained from 7 to 10 years (p>.05). Clinically relevant ALD (Grades III-IV) at 10 years was not significantly different from the 7-year incidence for one-level (25.0% vs. 26.2%; p=.47) or 2-level (17.0% vs. 13.7%; p=.16) CDA patients. The incidence of clinically relevant HO at 10 years was not significantly different from the 5-year incidence for one-level (28.9% vs. 33.3%; p=.88) or 2-level (35.8% vs. 26.9%; p=.21) CDA patients. From 7 to 10 years, 94% of patients had no progression of HO. Although patients with Grade 3/4 HO had diminished ROM, range of motion at the affected level(s) remained stable in these patients from 7 years (FE 3.7°; LB 2.7°) to 10 years (FE 3.5°; LB 2.6°). CONCLUSIONS We demonstrate continued maintenance of radiographic performance of cervical arthroplasty out to 10 years. At 10-year follow-up, both one- and two-level arthroplasty demonstrate sustained range of motion and sagittal alignment in comparison to baseline values. Progression of ALD and HO was limited from 7 to 10 years in these patients. Our preliminary results through 10 years demonstrate that total disc arthroplasty with Mobi-C continues to be an effective surgical treatment for patients with one- or two-level cervical degenerative disc disease. FDA DEVICE/DRUG STATUS The Mobi-C is approved for this indication.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P115. Clinical adjacent segment pathology following treatment with CDA or ACDF at one or two-levels through seven-years

BACKGROUND CONTEXT Adjacent segment pathology (ASP) continues to be a concern for surgeons and patients following cervical spine surgery. Most reports to date have focused on either reoperation at the index level or reoperation at any level. There is little debate that radiographic ASP (rASP) favors cervical disc arthroplasty (CDA), but few studies have explored clinical ASP (cASP). PURPOSE To evaluate cASP in patients treated with CDA or ACDF. STUDY DESIGN/SETTING Post-hoc analyses were performed on data that was collected through 7years in a prospective, randomized, controlled clinical trial comparing CDA to ACDF with allograft and anterior plate at one or two contiguous levels. PATIENT SAMPLE The patient population consisted of 575 randomized patients: 164 one-level CDA and 81 one-level ACDF; 225 two-level CDA and 105 two-level ACDF. OUTCOME MEASURES Adjacent level surgeries through 7years. METHODS Kaplan-Meier survival curves for adjacent level surgery were compared using the log-rank test. Cox regression was used to assess the impact of treatment on the relative risk of adjacent level surgery. RESULTS Follow-up rates through 7years were 74.6%. The proportion of patients undergoing an adjacent level surgery was 14.8% for 1-level ACDF, 4.3% for 1-level CDA, 12.4% for 2-level ACDF, and 4.9% for two-level CDA. Kaplan–Meier survival estimates of the probability of adjacent level surgery heavily favored CDA over ACDF (p CONCLUSIONS The adjacent level surgery rates of ACDF patients are over three times higher than CDA at one-level and 2.5times for two-level through 7-years follow-up. In this patient population the survival estimates strongly favor CDA, with estimated rates of adjacent level surgery per 100 patients three times higher for ACDF (p

2 - Comparison of 7-Year Results of One-Level vs Two-Level Cervical Disc Arthroplasty and Fusion

2 - Comparison of 7-Year Results of One-Level vs Two-Level Cervical Disc Arthroplasty and Fusion