Single-level Cervical Arthroplasty Research Articles

One-Year Follow-Up Study on Assessing the Range of Segmental Motion and Clinical Outcomes Following Cervical Disc Arthroplasty for Treatment of Severe Cervical Disc Degeneration

Though previous studies have documented various clinical outcomes after cervical arthroplasty for degenerative cervical disc disease, none of them reported the impact of cervical arthroplasty on severe cervical disc degeneration (CDD). This retrospective cohort study included severe 40 CDD (C3-C7) patients who underwent single-level cervical arthroplasty using ProDisc-C between January 2017 and December 2019. After surgical intervention, the range of motion (ROM) was determined, whereas clinical outcomes were measured in terms of the Visual Analogue Scale (VAS) and Neck Disability Index (NDI) to evaluate neck pain and disability, respectively. Compared to the mean preoperative ROM (6.57 ± 4.85°), the cervical dynamic ROM was increased 3months after cervical arthroplasty, and the increment was maintained for at least 1year. The increased ROM is attributed to the extension and not flexion components. The mean preoperative ROM of 6.57 ± 4.85° significantly increased to 11.67 ± 4.98° (P= 0.0005), 10.05 ± 5.18° (P= 0.0426) and 10.46 ± 4.73° (P= 0.0247) after 3months, 6months and 1year, respectively. The extension ROM also revealed a similar trend. VAS for neck and arm decreased from 7.4 and 6.6 to 1.4 and 1.2, respectively. Consistently, the preoperative mean Neck Disability Index (NDI) score of 27.6 decreased to 14.6. We recorded a case of device subsidence, but without extrusion. Cervical arthroplasty can improve clinical outcomes and restore ROM in severe CDD patients.

Single-Level Cervical Arthroplasty with a Keel-less Prosthesis: Results in a Series of 35 Patients Operated on for Soft Disk Herniation with a Minimum of 3 Years of Follow-Up.

Cervical arthroplasty with artificial cervical disks has gained popularity as an alternative to anterior discectomy and fusion. The main advantages of disk arthroplasty include maintenance of the range of movement, restitution of disk height and spinal alignment, and reduction of adjacent segment degeneration (ASD). In this article, we aimed to assess the outcomes of the use of a keel-less prosthesis. We included all the patients who underwent single-level cervical arthroplasties with the Discocerv Cervidisc Evolution for "soft" disk herniation. Clinical assessment included Neck Disability Index (NDI) and visual analog scale (VAS) for neck and arm pain. Radiologic studies investigated the occurrence of ASD and system failure or subsidence. The reoperation rate was also recorded. The study included 35 patients (14 men and 21 women; mean age: 42.5 years; mean follow-up: 57.8 months). There was a significant decrease in VAS neck and VAS arm scores, which went from 7.2 and 6.9 preoperatively to 2.2 and 1.7 postoperatively, 2.2 and 1.6 at 6 months, 2.0 and 1.8 at 1 year, and 2.1 and 1.3 at the last follow-up, respectively. The mean NDI score was 58.0 preoperatively, 19.4 postoperatively, 17.0 at 6 months, 16.1 at 1 year, and 16.2 at the last follow-up. Radiologic studies revealed a preserved range of motion in 33 of 35 patients. No ASD occurred and no reoperation was required. Cervical disk arthroplasty with a keel-less prosthesis can be a safe and effective alternative to fusion for degenerative disk disease in selected patients, with a possible reduction of ASD.

Single-level Cervical Arthroplasty with Prodisc-C Vivo Artificial Disc: Five-year Follow-up Results From One Center.

Retrospective study. The aim of this study was to evaluate the long-term clinical and radiographic outcomes of cervical arthroplasty using the ProDisc-C Vivo prosthesis. Previous reports have shown that cervical arthroplasty with ProDisc-C artificial disc has acceptable clinical outcomes at 5-year and 10-year follow-ups. Clinical and radiographic evaluations, including dynamic flexion-extension lateral images, were performed at baseline and at the 5-year follow-up. Twenty-eight patients who underwent single-level ProDisc-C Vivo arthroplasty were followed-up for a mean period of 65 months. The range of motion at the operated level was 8.9° ± 2.3° at baseline and 8.3° ± 4.8° at the final follow-up (P = 0.494). Fourteen of 28 levels (50%) developed heterotopic ossification (HO). According to McAfee's classification, one level was classified as grade I, nine levels as grade II, two levels as grade III, and two levels as grade IV. Only four of 28 levels (14.3%) had severe HO. Among patients with cervical spondylotic myelopathy, mJOA score was 13.9 ± 2.5° at baseline and 15.9° ± 1.0° at the final follow-up (P = 0.001 < 0.05). Among patients with cervical spondylotic radiculopathy, Visual Analog Scale (VAS) neck and shoulder was 5.4 ± 1.4° at baseline and 0.7° ± 1.2° at the final follow-up (p = 0.000 < 0.05), VAS arm was 5.1 ± 2.8° at baseline and 0.5° ± 1.2° at the final follow-up (P = 0.000 < 0.05). A total of 49 adjacent segments were observed and 13 (26.5%) had adjacent segment degeneration. No patient developed recurrent cervical radiculopathy or myelopathy due to adjacent segment disease. No patient underwent re-operation. ProDisc-C Vivo arthroplasty had satisfactory clinical and radiographic outcomes at 5-year follow-up.Level of Evidence: 4.

Single-level cervical arthroplasty with ProDisc-C artificial disc: 10-year follow-up results in one centre.

The aim of this study was to evaluate the long-term clinical and radiographic outcomes of cervical arthroplasty using the ProDisc-C prosthesis. Clinical and radiographic evaluations, including dynamic flexion-extension lateral images, were performed at baseline and at 10-year follow-up. Twenty-seven patients who had single-level ProDisc-C arthroplasty were followed up for a mean period of 123months. The range of motion at the operated level was 8.9° ± 3.9° at baseline and 6.6° ± 3.5° at final follow-up. Twenty of 27 levels (74%) developed heterotopic ossification. According to McAfee's classification, one level was classified as grade I, four levels were classified as grade II, 12 levels were classified as grade III and three levels were classified as grade IV. Three patients developed recurrent cervical radiculopathy or myelopathy due to adjacent segment disease and received the reoperations. The reoperations included two cases of cervical arthroplasty at adjacent segments and one case of cervical laminoplasty. ProDisc-C arthroplasty had acceptable clinical and radiographic results at 10-year follow-up. Heterotopic ossification was common after ProDisc-C arthroplasty, which decreased the range of motion. These slides can be retrieved under Electronic Supplementary Material.

Five-Year Trends in Center of Rotation After Single-Level Cervical Arthroplasty with the Prestige-LP Disc

To assess the invivo longitudinal kinematic performance of the Prestige-LP Disc and describe the 5-year trends in the center of rotation (COR) at the instrumented level. Forty-two patients with single-level cervical disc arthroplasty (CDA) were reviewed retrospectively. Lateral static and dynamic cervical radiographs were obtained preoperatively and postoperatively at 1, 3, and 5 years. Kinematic parameters collected included range of motion (ROM), COR, intervertebral disc height (IDH), functional spinal unit (FSU) angle. Japanese Orthopedic Association (JOA), visual analog scale (VAS), and Neck Disability Index (NDI) scores were used to evaluate clinical outcomes. The JOA score was increased significantly and VAS and NDI scores were decreased significantly after CDA. The ROM was preserved, stabilizing at 7.8° at the final follow-up. The mean IDH increased significantly from 4.4 ± 2.6 mm to 7.3 ± 1.9 mm after surgery, and remained unchanged thereafter. The mean FSU increased by nearly 4° from the preoperative value to 3.6° ± 4.4° at the 1-year follow-up but failed to maintain lordosis, decreasing to 0.4° ± 4.7° at the last follow-up. The mean COR-x was calculated as 38.9% preoperatively and remained unchanged throughout the follow-up period. The mean COR-y showed a significant cranial shift after surgery, and an upward trend continued in the subsequent measurements (12.7% at 1 year, 15.4% at 3 years, 19.2% at 5 years); however, there was no significant difference between the 1-year and 5-year measurements. Single-level CDA with the Prestige-LP Disc achieved favorable clinical outcomes and provided a durable solution for spinal motion at the instrumented level. The COR showed a significant cranial shift after surgery and remained relatively stable during the 5-year follow-up period.

The Norwegian Cervical Arthroplasty Trial (NORCAT): 2-year clinical outcome after single-level cervical arthroplasty versus fusion\u2014a prospective, single-blinded, randomized, controlled multicenter study

PurposeStandard surgical treatment for symptomatic cervical disc disease has been discectomy and fusion, but the use of arthroplasty, designed to preserve motion, has increased, and most studies report clinical outcome in its favor. Few of these trials, however, blinded the patients. We, therefore, conducted the Norwegian Cervical Arthroplasty Trial, and present 2-year clinical outcome after arthroplasty or fusion.MethodsThis multicenter trial included 136 patients with single-level cervical disc disease. The patients were randomized to arthroplasty or fusion, and blinded to the treatment modality. The surgical team was blinded to randomization until nerve root decompression was completed. Primary outcome was the self-rated Neck Disability Index. Secondary outcomes were the numeric rating scale for pain and quality of life questionnaires Short Form-36 and EuroQol-5Dimension-3 Level.ResultsThere was a significant improvement in the primary and all secondary outcomes from baseline to 2-year follow-up for both arthroplasty and fusion (P < 0.001), and no observed significant between-group differences at any follow-up times. However, linear mixed model analyses, correcting for baseline values, dropouts and missing data, revealed a difference in Neck Disability Index (P = 0.049), and arm pain (P = 0.027) in favor of fusion at 2 years. The duration of surgery was longer (P < 0.001), and the frequency of reoperations higher (P = 0.029) with arthroplasty.ConclusionThe present study showed excellent clinical results and no significant difference between treatments at any scheduled follow-up. However, the rate of index level reoperations was higher and the duration of surgery longer with arthroplasty.Trial registrationhttp://www.clinicaltrials.gov NCT 00735176.19.

Heterotopic ossification and clinical outcome in nonconstrained cervical arthroplasty 2 years after surgery: the Norwegian Cervical Arthroplasty Trial (NORCAT)

Heterotopic ossification is a phenomenon in cervical arthroplasty. Previous reports have mainly focused on various semiconstrained devices and only a few publications have focused on ossification around devices that are nonconstrained. The purpose of this study was to assess the occurrence of heterotopic ossification around a nonconstrained cervical device and how it affects clinical outcome 2years after surgery. Thirty-seven patients were included from a larger cohort of a randomized controlled trial (NORCAT) which compared single-level cervical arthroplasty with fusion. The occurrence of heterotopic ossification was assessed with a CT scan and two neuroradiologists determined its degree. For grading, we used the Mehren/Suchomel classification system (grade 0-4). The patients were divided by level of ossification, low grade (0-2) or high grade (3-4), and clinical outcomes were compared. Self-rated disability for neck and arm pain (Neck Disability Index), health-related quality of life (the Short Form-36 and EuroQol-5D), and pain (the Numeric Rating Scale 11) were used as clinical outcome measures. Heterotopic ossification was encountered in all patients 2years after surgery. Complete fusion (grade 4) was found in 16% of participants, and high-grade ossification (grade 3-4) occurred in 62%. The remaining patients were classified as having low-grade ossification (grade 2). There were no differences in the clinical outcomes of patients with low- and high-grade ossification. High-grade heterotopic ossification and spontaneous fusion 2years after surgery were seen in a significant number of patients. However, the degree of ossification did not influence the clinical outcome.

The effect of deviated center of rotation on flexion-extension range of motion after single-level cervical arthroplasty: an in vivo study.

A retrospective study. To report the clinical outcomes and sagittal kinematics after cervical total disc replacement (TDR). To evaluate the in vivo effect of deviated center of rotation (COR) on flexion-extension range of motion (ROM) at the instrumented level. A few studies showed that the location of COR after cervical TDR deviated from its preoperative location or inherent location in healthy subjects. However, little is known about the effect of deviated COR on ROM at the instrumented level. A total of 24 patients who underwent C5-C6 single-level TDR with Prestige LP (Medtronic Sofamor Danek) were retrospectively included. Japanese Orthopedic Association score and visual analogue scale were used to assess the clinical outcomes. ROM and COR were measured for radiographical analysis. Patients were categorized into 2 groups according to the change of ROM for further evaluation. Group 1, characterized by decreased postoperative ROM, consisted of 16 patients; group 2, characterized by increased postoperative ROM, consisted of 8 patients. Ten males and 14 females comprised the study cohort. The mean age was 45.05 years, and the mean follow-up time was 15.5 months. The Japanese Orthopedic Association score increased significantly and the neck and arm visual analogue scale decreased significantly after cervical TDR. On average, ROM was preserved after cervical TDR. The postoperative COR had a significant cranial shift from its preoperative location. The COR shift in anterior-posterior direction was larger in group 2 than that in group 1. No difference was observed in the COR shift in cranial-caudal direction between the 2 groups. Single-level cervical TDR with Prestige LP obtained satisfactory clinical outcomes and partially restored the natural cervical kinematics. At instrumented level, the deviated COR had a negative correlation with the flexion-extension ROM.

Long-Term Efficacy and Safety of Anterior Cervical Discectomy and Fusion in Single-Level Cervical Disk Disease: 7 Years Follow-up of Food and Drug Administration Investigational Exemption ProDisc-C Study

Introduction ProDisc-C (Synthes Spine USA Products; LLC, West Chester, PA) began its FDA Investigational Device Exemption multicenter randomized study in 2003 and has received marketing approval by the FDA in 2007. This study reports final results of the 7-year follow-up. The aim of this study is to compare long-term efficacy and safety of single-level cervical arthroplasty using ProDisc-C (DePuy-Synthes, Inc) to anterior cervical discectomy and fusion (ACDF) in patients with symptomatic cervical disk disease. Materials and Methods Between August 2003 and January 2005, 209 patients with symptomatic single-level cervical degenerative disk disease refractory to conservative management were enrolled in a prospective, randomized, controlled trial. Of these, 103 received ProDisc-C and 106 ACDF. Patients were followed up for 7 years. The outcomes included Visual Analog Scale for Arm and Neck Pain, Neck Disability Index (NDI), MOS-Short Form 36 (MOS-SF36), neurologic success, adverse events related to the surgery, and secondary surgeries. At the final follow-up at 7 years, the overall follow-up rate was 79.0%. Statistical Analysis Discrepancies between the groups in preoperative demographics and postoperative outcome valuations were analyzed using the Fisher exact test for the categorical variables, and the t-test for the continuous variables. The changes in outcome scores at 2 and 7 years were analyzed using two-way repeated measurements analysis of covariance (ANCOVA) with one fixed factor (“GROUP”) (ACDF and ProDisc-C), one repeated factor (“TIME”) with two levels corresponding to two follow-up times (2 and 7 years), as well as the interaction effect between the GROUP and the TIME factors. Differences in proportions of secondary operations on the index surgical levels were analyzed by Fisher exact test. In the case of multiple secondary surgeries, each subject was counted only once. The time until the secondary surgery was analyzed by Kaplan-Meyer survival estimates, and the differences in survival tested by log-rank test. Results Table 1 shows adjusted means and their confidence intervals by treatment group. All outcomes improved compared with preoperative status in both study arms at 2 years ( p &lt; 0.05), except for the SF36 General Health ( p &gt; 0.05). At 7 years postoperative, the improvements were maintained for the same variables as at 2 years postoperative ( p &lt; 0.05). There were no significant differences between the ACDF and ProDisc-C patients in the extent of the improvement (GROUP effect p &gt; 0.05 for all variables) for any outcome variable. Further, there were no differences in the extent of improvement between 2 and 7 years postoperative (TIME effect p &gt; 0.05) for all outcome variables. Finally, there were no differences in the time course changes by the group at 2 and 7 years (GROUP*TIME interaction p &gt; 0.05) for any outcome variable. Neurological success rate at 2 years was 88.0 and 90.9% in the ACDF and ProDisc-C groups, respectively ( p &gt; 0.05). At 7 years, the success rate was 88.9 and 87.7%, in the ACDF and ProDisc-C groups, respectively ( p &gt; 0.05). At 7 years postoperatively, 11.3% subjects in ProDisc-C group had evidence of bone bridging at index level. Of the 106 subjects in the ACDF group, 16 (15.1%) subjects required a secondary operation at the same level compared with 6 out of 103 (5.8%) in the ProDisk-C group ( p = 0.0410). Of six secondary surgeries in the ProDisc-C group, three were for device removal, one for reoperation, and two for revision. In the ACDF group, there were six removals, one reoperation, nine revisions, and three supplemental fixations. The reoperation-free survival time was better in the Pro-Disc-C compared with ACDF patients (log-rank p = 0.0221). The conditional incidence rate ratio for the secondary surgery was 3.09 (95% CI, 1.27-8.45, p = 0.0112). There were 6 surgeries in 6 subjects that involved adjacent levels in the ProDisc-C group, compared with 22 surgeries in 13 subjects in the ACDF group. The p-value for the subjects with any surgery at the adjacent level was 0.1134 and the p-value for surgery events was 0.0029 Conclusion Both ACDF and cervical arthroplasty with ProDisc-Care associated with significant long-term improvement in relevant symptoms, functional and health-related quality of life outcomes. There is no evidence of differential efficacy between the two treatments. Disc arthroplasty with ProDisc-C is associated with a significantly lower risk of secondary operation at both the index and adjacent surgical levels. Disclosure of Interest M. Janssen: Conflict with Depuy Synthes B. Kopjar: Conflict with Smith &amp; Nephew, Cerapedics, AO Foundation J. Zigler: Conflict with Depuy Synthes J. Spivak: Conflict with Depuy Synthes—Prodisc Teaching, Depuy Synthes—Prodisc Publications Committee Member D. Murrey: Conflict with Amedica, OrthoMedFlex, Stryker

Clinical and radiological follow-up of single-level Prestige LP cervical disc replacement

To evaluate the clinical outcomes and radiographic results of patients who underwent single-level cervical arthroplasty using the Prestige LP. Thirty-one patients with single-level cervical disc disease received the Prestige LP disc replacement from June 2008 to December 2009. The neck disability index (NDI), Japanese Orthopedic Association score (JOA) and visual analogue scale (VAS) were used to assessed clinical outcomes pre-operatively and post-operatively at 24months. The overall cervical alignment (C2-7 Cobb angle), the functional segmental unit (FSU) curvature, the range of motion (ROM) of treated and adjacent levels were measured, and the evidence of heterotopic ossification (HO) was observed from static and dynamic radiographs. There was a statistically significant improvement in the NDI from 20.2±7.5 to 6.4±3.5 (P<0.000), JOA from 12.8±2.2 to 16.6±0.6 (P<0.000), the neck VAS score from 4.1±2.5 to 1.4±1.1 (P<0.000), the arm VAS score from 4.6±2.5 to 0.7±1.1 (P<0.000). The post-operative overall cervical alignment (9.3°±7.2°), ROM of treated level (7.6°) and adjacent level (upper level 9.4°±3.1°, lower level 9.1°±3.5°) are well maintained. The FSU were 0.2°±5.4° and 1.9°±5.5° at pre-operation and final follow-up with statistical significance (P=0.011). Heterotopic ossification was evidenced in five operated segment (16%). The Prestige LP disc arthroplasty maintains favorable clinical outcomes, preserves the overall cervical alignment, FSU curvature, ROM of treated level and adjacent levels.

Uncovertebral hypertrophy is a significant risk factor for the occurrence of heterotopic ossification after cervical disc replacement: survivorship analysis of Bryan disc for single-level cervical arthroplasty

The purpose of this study is to investigate the incidence of heterotopic ossification (HO) in the Bryan cervical arthroplasty group and to identify associations between preoperative factors and the development of HO. We performed a retrospective review of clinical and radiological data on patients who underwent single-level cervical arthroplasty with Bryan prosthesis between January 2005 and September 2007. Patients were postoperatively followed-up at 1, 3, 6, 12 months and every year thereafter. The clinical assessment was conducted using Odom's criteria. The presence of HO was evaluated on the basis of X-ray at each time-point according to the McAfee classification. In this study, we focused on survivorship of Bryan prosthesis for single-level arthroplasty. The occurrence of ROM-affecting HO was defined as a functional failure and was used as an endpoint for determining survivorship. Through the analysis of 19 cases of Bryan disc arthroplasty for cervical radiculopathy and/or myelopathy, we revealed that ROM-affecting HO occurs in as many as 36.8% of cases and found that 37% of patients had ROM-affecting HO within 24 months following surgery. The overall survival time to the occurrence of ROM-affecting HO was 36.4 ± 4.4 months. Survival time of the prosthesis in the patient group without preoperative uncovertebral hypertrophy was significantly longer than that in the patient group with preoperative uncovertebral hypertrophy (47.2 months vs 25.5 months, p = 0.02). Cox regression proportional hazard analysis illustrated that preoperative uncovertebral hypertrophy was determined as a significant risk factor for the occurrence of ROM-affecting HO (hazard ratio = 12.30; 95% confidential interval = 1.10-137.03; p = 0.04). These findings suggest that the condition of the uncovertebral joint must be evaluated in preoperative planning for Bryan cervical arthroplasty.

Differences between soft-disc herniation and spondylosis in cervical arthroplasty: CT-documented heterotopic ossification with minimum 2 years of follow-up

Cervical arthroplasty is a valid option for patients with single-level symptomatic cervical disc diseases causing neural tissue compression, but postoperative heterotopic ossification (HO) can limit the mobility of an artificial disc. In the present study the authors used CT scanning to assess HO formation, and they investigated differences in radiological and clinical outcomes in patients with either a soft-disc herniation or spondylosis who underwent cervical arthroplasty. Medical records, radiographs, and clinical evaluations of consecutive patients who underwent single-level cervical arthroplasty were reviewed. Arthroplasty was performed using the Bryan disc. The patients were divided into a soft-disc herniation group and a spondylosis group. Clinical outcomes were measured using the visual analog scale (VAS) for neck and arm pain and the Neck Disability Index (NDI), whereas HO grading was determined by studying CT scans. Radiological and clinical outcomes were analyzed, and the minimum follow-up duration was 24 months. Forty-seven consecutive patients underwent a single-level cervical arthroplasty. Forty patients (85.1%) had complete radiological evaluations and clinical follow-up of more than 2 years. Patients were divided into 1 of 2 groups: soft-disc herniation (16 cases) and the spondylosis group (24 cases). Their mean age was 45.51 ± 11.12 years. Sixteen patients (40%) were female. Patients in the soft-disc herniation group were younger than those in the spondylosis group, but the difference was not statistically significant (42.88 vs 47.26, p = 0.227). The mean follow-up duration was 38.83 ± 9.74 months. Sex, estimated blood loss, implant size, and perioperative NSAID prescription were not significantly different between the groups (p = 0.792, 0.267, 0.581, and 1.000, respectively). The soft-disc herniation group had significantly less HO formation than the spondylosis group (1 HO [6.25%] vs 14 Hos [58.33%], p = 0.001). Almost all artificial discs in both groups remained mobile (100% and 95.8%, p = 0.408). The clinical outcomes were not significantly different between the groups at all postoperative time points of evaluation, and clinical improvements were also similar. Clinical outcomes of single-level cervical arthroplasty for soft-disc herniation and spondylosis were similar 3 years after surgery. There was a significantly higher rate of HO formation in patients with spondylosis than in those with a soft-disc herniation. The mobility of the artificial disc is maintained, but the long-term effects of HO and its higher frequency in spondylotic cases warrant further investigation.

Sagittal Alignment Comparison of Bryan Disc Arthroplasty With ProDisc-C Arthroplasty

A prospective, randomized study of the radiographic outcomes in patients undergoing single-level cervical arthroplasty with Bryan disc and ProDisc-C prosthesis. The purpose of this trial was to compare the alignment changes of Bryan disc arthroplasty (modified techniques) with ProDisc-C arthroplasty. Aggravation of kyphosis is the known challenge after Bryan disc arthroplasty. Both Bryan disc arthroplasty with modified techniques and ProDisc-C arthroplasty were reported to avoid the postoperative local kyphosis. There have been no studies comparing the alignment changes after Bryan disc arthroplasty with ProDisc-C arthroplasty. We conducted a randomized controlled clinical trial enrolling patients with cervical disc disease. Ultimately 20 patients received Bryan disc arthroplasty with modified surgical techniques and 26 patients received ProDisc-C arthroplasty. Functional spinal unit (FSU) and overall cervical alignment (Cobb angle of C2/7) were compared at final follow-up. (1) FSU angle: the FSU angle was maintained for the Bryan disc group (from 0.8 to 0.6 degrees) without statistical significance; the FSU angle increased 2.9 degrees for the ProDisc-C group (from -0.3 to 2.6 degrees) with statistical significance. (2) Overall alignment: the overall alignments did not change for both Bryan disc and ProDisc-C groups. Bryan disc arthroplasty with modified techniques can maintain the lordosis of FSU, whereas ProDisc-C arthroplasty can restore the lordosis of FSU. For the patients with preoperative FSU kyphosis, ProDisc-C arthroplasty may be a better choice to restore the lordosis.

Radiological changes of the operated and adjacent segments following cervical arthroplasty after a minimum 24-month follow-up: comparison between the Bryan and Prodisc-C devices

The purposes of this retrospective study were to determine the radiological changes at the index and adjacent levels after cervical arthroplasty using the Bryan disc and Prodisc-C disc after a minimum 24 months follow-up, and to demonstrate the possible clinical factors related to these changes. Following single-level cervical arthroplasty using either the Bryan disc or Prodisc-C, the degree of facet degeneration and other radiological changes at the index and adjacent levels were assessed by observing radiographs and CT scans at a minimum 24 months after the operations. These findings were determined in relation to the clinical outcome, various perioperative factors, and prosthesis factors. Thirty-six patients were included in this investigation (19 in the Bryan disc group and 17 in the Prodisc-C group). At the index level, progression of facet arthrosis (PFA) was observed in 7 of 36 levels (1 level with the Bryan disc, 6 with the Prodisc-C). At adjacent levels, PFA was minimally observed. Heterotopic ossification (HO) was observed at 19 levels (11 with the Bryan disc, 8 with Prodisc-C). Progression of facet arthrosis at the index segments was positively related to malposition of the prosthesis on the frontal plane, and decreased postoperative functional spinal unit range of motion at the index level. Occurrence of HO was correlated with the preoperative calcification of the posterior longitudinal ligament at the operated level, regardless of prosthesis type. Clinical outcome and the occurrence of PFA or HO did not show any significant relationship. This study demonstrates that the incidence of PFA at the index level is 19.4% after a minimum 24-month follow-up, and occurs more frequently in the Prodisc-C group. Progression of facet arthrosis is related to less functional spinal unit range of motion and anterior placement of the prosthesis. The occurrence rate of HO is high, regardless of the type of prosthesis, and it is significantly correlated with preoperative calcification of the posterior longitudinal ligament at the operated level.

Superiority of Multilevel Cervical Arthroplasty Outcomes Versus Single-Level Outcomes

Class 2 level of evidence: This is a prospective, consecutive series of 229 prosthetic implantations that were concurrently enrolled between single-level versus multilevel cervical arthroplasty comprising an FDA Pilot Study. This study investigated multilevel cervical disc replacement in relation to single-level cervical arthroplasty to find if the same reduction in clinical success would occur with this alternative treatment. Usually, the clinical outcomes of instrumented cervical fusions deteriorate as the number of vertebral levels of involvement increases. A total of 229 patients presented with cervical herniated nucleus pulposus, cervical spondylosis, and/or adjacent segment disease with cervical radiculopathy or myelopathy. Following anterior cervical neurologic decompression seventy-one patients required porous coated motion (PCM) cervical arthroplasties from C3-C4 to C7-T1 (Group S, single level). Sixty-nine patients underwent 158 multilevel PCM cervical arthroplasties (Group M, multilevel) during the same time interval, for the same indications, performed by the same surgeons under the same clinical protocol: double level, 53 cases; three levels, 12 cases: and 4 levels, 4 cases. The self-assessment outcomes instruments showed significantly more improvement for the multilevel cases. The mean improvement in the NDI for the single cases was 37.6% versus the multilevel cases mean improvement in NDI was 52.6% (P = 0.021). The difference between the two was statistically significant. The mean improvement in the VAS showed the same association: single-level mean improvement 58.4% versus the multilevel cases mean VAS improvement was 65.9%. The Odom's were also more improved for the multilevel versus the single-level group: 93.9% versus 90.5% in the excellent, good, and fair categories. The reoperation rates and serious adverse events were similar between the single-level (S = 3) to the multilevel arthroplasty (M = 2) groups. Kaplan-Meier implant survivorship analysis at 3 years for the cohort of 229 prostheses was 94.5% (confidence interval, 1.00-0.820). This prospective study of cervical arthroplasty is the first report to date showing significantly improved clinical outcomes for multilevel cervical arthroplasty compared with single-level cervical disc replacement using an FDA validated outcome instrument.

Sagittal alignment and the Bryan cervical artificial disc

The authors evaluated cervical spine radiographs to determine sagittal alignment in patients who underwent one- or two-level arthroplasty with the Bryan cervical artificial disc prosthesis. The curvature of the surgically treated spinal segments and the overall curvature of the cervical spine were evaluated in 13 patients who underwent 16 cervical arthroplasty device placements. Preoperative and postoperative lateral radiographs were reviewed and compared using standardized techniques for measuring spinal curvature. Patients who underwent a single-level cervical arthroplasty had a 4.7 degrees mean reduction (p < 0.05) in lordosis after cervical artificial disc replacement. The three patients who underwent two-level cervical arthroplasty had no significant changes in the sagittal alignment. Patients who underwent arthroplasty with a Bryan cervical artificial disc had a focal loss of lordosis (that is, kyphosis) at the treated levels after single-level procedures. Nevertheless, there was no significant change in the overall sagittal curvature of the cervical spine after single-level artificial disc replacements. The patients who underwent two-level artificial disc placement had no significant changes in lordosis at the treated levels or in the overall curvature. The likely source of this outcome appears to be the endplate milling procedures that reorient the vertebral endplates.

Two-level artificial disc placement for spondylotic cervical myelopathy

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