Anterior approaches to fusion of the cervical spine: a metaanalysis of fusion rates

Methodology and reporting of meta-analyses in the neurosurgical literature

OBJECT

Neurosurgeons are inundated with vast amounts of new clinical research on a daily basis, making it difficult and time-consuming to keep up with the latest literature. Meta-analysis is an extension of a systematic review that employs statistical techniques to pool the data from the literature in order to calculate a cumulative effect size. This is done to answer a clearly defined a priori question. Despite their increasing popularity in the neurosurgery literature, meta-analyses have not been scrutinized in terms of reporting and methodology.

METHODS

The authors performed a literature search using PubMed/MEDLINE to locate all meta-analyses that have been published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Accepted checklists for reporting (PRISMA) and methodology (AMSTAR) were applied to each meta-analysis, and the number of items within each checklist that were satisfactorily fulfilled was recorded. The authors sought to answer 4 specific questions: Are meta-analyses improving 1) with time; 2) when the study met their definition of a meta-analysis; 3) when clinicians collaborated with a potential expert in meta-analysis; and 4) when the meta-analysis was the only focus of the paper?

RESULTS

Seventy-two meta-analyses were published in the JNS Publishing Group journals and Neurosurgery between 1990 and 2012. The number of published meta-analyses has increased dramatically in the last several years. The most common topics were vascular, and most were based on observational studies. Only 11 papers were prepared using an established checklist. The average AMSTAR and PRISMA scores (proportion of items satisfactorily fulfilled divided by the total number of eligible items in the respective instrument) were 31% and 55%, respectively. Major deficiencies were identified, including the lack of a comprehensive search strategy, study selection and data extraction, assessment of heterogeneity, publication bias, and study quality. Almost one-third of the papers did not meet our basic definition of a meta-analysis. The quality of reporting and methodology was better 1) when the study met our definition of a meta-analysis; 2) when one or more of the authors had experience or expertise in conducting a meta-analysis; 3) when the meta-analysis was not conducted alongside an evaluation of the authors' own data; and 4) in more recent studies.

CONCLUSIONS

Reporting and methodology of meta-analyses in the neurosurgery literature is excessively variable and overall poor. As these papers are being published with increasing frequency, neurosurgical journals need to adopt a clear definition of a meta-analysis and insist that they be created using checklists for both reporting and methodology. Standardization will ensure high-quality publications.

Early Morbidity of Multilevel Anterior Cervical Discectomy and Fusion with Plating for Spondylosis: Does the Number of Levels Influence Early Complications? A Single Surgeon's Experience in 519 Consecutive Patients

Study Design This is a retrospective review of a prospectively maintained database of anterior cervical discectomy and fusion with plating (ACDFP) cases. Objective The aim of this study is to evaluate within a clinical practice evidence-based results of short-term morbidity with multilevel ACDFP. Methods Clinical morbidity, length of hospital stay, visual analog scale (VAS) and Odom scores, Neck Disability Index (NDI), hardware failure, and return-to-work (RTW) status were prospectively collected in an electronic database for 678 patients who underwent 1-, 2-, 3-, or 4-level ACDFP during an 8-year period. A total of 519 patients met the study criteria and were retrospectively analyzed. Results The majority of all patients noted "Excellent" or "Good" status for 1 month (91%), 2 months (92%), and 3 months (96%). Patients with 1-, 2-, and 3-level ACDFP returned to work sooner, 60% at 1 month, 70% at 2 months, and 68% at 3 months. For 4-level patients, the majority did not RTW until 3 months (71%). The only significant increase in morbidity with increasing levels was hospital stay for 3- and 4-level ACDFP and RTW for 4-level ACDFP. Conclusion Multilevel ACDFP can be performed with low initial morbidity. An individual practice can review results to allow for ongoing evidence-based care. [Table: see text].

Biomechanics of an integrated interbody device versus ACDF anterior locking plate in a single-level cervical spine fusion construct

BACKGROUND CONTEXT

No profile, integrated interbody cages are designed to act as implants for cervical spine fusion, which obviates the need for additional internal fixation, combining the functionality of an interbody device and the stabilizing benefits of an anterior cervical plate. Biomechanical data are needed to determine if integrated interbody constructs afford similar stability to anterior plating in single-level cervical spine fusion constructs.

PURPOSE

The purpose of this study was to biomechanically quantify the acute stabilizing effect conferred by a single low-profile device design with three integrated screws ("anchored cage"), and compare the range of motion reductions to those conferred by a standard four-hole rigid anterior plate following instrumentation at the C5-C6 level. We hypothesized that the anchored cage would confer comparable postoperative segmental rigidity to the cage and anterior plate construct.

STUDY DESIGN

Biomechanical laboratory study of human cadaveric spines.

METHODS

Seven human cadaveric cervical spines (C3-C7) were biomechanically evaluated using a nondestructive, nonconstraining, pure-moment loading protocol with loads applied in flexion, extension, lateral bending (right+left), and axial rotation (left+right) for the intact and instrumented conditions. Range of motion (ROM) at the instrumented level was the primary biomechanical outcome. Spines were loaded quasi-statically up to 1.5 N-m in 0.5 N-m increments and ROM at the C5-C6 index level was recorded. Each specimen was tested in the following conditions: 1. Intact 2. Discectomy+anchored cage (STA) 3. Anchored cage (screws removed)+anterior locking plate (ALP) 4. Anchored cage only, without screws or plates (CO) RESULTS: ROM at the C5-C6 level was not statistically different in any motion plane between the STA and ALP treatment conditions (p>.407). STA demonstrated significant reductions in flexion/extension, lateral bending, and axial rotation ROM when compared with the CO condition (p<.022).

CONCLUSIONS

In this in vitro biomechanical study, the anchored cage with three integrated screws afforded biomechanical stability comparable to that of the standard interbody cage+anterior plate cervical spine fusion approach. Due to its low profile design, this anchored cage device may avoid morbidities associated with standard anterior plating, such as dysphagia.

Two-level total disc replacement with Mobi-C(r) over 3-years

Objective: To evaluate the safety and effectiveness of two-level total disc replacement (TDR) using a Mobi-C(r) Cervical Artificial Disc at the 36 month follow-up. Methods: a Prospective, randomized, controlled, multicenter clinical trial of an artificial cervical disc (Mobi-C(r) Cervical Artificial Disc) was conducted under the Investigational Device Exemptions (IDE) and the U.S. Food & Drug Administration (FDA) regulations. A total of 339 patients with degenerative disc disease were enrolled to receive either two-level treatment with TDR, or a two-level anterior cervical discectomy and fusion (ACDF) as control. The 234 TDR patients and 105 ACDF patients were followed up at regular time points for three years after surgery. Results: At 36 months, both groups demonstrated an improvement in clinical outcome measures and a comparable safety profile. NDI scores, SF-12 PCS scores, patient satisfaction, and overall success indicated greater statistically significant improvement from baseline for the TDR group, in comparison to the ACDF group. The TDR patients experienced lower subsequent surgery rates and a lower rate of adjacent segment degeneration. On average, the TDR patients maintained segmental range of motion through 36 months with no device failure. Conclusion: Results at three-years support TDR as a safe, effective and statistically superior alternative to ACDF for the treatment of degenerative disc disease at two contiguous cervical levels.

Biomechanical comparison of a two-level anterior discectomy and a one-level corpectomy, combined with fusion and anterior plate reconstruction in the cervical spine

BACKGROUND

Common fusion techniques for cervical degenerative diseases include two-level anterior discectomy and fusion and one-level corpectomy and fusion. The aim of the study was to compare via in-vitro biomechanical testing the effects of a two-level anterior discectomy and fusion and a one-level corpectomy and fusion, with anterior plate reconstruction.

METHODS

Seven fresh frozen human cadaveric spines (C3-T1) were dissected from posterior musculature, preserving the integrity of ligaments and intervertebral discs. Initial biomechanical testing consisted of no-axial preload and 2Nm in flexion-extension, lateral bending and axial rotation. Thereafter, discectomies were performed at C4-5 and C5-6 levels, then two interbody cages and an anterior C4-C5-C6 plate was implanted. The flexibility tests were repeated and followed by C5 corpectomy and C4-C6 plate reconstruction. Biomechanical testing was performed again and statistical comparisons among the means of range of motion and axial rotation energy loss were investigated.

FINDINGS

The two-level cage-plate construct had significantly lower range of motion than the one-level corpectomy-plate construct (P≤0.03). Axial rotation energy loss was significantly (P≤0.03) greater for the corpectomy-plate construct than for the two-level cage-plate construct and the intact condition.

INTERPRETATION

A two-level cage-plate construct provides greater stability in flexion, extension and lateral bending motions when compared to a one-level corpectomy-plate construct. A two-level cage-plate is more likely to maintain axial balance by reducing the energy lost in axial rotation.

Differences between arthroplasty and anterior cervical fusion in two-level cervical degenerative disc disease

PURPOSE

Although arthroplasty is an accepted option for two-level disease, there is a paucity of data regarding outcomes of two-level cervical arthroplasty. The current study was designed to determine differences between two-level cervical arthroplasty and anterior fusion.

METHODS

Seventy-seven consecutive patients who underwent two-level anterior cervical operations for degenerative disc disease were divided into the arthroplasty (37 patients) and fusion (40 patients) groups. Clinical outcomes were measured by Visual Analogue Scale (VAS) of neck and arm pain, Japanese Orthopedic Association (JOA) scores, and Neck Disability Index (NDI). Every patient was evaluated by radiography and computed tomography for fusion or detection of heterotopic ossification.

RESULTS

Thirty-seven patients (with 74 levels of Bryan discs) were compared with 40 patients who had two-level anterior fusion (mean follow-up of 39.6 ± 6.7 months). There was no difference in sex, but the mean age of the arthroplasty group was significantly younger (52.1 ± 9.1 vs. 63.0 ± 10.6 years, p < 0.001). The mean estimated blood loss was similar (p = 0.135), but the mean operation time was longer in the arthroplasty group (315.5 ± 82.0 versus 224.9 ± 61.8 min, p < 0.001). At 24 months post-operation, the arthroplasty group had increased their range of motion than pre-operation (23.5° versus 20.1°, p = 0.018). There were significant improvements in neck or arm VAS, JOA scores, and NDI in both groups. However, there were no differences in clinical outcomes or adverse events between the two groups.

CONCLUSIONS

Clinical outcomes of two-level arthroplasty and anterior cervical fusion are similar 39.6 months after surgery. Cervical arthroplasty preserves mobility at the index levels without increased adverse effects.

Zero-P: a new zero-profile cage-plate device for single and multilevel ACDF. A single institution series with four years maximum follow-up and review of the literature on zero-profile devices

PURPOSE

To analyze the prospectively collected data in a series of patients treated with single- or multilevel ACDF with a stand-alone, zero-profile device, focusing on clinico-radiological outcome, complications and technical hints, and to review the literature on such new devices.

METHODS

Eighty-five patients harboring symptomatic DDD underwent ACDF with the Zero-P cage-plate: 29 at 1-level and 56 at 2-4 levels (total 162 devices). In the multilevel group, 9 patients received a combination of Zero-P and stand-alone cages (hybrid implants). This study focuses on 32 patients with follow-up ranging from 20 to 48 months. NDI, SF-36 and arm pain VAS scores were registered preoperatively and at follow-up visits. Dysphagia was assessed using the Bazaz score. Imaging included X-rays, CT and MRI, also to assess the presence of vertebral body fractures in multilevel cases. Paired Student t test was used for statistical analysis.

RESULTS

SF-36 and NDI showed a statistically significant improvement (p < 0.01) and mean arm pain VAS score decreased from 79 to 41. X-rays and CT demonstrated, respectively, a 94.5 % and a 92 % fusion rate. Three patients complained of moderate and two of mild transient dysphagia (15.5 %). No device-related complications occurred and no fractures, secondary to four screws insertion in one vertebral body (i.e., swiss cheese effect), were detected in multilevel cases. In patients with extensive anterior osteophytes only a "focal spondylectomy" was required.

CONCLUSION

The Zero-P device is safe and efficient, even in multilevel cases. Dysphagia is minimal, extensive anterior osteophytectomy is unnecessary and technical hints may ease the surgical workflow. This is the largest series, with the longest follow-up, reported.

Does smoking have an impact on fusion rate in single-level anterior cervical discectomy and fusion with allograft and rigid plate fixation?

Object

Although smoking has been shown to negatively affect fusion rates in patients undergoing multilevel fusions of the cervical and lumbar spine, the effect of smoking on fusion rates in patients undergoing single-level anterior cervical discectomy and fusion (ACDF) with allograft and plate fixation has yet to be thoroughly investigated. The objective of the present study was to address the effect of smoking on fusion rates in patients undergoing a 1-level ACDF with allograft and a locked anterior cervical plate.

Methods

This study is composed of patients from the control groups of 5 separate studies evaluating the use of an anterior cervical disc replacement to treat cervical radiculopathy. For each of the 5 studies the control group consisted of patients who underwent a 1-level ACDF with allograft and a locked cervical plate. The authors of the present study reviewed data obtained in a total of 573 patients; 156 patients were smokers and 417 were nonsmokers. A minimum follow-up period of 24 months was required for inclusion in this study. Fusion status was assessed by independent observers using lateral, neutral, and flexion/extension radiographs.

Results

An overall fusion rate of 91.4% was achieved in all 573 patients. A solid fusion was shown in 382 patients (91.6%) who were nonsmokers. Among patients who were smokers, 142 (91.0%) had radiographic evidence of a solid fusion. A 2-tailed Fisher exact test revealed a p value of 0.867, indicating no difference in the union rates between smokers and nonsmokers.

Conclusions

The authors found no statistically significant difference in fusion status between smokers and nonsmokers who underwent a single-level ACDF with allograft and a locked anterior cervical plate. Although the authors do not promote tobacco use, it appears that the use of allograft with a locked cervical plate in single-level ACDF among smokers produces similar fusion rates as it does in their nonsmoking counterparts.

Anterior corpectomy versus posterior laminoplasty for multilevel cervical myelopathy: a systematic review and meta-analysis

BACKGROUND

Surgical strategy for multilevel cervical myelopathy resulting from cervical spondylotic myelopathy (CSM) or ossification of posterior longitudinal ligament (OPLL) still remains controversial. There are still questions about the relative benefit and safety of direct decompression by anterior corpectomy (CORP) versus indirect decompression by posterior laminoplasty (LAMP).

OBJECTIVE

To perform a systematic review and meta-analysis evaluating the results of anterior CORP compared with posterior LAMP for patients with multilevel cervical myelopathy.

METHODS

Systematic review and meta-analysis of cohort studies comparing anterior CORP with posterior LAMP for the treatment of multilevel cervical myelopathy due to CSM or OPLL from 1990 to December 2012. An extensive search of literature was performed in Pubmed, Embase, and the Cochrane library. The quality of the studies was assessed according to GRADE. The following outcome measures were extracted: pre- and postoperative Japanese orthopedic association (JOA) score, neurological recovery rate (RR), surgical complications, reoperation rate, operation time and blood loss. Two reviewers independently assessed each study for quality and extracted data. Subgroup analysis was conducted according to the mean number of surgical segments.

RESULTS

A total of 12 studies were included in this review, all of which were prospective or retrospective cohort studies with relatively low quality. The results indicated that the mean JOA score system for cervical myelopathy and the neurological RR in the CORP group were superior to those in the LAMP group when the mean surgical segments were <3, but were similar between the two groups in the case of the mean surgical segments equal to 3 or more. There was no statistical difference in the surgical complication rate between the two groups when the mean surgical segments <3, but were significantly higher incidences of surgical complications and complication-related reoperation in the CORP group compared with the LAMP group in the case of the mean surgical segments equal to 3 or more. Besides, the operation time in the CORP group was longer than that in the LAMP group, and the average blood loss was significantly more in the CORP group compared with the LAMP group.

CONCLUSION

Based on the results above, anterior CORP and fusion is recommended for the treatment of multilevel cervical myelopathy when the involved surgical segments were <3. Given the higher rates of surgical complications and complication-related reoperation and the higher surgical trauma associated with multilevel CORP, however, it is suggested that posterior LAMP may be the preferred method of treatment for multilevel cervical myelopathy when the involved surgical segments were equal to 3 or more. In addition, taking the limitations of this study into consideration, it was still not appropriate to draw a strong conclusion claiming superiority for CORP or LAMP. A well-designed, prospective, randomized controlled trial is necessary to provide objective data on the clinical results of both procedures.

Cost-effectiveness analysis: comparing single-level cervical disc replacement and single-level anterior cervical discectomy and fusion: clinical article

OBJECT

In recent years, there has been increased interest in the use of cervical disc replacement (CDR) as an alternative to anterior cervical discectomy and fusion (ACDF). While ACDF is a proven intervention for patients with myelopathy or radiculopathy, it does have inherent limitations. Cervical disc replacement was designed to preserve motion, avoid the limitations of fusion, and theoretically allow for a quicker return to activity. A number of recently published systematic reviews and randomized controlled trials have demonstrated positive clinical results for CDR, but no studies have revealed which of the 2 treatment strategies is more cost-effective. The purpose of this study was to evaluate the cost-effectiveness of CDR and ACDF by using the power of decision analysis. Additionally, the authors aimed to identify the most critical factors affecting procedural cost and effectiveness and to define thresholds for durability and function to focus and guide future research.

METHODS

The authors created a surgical decision model for the treatment of single-level cervical disc disease with associated radiculopathy. The literature was reviewed to identify possible outcomes and their likelihood following CDR and ACDF. Health state utility factors were determined from the literature and assigned to each possible outcome, and procedural effectiveness was expressed in units of quality-adjusted life years (QALYs). Using ICD-9 procedure codes and data from the Nationwide Inpatient Sample, the authors calculated the median cost of hospitalization by multiplying hospital charges by the hospital-specific cost-to-charge ratio. Gross physician costs were determined from the mean Medicare reimbursement for each current procedural terminology (CPT) code. Uncertainty as regards both cost and effectiveness numbers was assessed using sensitivity analysis.

RESULTS

In the reference case, the model assumed a 20-year duration for the CDR prosthesis. Cervical disc replacement led to higher average QALYs gained at a lower cost to society if both strategies survived for 20 years ($3042/QALY for CDR vs $8760/QALY for ACDF). Sensitivity analysis revealed that CDR needed to survive at least 9.75 years to be considered a more cost-effective strategy than ACDF. Cervical disc replacement becomes an acceptable societal strategy as the prosthesis survival time approaches 11 years and the $50,000/QALY gained willingness-to-pay threshold is crossed. Sensitivity analysis also indicated that CDR must provide a utility state of at least 0.796 to be cost-effective.

CONCLUSIONS

Both CDR and ACDF were shown to be cost-effective procedures in the reference case. Results of the sensitivity analysis indicated that CDR must remain functional for at least 14 years to establish greater cost-effectiveness than ACDF. Since the current literature has yet to demonstrate with certainty the actual durability and long-term functionality of CDR, future long-term studies are required to validate the present analysis.

Cervical total disc replacement with the Mobi-C cervical artificial disc compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled multicenter clinical trial: clinical article

OBJECT

Cervical total disc replacement (TDR) is intended to treat neurological symptoms and neck pain associated with degeneration of intervertebral discs in the cervical spine. Anterior cervical discectomy and fusion (ACDF) has been the standard treatment for these indications since the procedure was first developed in the 1950s. While TDR has been shown to be a safe and effective alternative to ACDF for treatment of patients with degenerative disc disease (DDD) at a single level of the cervical spine, few studies have focused on the safety and efficacy of TDR for treatment of 2 levels of the cervical spine. The primary objective of this study was to rigorously compare the Mobi-C cervical artificial disc to ACDF for treatment of cervical DDD at 2 contiguous levels of the cervical spine.

METHODS

This study was a prospective, randomized, US FDA investigational device exemption pivotal trial of the Mobi-C cervical artificial disc conducted at 24 centers in the US. The primary clinical outcome was a composite measure of study success at 24 months. The comparative control treatment was ACDF using allograft bone and an anterior plate. A total of 330 patients were enrolled, randomized, and received study surgery. All patients were diagnosed with intractable symptomatic cervical DDD at 2 contiguous levels of the cervical spine between C-3 and C-7. Patients were randomized in a 2:1 ratio (TDR patients to ACDF patients).

RESULTS

A total of 225 patients received the Mobi-C TDR device and 105 patients received ACDF. At 24 months only 3.0% of patients were lost to follow-up. On average, patients in both groups showed significant improvements in Neck Disability Index (NDI) score, visual analog scale (VAS) neck pain score, and VAS arm pain score from preoperative baseline to each time point. However, the TDR patients experienced significantly greater improvement than ACDF patients in NDI score at all time points and significantly greater improvement in VAS neck pain score at 6 weeks, and at 3, 6, and 12 months postoperatively. On average, patients in the TDR group also maintained preoperative segmental range of motion at both treated segments immediately postoperatively and throughout the study period of 24 months. The reoperation rate was significantly higher in the ACDF group at 11.4% compared with 3.1% for the TDR group. Furthermore, at 24 months TDR demonstrated statistical superiority over ACDF based on overall study success rates.

CONCLUSIONS

The results of this study represent the first available Level I clinical evidence in support of cervical arthroplasty at 2 contiguous levels of the cervical spine using the Mobi-C cervical artificial disc. These results continue to support the use of cervical arthroplasty in general, but specifically demonstrate the advantages of 2-level arthroplasty over 2-level ACDF. Clinical trial registration no.: NCT00389597 (ClinicalTrials.gov).

Autologous iliac bone graft with anterior plating is advantageous over the stand-alone cage for segmental lordosis in single-level cervical disc disease

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) with autologous iliac bone graft and plating has been a standard surgical method for single-level cervical disc disease. The stand-alone cage was introduced to reduce graft-related morbidity. However, problems due to focal kyphosis at the operated level have been on the rise. It has been difficult to derive a conclusive answer from previous studies for the indications of each method.

OBJECTIVE

An interim analysis of a prospective randomized study was performed to compare the sagittal alignment between a stand-alone cage (ACDF cage) and autologous iliac bone graft and plating (ACDF plate).

METHODS

Twenty-nine patients were allocated to the ACDF-cage group (M:F = 17:12) and 23 to the ACDF-plate group (M:F = 14:9). Cobb angles at the operated segment (segmental angle, SA; lordosis vs kyphosis) were compared at postoperative 12 months and the other confounding factors were explored.

RESULTS

Demographic features were not different between groups. The fusion method significantly affected segmental alignment at 12 months (P = .03; odds ratio, 5.52). Preoperatively, the SA was not different between the groups (P = .18) and was similar (P = .22) immediately following the operation. However, the SA was significantly more lordotic (P < .05) in the ACDF-plate group at postoperative 12 months in comparison with the ACDF-cage group. There was no other significant risk factor for segmental kyphosis.

CONCLUSION

The stand-alone cage and autologous bone graft with plating had similar clinical outcomes, but stand-alone cage fusion may be disadvantageous from a radiological viewpoint.

Anterior approach versus posterior approach for the treatment of multilevel cervical spondylotic myelopathy: a systemic review and meta-analysis

PURPOSE

To compare the clinical outcomes, complications, and surgical trauma between anterior and posterior approaches for the treatment of multilevel cervical spondylotic myelopathy.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases for randomized controlled trials or non-randomized controlled trials that compared anterior and posterior surgical approaches for the treatment of multilevel cervical spondylotic myelopathy. Exclusion criteria were non-controlled studies, combined anterior and posterior surgery, follow-up <1 year, cervical kyphosis >15°, and cervical myelopathy caused by ossification of the posterior longitudinal ligament. The main end points included: recovery rate; Japanese Orthopedic Association (JOA) score; reoperation rate; complication rate; blood loss; and operation time. Subgroup analysis was conducted according to the mean number of surgical segments.

RESULT

A total of eight studies were included in the meta-analysis; none of which were randomized controlled trials. All of the selected studies were of high quality as indicated by the Newcastle-Ottawa scale. In five studies involving 351 patients, the preoperative JOA score was similar between the anterior and posterior groups [P > 0.05, WMD: -0.00 (-0.56, 0.56)]. In four studies involving 268 patients, the postoperative JOA score was higher in the anterior group compared with the posterior group [P < 0.05, WMD: 0.79 (0.16, 1.42)]. For recovery rate, there was significant heterogeneity among the four studies involving 304 patients, hence, only descriptive analysis was performed. In seven studies involving 447 patients, the postoperative complication rate was significant higher in the anterior group compared with the posterior group [P < 0.05, odds ratio: 2.60 (1.63, 4.15)]. Of the 245 patients in the 8 studies who received anterior surgery, 21 (8.57%) received reoperation. Of the 285 patients who received posterior surgery, only 1 (0.3%) received reoperation. The reoperation rate was significantly higher in the anterior group compared with the posterior group (P < 0.001). In the 3 studies involving 236 patients compared subtotal corpectomy and laminoplasty/laminectomy, blood loss and operation time were significantly higher in the anterior subtotal corpectomy group compared with the posterior laminoplasty/laminectomy group [P < 0.05, WMD: 150.10 (63.53, 236.66) and P < 0.05, WMD: 59.17 (45.69, 72.66)].

CONCLUSION

The anterior approach was associated with better postoperative neural function than the posterior approach in the treatment of multilevel cervical spondylotic myelopathy. There was no apparent difference in the neural function recovery rate. The complication and reoperation rates were significantly higher in the anterior group compared with the posterior group. The surgical trauma associated with corpectomy was significantly higher than that associated with laminoplasty/laminectomy.

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

OBJECTIVE

To evaluate the clinical outcomes and radiographic results of patients who underwent single-level cervical arthroplasty using the Prestige LP.

METHOD

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 24 months. 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.

RESULTS

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 %).

CONCLUSIONS

The Prestige LP disc arthroplasty maintains favorable clinical outcomes, preserves the overall cervical alignment, FSU curvature, ROM of treated level and adjacent levels.

The use of a zero-profile device compared with an anterior plate and cage in the treatment of patients with symptomatic cervical spondylosis

In a retrospective cohort study we compared the clinical outcome and complications, including dysphagia, following anterior cervical fusion for the treatment of cervical spondylosis using either a zero-profile (Zero-P; Synthes) implant or an anterior cervical plate and cage. A total of 83 patients underwent fusion using a Zero-P and 107 patients underwent fusion using a plate and cage. The mean follow-up was 18.6 months (sd 4.2) in the Zero-P group and 19.3 months (sd 4.1) in the plate and cage group. All patients in both groups had significant symptomatic and neurological improvement. There were no significant differences between the groups in the Neck Disability Index (NDI) and visual analogue scores at final follow-up. The cervical alignment improved in both groups. There was a higher incidence of dysphagia in the plate and cage group on the day after surgery and at two months post-operatively. All patients achieved fusion and no graft migration or nonunion was observed.

When compared with the traditional anterior cervical plate and cage, the Zero-P implant is a safe and convenient procedure giving good results in patients with symptomatic cervical spondylosis with a reduced incidence of dysphagia post-operatively.

Cite this article: Bone Joint J 2013;95-B:543–7.

Late results of anterior cervical discectomy and fusion with interbody cages

STUDY DESIGN

Retrospective analysis.

PURPOSE

To evaluate the effectiveness of anterior cervical discectomy with fusion for degenerative cervical disc disease.

OVERVIEW OF LITERATURE

Anterior spinal surgery originated in the mid-1950s and graft for fusion was also employed. Currently anterior cervical microdiscectomy and fusion with an intervertebral cage is a widely accepted procedure for treatment of cervical disc hernia. Artificial grafts and cages for fusion are preferred because of their lower morbidity, reduced operating time and acceptable fusion rate.

METHODS

The study involved retrospective analysis and investigation of long-term results for 41 consecutive patients who had undergone anterior cervical discectomy and fusion with an intervertebral cage for cervical disc hernia. The angle of lordosis, segmental height and range of motion were evaluated preoperatively and postoperatively at 1 month and 2 years. The clinical outcome was assessed by the visual analog scale and Odom's criteria.

RESULTS

The angle of lordosis increased by 2.62° and the range of motion angle increased by 5.14° after the operation. The segmental height did not change. The visual analog scale and Odom's criteria scores decreased significantly after the operation.

CONCLUSIONS

Using a cage in anterior cervical discectomy prevents segmental collapse, so the segmental height and the angle of lordosis are preserved and newly-developed pain does not occur.

Cervical intervertebral disc replacement

Symptomatic adjacent-level disease after cervical fusion has led to the development and testing of several disc-replacement prostheses. Randomized controlled trials of cervical disc replacement (CDR) compared with anterior cervical discectomy and fusion (ACDF) have demonstrated at least equivalent clinical results for CDR with similar or lower complication rates. Biomechanical, kinematic, and radiographic studies of CDR reveal that the surgical level and adjacent vertebral level motion and center of rotation more closely mimic the native state. Lower intradiscal pressures adjacent to CDR may help decrease the incidence of adjacent spinal-level disease, but long-term follow-up is necessary to evaluate this theory.

A meta-analysis of cervical arthroplasty compared to anterior cervical discectomy and fusion for single-level cervical disc disease

There is no consensus on whether anterior cervical arthroplasty or anterior cervical discectomy and fusion (ACDF) is the optimal treatment for single-level cervical radiculopathy or myelopathy. We conducted a meta-analysis of randomized controlled trials to compare the safety and efficacy of anterior cervical arthroplasty with ACDF. Eight studies met the inclusion criteria. Overall, there were significant differences between these two treatment approaches in the arm visual analog scale (VAS) scores [mean difference (MD)=-4.86, 95% confidence interval (CI)=-6.42 to -3.30], neck VAS scores (MD=-7.90, 95% CI=-10.36 to -5.44), overall success rate [odds ratio (OR)=1.84, 95% CI=1.43 to 2.36], neurological success rate (OR=1.75, 95% CI=1.20 to 2.55), and incidence of reoperation [risk ratio (RR)=0.50, 95% CI=0.26 to 0.97]. However, there were no significant differences in the neck disability index (NDI) scores (MD=-3.81, 95% CI=-8.12 to 0.51), number of adverse events (RR=0.77, 95% CI=0.48 to 1.23), or radiological success rate (OR=0.87, 95% CI=0.36 to 2.09). Based on this meta-analysis, cervical arthroplasty is a safe and effective surgical procedure for treating single-level cervical radiculopathy or myelopathy.

Biphasic calcium phosphate contained within a polyetheretherketone cage with and without plating for anterior cervical discectomy and fusion

OBJECTIVE

To evaluate the properties of a combination bone graft consisting of biphasic calcium phosphate ceramic, polyetheretherketone (PEEK) cage in one- and two-level surgery.

METHODS

Over a 12-month time period, a prospective single surgeon series of 75 patients were included in the study and 58 patients selected based on adequate data points. From these 58 patients, 32 were supplemented with anterior plate fixation and 26 patients without plating. Duration of clinical follow-up was a mean of 12.4 months (range, 6-26 months) in the Plated Group and 10.5 months (range, 6-21 months) in the Non-Plated Group.

RESULTS

A 100% fusion rate with nil graft related complications was achieved in the Plated group compared with 96.2% fusion and 11.5% subsidence rates reported in the Non-Plated group. Patients in both groups experienced statistically significant improvement in pain and functional outcomes compared to their pre-operative status; however, there was no significant difference in outcome between the Plated and Non-Plated Groups.

CONCLUSIONS

Biphasic calcium phosphate ceramic contained within a PEEK cage is an effective implant for use in anterior cervical surgery with high fusion rates and good clinical outcome.

Prospective randomized study of cervical arthroplasty and anterior cervical discectomy and fusion with long-term follow-up: results in 74 patients from a single site

Object

The purpose of this study was to evaluate the long-term results of cervical total disc replacement (TDR) and anterior cervical discectomy and fusion (ACDF) in the treatment of single-level cervical radiculopathy.

Methods

The results of 2 separate prospective, randomized, US FDA Investigational Device Exemption pivotal trials (Bryan Disc and Kineflex|C) from a single investigational site were combined to evaluate outcomes at long-term follow-up. The primary clinical outcome measures included the Neck Disability Index (NDI), visual analog scale (VAS), and neurological examination. Patients were randomized to receive cervical TDR in 2 separate prospective, randomized studies using the Bryan Disc or Kineflex|C cervical artificial disc compared with ACDF using structural allograft and an anterior plate. Patients were evaluated preoperatively; at 6 weeks; at 3, 6, and 12 months; and then yearly for a minimum of 48 months. Plain radiographs were obtained at each study visit.

Results

A total of 74 patients were enrolled and randomly assigned to either the cervical TDR (n = 41) or ACDF (n = 33) group. A total of 63 patients (86%) completed a minimum of 4 years follow-up. Average follow-up was 6 years (72 months) with a range from 48 to 108 months. In both the cervical TDR and ACDF groups, mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the minimum 48-month follow-up (p < 0.001). Similarly, the median VAS pain scores improved significantly by 6 weeks and remained significantly improved throughout the minimum 48-month follow-up (p < 0.001). There were no significant differences between groups in mean NDI or median VAS scores. The range of motion (ROM) in the cervical TDR group remained significantly greater than the preoperative mean, whereas the ROM in the ACDF group was significantly reduced from the preoperative mean. There was significantly greater ROM in the cervical TDR group compared with the ACDF group. There were 3 reoperations (7.3%) at index or adjacent levels in the cervical TDR group; all were cervical laminoforaminotomies. There were 2 adjacent-level reoperations in the cervical TDR group (4.9%). There was 1 reoperation (3.0%) in the ACDF group at an index or adjacent level (a second ACDF at the adjacent level). There was no statistically significant difference in overall reoperation rate or adjacent-level reoperation rate between groups.

Conclusions

Both cervical TDR and ACDF groups showed excellent clinical outcomes that were maintained over long-term follow-up. Both groups showed low index-level and adjacent-level reoperation rates. Both cervical TDR and ACDF appear to be viable options for the treatment of single-level cervical radiculopathy.

Multilevel arthroplasty for cervical spondylosis: more heterotopic ossification at 3 years of follow-up

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To investigate the differences between single- and multilevel degenerative disc diseases (DDDs) treated with cervical arthroplasty.

SUMMARY OF BACKGROUND DATA

The US Food and Drug Administration clinical trials compared arthroplasty with anterior cervical discectomy and fusion for single-level DDD. However, cervical arthroplasty for multilevel DDD is rarely addressed in the literature.

METHODS

A total of 102 consecutive patients who underwent Bryan arthroplasty were divided into either a single- or multilevel group. Clinical outcomes were measured by the visual analogue scale (VAS) of neck and arm, and by the neck disability index with a minimum follow-up of 25 months. Every patient had radiographical evaluations, and computed tomography.

RESULTS

Eighty-six patients (84.3%) completed the follow-up with a mean time of 38.3 ± 8.7 months. Postoperatively, there were significant improvements in clinical outcomes (i.e., VAS neck, VAS arm, and neck disability index) at each time point of evaluation (i.e., 3-, 6-, 12-, and 24 mo postoperation). The sex composition and clinical outcome improvements between the single- and multilevel groups were not significantly different. The multilevel group was older (51.3 ± 8.6 vs. 46.3 ± 11.2 yr; P = 0.02), had more intraoperative blood loss (218.0 ± 182.4 vs. 102.8 ± 79.2 mL; P = 0.001), and demonstrated a higher rate of heterotopic ossification (HO) than the single-level group (66.0% vs. 25.0%; P < 0.001). The majority (97.7%) of the artificial discs in this series remained mobile despite HO.

CONCLUSION

Clinical outcomes of cervical arthroplasty in multilevel spondylosis are similar to single-level outcomes. However, the significantly higher rate of HO found in multilevel arthroplasty and its long-term effect warrant further investigation.

Iliac crest autograft versus alternative constructs for anterior cervical spine surgery: Pros, cons, and costs

Background:

Grafting choices available for performing anterior cervical diskectomy/fusion (ACDF) procedures have become a major concern for spinal surgeons, and their institutions. The “gold standard”, iliac crest autograft, may still be the best and least expensive grafting option; it deserves to be reassessed along with the pros, cons, and costs for alternative grafts/spacers.

Methods:

Although single or multilevel ACDF have utilized iliac crest autograft for decades, the implant industry now offers multiple alternative grafting and spacer devices; (allografts, cages, polyether-etherketone (PEEK) amongst others). While most studies have focused on fusion rates and clinical outcomes following ACDF, few have analyzed the “value-added” of these various constructs (e.g. safety/efficacy, risks/complications, costs).

Results:

The majority of studies document 95%-100% fusion rates when iliac crest autograft is utilized to perform single level ACDF (X-ray or CT confirmed at 6-12 postoperative months). Although many allograft studies similarly quote 90%-100% fusion rates (X-ray alone confirmed at 6-12 postoperative months), a recent “post hoc analysis of data from a prospective multicenter trial” (Riew KD et. al., CSRS Abstract Dec. 2011; unpublished) revealed a much higher delayed fusion rate using allografts at one year 55.7%, 2 years 87%, and four years 92%.

Conclusion:

Iliac crest autograft utilized for single or multilevel ACDF is associated with the highest fusion, lowest complication rates, and significantly lower costs compared with allograft, cages, PEEK, or other grafts. As spinal surgeons and institutions become more cost conscious, we will have to account for the “value added” of these increasingly expensive graft constructs.

A meta-analysis of comparative outcomes following cervical arthroplasty or anterior cervical fusion: results from 4 prospective multicenter randomized clinical trials and up to 1226 patients

STUDY DESIGN

Meta-analysis of 4 prospective randomized controlled Food and Drug Administration (FDA) Investigational Device Exemption (IDE) clinical trials.

OBJECTIVE

To maximize the information available from 4 IDE studies by analyzing the combined outcomes of cervical arthroplasty versus fusion at 24-month follow-up.

SUMMARY OF BACKGROUND DATA

To date, 4 randomized clinical trials have been completed in the United States under FDA IDE protocols to study cervical arthroplasty. Each trial reported arthroplasty to be at least as successful as fusion controls based on noninferiority trial designs. However, sample sizes in any given trial may not be sufficient to demonstrate superiority of treatment effect. Meta-analysis enables pooling of results from comparable trials, which may lead to more precise and statistically significant estimates of treatment effect.

METHODS

Four cervical arthroplasty randomized clinical trials with comparable enrollment criteria and outcome measures were conducted independently by 3 separate sponsors to study the following devices: Bryan, Prestige, ProDisc-C, and PCM cervical disc replacements. A total of 1608 patients were treated across 98 investigative sites. Data were available for 1352 treated patients, of which 1226 were evaluable at 24 months. Assessments included clinical success definitions based on neck disability index, maintenance or improvement of neurological status, subsequent surgery or intervention at the index level (survivorship), and a composite score comprising these as well as serious device-related adverse events. Trial endpoint comparisons were made at 24 months postoperatively. For each endpoint, a random-effects meta-analysis was performed to compare the success rates of cervical arthroplasty with anterior cervical discectomy and fusion (ACDF). Also, supportive frequentist and bayesian analyses were performed.

RESULTS

The pooled primary overall success results indicated a statistically significant treatment effect favoring arthroplasty compared with ACDF. Overall success was achieved by 77.6% of the arthroplasty patients and by 70.8% of the ACDF patients (pooled odds ratio [OR]: 0.699, 95% confidence interval [CI]: 0.539-0.908, P = 0.007). The results of the individual subcomponent meta-analyses, all of which favored arthroplasty, were neck disability index success (OR: 0.786, 95% CI: 0.589-1.050, P = 0.103), neurological status (OR: 0.552, 95% CI: 0.364-0.835, P = 0.005), and survivorship (OR: 0.510, 95% CI: 0.275-0.946, P = 0.033). Only the survivorship endpoint suggested low heterogeneity.

CONCLUSION

These findings suggest that cervical arthroplasty is superior to ACDF in overall success, neurological success, and survivorship outcomes at 24 months postoperatively.

Radiographic Comparison of Four Anterior Fusion Methods in Two Level Cervical Disc Diseases : Autograft Plate Fixation versus Cage Plate Fixation versus Stand-Alone Cage Fusion versus Corpectomy and Plate Fixation

Objective

To evaluate radiographic results of anterior fusion methods in two-level cervical disc disease : tricortical autograft and plate fixation (ACDF-AP), cage and plate fixation (ACDF-CP), stand-alone cage (ACDF-CA), and corpectomy and plate fixation (ACCF).

Methods

The numbers of patients were 70 with a minimum 6 month follow-up (ACDF-AP : 12, ACDF-CP : 27, ACDF-CA : 15, and ACCF : 16). Dynamic simple X-ray and computed tomography were evaluated preoperatively, postoperatively, 6 month, and at the final follow-up. The fusion and subsidence rates at the final were determined, and global cervical lordosis (GCL), cervical range of motion, fused segment angle (FSA), and fused segment height (FSH) were analyzed.

Results

Nonunion was observed in 4 (25%) patients with ACDF-CA, 1 (8%) patient with ACDF-AP, 1 (4%) patient with ACDF-CP. The number of loss of FSH (%) more than 3 mm were 2 patients (16%) in ACDF-AP, 3 patients (11%) in ACDF-CP, 5 patients (33%) in ACDF-CA, and 3 patients (20%) in ACCF. The GCL was decreased with ACDF-CA and increased with others. The FSA was increased with ACDF-AP, ACDF-CP, and ACCF, but ACDF-CA was decreased. At the final follow-up, the FSH was slightly decreased in ACDF-CP, ACDF-AP, and ACCF, but ACDF-CA was more decreased. Graft related complication were minimal. Screw loosening, plate fracture, cage subsidence and migration were not identified.

Conclusion

ACDF-CP demonstrated a higher fusion rate and less minimal FSH loss than the other fusions in two-level cervical disc disease. The ACDF-AP and ACCF methods had a better outcome than the ACDF-CA with respect to GCL, FSA, and FSH.

Differences between 1- and 2-level cervical arthroplasty: more heterotopic ossification in 2-level disc replacement: Clinical article

OBJECT

The most currently accepted indication for cervical arthroplasty is 1- or 2-level degenerative disc disease (DDD) refractory to medical treatment. However, the randomized and controlled clinical trials by the US FDA investigational device exemption studies only compared cervical arthroplasty with anterior cervical discectomy and fusion for 1-level disease. Theoretically, 2-level cervical spondylosis usually implicates more advanced degeneration, whereas the 1-level DDD can be caused by merely a soft-disc herniation. This study aimed to investigate the differences between 1- and 2-level cervical arthroplasty.

METHODS

The authors analyzed data obtained in 87 consecutive patients who underwent 1- or 2-level cervical arthroplasty with Bryan disc. The patients were divided into the 1-level and the 2-level treatment groups. Clinical outcomes were measured using the visual analog scale (VAS) for the neck and arm pain and the Neck Disability Index (NDI), with a minimum follow-up of 30 months. Radiographic outcomes were evaluated on both radiographs and CT scans.

RESULTS

The study analyzed 98 levels of Bryan cervical arthroplasty in 70 patients (80.5%) who completed the evaluations in a mean follow-up period of 46.21 ± 9.85 months. There were 22 females (31.4%) and 48 males (68.6%), whose mean age was 46.57 ± 10.07 years at the time of surgery. The 1-level group had 42 patients (60.0%), while the 2-level group had 28 patients (40.0%). Patients in the 1-level group were younger than those in the 2-level group (mean 45.00 vs 48.93 years, p = 0.111 [not significant]). Proportional sex compositions and perioperative prescription of nonsteroidal antiinflammatory drugs were also similar in both groups (p = 0.227 and p = 1.000). The 2-level group had significantly greater EBL during surgery than the 1-level group (220.80 vs 111.89 ml, p = 0.024). Heterotopic ossification was identified more frequently in the 2-level group than the 1-level group (75.0% vs 40.5%, p = 0.009). Although most of the artificial discs remained mobile during the follow up, the 2-level group had fewer mobile discs (100% and 85.7%, p = 0.022) than the 1-level group. However, in both groups, the clinical outcomes measured by VAS for neck pain, VAS for arm pain, and NDI all significantly improved after surgery compared with that preoperatively, and there were no significant differences between the groups at any point of evaluation (that is, at 3, 6, 12, and 24 months after surgery).

CONCLUSIONS

Clinical outcomes of 1- and 2-level cervical arthroplasty were similar at 46 months after surgery, and patients in both groups had significantly improved compared with preoperative status. However, there was a significantly higher rate of heterotopic ossification formation and less mobility of the Bryan disc in patients who underwent 2-level arthroplasty. Although mobility to date has been maintained in the vast majority (94.3%) of patients, the long-term effects of heterotopic ossification warrant further investigation.

The choice of the best surgery after single level anterior cervical spine discectomy: a systematic review

Background:

The anterior cervical discectomy (ACD) is often used to treat spinal cord and nerve root compressions and the frequent use of interbody fusion (ACDF) has popularized it as a common practice associated or not with cages or plates for maintaining the intervertebral disc height.

Objective:

The aim of this study is to clarify the effectiveness of ACD compared with ACDF, with or without the use of anterior cervical spacer (Cage) or instrumentation with plate fixation (ACDFI).

Methods:

randomized controlled trials or quasi-randomized trials were selected for analysis in one segmental level. The comparison criteria were the rates of success and failure with surgery (Odom’s’ criteria), fusion rates and kyphosis rates. Electronic search was made in the MEDLINE database (Pubmed), in the Central Registry of randomized trials of Cochrane database and EMBASE.

Results:

Seven studies were selected for analysis.

Conclusion:

Implications for practice: There is moderate evidence that clinical results of ACD and ACDF are not significant different. There is moderate evidence that addition of intervertebral cage enhance clinical results.There is moderate evidence that anterior cervical plate does not change the clinical results of ACD.

There is moderate evidence that ACD produce more segmental kyphosis than ACDF and ACDFI, with use of cage or plate.There is moderate evidence that ACD produce lower rate of fusion than ACDF and than the cages. There is limited evidence of the lower capacity of PMMA to produce fusion. There is limited evidence that fused patients have better outcome than non fused patients.

Comparison of Operating Time between Stand-alone Cage and a Standard Method for a Single Level Cervical Disc Disease

Objective

Autologous bone graft with anterior plating had been a standard method for anterior cervical discectomy and fusion (ACDF). Drawbacks of a standard method were donor site problem and problem associated with anterior plate. The stand-alone cage was introduced to reduce such problems. However, problems associated with subsidence and local kyphosis at the index level (segmental kyphosis) still persist with stand-alone cage and a standard method would be required in some cases. It seems that harvest of autologous bone and anterior plating procedure is time consuming, but this has not been verified. The aim of this study was to compare the operating time between patients operated on with stand-alone cage versus a standard method for single-level cervical disc disease.

Methods

Consecutive 29 patients (M:F=18:11; mean age, 58.4±12.4 years), who had undergone ACDF for single-level disc disease by a single surgeon from incision to closure during 2009-2011, were selected for this retrospective study. Seventeen patients were operated with stand-alone cage (Group I), and twelve patients were with a standard method (Group II). Operating time (from incision to closure), estimated blood loss, clinical and radiological outcomes were compared. Follow-up period was 11.4±6.3 months.

Results

Operating time was not different between groups longer; Group I (96.1±28.7 minutes) and Group II (112.4±31.7 minutes) (p=0.13). There was no surgery related complication. Excellent or good outcome was achieved in 11 and 10 patients of group I and II, respectively. Bony fusion was achieved in 15 and 10 patients of group I and II respectively, while one subsidence occurred in each group. Postoperative segmental angle at the index level and cervical curvature was not different between groups. No patient complained donor site pain at the last follow-up.

Conclusions

ACDF with a standard method for single-level cervical disc disease was not a time-consuming procedure comparing stand-alone cage.

Cervical disc arthroplasty versus fusion for single-level symptomatic cervical disc disease: a meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the safety and effectiveness of cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) for single-level symptomatic cervical disc disease.

METHODS

We identified eligible randomized controlled trials (RCTs) in PubMed (April 2011), EMBASE (April 2011) and Cochrane Central Register of Controlled Trials (April 2011). Data were collected and extracted by two reviewers independently. The methodological quality and clinical relevance of the included studies were assessed. Data analysis was conducted with RevMan 5.0.

RESULTS

Six RCTs involving 1,745 patients were included. The pooled analysis showed a higher prevalence of neurological and overall success [(P = 0.004, RR = 1.06, 95% CI = 1.02-1.10), (P = 0.0005, RR = 1.14, 95% CI = 1.06-1.22)], and a lower incidence of dysphagia and reoperation related to adjacent-segment degeneration [(P = 0.04, RR = 0.30, 95% CI = 0.09-0.97), (P = 0.03, RR = 0.46, 95% CI = 0.23-0.91)] with CDA compared to ACDF. However, there was no statistical difference in neck disability index (P = 0.92, SMD = 0.01, 95% CI = -0.25 to 0.27), neck and arm pain scores[(P = 0.33, SMD = -0.12, 95% CI = -0.37 to 0.13), (P = 0.54, SMD = 0.17, 95% CI = -0.36 to 0.70)], incidence of complications related to the implant or surgical procedure and reoperation related to primary surgery [(P = 0.32, RR = 0.76, 95% CI = 0.45-1.30), (P = 0.09, RR = 0.48, 95% CI = 0.20-1.12)].

CONCLUSION

Compared with ACDF, CDA carry a lower incidence of dysphagia complications and reoperation related to adjacent-segment degeneration, and a higher prevalence of neurological and overall success at 2 years postoperatively. As the poor quality of the included studies, it is still uncertain whether CDR is more effective and safer than ACDF treating single-level symptomatic cervical disc disease. Future large-scale RCTs with long-term follow-up are needed to provide clear evidence.

The biomechanical stability of a novel spacer with integrated plate in contiguous two-level and three-level ACDF models: an in vitro cadaveric study

BACKGROUND CONTEXT

Anterior cervical plating increases stability and hence improves fusion rates to treat cervical spine pathologies, which are often symptomatic at multiple levels. However, plating is not without complications, such as dysphagia, injury to neural elements, and plate breakage. The biomechanics of a spacer with integrated plate system combined with posterior instrumentation (PI), in two-level and three-level surgical models, has not yet been investigated.

PURPOSE

The purpose of the study was to biomechanically evaluate the multidirectional rigidity of spacer with integrated plate (SIP) at multiple levels as comparable to traditional spacers and plating.

STUDY DESIGN

An in vitro cervical cadaveric model.

METHODS

Eight fresh human cervical (C2-C7) cadaver spines were tested under pure moments of ±1.5 Nm on spine simulator test frame. Each spine was tested in intact condition, with only anterior fixation and with both anterior and PI. Range of motion (ROM) was measured using Optotrak Certus (NDI, Inc., Waterloo, Ontario, Canada) motion analysis system in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) at the instrumented levels (C3-C6). Repeated-measures analysis of variance was used for statistical analysis.

RESULTS

All the surgical constructs showed significant reduction in motion compared with intact condition. In two-level fusion, SIP (C4-C6) construct significantly reduced ROM by 66.5%, 65.4%, and 60.3% when compared with intact in FE, LB, and AR, respectively. In three-level fusion, SIP (C3-C6) construct significantly reduced ROM by 65.8%, 66%, and 49.6% when compared with intact in FE, LB, and AR, respectively. Posterior instrumentation showed significant stability only in three-level fusion when compared with their respective anterior constructs. In both two-level and three-level fusion, SIP showed comparable stability to traditional spacer and plate constructs in all loading modes.

CONCLUSIONS

The anatomically profiled spacer with integrated plate allows treatment of cervical disorders with fewer steps and less impact to cervical structures. In this biomechanical study, spacer with integrated plate construct showed comparable stability to traditional spacer and plate for two-level and three-level fusion. Posterior instrumentation showed significant effect only in three-level fusion. Clinical data are required for further validation of using spacer with integrated plate at multiple levels.

Anterior approach for complex cervical spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is a slowly progressive disease resulting from age-related degenerative changes in the spine that can lead to spinal cord dysfunction and significant functional disability. The degenerative changes and abnormal motion lead to vertebral body subluxation, osteophyte formation, ligamentum flavum hypertrophy, and spinal canal narrowing. Repetitive movement during normal cervical motion may result in microtrauma to the spinal cord. Disease extent and location dictate the choice of surgical approach. Anterior spinal decompression and instrumented fusion is successful in preventing CSM progression and has been shown to result in functional improvement in most patients.

Long-term follow-up of cervical radiographic sagittal spinal alignment after 1- and 2-level cervical corpectomy for the treatment of spondylosis of the subaxial cervical spine causing radiculomyelopathy or myelopathy: a retrospective study

Object

Few data exist regarding long-term outcomes after cervical corpectomy for spondylotic cervical myelopathy and radiculomyelopathy. In this retrospective review, long-term radiographic outcomes are reported for 130 patients after 1- or 2-level cervical corpectomy for spondylotic myelopathy or radiculomyelopathy.

Methods

Electronic medical records including clinical data and radiographic images during a 15-year period (1993–2008) were reviewed at the Cincinnati Department of Veterans Affairs Medical Center. All patients underwent radiographic follow-up for at least 12 months (range 12–156, mean 45 ± 39.3 months), as well as clinical follow-up performed by neurosurgery staff for a mean of 29.3 ± 39.6 months (range 4–156 months). Clinical parameters at surgery and last examination included the Chiles modified Japanese Orthopaedic Association (mJOA) Myelopathy Scale. Measurements included cervical spine sagittal alignment on lateral radiographs preoperatively and postoperatively, focal Cobb angles at operated levels, and C2–7 regional alignment. Statistical analysis included the Student t-test and chi-square test. Perioperative complications and additional surgery in the cervical spine were recorded.

Results

The mJOA scores improved from a mean of 11.91 ± 2.4 preoperatively to 14.9 ± 2.33 postoperatively. The mean sagittal lordosis of the C2–7 spine increased from −16.2° ± 9.2° preoperatively to −18.5° ± 11.9° at last follow-up. Focal Cobb angles averaged a slight kyphotic angulation of 4.1° ± 2.3° at latest radiographic follow-up; of note, 7 patients (5.4%), all who had cylindrical titanium mesh cages (CTMCs), showed severe kyphotic angulation (+8.4° ± 2.4°). Patients with preoperative myelopathy showed clinical improvement at follow-up. The fusion rate was 96.2%; 3 of the 5 patients with radiographic evidence of nonfusion were smokers. Patients with postoperative kyphosis had significantly more chronic neck pain (visual analog scale score >4 lasting more than 6 months) and visits related to pain (p <0.01). Those with CTMCs had higher rates of postoperative kyphosis, chronic neck pain, and visits related to pain, irrespective of the number of levels fused (p <001). At latest follow-up, although a kyphotic increase occurred in the focal cervical sagittal Cobb angles, lordosis increased in C2–7 sagittal Gore angles. Two patients (1.5%) underwent revision of the implanted graft and/or hardware, and 5 patients (3.8%) had another procedure for adjacent-level pathologies 1–9 years later (mean 4.4 ± 2.7 years).

Conclusions

Long-term follow-up data in our veteran population support cervical corpectomy as an effective, long-lasting treatment for spondylotic myelopathy of the cervical spine. Use of CTMCs without end caps was associated with statistically significant increased postoperative kyphotic angulation and chronic pain. Despite an increase in focal kyphosis over time, regional cervical sagittal lordotic alignment had increased at the latest follow-up. Further investigation will include the association of chronic neck pain and postoperative kyphosis, and high fusion rates among a veteran population of heavy smokers.

Cage subsidence does not, but cervical lordosis improvement does affect the long-term results of anterior cervical fusion with stand-alone cage for degenerative cervical disc disease: a retrospective study

OBJECTIVE

Clinical outcomes of the stand-alone cage have been encouraging when used in anterior cervical discectomy and fusion (ACDF), but concerns remain regarding its complications, especially cage subsidence. This retrospective study was undertaken to investigate the long-term radiological and clinical outcomes of the stand-alone titanium cage and to evaluate the incidence of cage subsidence in relation to the clinical outcome in the surgical treatment of degenerative cervical disc disease.

METHODS

A total of 57 consecutive patients (68 levels) who underwent ACDF using a titanium box cage for the treatment of cervical radiculopathy and/or myelopathy were reviewed for the radiological and clinical outcomes. They were followed for at least 5 years. Radiographs were obtained before and after surgery, 3 months postoperatively, and at the final follow-up to determine the presence of fusion and cage subsidence. The Cobb angle of C2-C7 and the vertebral bodies adjacent to the treated disc were measured to evaluate the cervical sagittal alignment and local lordosis. The disc height was measured as well. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) score for cervical myelopathy, before and after surgery, and at the final follow-up. The recovery rate of JOA score was also calculated. The Visual Analogue Scale (VAS) score of neck and radicular pain were evaluated as well. The fusion rate was 95.6% (65/68) 3 months after surgery.

RESULTS

Successful bone fusion was achieved in all patients at the final follow-up. Cage subsidence occurred in 13 cages (19.1%) at 3-month follow-up; however, there was no relation between fusion and cage subsidence. Cervical and local lordosis improved after surgery, with the improvement preserved at the final follow-up. The preoperative disc height of both subsidence and non-subsidence patients was similar; however, postoperative posterior disc height (PDH) of subsidence group was significantly greater than of non-subsidence group. Significant improvement of the JOA score was noted immediately after surgery and at the final follow-up. There was no significant difference of the recovery rate of JOA score between subsidence and non-subsidence groups. The recovery rate of JOA score was significantly related to the improvement of the C2-C7 Cobb angle. The VAS score regarding neck and radicular pain was significantly improved after surgery and at the final follow-up. There was no significant difference of the neck and radicular pain between both subsidence and non-subsidence groups.

CONCLUSIONS

The results suggest that the clinical and radiological outcomes of the stand-alone titanium box cage for the surgical treatment of one- or two-level degenerative cervical disc disease are satisfactory. Cage subsidence does not exert significant impact upon the long-term clinical outcome although it is common for the stand-alone cages. The cervical lordosis may be more important for the long-term clinical outcome than cage subsidence.

Analysis of the three United States Food and Drug Administration investigational device exemption cervical arthroplasty trials

OBJECT

There are now 3 randomized, multicenter, US FDA investigational device exemption, industry-sponsored studies comparing arthroplasty with anterior cervical discectomy and fusion (ACDF) for single-level cervical disease with 2 years of follow-up. These 3 studies evaluated the Prestige ST, Bryan, and ProDisc-C artificial discs. The authors analyzed the combined results of these trials.

METHODS

A total of 1213 patients with symptomatic, single-level cervical disc disease were randomized into 2 treatment arms in the 3 randomized trials. Six hundred twenty-one patients received an artificial cervical disc, and 592 patients were treated with ACDF. In the three trials, 94% of the arthroplasty group and 87% of the ACDF group have completed 2 years of follow-up. The authors analyzed the 2-year data from these 3 trials including previously unpublished source data. Statistical analysis was performed with fixed and random effects models.

RESULTS

The authors' analysis revealed that segmental sagittal motion was preserved with arthroplasty (preoperatively 7.26° and postoperatively 8.14°) at the 2-year time point. The fusion rate for ACDF at 2 years was 95%. The Neck Disability Index, 36-Item Short Form Health Survey Mental, and Physical Component Summaries, neck pain, and arm pain scores were not statistically different between the groups at the 24-month follow-up. The arthroplasty group demonstrated superior results at 24 months in neurological success (RR 0.595, I(2) = 0%, p = 0.006). The arthroplasty group had a lower rate of secondary surgeries at the 2-year time point (RR 0.44, I(2) = 0%, p = 0.004). At the 2-year time point, the reoperation rate for adjacent-level disease was lower for the arthroplasty group when the authors analyzed the combined data set using a fixed effects model (RR 0.460, I(2) = 2.9%, p = 0.030), but this finding was not significant using a random effects model. Adverse event reporting was too heterogeneous between the 3 trials to combine for analysis.

CONCLUSIONS

Both anterior cervical discectomy and fusion as well as arthroplasty demonstrate excellent 2-year surgical results for the treatment of 1-level cervical disc disease with radiculopathy. Arthroplasty is associated with a lower rate of secondary surgery and a higher rate of neurological success at 2 years. Arthroplasty may be associated with a lower rate of adjacent-level disease at 2 years, but further follow-up and analysis are needed to confirm this finding.

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

OBJECT

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Three-dimensional kinematic analysis of the cervical spine after anterior cervical decompression and fusion at an adjacent level: a preliminary report

PURPOSE

Development of adjacent segment degeneration following anterior cervical decompression and fusion (ACDF) is still controversial, as adjacent-level kinematics is poorly understood. This study reports preliminary data from a high-accuracy 3D analysis technique developed for in vivo cervical kinematics.

METHODS

From nine cervical spondylosis patients, four underwent single-level ACDF, and five underwent two-level ACDF using cylindrical titanium cage implant(s). Pre- and post-surgical CT scans were taken in flexion, neutral and extended positions, allowing us to compute segmental ranges of motion for rotation and translation, and 3D disc-height distributions. Differences in segmental motions and disc-height between fused and adjacent levels were analyzed with a Wilcoxon signed-rank test. Results are presented as mean ± SEM.

RESULTS

The flexion/extension angular-ROM at the fusion level decreased after surgery (7.46 ± 1.17° vs. 3.14 ± 0.56°, p < 0.003). The flexion/extension angular-ROM at one caudal adjacent level to the fusion level (3.97 ± 1.29°) tended to be greater post-operatively (6.11 ± 1.44°, p = 0.074). Translation in the anterior-posterior direction during flexion/extension at the fusion level decreased after surgery (1.22 ± 0.20 mm vs. 0.32 ± 0.11 mm, p < 0.01). No differences were found in adjacent-level disc heights between both study time-points.

CONCLUSIONS

This study showed increased segmental motion in flexion/extension angular-ROM at one level adjacent to ACDF. However, increases in the rotational angular-ROM were not statistically significant when cranial/caudal adjacent levels were analyzed separately. This preliminary study highlighted the capabilities of a 3D-kinematic analysis method to detect subtle changes in kinematics and disc height at the adjacent levels to ACDF. Thus, reliable evidence related to ACDF's influence on adjacent-level cervical kinematics can be collected.

Middle-term results of a prospective comparative study of anterior decompression with fusion and posterior decompression with laminoplasty for the treatment of cervical spondylotic myelopathy

STUDY DESIGN

A clinical prospective study.

OBJECTIVE

To assess whether clinical and radiologic outcomes differ between anterior decompression and fusion (ADF) and laminoplasty (LAMP) in the treatment of cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA

No reports to date have accurately and prospectively compared middle-term clinical outcomes after anterior and posterior decompression for CSM.

METHODS

We prospectively performed LAMP (n = 50) in 1996, 1998, 2000, and 2002, and ADF (n = 45) in 1997, 1999, 2001, and 2003. The Japanese Orthopedic Association (JOA) score, recovery rate, and each item of the JOA score were evaluated. For radiographic evaluation, the lordotic angle and range of motion (ROM) at C2-C7 and residual anterior compression to the spinal cord (ACS) after LAMP on magnetic resonance imaging were investigated.

RESULTS

Eighty-six patients (ADF n = 39; LAMP n = 47) could be followed for more than 5 years (follow-up rate 91.5%). Demographics were similar between the two groups. The mean JOA score and recovery rate in the ADF group were superior to those in the LAMP group from 2-year data collected after surgery. However, LAMP was safer and less invasive than ADF with respect to physical status and complications in the perioperative period. For individual items of the JOA score, the ADF group showed significantly more improvement of upper extremity motor function than the LAMP group (P < 0.05). There was a significant difference in maintenance of the lordotic angle in the ADF group compared with the LAMP group despite no difference in ROM.The LAMP group was divided into two subgroups: (1) LAMP(+) (n = 16) comprising patients who had ACS at 2 years after surgery, and (2) LAMP(-) (n = 31) comprising patients without ACS. Recovery rate differed significantly between the LAMP(+) and LAMP(-) groups despite there being no difference between the LAMP(-) and ADF groups.

CONCLUSION

The recovery rate of the JOA score in the ADF group was better than that in the LAMP group. The clinical outcomes after LAMP could be influenced by ACS.

Cervical radiculopathy: a review

BACKGROUND

Cervical radiculopathy is defined as a syndrome of pain and/or sensorimotor deficits due to compression of a cervical nerve root. Understanding of this disease is vital for rapid diagnosis and treatment of patients with this condition, facilitating their recovery and return to regular activity.

PURPOSE

This review is designed to clarify (1) the pathophysiology that leads to nerve root compression; (2) the diagnosis of the disease guided by history, physical exam, imaging, and electrophysiology; and (3) operative and non-operative options for treatment and how these should be applied.

METHODS

The PubMed database was searched for relevant articles and these articles were reviewed by independent authors. The conclusions are presented in this manuscript.

RESULTS

Facet joint spondylosis and herniation of the intervertebral disc are the most common causes of nerve root compression. The clinical consequence of radiculopathy is arm pain or paresthesias in the dermatomal distribution of the affected nerve and may or may not be associated with neck pain and motor weakness. Patient history and clinical examination are important for diagnosis. Further imaging modalities, such as x-ray, computed tomography, magnetic resonance imaging, and electrophysiologic testing, are of importance. Most patients will significantly improve from non-surgical active and passive therapies. Indicated for surgery are patients with clinically significant motor deficits, debilitating pain that is resistant to conservative modalities and/or time, or instability in the setting of disabling radiculopathy. Surgical treatment options include anterior cervical decompression with fusion and posterior cervical laminoforaminotomy.

CONCLUSION

Understanding the pathophysiology, diagnosis, treatment indications, and treatment techniques is essential for rapid diagnosis and care of patients with cervical radiculopathy.

Anterior cervical multilevel decompression and fusion using fibular strut as revision surgery for failed cervical laminoplasty

STUDY DESIGN

Retrospective analyses of six cases.

OBJECTIVE

To describe six patients with previous failed laminoplasty who were subsequently managed by anterior cervical decompression and fusion (ACDF) using fibular strut as revision surgeries.

SUMMARY OF BACKGROUND DATA

While several complications and unsatisfactory results of cervical laminoplasty have been reported, there is no general consensus on how to best surgically treat these pathological conditions.

METHODS

Six patients, who had been treated by laminoplasty for cervical spondylotic myelopathy (n = 2) or ossification of posterior longitudinal ligament (OPLL, n = 4) and had unfavorable outcomes, underwent ACDF using autogenous fibular strut grafts. The pathological factors associated with the poor outcomes were intraforaminal spur, slip, spondylotic change, disc herniation, and increase of OPLL in size. Clinical outcomes were assessed by evaluating the modified Japanese Orthopedic Association score (JOA score) of cervical myelopathy, severity of radicular pains, axial pains, and perioperative complications. In addition, C2-7 angle and the presence of bony union were analyzed.

RESULTS

The revision ACDF significantly increased the mean ± SD. JOA score, from 10.3 ± 3.9 to 13.5 ± 2.7 points (p = 0.028), with a recovery rate of 47.1 ± 26.7%. Radicular pain and axial pain also improved. C2-7 angle was not changed significantly. Solid fusion was achieved in all patients at 12.2 ± 4.2 months after revision surgery.

CONCLUSION

ACDF with fibular strut graft was effective as a revision procedure for failed laminoplasty.

The Incidence of Adjacent Segment Disease Requiring Surgery After Anterior Cervical Diskectomy and Fusion: Estimation Using an 11-Year Comprehensive Nationwide Database in Taiwan

Background:

The incidence of symptomatic adjacent segment disease (ASD) after anterior cervical diskectomy and fusion (ACDF) was reported as 2.9%/y in a previous cohort of 374 patients. Few other data corroborate the incidence and natural history of ASD.

Objective:

To calculate the incidence of ASD after ACDF that required secondary fusion surgery.

Methods:

The retrospective study used an 11-year nationwide database to analyze the incidences. All patients who underwent ACDF for cervical disk diseases were identified through diagnostic and procedure codes. Kaplan-Meier and Cox regression analyses were performed.

Results:

From 1997 to 2007, covering 241 800 725.8 person-years, 19 385 patients received ACDF and 568 had ≥ 2 ACDF operations. The incidence of secondary ACDF operations was 7.6 per 1000 person-years. At the end of the 10-year cohort, 94.4% of patients who had received 1 ACDF remained free from secondary ACDF. The average time interval between the first and second ACDF was 23.3 months. After adjustment for comorbidities and socioeconomic status, secondary ACDF operations were more likely performed on male patients (hazard ratio = 1.27; P = .008) 15 to 39 years of age (hazard ratio = 1.45; P = .009) and 40 to 59 years of age (hazard ratio = 1.41, P = .002, respectively).

Conclusion:

Repeat ACDF surgery for ASD cumulated steadily in an annual incidence of approximately 0.8%, much lower than the reported incidence of symptomatic ASD. However, at the end of this 10-year cohort, a considerable portion of patients (5.6%) received a second operation. Younger and male patients are more likely to receive such second operations.

Prospective, randomized, multicenter study of cervical arthroplasty: 269 patients from the Kineflex|C artificial disc investigational device exemption study with a minimum 2-year follow-up: clinical article

OBJECT

Cervical total disc replacement (CTDR) represents a relatively novel procedure intended to address some of the shortcomings associated with anterior cervical discectomy and fusion (ACDF) by preserving motion at the treated level. This prospective, randomized, multicenter study evaluates the safety and efficacy of a new metal-on-metal CTDR implant (Kineflex|C) by comparing it with ACDF in the treatment of single-level spondylosis with radiculopathy.

METHODS

The study was a prospective, randomized US FDA Investigational Device Exemption (IDE) pivotal trial conducted at 21 centers across the US. The primary clinical outcome measures included the Neck Disability Index (NDI), visual analog scale (VAS) scores, and a composite measure of clinical success. Patients were randomized to CTDR using the Kineflex|C (SpinalMotion, Inc.) cervical artificial disc or ACDF using structural allograft and an anterior plate.

RESULTS

A total of 269 patients were enrolled and randomly assigned to either CTDR (136 patients) or to ACDF (133 patients). There were no significant differences between the CTDR and ACDF groups when comparing operative time, blood loss, length of hospital stay, or the reoperation rate at the index level. The overall success rate was significantly greater in the CTDR group (85%) compared with the ACDF group (71%) (p = 0.05). In both groups, the mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the 24-month follow-up (p < 0.0001). Similarly, the VAS pain scores improved significantly by 6 weeks and remained significantly improved through the 24-month follow-up (p < 0.0001). The range of motion (ROM) in the CTDR group decreased at 3 months but was significantly greater than the preoperative mean at 12- and 24-month follow-up. The ROM in the ACDF group was significantly reduced by 3 months and remained so throughout the follow-up. Adjacent-level degeneration was also evaluated in both groups from preoperatively to 2-year follow-up and was classified as none, mild, moderate, or severe. Preoperatively, there were no significant differences between groups when evaluating the different levels of adjacent-level degeneration. At the 2-year follow-up, there were significantly more patients in the ACDF group with severe adjacent-level radiographic changes (p < 0.0001). However, there were no significant differences between groups in adjacent-level reoperation rate (7.6% for the Kineflex|C group and 6.1% for the ACDF group).

CONCLUSIONS

Cervical total disc replacement allows for neural decompression and clinical results comparable to ACDF. Kineflex|C was associated with a significantly greater overall success rate than fusion while maintaining motion at the index level. Furthermore, there were significantly fewer Kineflex|C patients showing severe adjacent-level radiographic changes at the 2-year follow-up. These results from a prospective, randomized study support that Kineflex|C CTDR is a viable alternative to ACDF in select patients with cervical radiculopathy.

Systematic review of anterior interbody fusion techniques for single- and double-level cervical degenerative disc disease

STUDY DESIGN

A systematic review of randomized controlled trials.

OBJECTIVE

To determine which technique of anterior cervical interbody fusion (ACIF) gives the best outcome in patients with cervical degenerative disc disease.

SUMMARY OF BACKGROUND DATA

The number of surgical techniques for decompression and ACIF as treatment for cervical degenerative disc disease has increased rapidly, but the rationale for the choice between different techniques remains unclear.

METHODS

From a comprehensive search, we selected randomized studies that compared anterior cervical decompression and ACIF techniques, in patients with chronic single- or double-level degenerative disc disease or disc herniation. Risk of bias was assessed using the criteria of the Cochrane back review group.

RESULTS

Thirty-three studies with 2267 patients were included. The major treatments were discectomy alone and addition of an ACIF procedure (graft, cement, cage, and plates). At best, there was very low-quality evidence of little or no difference in pain relief between the techniques. We found moderate quality evidence for few secondary outcomes. Odom's criteria were not different between iliac crest autograft and a metal cage (risk ratio [RR]: 1.11; 95% confidence interval [CI]: 0.99-1.24). Bone graft produced more fusion than discectomy (RR: 0.22; 95% CI: 0.17-0.48). Complication rates were not different between discectomy and iliac crest autograft (RR: 1.56; 95% CI: 0.71-3.43). Low-quality evidence was found that iliac crest autograft results in better fusion than a cage (RR: 1.87; 95% CI: 1.10-3.17); but more complications (RR: 0.33; 95% CI: 0.12-0.92).

CONCLUSION

When fusion of the motion segment is considered to be the working mechanism for pain relief and functional improvement, iliac crest autograft appears to be the golden standard. When ignoring fusion rates and looking at complication rates, a cage as a golden standard has a weak evidence base over iliac crest autograft, but not over discectomy.

Anterior hybrid decompression and segmental fixation for adjacent three-level cervical spondylosis

OBJECTIVE

To evaluate the outcomes of anterior hybrid decompression and segmental fixation for adjacent three-level cervical spondylosis.

METHODS

53 patients with adjacent three-level cervical spondylosis underwent anterior hybrid decompression and segmental fixation. Titanium mesh and PEEK cage were used to span the defects due to decompression and anterior locking plate was placed over the entire construct. Japanese Orthopedic Association (JOA) scores, segmental and C2-C7 angles before and after operation were analyzed.

RESULTS

The average follow up was 37.3 ± 7.0 months. Bone fusions were observed in all patients at follow-up intervals. JOA scores improved from preoperative 8.1 ± 2.2 (range 4-13) to 13.1 ± 2.3 (range 7-16) at final follow-up (P = 0.000). Meanwhile, surgical segmental angle was significantly improved from preoperative 6.9 ± 8.3° (range -10.4° to 27.6°) to postoperative 16.3 ± 7.2° (range -2.0° to 37.6°)(P = 0.000), and C2-C7 angle from 9.7 ± 8.6° (range -9.9° to 27.4°) to 17.8 ± 7.7° (range -1.2° to 34.3°) (P = 0.000). Postoperative complications included C5 palsy, cerebrospinal fluid leakage, hematoma, and titanium mesh subsidence.

CONCLUSION

Anterior hybrid decompression and segmental fixation is a safe and effective procedure for adjacent three-level cervical spondylosis.

Outcomes of three anterior decompression and fusion techniques in the treatment of three-level cervical spondylosis

The purpose of this article is to compare the outcomes of three different anterior approaches for three-level cervical spondylosis. The records of 120 patients who underwent anterior approaches because of three-level cervical spondylosis between 2006 and 2008 were reviewed. Based on the type of surgery, the patients were divided into three groups: Group 1 was three-level anterior cervical discectomy and fusion (ACDF); Group 2 anterior cervical hybrid decompression and fusion (ACHDF, combination of ACDF and ACCF); and Group 3 two-level anterior cervical corpectomy and fusion (ACCF). The clinical outcomes including blood loss, operation time, complications, Japanese Orthopedic Association (JOA) scores, C2-C7 angle, segmental angle, and fusion rate were compared. There were no significant differences in JOA improvement and fusion rate among three groups. However, in terms of segmental angle and C2-C7 angle improvement, Group 2 was superior to Group 3 and inferior to Group 1 (all P < 0.01). Group 2 was less in operation time than Group 3 (P < 0.01) and more than Group 1 (P < 0.01). Group 3 had more blood loss than Group 1 and Group 2 (all P < 0.01) and had higher complication rate than Group 1 (P < 0.05). No significant differences in blood loss and complication rate were observed between Group 1 and Group 2 (P > 0.05). ACDF was superior in most outcomes to ACCF and ACHDF. If the compressive pathology could be resolved by discectomy, ACDF should be the treatment of choice. ACHDF was an ideal alternative procedure to ACDF if retro-vertebral pathology existed. ACCF was the last choice considered.

Two-level noncontiguous versus three-level anterior cervical discectomy and fusion: a biomechanical comparison

STUDY DESIGN

Biomechanical study.

OBJECTIVE

To determine biomechanical forces exerted on intermediate and adjacent segments after two- or three-level fusion for treatment of noncontiguous levels.

SUMMARY OF BACKGROUND DATA

Increased motion adjacent to fused spinal segments is postulated to be a driving force in adjacent segment degeneration. Occasionally, a patient requires treatment of noncontiguous levels on either side of a normal level. The biomechanical forces exerted on the intermediate and adjacent levels are unknown.

METHODS

Seven intact human cadaveric cervical spines (C3-T1) were mounted in a custom seven-axis spine simulator equipped with a follower load apparatus and OptoTRAK three-dimensional tracking system. Each intact specimen underwent five cycles each of flexion/extension, lateral bending, and axial rotation under a ± 1.5 Nm moment and a 100-Nm axial follower load. Applied torque and motion data in each axis of motion and level were recorded. Testing was repeated under the same parameters after C4-C5 and C6-C7 diskectomies were performed and fused with rigid cervical plates and interbody spacers and again after a three-level fusion from C4 to C7.

RESULTS

Range of motion was modestly increased (35%) in the intermediate and adjacent levels in the skip fusion construct. A significant or nearly significant difference was reached in seven of nine moments. With the three-level fusion construct, motion at the infra- and supra-adjacent levels was significantly or nearly significantly increased in all applied moments over the intact and the two-level noncontiguous construct. The magnitude of this change was substantial (72%).

CONCLUSION

Infra- and supra-adjacent levels experienced a marked increase in strain in all moments with a three-level fusion, whereas the intermediate, supra-, and infra-adjacent segments of a two-level fusion experienced modest strain moments relative to intact. It would be appropriate to consider noncontiguous fusions instead of a three-level fusion when confronted with nonadjacent disease.

Five-year outcome of stand-alone fusion using carbon cages in cervical disc arthrosis

From January 1, 2001 to December 31, 2003, in the Neurosurgery Department of Rome University o "Sapienza," 167 patients underwent anterior surgery for cervical spondylodiscoarthrosis. The levels treated by the anterior stand-alone technique were: C3-C4 (11%), C4-C5 (19%), C5-C6 (40%), and C6-C7 (30%). All patients underwent left anterior presternocleidomastoid-precarotid approach, microdiscectomy, and interbody fusion using a carbon fiber cage filled with hydroxyapatite. All patients were discharged within 48 h after surgery with cervical orthosis. In one case, a hematoma of the surgical site occurred within 12 h of surgery; for this reason the patient underwent surgical revision and was discharged 4 days later. All patients have worn cervical orthosis for a mean period of 7 weeks and underwent radiological follow-up with cervical RX at 1 and 3 months after surgery. All patients underwent follow-up from 54 to 90 months after surgery, and all of them underwent cervical RX, cervical CT scans for the estimate of fusion, and evaluation of neurological status using VAS and NDI. Of 167 patients, 132 were cooperative for this study, 18 were non-cooperative, and 17 died. The estimation of fusion made by cervical CT scans with sagittal reconstruction showed complete osteointegration of the cage in 115 patients (87.1%), while it showed pseudoarthrosis in 17 patients (12.9%). In 24 patients, we observed adjacent segment degeneration, and 13 of these underwent new surgical procedures in this institute or in another hospital. Clinical evaluation with VAS and NDI showed a good outcome, with poorest benefit in patients over 60 years. The clinical analysis showed a good fusion rate in according with literature, 13% of non-fusion rate without clinical evidence and 20% of ASDegeneration but only 10% had required new surgery. We also observed that patients over 60 years of age had less satisfactory outcome, probably related with the evolution of pathophysiological degeneration of the cervical spine. In the opinion, pseudoarthrosis is caused by malpositioning of the carbon fiber cage.

A new zero-profile implant for stand-alone anterior cervical interbody fusion

BACKGROUND

Several studies suggest fusion rates are higher with anterior cervical discectomy and fusion procedures if supplemented with a plate. However, plates may be associated with higher postoperative morbidity and higher rates of dysphagia. This led to the development of a cervical stand-alone cage with integrated fixation for zero-profile segmental stabilization.

QUESTIONS/PURPOSES

We asked whether this new implant would be associated with a low rate of dysphagia and other short-term complications in patients having anterior cervical discectomy and fusion and would be able to achieve solid fusion and maintain postoperative reduction in pain.

METHODS

We prospectively followed 38 patients with radiculopathy/myelopathy undergoing anterior cervical discectomy and fusion using the new implant. Intraoperative parameters, clinical features (Neck Pain Disability Index, visual analog scale score for neck/arm pain, Odom's criteria), and dysphagia scores were recorded. Radiographs were taken to assess implant failure. Thirty-four patients had a minimum 6 months' followup (mean, 8 months; range, 6-11 months).

RESULTS

Three patients at 6 weeks and one patient at 6 months complained about minor dysphagia-related symptoms. There was no hardware failure recordable and all patients had evidence of fusion. Compared to preoperatively, visual analog scale pain score and Neck Pain Disability Index were reduced at 6 weeks' followup without change during further followup.

CONCLUSIONS

The new cervical stand-alone anterior fusion device allows decompression and fusion with low complication rates. The incidence of chronic postoperative dysphagia was infrequent in comparison to published data. Prospective randomized trials with more patients and longer followup are necessary to confirm these observations.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Efficacy and outcomes of dynamic-plated single-level anterior diskectomy/fusion with additional analysis of comparative costs

Background:

Few studies focus on the fusion rates and outcomes for single-level anterior cervical diskectomy/fusion (1-ACDF) utilizing iliac autograft and dynamic plates.

Methods:

Fusion rates and outcomes were prospectively evaluated in 60 consecutive patients undergoing 1-ACDF utilizing iliac autograft and dynamic plates (ABC; Aesculap, Tuttlingen, Germany). Eighteen patients had radiculopathy, while 42 were myelopathic (average Nurick Score 3.3). Pathology included single-level disc disease/spondylosis (38 patients) and/or ossification of the posterior longitudinal ligament (OPLL, 22 patients). Fusion was assessed at 3, 6, and up to 12 months postoperatively utilizing dynamic X-rays and 2D-CT scans. Outcomes were evaluated up to 24 months postoperatively utilizing Odom's Criteria, Nurick Grades, and Short-Form 36 (SF-36) outcome questionnaires. Patients were followed for an average of 4.8 postoperative years (minimum 2 years).

Results:

Although dynamic X-rays/2D-CT studies documented 100% fusion an average of 3.8 months (range 2.5-8 months] postoperatively, 5 heavy smokers exhibited delayed fusions [6-8 months postoperatively]. Two years postoperatively, the average Nurick Score was 0.3 (mild radiculopathy), while Odom's Criteria revealed 52 excellent, 6 good, and 2 fair outcomes [the latter 8 patients were heavy smokers]). Utilizing SF-36 outcome questionnaires, patients markedly improved (>10.0 point gain) on 5 of 8 Health Scales within 6 months, 7 of 8 within 1 year, and all 8 within 2 postoperative years.

Conclusions:

For 60 patients undergoing 1-ACDF utilizing dynamic plates, ultimately a 100% fusion rate was achieved (5 heavy smokers exhibited delayed fusions). Two years postoperatively, Nurick Grades, Odom's Criteria, and SF-36 questionnaires revealed adequate outcomes.

Comparison of post-operative lordosis with the PEEK cage and the cervical plate

OBJECTIVE

The maintenance of post-operative lordosis has been shown to be a key factor in decreasing adjacent level disc stress. Previous studies of the PEEK (polyether ketone) cage have used intervertebral bony fusion as the primary measure of surgical success; however, little is known about its effects on spinal curvature. Our objective was to compare the PEEK cage to the cervical plate with respect to the maintenance of cervical lordosis at one year. Secondary outcomes included fusion and complication rates.

METHODS

We performed a retrospective study of patients who underwent ACDF (anterior cervical discectomy and fusion) by two different methods; 13 patients were treated with the PEEK cage, and 22 with allograft and plating.

RESULTS

Patient and treatment characteristics were similar in both groups. Average global lordotic curvature (C2-C7) was increased by 1.7 degrees for the PEEK cage and decreased by 1.6 degrees for the plate after an average follow-up of 12.46 and 14.95 months, respectively. Regional lordosis for the PEEK cage and plate was decreased by 2.5 and 2.1 degrees, respectively for the same time period. These differences did not achieve statistical significance. Bony fusion was observed in all patients. One patient in each group developed persistent mild dysphagia.

CONCLUSIONS

The PEEK cage is comparable to the anterior cervical plate in the maintenance of post-operative cervical lordosis.