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

Anterior transcorporeal approach combined with posterior translaminar approach in percutaneous endoscopic cervical discectomy for two-segment cervical disc herniation treatment: a technical report and early follow-up

OBJECTIVE

Full endoscopic techniques are being gradually introduced from single-segment cervical disc herniation surgery to two-segment cervical disc herniation surgery. However, there is no suitable full endoscopic treatment for mixed-type two-segment cervical disc herniation (MTCDH) in which one segment herniates in front of the spinal cord and the other segment herniates behind the spinal cord. Therefore, we introduce a new full endoscopic technique by combining an anterior transcorporeal approach and a posterior translaminar approach. In addition, we provide a brief description of its safety, efficacy, feasibility, and surgical points.

METHODS

Thirty patients with MTCDH were given full endoscopic surgical treatment by a combined transcorporeal and transforaminal approach and were followed up for at least 12 months.

RESULTS

Clinical assessment scales showed that the patient's symptoms and pain were significantly reduced postoperatively. Imaging results showed bony repair of the surgically induced bone defect and the cervical Cobb angle was increased. No serious complications occurred.

CONCLUSION

This technique enables minimally invasive surgery to relieve the compression of the spinal cord by MTCDH. It avoids the fusion of the vertebral body for internal fixation, preserves the vertebral motion segments, avoids medical destruction of the cervical disc to the greatest extent possible, and expands the scope of adaptation of full endoscopic technology in cervical surgery.

Comparison Between Sagittal Balance Outcomes After Corpectomy, Laminectomy, and Fusion for Cervical Spondylotic Myelopathy: A Matched Cohort Study

Cervical spondylotic myelopathy (CSM) can be successfully decompressed via either anterior cervical corpectomy and fusion (ACCF) or posterior laminectomy with fusion (LMF). However, few studies have compared the isolated effect of both techniques on cervical sagittal balance, a surrogate end point for clinical outcomes.We aimed to compare the sagittal balance radiological outcomes of ACCF against LMF. A case-matched controlled study of radiological cervical alignment parameters (C0-2, C2-3, index angles, T1 slope, and sagittal vertical axis (SVA)) in two groups of patients was performed by using pre- and postoperative neutral cervical X-rays.In total, 34 patients were enrolled (ACCF n = 17; LMF n = 17). The mean preoperative C2-7 angle was similar (11.58 ± 16.00° for ACCF; 13.36 ± 12.21° for LMF) in both cohorts. Both led to a loss of lordosis (-2.68 ± 13.8°, p = 0.43; -2.94 ± 11.5°, p = 0.31, respectively). At the C0-2, the two operations induced opposite variations (-0.9 ± 8.0°, p = 0.709 for ACCF; 3.5 ± 15.4°, p = 0.357 for LMF). ACCF led to a significant increase in SVA (7.1 ± 11.9 mm, p = 0.002). The C2-3 disk angle more pronouncedly increased with LMF.Both techniques show an equivalent kyphotic effect, with a greater disadvantage for ACCF. The negative impact on SVA changes is greater with ACCF. Both affect the C0-2 unit, with a tendency for kyphosis with ACCF and one for lordosis with LMF. When choosing the appropriate decompression and fusion technique, preoperative sagittal balance parameters should be included in the decision-making process.

Biomechanical influence of T1 tilt alteration on adjacent segments after anterior cervical fusion

Background: Anterior cervical fusion (ACF) has become a standard treatment approach to effectively alleviate symptoms in patients with cervical spondylotic myelopathy and radiculopathy. However, alteration of cervical sagittal alignment may accelerate degeneration at segments adjacent to the fusion and thereby compromise the surgical outcome. It remains unknown whether changes in T1 tilt, an important parameter of cervical sagittal alignment, may cause redistribution of biomechanical loading on adjacent segments after ACF surgery. Objective: The objective was to examine the effects of T1 tilt angles on biomechanical responses (i.e.range of motion (ROM) and intradiscal VonMises stress) of the cervical spine before and after ACF. Methods: C2-T1 FE models for pre- and postoperative C4-C6 fusion were constructed on the basis of our previous work. Varying T1 tilts of -10°, -5°, 0°, 5°, and 10° were modeled with an imposed flexion-extension rotation at the T1 inferior endplate for the C2-T1 models. The flexion-extension ROM and intradiscal VonMises stress of functional spinal units were compared between the pre- and postoperative C2-T1 FE models of different T1 tilts. Results: The spinal segments adjacent to ACF demonstrated higher ROM ratios after the operation regardless of T1 tilt. The segmental ROM ratio distribution was influenced as T1 tilt varied and loading conditions, which were more obvious during displacement-control loading of extension. Regardless of T1 tilt, intradiscal VonMises stress was greatly increased at the adjacent segments after the operation. As T1 tilt increased, intradiscal stress at C3-C4 decreased under 30° flexion and increased under 15° extension. The contrary trend was observed at the C6-C7 segment, where the intradiscal stress increased with the increasing T1 tilt under 30° flexion and decreased under 15° extension. Conclusion: T1 tilt change may change biomechanical loadings of cervical spine segments, especially of the adjacent segments after ACF. Extension may be more susceptible to T1 tilt change.

Comparison of Complications between Anterior Cervical Diskectomy and Fusion versus Anterior Cervical Corpectomy and Fusion in Two- and Three-Level Cervical Spondylotic Myelopathy: A Meta-analysis

BACKGROUND

 In this study, we systematically analyze the differences in complications between anterior cervical diskectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF) in two- and three-level cervical spondylotic myelopathy (CSM).

METHODS

 We performed a systematic search in MEDLINE, EMBASE, PubMed, Web of Science, Cochrane databases, Chinese Biomedical Literature Database, CNKI, and Wan Fang Data for all relevant studies. All statistical analyses were performed using Review Manager version 5.3.

RESULTS

 A total of 11 articles with 849 study subjects were included, with 474 patients in the ACDF group and 375 patients in the ACCF group. The results of the meta-analysis showed that in C5 palsy (odds ratio [OR]: 0.41; 95% confidence interval [CI]: 0.16-1.06), pseudarthrosis (OR: 1.07; 95% CI: 0.23-5.07), dysphagia (OR: 1.06; 95% CI: 0.60-1.86), infection (OR: 0.41; 95% CI: 0.16-1.09), cerebrospinal fluid leakage (OR: 1.21; 95% CI: 0.39-3.73), graft dislodgment (OR: 0.28; 95% CI: 0.06-1.37), and hematoma (OR: 0.32; 95% CI: 0.06-1.83), there are no significant differences between the ACDF and ACCF groups, whereas total complication (OR: 0.50; 95% CI: 0.31-0.80) showed that the ACDF group had a significantly lower morbidity than the ACCF group. Furthermore, the three-level subgroup of ACDF had significantly better results in C5 palsy (OR: 0.31; 95% CI: 0.11-0.88), infection (OR: 0.22; 95% CI: 0.05-0.94), graft dislodgment (OR: 0.07; 95% CI: 0.01-0.40), and total complication (OR: 0.37; 95% CI: 0.23-0.60) compared with the ACCF subgroup.

CONCLUSION

 In general, postoperative pseudarthrosis, dysphagia, cerebrospinal fluid leakage, hematoma, C5 palsy, infection, and graft dislodgment did not differ significantly between the two groups. Total complication was significantly less in the ACDF group compared to the ACCF group. In the three-level subgroup, the morbidity of C5 palsy, infection, and graft dislodgment was significantly lower in ACDF than in ACCF.

In-vitro Biomechanics of the Cervical Spine: a Systematic Review

In-vitro testing has been conducted to provide a comprehensive understanding of the biomechanics of the cervical spine. This has allowed a characterization of the stability of the spine as influenced by the intrinsic properties of its tissue constituents and the severity of degeneration or injury. This also enables the pre-clinical estimation of spinal implant functionality and the success of operative procedures. The purpose of this review paper was to compile methodologies and results from various studies addressing spinal kinematics in pre- and post-operative conditions so that they could be compared. The reviewed literature was evaluated to provide suggestions for a better approach for future studies, to reduce the uncertainties and facilitate comparisons among various results. The overview is presented in a way to inform various disciplines, such as experimental testing, design development, and clinical treatment. The biomechanical characteristics of the cervical spine, mainly the segmental range of motion (ROM), intradiscal pressure (IDP), and facet joint load (FJL), have been assessed by testing functional spinal units (FSUs). The relative effects of pathologies including disc degeneration, muscle dysfunction, and ligamentous transection have been studied by imposing on the specimen complex load scenarios imitating physiological conditions. The biomechanical response is strongly influenced by specimen type, test condition, and the different types of implants utilized in the different experimental groups.

Cage-screw and anterior plating combination reduces the risk of micromotion and subsidence in multilevel anterior cervical discectomy and fusion-a finite element study

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) is widely used to treat patients with spinal disorders, where the cage is a critical component to achieve satisfactory fusion results. However, it is still not clear whether a cage with screws or without screws will be the best choice for long-term fusion as the micromotion (sliding distance) and subsidence (penetration) of the cage still take place repeatedly.

PURPOSE

This study aims to examine the effect of cage-screws on the biomechanical characteristics of the human spine, implanted cage, and associate hardware by comparing the micromotion and subsidence.

STUDY DESIGN

A finite element (FE) analysis study.

METHODS

A FE model of a C3-C5 cervical spine with ACDF was developed. The spinal segment was modeled with the removal of the anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), and discectomy was then implanted with a cage-screw system. Three models were analyzed: the first was the original spine (S1 model), the second, S2, was implanted with cages and anterior plating, and the third, S3, was implanted with a cage-screw system in addition to the anterior plate. All investigations were under 1 N•m in flexion, extension, lateral bending, and axial rotation situations.

RESULTS

Finite element analysis (FEA) demonstrated that range of motion (ROM) at C3-C4 in the S2 model was significantly reduced more than that in the S3 model, while the ROM at both C4-C5 in the S3 model was reduced more than that in the S2 model in all simulations. The ROM at C3-C5 in the S1 model was reduced by over 5° in the S2 and S3 models in all loading conditions. The micromotion and subsidence at all contacts of C3-C5 in the S3 model were lower than that in the S2 model in all flexion, extension, bending, and axial simulations. The subsidence and micromotion could be seen in the barrier area of the S2 model, while they occurred near the edge of the screw in the S3 model.

CONCLUSIONS

These results showed that the cage-screw and anterior plating combination has promising potential to reduce the risk of micromotion and subsidence of implanted cages in two or more level ACDFs.

CLINICAL SIGNIFICANCE

The use of double segmental fixation with cage-screw anterior plating combination constructs may increase the stiffness of the construct and reduce the incidence of clinical and radiographic pseudarthrosis following multilevel ACDF, which in turn, could decrease the need for revision surgeries or supplemental posterior fixation.

The Effect of Rod Pattern, Outrigger, and Multiple Screw-Rod Constructs for Surgical Stabilization of the 3-Column Destabilized Cervical Spine - A Biomechanical Analysis and Introduction of a Novel Technique

Objective

Anterior-only reconstructions for cervical multilevel corpectomies are prone to fail under continuous mechanical loading. This study sought to define the mechanical characteristics of different constructs in reducing a range of motion (ROM) of the 3-column destabilized cervical spine, including posterior cobalt-chromium (CoCr)-rods, outrigger-rods (OGR), and a novel triple rod construct using lamina screws (6S3R). The clinical implications of biomechanical findings are discussed in depth from the perspective of the challenges surgeons face cervical deformity correction.

Methods

Three-column deficient cervical spinal models were produced based on reconstructed computed tomography scans. The corpectomy defect between C3 and C7 end-level vertebrae was restored with anterior titanium (Ti) mesh-cage. The ROM was evaluated in a customized 6-degree of freedom spine tester. Tests were performed with different rod materials (Ti vs. CoCr), varying diameter rods (3.5 mm vs. 4.0 mm), with and without anterior plating, and using different construct patterns: bilateral rod fixation (standard-group), OGR-group, and 6S3R-Group. Construct stability was expressed in changes and differences of ROM (°).

Results

The largest reduction of ROM was noticed in the 6S3R-group compared to the standard- and the OGR-group. All differences observed were emphasized with an increasing number of corpectomy levels and if anterior plating was not added. For all simulated 1-, 2-, and 3-level corpectomy constructs, the OGR-group revealed decreased ROM for all motion directions compared to the standard-group. An increase of construct stiffness was also recorded for increased rod diameter (4.0 mm) and stiffer rod material (CoCr), though these effects lacked behind the more advanced construct pattern.

Conclusion

A novel reconstructive technique, the 6S3R-construct, was shown to outperform all other constructs and might resemble a new standard of reference for advanced posterior fixation.

Adjacent two-level anterior cervical discectomy and fusion versus one-level corpectomy and fusion in cervical spondylotic myelopathy: Analysis of perioperative parameters and sagittal balance

OBJECTIVES

The optimal surgical strategy for cervical spondylotic myelopathy (CSM) remains controversial; thus, the current study was designed to compare the outcomes of two different anterior approach surgeries for two-level CSM, namely, adjacent two-level anterior cervical discectomy and fusion (ACDF) and one-level anterior cervical corpectomy and fusion (ACCF).

PATIENTS AND METHODS

A total of 53 patients who underwent adjacent two-level ACDF and 68 patients who underwent one-level ACCF in the Spinal Surgery Department from January 2010 to October 2017 were retrospectively analyzed. Independent sample t tests and chi-square tests were used to compare perioperative parameters (hospital stays, bleeding amounts and operation times), clinical parameters (Neck Disability Index scores and Visual Analog Scale scores for neck and arm pain), and radiologic parameters (difference in segmental height, T1 slope, C2-7 sagittal vertical axis, C2-7 lordosis, segmental angle, and fusion rate).

RESULTS

The length of hospital stay (p < 0.01), bleeding amount (p < 0.01), operation time (p < 0.001) and difference in segmental height (p < 0.001) were significantly greater in the ACCF group than in the ACDF group, whereas C2-7 lordosis (p < 0.05) and the segmental angle (p < 0.001) were significantly lower in the ACCF group than in the ACDF group. Other parameters were not significantly different between the two groups.

CONCLUSION

Both ACDF and ACCF provided satisfactory clinical outcomes and fusion rates for CSM. However, adjacent two-level ACDF was associated with shorter hospital stays, less blood loss, shorter operative times, fewer differences in segmental height and greater improvement in segmental lordotic curvature. On most occasions, when either surgical method could be selected, adjacent two-level ACDF as a surgical treatment for CSM may be a worthwhile alternative method to one-level ACCF.

Cranial Kyphotic Change After Multilevel Anterior Cervical Corpectomy and Fusion May Lead to Myelopathy Recurrence

OBJECTIVE

To determine the characteristic alignment change in patients with myelopathy recurrence after multilevel anterior cervical corpectomy and fusion (m-ACCF).

METHODS

We analyzed 52 patients who underwent m-ACCF, including 20 who underwent revision surgeries for myelopathy recurrence (R group) and 32 postoperative asymptomatic patients (A group). Classic alignment parameters (cervical lordosis angle, cervical sagittal vertical axis, and fusion area angle and length) and original alignment parameters (α-β, β-bone graft [BG], BG-γ, and γ-δ angles) were measured preoperatively, postoperatively, and at follow-up or before revision surgery. The difference in the amount of change in parameters between groups was analyzed. The relationship between distribution of restenotic lesions and characteristic alignment change in the R group was evaluated.

RESULTS

Cervical lordosis angle, fusion area angle, and fusion area length in the R group significantly decreased postoperatively compared with the A group (P < 0.01, P < 0.01, and P = 0.04). Compared with the A group, α-β and β-BG angles in the R group significantly decreased (P < 0.01), indicating kyphotic change on the cranial side. BG-γ and γ-δ angles in the R group significantly increased (P < 0.01), indicating lordotic change in the caudal fused area. Restenotic lesions significantly increased on the cranial side in the R group (cranial side, 19 levels; caudal side, 5 levels; P < 0.01).

CONCLUSIONS

In patients with myelopathy recurrence after m-ACCF, the cranial side has significant kyphosis and the caudal side has lordosis. Moreover, 79.2% of the restenotic lesions were significantly maldistributed on the cranial side. Surgeons should pay close attention to cranial kyphosis inducing myelopathy recurrence after m-ACCF.

Hybrid decompression and reconstruction technique for cervical spondylotic myelopathy: case series and review of the literature

The primary treatment of choice for patients with cervical spondylotic myelopathy (CSM) is surgical decompression. The benefit of operative intervention has been well established but, the surgeons' decision of operative approach remains nuanced based on patient-specific variables and surgeon preference. Decompression can involve a cervical corpectomy or a discectomy. A hybrid construct is when both a cervical corpectomy and a discectomy are done in the same patient. The purpose of this study was to review the evidence on the clinical and biomechanical outcomes of hybrid decompression and reconstruction techniques in patients with multilevel CSM. A retrospective study was performed on consecutive patients who received hybrid anterior decompression and reconstruction at Rush University between 2013-2018. Preoperative clinical and radiographic variables were analyzed to characterize specific factors leading to the decision of the surgical approach. In addition, we performed a systematic review and meta-analysis to assess superiority in terms of operative time, blood loss, cervical lordosis, patient-reported outcomes (PRO), fusion rates, and complications. Hybrid surgery (HS) was utilized in cases where multilevel CSM was present in conjunction with stenosis posterior to the vertebral body or acute kyphotic deformity. Our meta-analysis highlighted comparable PRO, complications, and rate of success fusion between 3-level anterior cervical discectomy and fusion (ACDF) and hybrid technique. Furthermore, hybrid fusion led to increased postoperative cervical lordosis, higher fusion rate, lower total complication rate, lower implant failure/mesh subsidence rate, and lower blood loss than 2-level corpectomy. The cervical hybrid technique that combines cervical corpectomy and discectomy represents a balanced option with the benefits of two commonly utilized cervical spine procedures in patients with multilevel CSM. The literature on hybrid technique suggests in cases where multilevel ACDF is not feasible, combining discectomy and corpectomy is superior to two-level corpectomy with lower complication rates, improved clinical outcome, spinal alignment correction, and stronger biomechanical properties.

Compensatory Mechanisms for Kyphotic Change in the Cervical Spine According to Alignment Analysis of the Cases after Anterior Cervical Corpectomy and Fusion

BACKGROUND

Compensatory mechanisms for cervical kyphosis are unclear. Few alignment analyses have targeted ongoing cervical kyphosis and detailed the effects of compensatory alignment changes.

METHODS

We analyzed the radiographic alignment parameters of 31 patients (21 men and 10 women) with postoperative kyphotic changes after anterior cervical corpectomy and fusion (ACCF) between 2006 and 2015. This analysis included lordotic angle of the fusion area, fusion area length, cervical lordosis angle (CL), O-C7 angle (O-C7a), and cervical sagittal vertical axis (cSVA) as basic parameters and occipito-C2 angle (O-C2a), adjacent cranial angle, adjacent caudal angle, and T1 slope as compensatory parameters at 2 time points after surgery.

RESULTS

Alignment analysis revealed that CL was significantly decreased by 5.0 ± 7.7° (P < 0.01) and O-C7a was changed by only -0.2 ± 6.8° (P = 0.75). An inverse correlation was found between ΔCL and ΔO-C2a (ρ = -0.40), with a nearly 1:1 relationship in the scatter diagram. ΔT1 slope had no direct compensatory correlation with ΔCL (P = 0.28) but was strongly correlated with ΔcSVA (ρ = 0.78). The scatter diagram of ΔcSVA and ΔT1 slope showed compensatory relevance and a shifted point to its collapse as the T1 slope lost control of cSVA; thereafter, both parameters incessantly increased, and ΔT1 and ΔcSVA became positive.

CONCLUSIONS

When CL decreased after ACCF, ΔO-C2 immediately compensated for the CL loss that could lead to failure to obtain horizontal gaze. If cSVA increased, Δcaudal adjacent angle and ΔT1 slope (extension below the kyphosis) compensated for the horizontal offset translation. The noncompensatory status (ΔcSVA and ΔT1 positive) may necessitate further correction surgery in which the caudal fused level is beyond T1.

Clinical Comparison of Surgical Constructs for Anterior Cervical Corpectomy and Fusion in Patients With Cervical Spondylotic Myelopathy or Ossified Posterior Longitudinal Ligament: A Systematic Review and Meta-Analysis

STUDY DESIGN

This is a systematic review and meta-analysis.

OBJECTIVE

To examine the differences in outcomes among current constructs and techniques for anterior cervical corpectomy and fusion (ACCF) in patients with single or multiple level cervical myelopathy (CM) secondary to cervical spondylosis or ossified posterior longitudinal ligament.

SUMMARY OF BACKGROUND DATA

The natural history of CM can be a progressive disease process. In such cases, where surgical decompression is indicated to halt the progression, ACCF is typically chosen for pathology located posterior to the vertebral body. Numerous studies have shown that decompression with appropriate stabilization not only halts progression, but also improves patient outcomes. However, several constructs are available for this procedure, all with variable outcomes.

MATERIALS AND METHODS

A systematic review was conducted using Cochrane Database, Medline, and PubMed. Only studies with a minimum patient population of 10, reporting on CM because of cervical spondylosis or ossified posterior longitudinal ligament were included; a minimum follow-up period of 12 months and 1 clinical and/or radiographic outcome were required. Studies examining patients with cervical trauma/fracture, tumor, and infection or revision cases were excluded. Data analysis was carried out with Microsoft Excel.

RESULTS

A total of 30 studies met the inclusion criteria for qualitative analysis, while 26 studies were included for quantitative analysis. Constructs that were reported in these studies included titanium mesh cages, nano-hydroxyapatite/polyamide 66 composite struts, bone graft alone, expandable corpectomy cages, and polyetheretherketone cages. Clinical outcomes included Japanese Orthopaedic Association and modified Japanese Orthopaedic Association scores, Visual Analog Scale scores, Neck Disability Index scores, and Nurick grades. Radiographic outcomes included C2-C7 and segmental Cobb angles and pseudarthrosis rates. Each construct type had variable and unique benefits and shortcomings.

CONCLUSIONS

ACCF is a common surgical option for CM, despite carrying certain risks expected of any anterior cervical approach. Several constructs are available for ACCF, all with variable clinical and radiographic outcomes.

Anterior cervical discectomy and fusion versus corpectomy and fusion in treating two-level adjacent cervical spondylotic myelopathy: a minimum 5-year follow-up study

OBJECTIVE

A retrospective study was performed to compare the clinical and radiological outcomes of two-level anterior cervical discectomy and fusion (ACDF) with those of single-level anterior cervical corpectomy and fusion (ACCF) in treating two adjacent level cervical spondylotic myelopathy (CSM) with at least 5-year follow-up.

METHODS

A total of 46 consecutive patients who underwent surgery for the treatment of two-level CSM in our institution were evaluated from February 2002 to December 2007. In this series, 22 patients underwent two-level ACDF (group ACDF) and 24 received single-level ACCF (group ACCF). The operation duration, blood loss, perioperative complication, fusion rate, neural function (mJOA score) and the segmental lordosis of the surgical level were compared between the two groups.

RESULTS

The mean follow-up time was 84.5 ± 13 months in group ACDF and 86 ± 11 months in group ACCF (P = 0.723). The rates of perioperative complications were 18.2 % in group ACDF and 20.8 % in group ACCF, respectively (P > 0.05). Although there was no significant difference in neural function (mJOA score) between the two groups at the final follow-up (P > 0.05), the blood loss and the operation duration were significantly less in group ACDF than those in group ACCF (P < 0.05). The fusion rates at the 12th week after surgery were 86.4 % (19/22) in group ACDF and 87.5 % (21/24) in group ACCF (P > 0.05). According to the radiographs measurement, the segmental lordosis at the surgical segment was significantly greater in group ACDF than that in group ACCF (P < 0.05).

CONCLUSION

There were high fusion rates and excellent clinical outcomes in both ACDF and ACCF for treating two adjacent level CSM. However, there were less blood loss, less operation duration and better cervical lordosis in group ACDF than those in group ACCF.

Cervical disc arthroplasty versus anterior cervical discectomy and fusion for treatment of symptomatic cervical disc disease: a meta-analysis of randomized controlled trials

OBJECTIVE

The purpose of this study is to compare the effectiveness and safety of cervical disc arthroplasty with anterior cervical discectomy and fusion for treatment of symptomatic cervical disc disease. Anterior cervical discectomy and fusion (ACDF) is the conventional surgical treatment for symptomatic cervical disc disease. Recently, cervical disc arthroplasty (CDA) has been developed to address some of the shortcomings associated with ACDF by preserving function of the motion segment. Controversy still surrounds regarding whether CDA is better.

METHODS

We systematically searched six electronic databases (Medline, Embase, Clinical, Ovid, BIOSIS and Cochrane registry of controlled clinical trials) to identify randomized controlled trials (RCTs) published up to April 2014 in which CDA was compared with ACDF for the treatment of symptomatic cervical disc disease. Effective data were extracted after the assessment of methodological quality of the trials. Then, we performed the meta-analysis.

RESULTS

Eighteen relevant RCTs with a total of 4061 patients were included. The results of the meta-analysis indicated that CDA was superior to ACDF regarding better neurological success (P < 0.00001), greater motion preservation at the operated level (P < 0.00001), fewer secondary surgical procedures (P < 0.00001), and fewer rates of adverse events (P < 0.00001) but inferior to ACDF regarding operative times (P < 0.00001). No significant difference was identified between the two groups regarding blood loss (P = 0.87), lengths of hospital stay (P = 0.76), neck pain scores (P = 0.11) and arm pain scores (P = 0.78) reported on a visual analog scale.

CONCLUSION

The meta-analysis revealed that CDA demonstrated superiorities in better neurological success, greater motion preservation at the operated level, lower rate of adverse events and fewer secondary surgical procedures compared with ACDF. However, the benefits of blood loss, lengths of hospital stay, neck and arm pain functional recovery are still unable to be proved.