| BackgroupMultilevel cervical myelopathy(MCM) caused by multisegment cervical spondylotic myelopathy(MCSM) or ossification of posterior longitudinal ligament(OPLL) is frequently encountered in clinical practice. Patients with obvious clinical symptoms and severe or deteriorative nerve dysfunction should require surgical treatment generally. Since lower surgical risk for cervical myelopathy of1or2segments, most scholars choose preferentially the anterior decompression and fusion procedure. However, as the surgical efficacy is generally difficult to predict and the high incidence of complications for cervical myelophy of3or more than3segments, there is considerable controversy over which surgical approach (anterior or posterior) will receive the best clinical outcomes.In1895, Chipault firstly explained the exposed approach of anterior cervical operation on the French neurosurgery teaching materials. In1955, the orthopaedic surgery experts, Robinson and Smith had reported the anterior cervical discectomy, which marked a new era for the surgical treatment of cervical spondylosis. In the subsequent decades, with the introduction of the intervertebral fusion and anterior plate internal fixation technique, anterior cervical surgery had received further development and improvement. At present, anterior cervical surgeries mainly include the anterior cervical discectomy and fusion, the anterior corpectomy (CORP) and fusion, the discontinuous segmental decompression, and the artificial disc replacement approach. But for the patients with multilevel cervical myelopathy caused by MCSM or OPLL, anterior CORP and fusion is the most used operation amount the anterior approaches.Until the1960s, posterior cervical laminectomy had been the standard surgical treatment for the multilevel cervical myelopathy caused by MCSM or OPLL. The spinal cord could obtain extensive decompression by removing the cervical lamina. However, the integrity of the anatomical structure function at the back of the cervical spine also suffered damage during the procedure. More and more surgical complications after laminectomy, such as cervical instability, kyphotic deformity and long-term neurologic deterioration, were gradually reported, which promote greatly the exploration and research of the alternative posterior surgery. Besides, the orthopaedic surgeons who adhere to the application of posterior cervical laminectomy began to use the lateral mass screw and rod system to fix the cervical vertebra after surgical decompression. In1983, Hirabayashi firstly reported the posterior cervical laminoplasty(LAMP), and demonstrated an excellent clinical efficacy for the treatment of multilevel cervical myelopathy caused by OPLL. After that, LAMP has been widely used, and through continuous improvement and development, it has gradually replaced the lamincetomy and become the main posterior approach for the treatment of multilevel cervical myelopathy caused by MCSM or OPLL.The choice of anterior approach is mainly based on that the constriction resulting in the cervical myelopathy is at the front of the spinal cord. Anterior approach can remove directly the lesions such as the protruded intervertebral disc, osteophyte and ossified ligament. In addition, through intervertebral bone graft and fusion, anterior approach can also receive immediate stability in cervical vertebra and correct the cervical kyphotic deformity at the same time. However, for patients with multilevel cervical myelopathy, anterior approach seems to be of more surgical risk and complications as the more segments of cervical myelophy. The common complications include fusion failure, dysphagia and dysphonia. Besides, recurrent neurologic deterioration caused by the adjacent segment degeneration after anterior decompression and fusion is another important issue needed to be resolved for anterior approach surgery. By contrast, posterior approach is relatively safe and takes less time, but can’t remove the constriction lesion directly. It can relieve the spinal cord and obtain decompression by expanding the volume of cervical canal indirectly. Whereas, indirect decompression is often unable to receive satisfactory clinical efficacy if the constriction lesion in front of the spinal cord is too huge, or there exist cervical kyphotic deformity preoperatively. In addition, the reasons for surgical complications including the nerve paralysis and axial neck pain are unclear, which may affect the outcome of surgical treatment severely once it happen. Therefore, as for the treatment of multilevel cervical myelopathy caused by MCSM or OPLL, there is considerable controversy over which surgical approach will receive the best clinical outcome for the minimum cost, which needs to be proved with further study and discussion.Although there are many articles that reported the comparison of clinical outcomes between anterior CORP and posterior LAMP for the treatment of multilevel cervical myelophy, these studies contained relatively small sample size, lack of unified case selection criteria, and adopted varied evaluation parameters. All of these defects existing in these studies make it difficult to conclude specific surgical selection criteria. While Meta-analysis is a new analysis method used in medical field that integrates the results of several independent studies considered to be combinable. The Meta-analysis approach may overcome the deficiencies of individual studies by combing multiple independent trials evaluating the same interventions, more accurately reflect the results in mathematics and realize the combination of literature evaluation and statistical methods. Since its introduction, Meta-analysis has established itself as an influential blanch of clinical epidemiology and health service research. Therefore, through using the Meta-analysis, the present study systematically assessed the clinical efficacy and surgery-related complications of anterior CORP and posterior LAMP for the treatment of multilevel cervical myelophy, expecting to provide reference to some extent for clinical practice and decision.ObjectiveTo systematically evaluate the clinical efficacy and surgical-related complications of anterior CORP and posterior LAMP for the treatment of multilevel cervical myelophy, in order to provide reference for clinical practice and decision.Methods1、According to the requisition of systematic evaluation, we formulate detailed standardization of the inclusion and exclusion criteria including the type of research subjects, study population, interventions and outcome of events.2、An extensive search of literature was performed in Pubmed, Embase, and the Cochrane library. The language was restricted to English and the year of publication from1990to May2013. The following search terms and strategies were used:(1) cervical myelopathy OR cervical stenosis OR OPLL;(2) CORP OR anterior decompression OR anterior approach OR ventral decompression OR ventral approach;(3) LAMP OR posterior decompression OR posterior approach OR dorsal decompression OR dorsal approach;(1) and (2) or (3). Reference lists from the studies selected by searching were checked to identify additional articles meeting the inclusion in this systematic review.3、To assess the overall strength and quality of evidence for the various outcome parameters, a quality assessment was carried out in the style of the GRADE profiler. Study design, study limitations, risk for bias, study inconsistency, indirectness, and imprecision were rated according to the GRADE profiler(Grades of Recommendation, Assessment, Development and Evaluation).4、All statistical tests were performed with SPSS software (Version18.0, IBM Corporation, USA) and Review Manager version5.2(Cochrane Collaboration, Oxford, UK). Considering different number of surgical segments may affect the combined effect size, a subgroup analysis was performed according to the mean number of surgical segments:subgroup A included the studies in which the mean number of surgical segments was between2and3, whereas subgroup B included the studies in which the mean number of surgical segments was equal to3or more. Heterogeneity was tested using Chi-square test and quantified by calculating I2statistic, for which P<0.1and I2>50%was considered to be statistically significant. For the pooled effects, weighted mean difference (WMD) or standard mean difference (SMD) was calculated for continuous variables according to the consistency of measurement units, and odds ratio (OR) was calculated for dichotomous variables. Continuous variables are presented as mean differences and95%confidence intervals (CI), whereas dichotomous variables are presented as odds ratios and95%CI. Random-effects or fixed-effects models were used depending on the heterogeneity of the studies included. If meta-analysis was impractical, only descriptive analysis was performed. Sensitivity analysis was applied to test the strength and stability of the outcomes. Publication bias was evaluated through funnel plots and with the Egger’s tests. Results1、General characteristics of the enrolled studiesAccording to the restricted conditions, inclusion and exclusion criteria, a total of12articles were included for this systematic review and meta-analysis, of which2were prospective cohort studies and10were retrospective cohort studies. The quality of evidence using GRADE was not upgraded and remained relatively low due to the unspecific description of study design and the less rigorous methodology in observational studies. These12studies contained12cohorts with a total of768patients, of which320underwent anterior CORP and448underwent posterior LAMP. There were no significant differences between the two groups in terms of surgical age, gender ratio, duration of symptoms and follow up (P<0.05).2、Results of Meta-analysis2.1Meta-analysis of JO A scoreNine studies used the JOA score to assess the clinical outcome, seven of which provided preoperative JOA score with standard deviation. The test of heterogeneity showed that there was no statistical heterogeneity among studies included in the Meta-analysis (subgroup A:P=0.35,12=10%; subgroup B:P=0.84,I2=0%), indicating using the fixed-effects model. Meta-analysis demonstrated that there was no significant difference in the preoperative JOA score between the two groups in either subgroup A or subgroup B [subgroup A:WMD=-0.24(-0.82,0.34), P=0.42; subgroup B:WMD=0.63(-0.32,1.57), P=0.19], indicating that the preoperative neurological function was similar between the CORP group and the LAMP group.Nine studies used the JOA score to assess the clinical outcome, seven of which provided postoperative JOA score with standard deviation. The test of heterogeneity showed that there was no statistical heterogeneity among studies included in subgroup A (P=0.35, I2=10%), and significant heterogeneity among studies included in subgroup B (P=0.84,I2=0%), indicating using the random-effects model. Meta-analysis demonstrated that there was a significant difference in the postoperative JOA score between the two groups in subgroup A [WMD=1.03(0.46,1.61), P<0.01]. But in subgroup B, there was no significant difference in the postoperative JOA score between the two groups [WMD=0.22(-1.34,1.78), P=0.79], indicating that in subgroup A, the postoperative neurological function in the CORP group was superior to that in the LAMP group, but was similar between the two groups in subgroup B.2.2Meta-analysis of neurological recovery rateNine studies used neurological recovery rate to assess the degree of neurological function improvement, six of which provided the mean with standard deviation. The test of heterogeneity showed that there was no statistical heterogeneity among studies included in subgroup A (P=0.14, I2=46%), and significant heterogeneity among studies included in subgroup B (P=0.01,12=84%), indicating using the random-effects model. Meta-analysis demonstrated that there was a significant difference in the postoperative neurological recovery rate between the two groups in subgroup A [WMD=12.94(4.45,21.43), P<0.01]. But in subgroup B, there was no significant difference in the postoperative neurological recovery rate between the two groups [WMD=2.35(-23.09,27.78), P=0.86], indicating that in subgroup A, the postoperative neurological recovery rate in the CORP group was superior to that in the LAMP group, but was similar between the two groups in subgroup B.2.3Meta-analysis of complication rateThere were3articles that did not report any complication related to surgery. Therefore, only nine studies provided a list of the postoperative complications. The test of heterogeneity showed that there was no statistical heterogeneity among studies included in the Meta-analysis (subgroup A:P=0.63, I2=0%; subgroup B:P=0.71, I2=0%), indicating using the fixed-effects model. Meta-analysis demonstrated that there was no significant difference in the postoperative complication rate between the two groups in subgroup A [OR=1.28(0.73,2.25), P=0.39]. But in subgroup B, there was a significant difference in the postoperative complication rate between the two groups [OR=1.84(1.09,3.12), P=0.02], indicating that in subgroup A, the postoperative complication rate was similar between the two groups, but was higher in the CORP group than that in the LAMP group in subgroup B.2.4Meta-analysis of reoperation rateThere were nine studies that reported the complication-related reoperation rates. The test of heterogeneity showed that there was no statistical heterogeneity among studies included in the Meta-analysis (subgroup A:P=0.13, I=47%; subgroup B: P=0.40,12=2%), indicating using the fixed-effects model. Meta-analysis demonstrated that there was significant difference in the reoperation rate between the two groups in either subgroup A or subgroup B [subgroup A:OR=6.99(2.11,23.13), P<0.01; subgroup B:OR=12.13(3.92,37.54), P<0.01], indicating that the reoperation rate in the CORP group was significantly higher than that in the LAMP group.2.5Meta-analysis of operation time and blood lossA total of five studies reported the operation time and blood loss. The test of heterogeneity showed that there was statistical heterogeneity among studies included in the Meta-analysis of operation time (subgroup A:P<0.01, I2=89%; subgroup B: P=0.02, I2=82%), and significant heterogeneity among studies included in the Meta-analysis of blood loss (subgroup A:P=0.01, I2=55%; subgroup B:P=0.02, I2=82%), indicating using the random-effects model. Meta-analysis demonstrated that operation time and blood loss were apparent higher in the CORP group compared with the LAMP group in either subgroup A or subgroup B, although there were significant heterogeneity among the studies in the two subgroups. This indicated that the surgical trauma in the CORP group was obviously higher than that in the LAMP group.Conclusions1、For cervical myelophy of less than3segments, anterior CORP is superior to posterior LAMP in terms of postoperative neurological function condition and recovery rate, similar in surgical complication rate, but higher reoperation rate and more surgical trauma for anterior CORP compared with posterior LAMP.2、For cervical myelophy of equal to3or more, posterior LAMP has similar postoperative neurological function condition and recovery rate compared with anterior CORP, but lower surgical complication rate and reoperation rate, and less surgical trauma in posterior LAMP than that in anterior CORP.3、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. |
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