Anterior Versus Posterior Approach for Four-Level Cervical Spondylotic Myelopathy

n Feature Article

Anterior Versus Posterior Approach for Four-level Cervical Spondylotic Myelopathy

Dasheng Lin, MD; Wenliang Zhai, MD; Kejian Lian, MD; Liangqi Kang, MD; Zhenqi Ding, MD

abstract Full article available online at Healio.com/Orthopedics. Search: 20131021-28

The purpose of this study was to compare the results of 2 surgical strategies for 4-level cervical spondylotic myelopathy: a hybrid procedure using anterior cervical diskectomy and fusion (ACDF) combined with segmental corpectomy versus posterior laminectomy and fixation. Between 2002 and 2010, fifty-one patients with consecutive 4-level cervical spondylotic myelopathy were treated surgically, with 27 patients undergoing the Figure: Intraoperative photograph showing how hybrid procedure and 24 undergoing posterior laminectomy and fixation. Radiologic the laminae were resected and the spinal cord was data were compared between the 2 groups, including cervical curvature and cervical floated. range of motion (ROM) in the sagittal plane. Pre- and postoperative neurological status was evaluated using the Japanese Orthopaedic Association (JOA) scoring system and the Nurick grading system. Mean ROM at last follow-up was not significantly different between the 2 groups (P..05). In the hybrid group, mean JOA score and Nurick grade improved from 9.661.4 and 2.7460.45 respectively, preoperatively, to 13.961.3 and 0.8660.38 respectively, postoperatively. In the fixation group, mean JOA score and Nurick grade improved from 9.461.2 and 2.8160.42 respectively, preoperatively, to 13.161.5 and 1.3260.36 respectively, postoperatively. The JOA scores and Nurick grades at last follow-up were significantly different between the 2 groups P( ,.05). In patients with preoperative cervical kyphosis, preoperative JOA score and Nurick grade were not significantly different between the 2 groups P( ..05); however, JOA scores and Nurick grades at last follow-up showed better improvement in the hybrid group than in the fixation group P( ,.01). In patients with preoperative cervical lordosis, the preoperative and last follow-up JOA score and Nurick grade were not significantly different between the 2 groups (P..05).

The authors are from the Department of Orthopaedic Surgery, the Affiliated Southeast Hospital of Xiamen University, Orthopaedic Center of People’s Liberation Army, Zhangzhou, China. The authors have no relevant financial relationships to disclose. Correspondence should be addressed to: Zhenqi Ding, MD, Department of Orthopaedic Surgery, Affiliated Southeast Hospital of Xiamen University, Orthopaedic Center of People’s Liberation Army, #269 Zhanghua Rd, Zhangzhou 363000, Fujian, China ([email protected]). doi: 10.3928/01477447-20131021-28

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he optimal surgical approach for multilevel cervical spondylotic Table 1 Tmyelopathy remains controversial. Pre- and Postoperative Characteristics of the Groups When 3 or more levels are involved in anterior corpectomy and fusion, failure rates Characteristic Anterior Posterior P increase. Lack of stability after anterior re- No. (male:female) 27 (19:8) 24 (17:7) ..05 construction seems to be the cause of this Mean age at surgery, y 52.269.7 54.5610.3 ..05 failure.1-3 Multilevel anterior cervical diskectomy and fusion (ACDF) can be asso- Mean follow-up, mo 39.865.2 41.566.4 ..05 ciated with high rates of fusion. The tech- Mean cervical curvature, deg ..05 nique is safe and effective for managing Lordotic 12 14 multilevel cervical spondylotic myelopa- Kyphotic 15 10 thy and may obviate the need for circum- Mean ROM, deg ..05 4 ferential procedures. However, in many Preoperative 65.263.4 67.663.8 patients, stenotic pathology is not found at Postoperative 42.762.7 40.562.2 the disk level alone and the available space Mean operative time, min 124647 115636 ..05 required for removal of the osteophytes is limited.4 Posterior strategies can also pro- Mean intraoperative blood loss, mL 2596131 2846120 ..05 vide canal decompression, but the degree Mean JOA score of decompression is sometimes insufficient Preoperative 9.661.4 9.461.2 ..05 because the ventral compression is not Postoperative 13.961.3 13.161.5 ,.05 solved. Instability following laminectomy Mean Nurick grade has also raised concerns.5,6 Therefore, for Preoperative 2.7460.45 2.816.42 ..05 multilevel cervical spondylotic myelopa- Postoperative 6 6 , thy, the optimal approach to provide satis- .86 .38 1.32 .36 .05 factory decompression and minimize com- Abbreviations: deg, degrees; JOA, Japanese Orthopaedic Association; ROM, range of motion. aAs measured in the sagittal plane. plications remains to be determined. The current study was designed to compare the use of a hybrid procedure (ACDF combined with segmental corpec- of follow-up data. Patients with cervical routine procedures to expose the anterior tomy) with the use of posterior laminec- ossification of the posterior longitudinal longitudinal ligament, a rectangular area tomy and fixation for the treatment of cer- ligament or spinal injuries due to trauma of the ligament was resected. According vical spondylotic myelopathy involving 4 were excluded. Informed written consent to preoperative imaging findings, the ver- levels and to evaluate the factors that in- was acquired from all patients. tebrae corresponding with the level of the fluence the outcomes of the 2 techniques. Of the 51 patients, 27 were treated with most severe stenosis was confirmed. At the hybrid procedure (hybrid group) and 24 the other levels, a curette and a laminec- Materials and Methods were treated with posterior laminectomy tomy rongeur were used for diskectomy, Patient Recruitment and fixation (fixation group). No signifi- and distraction posts were inserted in a From July 2002 to July 2010, fifty-one cant differences were found in the baseline convergent fashion to restore regional patients seen at the authors’ department characteristics of the 2 groups, including kyphosis. All osteophytes were removed who met the following criteria were re- patients’ preoperative cervical curvature, from the anterior face of the spine, and a cruited: (1) underwent either the hybrid mean preoperative cervical range of motion wedge-shaped autogenous iliac crest graft procedure or the posterior laminectomy (ROM) in the sagittal plane, and Japanese was used for fusion. Then, corpectomy of and fixation procedure for 4-level cervical Orthopaedic Association (JOA) scores and the vertebrae was performed correspond- spondylotic myelopathy; (2) had complete Nurick grades7 (P..05) (Table 1). ing with the level of the most severe ste- medical records and related radiographic nosis, and distraction posts were inserted data, including pre- and postoperative ra- Surgical Technique in a convergent fashion to restore regional diographs, computed tomography (CT) For the hybrid procedure, patients kyphosis. A wedge-shaped autogenous scans, and magnetic resonance imaging were placed in the supine position with iliac crest graft or a titanium mesh cage (MRI); and (3) had 24 months or more the head slightly extended. Following and plate was used for fixation (Figure 1).

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2 1A 1B Figure 2: Intraoperative photograph showing how the laminae were resected and the spinal cord was floated.

inserted into the start- were taken the day of surgery; 3, 6, 12, ing hole, angling lat- and 24 months postoperatively; and at last erally approximately follow-up. The JOA scoring system and 20° and parallel to the Nurick grading system were used to the facet joint in the assess the postoperative improvement of sagittal plane. This neurological status.7,8 can be judged best by placing a thin, flat in- Statistical Analyses strument into the joint Statistical analyses were performed us- to be fused. Drill- ing SPSS version 13.0 statistical software ing proceeded care- (SPSS, Inc, Chicago, Illinois). A paired t fully just to, but not test and group t test were used for com- through, the second parison of quantitative data. Fisher’s exact 1C 1D cortex because bicor- test was applied for qualitative data. The Figure 1: Preoperative sagittal T2-weighted magnetic resonance image of a tical fixation has not results were considered significant at aP 45-year-old man with consecutive 4-level cervical spondylotic myelopathy been demonstrated to value less than .05. (A). The patient underwent anterior cervical diskectomy and fusion combined with segmental corpectomy. Postoperative anteroposterior (B) and be of biomechanical lateral (C) radiographs and sagittal T2-weighted magnetic resonance image advantage. A depth Results (D) showing that anterior cervical diskectomy and fusion combined with gauge was then in- Mean operative times were 124647 segmental corpectomy achieved effective decompression and stability. serted to determine minutes (range, 90-180 minutes) for the screw length, and a hybrid group and 115636 minutes (range, pedicle screw system 75-180 minutes) for the fixation group. For the fixation procedure, patients were was used for fixation. The laminae were Mean intraoperative blood loss was placed in the prone position and a midline resected on the levels to be decompressed 2596131 mL (range, 160-400 mL) for the incision was made. Subsequently, the para- (Figure 2), and small wedges of bone were hybrid group and 2846120 mL (range, spinous muscles were peeled back to ex- placed adjacent to bilateral joints to facili- 200-600 mL) for the fixation group. pose the bilateral laminae of the affected tate fusion. Mean operative time and blood loss were vertebrae. The starting point for the pedicle not significantly different between the 2 screw is just medial to the hillock of the lat- Postoperative Care and Assessment of groups (P..05). Patients were followed eral mass in the coronal plane and midway Surgical Outcomes up for a mean of 39.865.2 months (range, between the surfaces of the superior and Postoperatively, patients were told to 24-56 months) in the hybrid group and inferior articular process. A 2-mm burr was wear neck braces for 3 months for protec- 41.566.4 months (range, 24-60 months) used to start the hole. Next, a hand drill was tion. Radiographs, CT scans, and MRIs in the fixation group.

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performed. Three patients demonstrated Table 2 asymptomatic adjacent segment degenera- Surgical Outcomes in the Anterior or Posterior With tion, and no specific measure was taken. Different Cervical Curvature No case of implant failure was observed. In the fixation group, 3 patients had C5 Mean JOA Score Mean Nurick Grade nerve root palsy symptoms (1 bilaterally Cervical Curvature No. of Cases Preop Postop Preop Postop and 2 laterally). The time of initial onset of C5 palsy symptoms was within 8 hours Anterior postoperatively. Patients were treated con- Lordotic 12 9.761.1 13.561.3 2.586.38 0.766.35 servatively using oral neurotrophic drugs, Kyphotic 15 9.561.5 14.261.2 2.826.46 0.946.33 hyperbaric oxygen therapy, and exercise. Posterior Three months postoperatively, all patients’ Lordotic 14 9.461.1 13.361.5 2.786.35 1.116.36 symptoms resolved. Two patients had asymptomatic adjacent segment degeneration, Kyphotic 10 9.461.4 12.761.3 2.856.41 1.596.43 and no specific measures were taken. Abbreviations: JOA, Japanese Orthopaedic Association; postop, postoperative; preop, preoperative. Discussion The optimal surgical approach for cervical spondylotic myelopathy remains a In the hybrid group, 12 patients had decreased from 2.7460.45 (range, 2-4) matter of debate, especially for multilevel preoperative cervical lordosis (mean, preoperatively to 0.8660.38 (range, 0-2) cervical spondylotic myelopathy. Many 9.5°63.8°; range, 5°-12°), and 15 had postoperatively. Mean Nurick grade for the articles on cervical reconstruction after cervical kyphosis (mean, 8.9°64.1°; fixation group improved from 2.8160.42 a multilevel corpectomy have reported range, 6°-13°). At last follow-up, mean (range, 2-4) preoperatively to 1.3260.36 a high failure rate of long segment ante- ROM in the sagittal plane decreased (range, 0-3) postoperatively. Mean Nurick rior cervical plate fixation or fibular strut from 65.2°63.4° (range, 52°-78°) preop- grade at last follow-up was significantly grafting after a corpectomy spanning eratively to 42.7°62.7° (range, 34°-66°) different between the 2 groups (P,.05). more than 3 levels.1-3 The lack of fixation postoperatively. In the fixation group, 14 For patients with preoperative cervi- points is likely the mechanism underlying patients had preoperative cervical lordosis cal kyphosis, mean preoperative JOA the relatively high complication rates and (mean, 9.7°64.3°; range, 6°-15°), and 10 scores and Nurick grades were not sig- lower fusion rates seen in series with lon- had cervical kyphosis (mean, 8.5°63.7°; nificantly different between the 2 groups ger corpectomy constructs.9,10 range, 5°-12°). At last follow-up, mean (P..05), but the JOA score and Nurick Ikenaga et al11 introduced an anterior ROM in the sagittal plane decreased grade showed better improvement at last pedicle screw fixation technique after from 67.6°63.8° (range, 58°-82°) preop- follow-up for the hybrid procedures group multilevel corpectomy. It is likely that this eratively to 40.5°62.2° (range, 32°-60°) than for the fixation group P( ,.01). In the technique will result in better clinical out- postoperatively. Mean preoperative and patients with preoperative cervical lordo- comes with fewer complications for the last follow-up ROM were not significantly sis, mean preoperative and last follow-up treatment of patients with multilevel cer- different between the 2 groups (P..05). JOA score and Nurick grade were not sig- vical spondylotic myelopathy. However, Mean JOA score for the hybrid group nificantly different between the 2 groups this is a plurality of special techniques increased from 9.661.4 (range, 6-13) pre- (P..05) (Tables 1, 2; Figure 3). for an even greater plurality of potential operatively to 13.961.3 (range, 10-16) Complications for the hybrid procedure difficulties. Multilevel anterior cervical postoperatively, with a mean improvement include dysphagia symptoms, with 2 pa- diskectomy and fusion can be associated rate of 57.7%610.4%. Mean JOA score for tients reporting this complication. The time with high rates of fusion. The technique the fixation group improved from 9.4 61.2 of initial onset of the dysphagia symptom is safe and effective for managing multi- (range, 5-14) preoperatively to 13.161.5 was within 3 days postoperatively. One level cervical spondylotic myelopathy and (range, 9-16) postoperatively, with a mean month postoperatively, 1 patient’s symp- results in shorter hospital stays, less intra- improvement rate of 49.3%611.2%. Mean toms resolved and symptoms in the other operative blood loss, and shorter operative JOA score at last follow-up was significant- patient were relieved but not completely times for patients.4,12,13 However, in many ly different between the 2 groups (P,.05). resolved. Physical examination showed patients, stenotic pathology is not simply Mean Nurick grade for the hybrid group no abnormalities, and no intervention was at the disk level, and the available space

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required for removal of the osteophytes is limited. During the process, the gradu- ally decompressed bony structure causes repeated bulging of the spinal cord. This leads to repeated severing, which may cause spinal damage or even paraplegia. Yilmaz et al14 demonstrated that skip corpectomy is a good alternative to standard 3-level corpectomy to improve stability, especially during lateral bending. Under pure moment loading, the screws of a cervical multilevel plate experience the highest pullout forces during axial ro- tation. According to the theoretical analysis, direct removal of the osteophytes by hybrid procedures, such as ACDF combined with segmental corpectomy, offers better decompression, reserves more vertebrae, and provides an additional screw purchase and strengthened the construct. Moreover, the wedge-shaped autogenous iliac crest graft allows substantial restora- 3A 3B tion of cervical lordosis, and hence is the- Figure 3: Preoperative sagittal T2-weighted magnetic resonance image showing significant cervical spinal oretically the optimal option. Compared stenosis resulting in compression of the spinal cord (A). Postoperative sagittal T2-weighted magnetic with posterior laminectomy and fixation resonance image showing that posterior laminectomy and fixation achieved effective decompression for preoperative cervical lordosis (B). in the current study, the hybrid procedures showed better clinical outcomes, especially for the preoperative kyphotic alignment of patients.15 Meanwhile, posterior surgery rable preoperative JOA scores and Nurick of the cervical spine.14 had no advantage for preoperative kyphotic grades, the preoperative kyphotic align- Posterior laminectomy with decompres- alignment of the cervical spine in the cur- ment of the cervical spine managed ante- sion and fixation is a well-established tech- rent study. Therefore, knowledge of the riorly had better outcomes than that man- nique and is relatively simple and safe. The preoperative cervical curvature is essential aged posteriorly. Anterior cervical current authors found that it is an effective for the efficacy of posterior decompression, diskectomy and fusion combined with strategy for multilevel cervical spondylotic thus narrowing the scope of application. segmental corpectomy can directly relieve myelopathy. Effective and safe decompres- In the hybrid group, although no case compression, provide an additional screw sion of the spinal cord was accomplished of implant failure was observed at the last purchase and strengthen the construct, for most patients. It can also provide imme- follow-up, 3 patients demonstrated asymp- and allow substantial restoration of cervi- diate and long-term stability of the cervical tomatic adjacent segment degeneration. cal lordosis. Despite its limitations with spine and avoid development of kyphosis. Meanwhile, patients undergoing multilevel regard to cervical curvature, posterior fix- Nevertheless, because the compression is procedures have a high risk for dyspha- ation can achieve effective decompression located anteriorly, decompression in pos- gia. Long-term follow-up is necessary to and maintain or restore stability of the cer- terior surgery is indirect, without removal evaluate the safety and effectiveness of this vical spine using multilevel laminectomy, of the osteophytes. Moreover, multilevel technique, especially with regard to the po- thereby improving symptoms of spinal cervical spondylotic myelopathy is often tential complications and the incidence of cord compression, especially for patients accompanied by various levels of nerve adjacent segment degeneration.16-19 with cervical lordosis. root compression, and posterior surgery is ineffective for the decompression of nerve Conclusion References roots, causing postoperative symptoms. Both anterior and posterior surgery can 1. Vaccaro AR, Falatyn SP, Scuderi GJ, et al. Furthermore, it has been reported that seg- achieve satisfactory outcomes. Although Early failure of long segment anterior cervical plate fixation.J Spinal Disord. 1998; mental root palsy occurs in 3.2% to 28.6% patients in the current study had compa- 11(5):410-415.

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