Eur Spine J (2015) 24:31–39 DOI 10.1007/s00586-014-3607-1
REVIEW ARTICLE
Anterior cervical discectomy versus corpectomy for multilevel cervical spondylotic myelopathy: a meta-analysis Shan-Wen Xiao • Hua Jiang • Li-Jing Yang Zeng-Ming Xiao
•
Received: 12 April 2014 / Revised: 27 September 2014 / Accepted: 28 September 2014 / Published online: 18 October 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose This is a meta-analysis to compare the results between anterior cervical discectomy fusion (ACDF) and anterior cervical corpectomy fusion (ACCF) for the patients with multilevel cervical spondylotic myelopathy (MCSM). Methods Systematic review and meta-analysis of cohort studies between ACDF with plate fixation and ACCF with plate fixation for the treatment of MCSM. An extensive search of literature was performed in PubMed, Mediline, Embase and the Cochrane library. The following outcome measures were extracted: JOA scores, fusion rate, cervical lordosis (C2–7), complications, blood loss and operation time. Data analysis was conducted with RevMan 5.0. Results Four cohorts (six studies) involving 258 patients were included in this study. The pooled analysis showed that there was no significant difference in the postoperative JOA score [WMD = -0.14 (-1.37, 1.10), P = 0.83], fusion rate [OR = 0.84 (0.15, 4.86), P = 0.85] between two group. However, there was significant difference in the cervical lordosis [WMD = 3.38 (2.52, 4.23), P \ 0.00001], surgical complication rate and instrument related complication rate (P = 0.01, 0.005 respectively), blood loss [WMD = -52.53 (-73.53, -31.52), P \ 0.00001], and operation time [WMD = -14.10 (-20.27, -7.93), P \ 0.00001].
S.-W. Xiao and H. Jiang contributed equally to this work. S.-W. Xiao H. Jiang L.-J. Yang Z.-M. Xiao (&) Department of Spine Surgery, The First Affiliated Hospital of Guangxi Medical University, Shuangyong Road No. 6, Nanning 530021, China e-mail: [email protected]
Conclusions As compared with ACCF with plate fixation, ACDF with plate fixation showed no significant differences in terms of postoperative JOA score, fusion rate, but better improved cervical lordosis, lower complication and smaller surgical trauma. As the limitations of small sample and short follow-up in this study, it still could not be identified whether ACDF with plate fixation is more effective and safer than ACCF with plate fixation. Keywords Anterior decompression Cervical spondylotic myelopathy Discectomy Corpectomy Meta-analysis
Introduction Cervical spondylotic myelopathy is a common age-related degenerative disease, which can lead to motor and sensory dysfunction (significant pain, instability, disturbances). If the symptoms do not respond to conservative treatment, surgical treatment should be considered [1, 2]. The anterior procedures, including multi-level ACDF (anterior cervical discectomy fusion) and single-/multilevel ACCF (anterior cervical corpectomy fusion) [3–5], were recognized as reliable and effective way in treating cervical spondylotic myelopathy [6–8]. But there is no clear conclusion on which method, ACDF or ACCF, is better [9]. Therefore, a randomized controlled trial (RCT) is a necessary guide to determine which method is better for the treatment of MCSM. However, there was no RCT on this subject in the published papers; therefore, we performed a meta-analysis to assess the effectiveness and safety of these two surgical procedures for MCSM without continuous ossification of posterior longitudinal ligament or large dorsal osteophytes.
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Materials and methods Inclusion criteria All studies on treatment of MCSM were reviewed. The criteria for inclusion of an article were: (1) patients were 18 years old or greater; (2) patients with symptomatic cervical compressive myelopathy (C2 segments) due to CSM; (3) purpose of interventions: ACDF with plate fixation (ACDF group) and ACCF with plate fixation (ACCF group), ACDF with cage fusion and ACCF with titanium mesh fusion; (4) outcome measurements: preoperative and postoperative Japanese orthopedic association (JOA) scores, fusion rate, preoperative and postoperative cervical lordosis (C2–C7), complications, blood loss, operation time; (5) all included trials were followed up at least 1-year after surgery; (6) patients were excluded if they only had one-level disc disease, acute spinal fracture, infection, tumor, osteoporosis, rheumatoid arthritis, severe spondylolisthesis, continuous ossification of posterior longitudinal ligament (OPLL), multiple large dorsal osteophytes at multiple levels behind the vertebral body, ligamentum flavum hypertrophy, had surgical history of cervical spine, without anterior plate or cage/titanium mesh. Search strategy A computerized search of literature published between 1900 and December 2013 was performed using PubMed, Mediline, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) (Wiley Online Library). The following key words were used for search: ‘‘cervical spondylotic myelopathy’’, ‘‘anterior cervical discectomy fusion’’, ‘‘anterior cervical corpectomy’’, ‘‘anterior decompression’’, ‘‘anterior surgery’’, with various combinations of the operators ‘‘AND’’, ‘‘NOT’’, and ‘‘OR’’. We restricted the language to English. Selection of studies Two reviewers (SWX and HJ) independently reviewed all subjects, abstracts, reference lists and the full text of articles that were potentially eligible based on abstract review. Then the eligible trials were selected according to the inclusion criteria. When consensus could not be reached, a third reviewer (lJY) was consulted to resolve the disagreement. Data extraction Two reviewers (SWX and HJ) extracted data independently and cross checked mutually. The data extracted included the following categories: patients (selection criteria and
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Fig. 1 The procedure of literature search
diagnoses, age, sex, length of follow-up), treatments (type of graft, intervention details) and clinical outcomes (JOA, fusion rate, cervical lordosis, complications, blood loss and operation time). Data analysis Data analysis was performed with RevMan 5.0 (the Cochrane Collaboration). Two reviewers (SWX and HJ) monitored the data input to ensure there were no errors. Risk ratio (RR) was used as a summary statistic to analyze dichotomous variables, and the standardized mean difference (SMD) was used to analyze continuous variables. Both were reported with 95 % confidence intervals (CIs), and a P value of 0.05 was used as the level of statistical significance. Random-effects or fixed-effects models were used depended on the heterogeneity of the studies included. Heterogeneity was tested by using I-square test, where I2 [ 50 % implied heterogeneity.
Results Search results The search strategy yielded 387 relevant citations, yielding 6 studies meet the inclusion criteria. Three studies [10–12] studied at the same institute and team, the cases maybe overlapped, and we selected one article [10]. As a result, a total of four studies [10, 13–15] were used for this meta-
94.3 ± 25.3 87.3 ± 21.7 Autograft, CSLP plate Autograft, SOLIS cage, CSLP plate
C4–7: 11
C3–6:4
C4–7:6
C3–7:5
C4–7: 17
C3–6: 10
C4–7: 8,
C3–7:7
15 (11/4) 2012 Song [15]
25 (19/6)
50.3 ± 7.5
54.1 ± 9.8
Autograft, Titanium cage, plate
These 6 studies contained 4 cohorts with a total of 258 patients, of which 139 underwent ACDF and 119 underwent ACCF. There were no significant differences between the two groups in terms of age, gender ratio, location of surgery, length of fusion and follow-up (P \ 0.05). Baseline characteristics of the two treatment groups are presented in Table 1. No RCT were identified, all studies included were retrospective studies. We used the Newcastle Ottawa Quality Assessment Scale (NOQAS) to assess the quality of each study. This scale for non-randomized case controlled studies and cohort studies was used to allocate a maximum of nine points for the quality of selection, comparability, exposure, and outcomes for study participants. Of the studies, three scored 8 points and one scored 7 points. Hence, the quality of each study was relatively high (Table 2).
Autograft and PEEK cages, plate C3–7: 12
Baseline characteristics and quality assessment
C3–6: 13
C3–7: 11
analysis. The literature search procedure was shown in Fig. 1.
C3–6: 26 55.2 ± 10.1 24 (13/11) 2011 Guo [14]
43 (24/19)
52.7 ± 9.4
Autograft.TMC, semi- [2 years constrained, plate Autograft, cages, semiconstrained, plate C3–6: 23 C4–7: 28 C3–6: 21 C4–7: 25 57.91 ± 10 63 (43/20) 2012 Lin [11]
57 (38/19)
58.74 ± 9.7
24.9 m (12–36) C5–7: 9
C4–6: 7, C5–7: 7 55.12 (28–77) 17 (41/22) 2009 Oh [10]
14 (17/28)
52.64 (28.77)
[2 years
Autograft, Atlantis plate Cage, allograft, Atlantis plate C4–6: 8
27.33 m (12–63)
ACDF ACCF ACDF ACCF ACCF ACDF
ACDF
ACCF
ACDF
ACCF
Follow-up (months, years) Graft/plate Fusion levels Age (years) Sample size (male/ female) Publication Study
Table 1 The baseline characteristics of two groups
33 37.7 ± 7.2 m 37.3 ± 7.3 m
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Effectiveness All studies provided JOA score, fusion rate and cervical lordosis of C2–7 in detail. There was no significant difference in the preoperative JOA score [WMD = 0.38 (-0.08, 0.85), P = 0.11, Fig. 2] and postoperative JOA score[WMD = -0.14 (-1.37, 1.10), P = 0.83, Fig. 3] between the two groups, indicating that the improvement outcome of neurologic function was similar. There was also no significant difference in the fusion rate between the two groups [OR = 0.84 (0.15, 4.86), P = 0.85, Fig. 4], indicating that the outcome of radiographic outcome was similar. There was no significant difference in the preoperative cervical lordosis (C2–7) [WMD = -1.18 (-5.74, 3.39), P = 0.61, Fig. 5] between the two groups. However, there was a significant difference in the postoperative cervical lordosis [WMD = 3.38(2.52, 4.23), P \ 0.00001, Fig. 6]. It indicated that the improvement of cervical lordosis was significantly higher in the ACDF group than that in the ACCF group. Safety All studies reported the complication related to surgery and instrument. The complication of graft included cage or titanium mesh migrate and the hardware related complication included loose, rupture and malposition of screws or plate. General complication included hoarseness, dysphagia, pseudoarthrosis, donor site pain, superficial wound infection, dural laceration, transient motor weakness (C5 palsy), hematoma and reoperation. The detail of each
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Table 2 The quality assessment according to the Newcastle Ottawa Quality Assessment Scale (NOQAS) of each study Study
Selection
Comparability
Exposure
Total score
Oh [10]
2
2
3
7
Lin [11]
3
2
3
8
Guo [14]
3
2
3
8
Song [15]
3
2
3
8
Fig. 2 The standardized mean difference (SMD) estimate for preoperative JOA score
Fig. 3 The standardized mean difference (SMD) estimate for postoperative JOA score
Fig. 4 The odds ratio (OR) estimate for fusion rate
Fig. 5 The standardized mean difference (SMD) estimate for preoperative cervical lordosis
Fig. 6 The standardized mean difference (SMD) estimate for postoperative cervical lordosis
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complication was shown in the Table 3. There was a significant difference in the surgical complication rate [RR = 0.42 (0.22, 0.82), P = 0.01, Fig. 7], the instrument related complication rate [RR = 0.15 (0.04, 0.56), P = 0.005, Fig. 7]. This meant that the incidence of complication was significantly lower in the ACDF group than in the other group. All studies provided blood loss and operation time with mean and standard deviation in detail
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Table 3 The number of each complication Complication
Oh [14]
Lin [10]
Guo [13]
Song [15]
Total
ACDF
ACCF
ACDF
ACCF
ACDF
ACCF
ACDF
ACCF
ACDF
ACCF
Hoarseness
0
1
2
3
–
–
2
2
4 (2.88 %)
6 (5.04 %)
Dysphagia
–
–
4
5
–
–
3
3
7 (5.04 %)
8 (5.76 %)
Pseudoarthrosis
–
–
–
–
1
0
3
1
4 (2.88 %)
1 (0.72 %)
Reoperation
–
–
1
2
0
2
2
1
3 (2.16 %)
5 (4.2 %)
Donor site pain
–
–
–
–
–
–
1
4
1 (0.72 %)
4 (3.36 %)
C5 palsy Hematoma
0 –
1 –
2 1
3 2
0 0
0 1
–
– –
2 (1.44 %) 1 (0.72 %)
4 (3.36 %) 3 (2.52 %)
Wound infection
0
1
–
–
–
–
–
0
1 (0.72 %)
Dural tear
–
–
2
1
0
1
0
1
2 (1.44 %)
3 (2.52 %)
Graft related
–
–
0
6
0
4
0
2
0
Hardware related
–
–
–
–
–
–
2
0
2 (1.44 %)
Total
0
3
12
22
1
8
13
14
Surgery related
Instrument related 12 (10.08 %) 0
– not reported
Fig. 7 The risk ratio (RR) estimate for complications
Fig. 8 The standardized mean difference (SMD) estimate for blood loss
to evaluate the operational trauma. There was significant difference in the blood loss [WMD = -52.53 (-73.53, -31.52), P \ 0.00001, Fig. 8] and in the operation time [WMD = -14.10 (-20.27, -7.93), P \ 0.00001, Fig. 9] between the two groups, indicating that the surgical trauma was smaller in the ACDF group than in the other group.
Discussion Multilevel CSM usually occurs in the elderly patients, in which MRI scans often show the anterior compressive pathology such as the disc herniation, osteophyte, or ligament hyperplasia and so on. However, the optimal
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Fig. 9 The standardized mean difference (SMD) estimate for operation time
surgical procedure still remains controversial. The common surgical procedures include anterior, posterior, and combined anteroposterior approaches. For the CSM, the compressions always come from the herniated disc, osteophyte or others, which can be directly removed by the anterior approach. Since its initial description in the mid 1950s by Smith [16] and Cloward [17], anterior approach for cervical spondylosis was reliable and effective [6, 8, 18]. Anterior decompression could directly remove the object, including soft disc herniations, osteophytic proliferation [19]. Furthermore, anterior fixation improves the cervical spine stability, which can increase the fusion rate, maintain the intervertebral height, and reducing the complications of postoperative graft collapse [10, 15, 20]. Although some relevant studies have compared the ACDF and ACCF, the evidence regarding whether ACDF is superior to ACCF is insufficient [21]. Therefore, we make a meta-analysis to assess which one is the optimal surgical procedure between ACDF with plate fixation and ACCF with plate fixation for MCSM. Although there was not RCT studies including in this meta-analysis, all selected studies were of high quality according to the NOQAS and the baseline variables were similar. Besides, metaanalysis uses quantitative methods to combine the results of several independent latest studies to produce summary statistics [22, 23]. Therefore, we considered the included dates suitable for meta-analysis. JOA score has been well known as one of the most important factors to evaluate the improvement of nerve function. This study showed that there was significant postoperative increase JOA score between two groups. However, the difference in preoperative and postoperative JOA score was not statistically significant, which indicated that the two surgical approaches can have sufficient decompression, and the outcome of nerve improvement was similar. Whereas, it is noteworthy that the heterogeneity in the postoperative JOA score in this study is large (I2 = 82 %), the quality of evidence for this outcome is low. In addition, the JOA score evaluation is more dependent on the subjective experience of patients and the scores may be acquired variably by different investigators. So the reliability of the results was investigated and the conclusions were consistent following sensitivity analysis.
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Some studies reported higher fusion rates after ACCF than multi-level ACDF [15, 24]. However, other studies demonstrated the opposite results [11, 12, 25]. Our metaanalysis showed that the fusion rate and the pseudoarthrosis rate had no statistical difference. The fusion rate of two groups is quite high, it may be considered all patients used anterior plate fixation; which can provide a stable biomechanics environment for bone healing [26–28]. The local stability could increase the fusion rate [29, 30]. Stewart et al. [31] reported that it prevents subsidence and may preserve proper contact of the graft with vertebral end plates. Therefore, it was regarded as standard practice to use anterior plate fixation after anterior decompression of the cervical spine [30]. This study showed that both groups had significantly increased lordosis of C2–C7 after surgery, but it was greater in the ACDF group. Lin et al. [10] indicated that ACDF can provide multiple points of distraction and pull the involved vertebral bodies towards the lordotic ventral plate, which can more easily restore lordosis. However, ACDF graft is long and cannot be prevent, which straightens the cervical spinal column of fusional segments. All patients in this study used anterior plate fixation to increase cervical lordosis, Troyanovich et al. [32] proved that anterior cervical plate can increase the magnitude of lordosis of the fusional segments and preserve the overall lordosis of C2–C7. Improving the cervical physiological curvature could increase the cervical motion of the head and decrease the incidence of adjacent segment degeneration [12, 33]. Complication is a very important factor for surgical safety. This study showed that the incidence was lower in ACDF group than in the other group, indicating the risk in the ACDF group was smaller. Hoarseness and dysphagia are the most common complications after anterior cervical spine surgery [34]. The incidence of dysphagia was 2.3–88.8 % [11, 34–37], and the hoarseness was 3.45–41 % [11, 34, 38], but these symptoms are usually transient [39]. The etiology of dysphagia may be multifactorial, including hematoma formation, location of surgery, revision surgeries and multilevel surgeries [34, 35, 37]. The etiology of hoarseness has been postulated to be related to direct injury to the recurrent or superior laryngeal nerves. The incidence of dysphagia and hoarseness in this study is similar, maybe considering from the fact
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that they both use anterior cervical approaches, and the injury of cervical soft tissue is similar. Some studies reported that ACDF has a high rate of non-union, because ACDF have more graft-host interfaces than ACCF [13, 15, 26, 40]. This study also showed that the rate of nonunion was higher in the ACDF group than in the ACCF group, but the difference was not significant. We considered that it was related to all patients in this study employing anterior plate fixation and ideal grafting bed preparing, because it could decrease 4.4 % of pseudoarthrosis per level if we remove the endplates with exposure of the subchondral bone [41]. This study showed that the incidence of complication relate to immobilization was lower in the ACDF group than that in the ACCF group. Lin et al. [10] indicated that it was due to the piston motion of the graft and the anterior plating excessively loading the graft in the extension [42, 43]. Some studies proved that it relate to the fixation points [44, 45]. ACDF provide more fixation points to hold the construction rigidly in place, but there are only two points of fixation in ACCF. Furthermore, Uribe et al. [25] indicated that the fusion level affect the graft stability. If the fusion level extends to C7, the incidence rate may be more, because the sharp angular change from cervical lordosis to thoracic kyphosis could increase stress at the interface between the graft and bone plate [46]. This complication may be related to the length of fusion, the incidence of early plate/construct failure increases significantly with three-level compared with one or two levels [44]. We considered that excising most of the vertebral body structure in ACCF might affect on the stability of the anterior column structure of the cervical spine. Although adding fixed plate can increase the local biomechanical stability, the titanium mesh often crosses more than one vertebra, its edge is relatively sharp, and the contact area is relatively small, the shear stress is relatively large. Operation time and blood loss were important factors for assessing surgical trauma. There was significantly different in the blood loss and the operation time between two groups, which means that the surgical trauma is smaller in the ACDF group than in the other group. We think the surgical trauma may be an important factor to explain why the complication was more in the ACCF group than in the ACDF group. However, we should pay attention that the heterogeneity is large (I2 = 77 %) in the blood loss and (I2 = 95 %) in the operation time. Therefore, the quality of evidence for this outcome is low. There are several limitations in this study. First, the qualified studies included this study were few. Second, different type of graft and plate were used, which may affect the accuracy of conclusion. Third, clinical heterogeneity may be caused by the various indications for
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surgery and the surgical technologies in different treatment centers. Finally, these studies lack a gold standard outcome to assess the postoperative clinical effect.
Conclusions This meta-analysis only highlights the surgical and outcome differences between ACDF with plate and ACCF with plate in the treatment of MCSM without continuous OPLL or large dorsal osteophytes. Compared with ACCF with plate, ACDF with plate had the similar postoperative JOA score, fusion rate and higher cervical lordosis improvement, lower complications and smaller surgical trauma. However, it is still uncertain whether ACDF with plate fixation is more effective and safer than ACCF with plate fixation. To provide objective data on the clinical results of both procedures, a well-designed and prospective RCT should be performed in the future. Acknowledgments This work was supported by the Natural Science Foundation of China (81372016). The Manuscript submitted does not contain information about medical device(s)/drug(s). No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript. Conflict of interest
None.
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Eur Spine J (2015) 24:31–39 25. Uribe JS, Sangala JR, Duckworth EA, Vale FL (2009) Comparison between anterior cervical discectomy fusion and cervical corpectomy fusion using titanium cages for reconstruction: analysis of outcome and long-term follow-up. Eur Spine J 18:654–662. doi:10.1007/s00586-009-0897-9 26. Fraser JF, Ha¨rtl R (2007) Anterior approaches to fusion of the cervical spine: a metaanalysis of fusion rates. J Neurosurg Spine 6:298–303 27. Setzer M, Eleraky M, Johnson WM, Aghayev K, Tran ND, Vrionis FD (2012) Biomechanical comparison of anterior cervical spine instrumentation techniques with and without supplemental posterior fusion after different corpectomy and discectomy combinations: laboratory investigation. J Neurosurg Spine 16:579–584 28. Singh K, Vaccaro AR, Kim J, Lorenz EP, Lim T, An HS (2004) Enhancement of stability following anterior cervical corpectomy: a biomechanical study. Spine 29:845–849 29. Schmieder K, Wolzik-Grossmann M, Pechlivanis I, Engelhardt M, Scholz M, Harders A (2006) Subsidence of the wing titanium cage after anterior cervical interbody fusion: 2-year follow-up study. J Neurosurg Spine 4:447–453 30. Wang JC, McDonough PW, Endow KK, Delamarter RB (2000) Increased fusion rates with cervical plating for two-level anterior cervical discectomy and fusion. Spine 25:41 31. Stewart TJ, Schlenk RP, Benzel EC (2007) Multiple level discectomy and fusion. Neurosurgery 60:S1–S143 32. Troyanovich SJ, Stroink AR, Kattner KA, Dornan WA, Gubina I (2002) Does anterior plating maintain cervical lordosis versus conventional fusion techniques? A retrospective analysis of patients receiving single-level fusions. J Spinal Disord Tech 15:69–74 33. Hansen MA, Kim HJ, Van Alstyne EM, Skelly AC, Fehlings MG (2012) Does postsurgical cervical deformity affect the risk of cervical adjacent segment pathology? A systematic review. Spine 37:S75–S84 34. Baron E, Soliman AM, Gaughan JP, Simpson L, Young WF (2003) Dysphagia, hoarseness, and unilateral true vocal fold motion impairment following anterior cervical diskectomy and fusion. Ann Otol Rhi 112:921–927 35. Lee MJ, Bazaz R, Furey CG, Yoo J (2007) Risk factors for dysphagia after anterior cervical spine surgery: a two-year prospective cohort study. Spine J 7:141–147 36. Yue W, Brodner W, Highland TR (2005) Persistent swallowing and voice problems after anterior cervical discectomy and fusion with allograft and plating: a 5-to 11-year follow-up study. Eur Spine J 14:677–682 37. Kalb S, Reis MT, Cowperthwaite MC, Fox DJ, Lefevre R, Theodore N, Papadopoulos SM, Sonntag VK (2012) Dysphagia after anterior cervical spine surgery: incidence and risk factors. World Neurosurg 77:183–187 38. Fehlings MG, Smith JS, Kopjar B, Arnold PM, Yoon ST, Vaccaro AR, Brodke DS, Janssen ME, Chapman JR, Sasso RC, Woodard EJ, Banco RJ, Massicotte EM, Dekutoski MB, Gokaslan ZL, Bono CM, Shaffrey CI (2012) Perioperative and delayed complications associated with the surgical treatment of cervical spondylotic myelopathy based on 302 patients from the AOSpine North America Cervical Spondylotic Myelopathy Study. J Neurosurg Spine 16:425–432. doi:10.3171/2012.1.SPINE11467 39. Rihn JA, Kane J, Albert TJ, Vaccaro AR, Hilibrand AS (2011) What is the incidence and severity of dysphagia after anterior cervical surgery? Clin Orthop Related Res 469:658–665 40. Shoji A, Yamanaka H, Kamatani N (2004) A retrospective study of the relationship between serum urate level and recurrent attacks of gouty arthritis: evidence for reduction of recurrent gouty arthritis with antihyperuricemic therapy. Arthritis Care Res 51:321–325
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39 44. Sasso RC, Ruggiero RA Jr, Reilly TM, Hall PV (2003) Early reconstruction failures after multilevel cervical corpectomy. Spine 28:140–142 45. Vaccaro AR, Falatyn SP, Scuderi GJ, Eismont FJ, McGuire RA, Singh K, Garfin SR (1998) Early failure of long segment anterior cervical plate fixation. J Spinal Disord Tech 11:410–415 46. Gonugunta V, Krishnaney AA, Benzel EC (2005) Anterior cervical plating. Neurol India 53:424
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REVIEW ARTICLE
Anterior cervical discectomy versus corpectomy for multilevel cervical spondylotic myelopathy: a meta-analysis Shan-Wen Xiao • Hua Jiang • Li-Jing Yang Zeng-Ming Xiao
•
Received: 12 April 2014 / Revised: 27 September 2014 / Accepted: 28 September 2014 / Published online: 18 October 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose This is a meta-analysis to compare the results between anterior cervical discectomy fusion (ACDF) and anterior cervical corpectomy fusion (ACCF) for the patients with multilevel cervical spondylotic myelopathy (MCSM). Methods Systematic review and meta-analysis of cohort studies between ACDF with plate fixation and ACCF with plate fixation for the treatment of MCSM. An extensive search of literature was performed in PubMed, Mediline, Embase and the Cochrane library. The following outcome measures were extracted: JOA scores, fusion rate, cervical lordosis (C2–7), complications, blood loss and operation time. Data analysis was conducted with RevMan 5.0. Results Four cohorts (six studies) involving 258 patients were included in this study. The pooled analysis showed that there was no significant difference in the postoperative JOA score [WMD = -0.14 (-1.37, 1.10), P = 0.83], fusion rate [OR = 0.84 (0.15, 4.86), P = 0.85] between two group. However, there was significant difference in the cervical lordosis [WMD = 3.38 (2.52, 4.23), P \ 0.00001], surgical complication rate and instrument related complication rate (P = 0.01, 0.005 respectively), blood loss [WMD = -52.53 (-73.53, -31.52), P \ 0.00001], and operation time [WMD = -14.10 (-20.27, -7.93), P \ 0.00001].
S.-W. Xiao and H. Jiang contributed equally to this work. S.-W. Xiao H. Jiang L.-J. Yang Z.-M. Xiao (&) Department of Spine Surgery, The First Affiliated Hospital of Guangxi Medical University, Shuangyong Road No. 6, Nanning 530021, China e-mail: [email protected]
Conclusions As compared with ACCF with plate fixation, ACDF with plate fixation showed no significant differences in terms of postoperative JOA score, fusion rate, but better improved cervical lordosis, lower complication and smaller surgical trauma. As the limitations of small sample and short follow-up in this study, it still could not be identified whether ACDF with plate fixation is more effective and safer than ACCF with plate fixation. Keywords Anterior decompression Cervical spondylotic myelopathy Discectomy Corpectomy Meta-analysis
Introduction Cervical spondylotic myelopathy is a common age-related degenerative disease, which can lead to motor and sensory dysfunction (significant pain, instability, disturbances). If the symptoms do not respond to conservative treatment, surgical treatment should be considered [1, 2]. The anterior procedures, including multi-level ACDF (anterior cervical discectomy fusion) and single-/multilevel ACCF (anterior cervical corpectomy fusion) [3–5], were recognized as reliable and effective way in treating cervical spondylotic myelopathy [6–8]. But there is no clear conclusion on which method, ACDF or ACCF, is better [9]. Therefore, a randomized controlled trial (RCT) is a necessary guide to determine which method is better for the treatment of MCSM. However, there was no RCT on this subject in the published papers; therefore, we performed a meta-analysis to assess the effectiveness and safety of these two surgical procedures for MCSM without continuous ossification of posterior longitudinal ligament or large dorsal osteophytes.
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Materials and methods Inclusion criteria All studies on treatment of MCSM were reviewed. The criteria for inclusion of an article were: (1) patients were 18 years old or greater; (2) patients with symptomatic cervical compressive myelopathy (C2 segments) due to CSM; (3) purpose of interventions: ACDF with plate fixation (ACDF group) and ACCF with plate fixation (ACCF group), ACDF with cage fusion and ACCF with titanium mesh fusion; (4) outcome measurements: preoperative and postoperative Japanese orthopedic association (JOA) scores, fusion rate, preoperative and postoperative cervical lordosis (C2–C7), complications, blood loss, operation time; (5) all included trials were followed up at least 1-year after surgery; (6) patients were excluded if they only had one-level disc disease, acute spinal fracture, infection, tumor, osteoporosis, rheumatoid arthritis, severe spondylolisthesis, continuous ossification of posterior longitudinal ligament (OPLL), multiple large dorsal osteophytes at multiple levels behind the vertebral body, ligamentum flavum hypertrophy, had surgical history of cervical spine, without anterior plate or cage/titanium mesh. Search strategy A computerized search of literature published between 1900 and December 2013 was performed using PubMed, Mediline, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) (Wiley Online Library). The following key words were used for search: ‘‘cervical spondylotic myelopathy’’, ‘‘anterior cervical discectomy fusion’’, ‘‘anterior cervical corpectomy’’, ‘‘anterior decompression’’, ‘‘anterior surgery’’, with various combinations of the operators ‘‘AND’’, ‘‘NOT’’, and ‘‘OR’’. We restricted the language to English. Selection of studies Two reviewers (SWX and HJ) independently reviewed all subjects, abstracts, reference lists and the full text of articles that were potentially eligible based on abstract review. Then the eligible trials were selected according to the inclusion criteria. When consensus could not be reached, a third reviewer (lJY) was consulted to resolve the disagreement. Data extraction Two reviewers (SWX and HJ) extracted data independently and cross checked mutually. The data extracted included the following categories: patients (selection criteria and
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Fig. 1 The procedure of literature search
diagnoses, age, sex, length of follow-up), treatments (type of graft, intervention details) and clinical outcomes (JOA, fusion rate, cervical lordosis, complications, blood loss and operation time). Data analysis Data analysis was performed with RevMan 5.0 (the Cochrane Collaboration). Two reviewers (SWX and HJ) monitored the data input to ensure there were no errors. Risk ratio (RR) was used as a summary statistic to analyze dichotomous variables, and the standardized mean difference (SMD) was used to analyze continuous variables. Both were reported with 95 % confidence intervals (CIs), and a P value of 0.05 was used as the level of statistical significance. Random-effects or fixed-effects models were used depended on the heterogeneity of the studies included. Heterogeneity was tested by using I-square test, where I2 [ 50 % implied heterogeneity.
Results Search results The search strategy yielded 387 relevant citations, yielding 6 studies meet the inclusion criteria. Three studies [10–12] studied at the same institute and team, the cases maybe overlapped, and we selected one article [10]. As a result, a total of four studies [10, 13–15] were used for this meta-
94.3 ± 25.3 87.3 ± 21.7 Autograft, CSLP plate Autograft, SOLIS cage, CSLP plate
C4–7: 11
C3–6:4
C4–7:6
C3–7:5
C4–7: 17
C3–6: 10
C4–7: 8,
C3–7:7
15 (11/4) 2012 Song [15]
25 (19/6)
50.3 ± 7.5
54.1 ± 9.8
Autograft, Titanium cage, plate
These 6 studies contained 4 cohorts with a total of 258 patients, of which 139 underwent ACDF and 119 underwent ACCF. There were no significant differences between the two groups in terms of age, gender ratio, location of surgery, length of fusion and follow-up (P \ 0.05). Baseline characteristics of the two treatment groups are presented in Table 1. No RCT were identified, all studies included were retrospective studies. We used the Newcastle Ottawa Quality Assessment Scale (NOQAS) to assess the quality of each study. This scale for non-randomized case controlled studies and cohort studies was used to allocate a maximum of nine points for the quality of selection, comparability, exposure, and outcomes for study participants. Of the studies, three scored 8 points and one scored 7 points. Hence, the quality of each study was relatively high (Table 2).
Autograft and PEEK cages, plate C3–7: 12
Baseline characteristics and quality assessment
C3–6: 13
C3–7: 11
analysis. The literature search procedure was shown in Fig. 1.
C3–6: 26 55.2 ± 10.1 24 (13/11) 2011 Guo [14]
43 (24/19)
52.7 ± 9.4
Autograft.TMC, semi- [2 years constrained, plate Autograft, cages, semiconstrained, plate C3–6: 23 C4–7: 28 C3–6: 21 C4–7: 25 57.91 ± 10 63 (43/20) 2012 Lin [11]
57 (38/19)
58.74 ± 9.7
24.9 m (12–36) C5–7: 9
C4–6: 7, C5–7: 7 55.12 (28–77) 17 (41/22) 2009 Oh [10]
14 (17/28)
52.64 (28.77)
[2 years
Autograft, Atlantis plate Cage, allograft, Atlantis plate C4–6: 8
27.33 m (12–63)
ACDF ACCF ACDF ACCF ACCF ACDF
ACDF
ACCF
ACDF
ACCF
Follow-up (months, years) Graft/plate Fusion levels Age (years) Sample size (male/ female) Publication Study
Table 1 The baseline characteristics of two groups
33 37.7 ± 7.2 m 37.3 ± 7.3 m
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Effectiveness All studies provided JOA score, fusion rate and cervical lordosis of C2–7 in detail. There was no significant difference in the preoperative JOA score [WMD = 0.38 (-0.08, 0.85), P = 0.11, Fig. 2] and postoperative JOA score[WMD = -0.14 (-1.37, 1.10), P = 0.83, Fig. 3] between the two groups, indicating that the improvement outcome of neurologic function was similar. There was also no significant difference in the fusion rate between the two groups [OR = 0.84 (0.15, 4.86), P = 0.85, Fig. 4], indicating that the outcome of radiographic outcome was similar. There was no significant difference in the preoperative cervical lordosis (C2–7) [WMD = -1.18 (-5.74, 3.39), P = 0.61, Fig. 5] between the two groups. However, there was a significant difference in the postoperative cervical lordosis [WMD = 3.38(2.52, 4.23), P \ 0.00001, Fig. 6]. It indicated that the improvement of cervical lordosis was significantly higher in the ACDF group than that in the ACCF group. Safety All studies reported the complication related to surgery and instrument. The complication of graft included cage or titanium mesh migrate and the hardware related complication included loose, rupture and malposition of screws or plate. General complication included hoarseness, dysphagia, pseudoarthrosis, donor site pain, superficial wound infection, dural laceration, transient motor weakness (C5 palsy), hematoma and reoperation. The detail of each
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Table 2 The quality assessment according to the Newcastle Ottawa Quality Assessment Scale (NOQAS) of each study Study
Selection
Comparability
Exposure
Total score
Oh [10]
2
2
3
7
Lin [11]
3
2
3
8
Guo [14]
3
2
3
8
Song [15]
3
2
3
8
Fig. 2 The standardized mean difference (SMD) estimate for preoperative JOA score
Fig. 3 The standardized mean difference (SMD) estimate for postoperative JOA score
Fig. 4 The odds ratio (OR) estimate for fusion rate
Fig. 5 The standardized mean difference (SMD) estimate for preoperative cervical lordosis
Fig. 6 The standardized mean difference (SMD) estimate for postoperative cervical lordosis
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complication was shown in the Table 3. There was a significant difference in the surgical complication rate [RR = 0.42 (0.22, 0.82), P = 0.01, Fig. 7], the instrument related complication rate [RR = 0.15 (0.04, 0.56), P = 0.005, Fig. 7]. This meant that the incidence of complication was significantly lower in the ACDF group than in the other group. All studies provided blood loss and operation time with mean and standard deviation in detail
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Table 3 The number of each complication Complication
Oh [14]
Lin [10]
Guo [13]
Song [15]
Total
ACDF
ACCF
ACDF
ACCF
ACDF
ACCF
ACDF
ACCF
ACDF
ACCF
Hoarseness
0
1
2
3
–
–
2
2
4 (2.88 %)
6 (5.04 %)
Dysphagia
–
–
4
5
–
–
3
3
7 (5.04 %)
8 (5.76 %)
Pseudoarthrosis
–
–
–
–
1
0
3
1
4 (2.88 %)
1 (0.72 %)
Reoperation
–
–
1
2
0
2
2
1
3 (2.16 %)
5 (4.2 %)
Donor site pain
–
–
–
–
–
–
1
4
1 (0.72 %)
4 (3.36 %)
C5 palsy Hematoma
0 –
1 –
2 1
3 2
0 0
0 1
–
– –
2 (1.44 %) 1 (0.72 %)
4 (3.36 %) 3 (2.52 %)
Wound infection
0
1
–
–
–
–
–
0
1 (0.72 %)
Dural tear
–
–
2
1
0
1
0
1
2 (1.44 %)
3 (2.52 %)
Graft related
–
–
0
6
0
4
0
2
0
Hardware related
–
–
–
–
–
–
2
0
2 (1.44 %)
Total
0
3
12
22
1
8
13
14
Surgery related
Instrument related 12 (10.08 %) 0
– not reported
Fig. 7 The risk ratio (RR) estimate for complications
Fig. 8 The standardized mean difference (SMD) estimate for blood loss
to evaluate the operational trauma. There was significant difference in the blood loss [WMD = -52.53 (-73.53, -31.52), P \ 0.00001, Fig. 8] and in the operation time [WMD = -14.10 (-20.27, -7.93), P \ 0.00001, Fig. 9] between the two groups, indicating that the surgical trauma was smaller in the ACDF group than in the other group.
Discussion Multilevel CSM usually occurs in the elderly patients, in which MRI scans often show the anterior compressive pathology such as the disc herniation, osteophyte, or ligament hyperplasia and so on. However, the optimal
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Fig. 9 The standardized mean difference (SMD) estimate for operation time
surgical procedure still remains controversial. The common surgical procedures include anterior, posterior, and combined anteroposterior approaches. For the CSM, the compressions always come from the herniated disc, osteophyte or others, which can be directly removed by the anterior approach. Since its initial description in the mid 1950s by Smith [16] and Cloward [17], anterior approach for cervical spondylosis was reliable and effective [6, 8, 18]. Anterior decompression could directly remove the object, including soft disc herniations, osteophytic proliferation [19]. Furthermore, anterior fixation improves the cervical spine stability, which can increase the fusion rate, maintain the intervertebral height, and reducing the complications of postoperative graft collapse [10, 15, 20]. Although some relevant studies have compared the ACDF and ACCF, the evidence regarding whether ACDF is superior to ACCF is insufficient [21]. Therefore, we make a meta-analysis to assess which one is the optimal surgical procedure between ACDF with plate fixation and ACCF with plate fixation for MCSM. Although there was not RCT studies including in this meta-analysis, all selected studies were of high quality according to the NOQAS and the baseline variables were similar. Besides, metaanalysis uses quantitative methods to combine the results of several independent latest studies to produce summary statistics [22, 23]. Therefore, we considered the included dates suitable for meta-analysis. JOA score has been well known as one of the most important factors to evaluate the improvement of nerve function. This study showed that there was significant postoperative increase JOA score between two groups. However, the difference in preoperative and postoperative JOA score was not statistically significant, which indicated that the two surgical approaches can have sufficient decompression, and the outcome of nerve improvement was similar. Whereas, it is noteworthy that the heterogeneity in the postoperative JOA score in this study is large (I2 = 82 %), the quality of evidence for this outcome is low. In addition, the JOA score evaluation is more dependent on the subjective experience of patients and the scores may be acquired variably by different investigators. So the reliability of the results was investigated and the conclusions were consistent following sensitivity analysis.
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Some studies reported higher fusion rates after ACCF than multi-level ACDF [15, 24]. However, other studies demonstrated the opposite results [11, 12, 25]. Our metaanalysis showed that the fusion rate and the pseudoarthrosis rate had no statistical difference. The fusion rate of two groups is quite high, it may be considered all patients used anterior plate fixation; which can provide a stable biomechanics environment for bone healing [26–28]. The local stability could increase the fusion rate [29, 30]. Stewart et al. [31] reported that it prevents subsidence and may preserve proper contact of the graft with vertebral end plates. Therefore, it was regarded as standard practice to use anterior plate fixation after anterior decompression of the cervical spine [30]. This study showed that both groups had significantly increased lordosis of C2–C7 after surgery, but it was greater in the ACDF group. Lin et al. [10] indicated that ACDF can provide multiple points of distraction and pull the involved vertebral bodies towards the lordotic ventral plate, which can more easily restore lordosis. However, ACDF graft is long and cannot be prevent, which straightens the cervical spinal column of fusional segments. All patients in this study used anterior plate fixation to increase cervical lordosis, Troyanovich et al. [32] proved that anterior cervical plate can increase the magnitude of lordosis of the fusional segments and preserve the overall lordosis of C2–C7. Improving the cervical physiological curvature could increase the cervical motion of the head and decrease the incidence of adjacent segment degeneration [12, 33]. Complication is a very important factor for surgical safety. This study showed that the incidence was lower in ACDF group than in the other group, indicating the risk in the ACDF group was smaller. Hoarseness and dysphagia are the most common complications after anterior cervical spine surgery [34]. The incidence of dysphagia was 2.3–88.8 % [11, 34–37], and the hoarseness was 3.45–41 % [11, 34, 38], but these symptoms are usually transient [39]. The etiology of dysphagia may be multifactorial, including hematoma formation, location of surgery, revision surgeries and multilevel surgeries [34, 35, 37]. The etiology of hoarseness has been postulated to be related to direct injury to the recurrent or superior laryngeal nerves. The incidence of dysphagia and hoarseness in this study is similar, maybe considering from the fact
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that they both use anterior cervical approaches, and the injury of cervical soft tissue is similar. Some studies reported that ACDF has a high rate of non-union, because ACDF have more graft-host interfaces than ACCF [13, 15, 26, 40]. This study also showed that the rate of nonunion was higher in the ACDF group than in the ACCF group, but the difference was not significant. We considered that it was related to all patients in this study employing anterior plate fixation and ideal grafting bed preparing, because it could decrease 4.4 % of pseudoarthrosis per level if we remove the endplates with exposure of the subchondral bone [41]. This study showed that the incidence of complication relate to immobilization was lower in the ACDF group than that in the ACCF group. Lin et al. [10] indicated that it was due to the piston motion of the graft and the anterior plating excessively loading the graft in the extension [42, 43]. Some studies proved that it relate to the fixation points [44, 45]. ACDF provide more fixation points to hold the construction rigidly in place, but there are only two points of fixation in ACCF. Furthermore, Uribe et al. [25] indicated that the fusion level affect the graft stability. If the fusion level extends to C7, the incidence rate may be more, because the sharp angular change from cervical lordosis to thoracic kyphosis could increase stress at the interface between the graft and bone plate [46]. This complication may be related to the length of fusion, the incidence of early plate/construct failure increases significantly with three-level compared with one or two levels [44]. We considered that excising most of the vertebral body structure in ACCF might affect on the stability of the anterior column structure of the cervical spine. Although adding fixed plate can increase the local biomechanical stability, the titanium mesh often crosses more than one vertebra, its edge is relatively sharp, and the contact area is relatively small, the shear stress is relatively large. Operation time and blood loss were important factors for assessing surgical trauma. There was significantly different in the blood loss and the operation time between two groups, which means that the surgical trauma is smaller in the ACDF group than in the other group. We think the surgical trauma may be an important factor to explain why the complication was more in the ACCF group than in the ACDF group. However, we should pay attention that the heterogeneity is large (I2 = 77 %) in the blood loss and (I2 = 95 %) in the operation time. Therefore, the quality of evidence for this outcome is low. There are several limitations in this study. First, the qualified studies included this study were few. Second, different type of graft and plate were used, which may affect the accuracy of conclusion. Third, clinical heterogeneity may be caused by the various indications for
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surgery and the surgical technologies in different treatment centers. Finally, these studies lack a gold standard outcome to assess the postoperative clinical effect.
Conclusions This meta-analysis only highlights the surgical and outcome differences between ACDF with plate and ACCF with plate in the treatment of MCSM without continuous OPLL or large dorsal osteophytes. Compared with ACCF with plate, ACDF with plate had the similar postoperative JOA score, fusion rate and higher cervical lordosis improvement, lower complications and smaller surgical trauma. However, it is still uncertain whether ACDF with plate fixation is more effective and safer than ACCF with plate fixation. To provide objective data on the clinical results of both procedures, a well-designed and prospective RCT should be performed in the future. Acknowledgments This work was supported by the Natural Science Foundation of China (81372016). The Manuscript submitted does not contain information about medical device(s)/drug(s). No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript. Conflict of interest
None.
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