Orthopedics

Review Article 

Anterior Cervical Corpectomy and Fusion Versus Posterior Laminoplasty for Cervical Oppressive Myelopathy Secondary to Ossification of the Posterior Longitudinal Ligament: A Meta-analysis

Rongqing Qin, MD; Weiwei Sun, MD; Baiyu Qian, MD; Jie Hao, MD; Pin Zhou, MSc; Chunxiang Xu, MSc; Cheng Chen, MD; Kai Yang, MD; Feng Zhang, MD; Xiaoqing Chen, MD

Abstract

The purpose of this study was to compare the clinical effect of anterior cervical corpectomy with fusion vs laminoplasty for cervical ossification of the posterior longitudinal ligament. The outcome measures included the Japanese Orthopaedic Association score, neurological recovery rate, and complication rate. Subgroup A represented studies with the mean preoperative canal occupying ratio being less than 50%, whereas subgroup B represented studies with the mean canal occupying ratio being 50% or greater. In subgroup A, no difference was found between the 2 groups in the postoperative Japanese Orthopaedic Association score and neurological recovery rate. In subgroup B, the anterior cervical corpectomy with fusion group had a higher postoperative Japanese Orthopaedic Association score and neurological recovery rate. The authors recommend anterior cervical corpectomy with fusion for cervical ossification of the posterior longitudinal ligament when the canal occupying ratio is 50% or greater, and they prefer laminoplasty when the canal occupying ratio is less than 50%. [Orthopedics. 2019; 42(3):e309–e316.]

Abstract

The purpose of this study was to compare the clinical effect of anterior cervical corpectomy with fusion vs laminoplasty for cervical ossification of the posterior longitudinal ligament. The outcome measures included the Japanese Orthopaedic Association score, neurological recovery rate, and complication rate. Subgroup A represented studies with the mean preoperative canal occupying ratio being less than 50%, whereas subgroup B represented studies with the mean canal occupying ratio being 50% or greater. In subgroup A, no difference was found between the 2 groups in the postoperative Japanese Orthopaedic Association score and neurological recovery rate. In subgroup B, the anterior cervical corpectomy with fusion group had a higher postoperative Japanese Orthopaedic Association score and neurological recovery rate. The authors recommend anterior cervical corpectomy with fusion for cervical ossification of the posterior longitudinal ligament when the canal occupying ratio is 50% or greater, and they prefer laminoplasty when the canal occupying ratio is less than 50%. [Orthopedics. 2019; 42(3):e309–e316.]

Ossification of the posterior longitudinal ligament (OPLL) and cervical spondylotic myelopathy are 2 principal causes of cervical oppressive myelopathy. The prevalence of OPLL ranges from 1.9% to 4.3% in East Asians and from 0.01% to 1.7% in whites.1 Conservative treatment usually has no effect on cervical oppressive myelopathy secondary to OPLL, and surgery seems to be the only option. Surgical approaches include anterior cervical diskectomy with fusion, anterior cervical corpectomy with fusion (ACCF), laminoplasty (LAMP), laminectomy with (or without) instrumented fusion, and combined anterior and posterior approaches. For cervical OPLL, ACCF and LAMP are both frequently used. However, which procedure provides a superior clinical effect remains controversial.

Regarding ACCF, it seems that direct anterior decompression is feasible by resecting the ossified objects. This offers 2 main advantages: complete decompression by removing the ossified mass and reconstruction of the stability of the cervical vertebra via bone grafting and fusion. However, the disadvantages of ACCF are well documented. It requires greater surgical skill and more bone grafts, has a higher incidence of cerebrospinal fluid leakage, leads to a greater surgical wound, and has longer cervical immobilization postoperatively.2

Laminoplasty is a relatively simple and safe operation that was first introduced by Tsuji.3 It also seems feasible through indirect decompression for enlarging the spinal canal with the purpose of backward movement of the spinal cord. However, sufficient cervical lordosis must exist before the operation, and its clinical effect depends on backward movement of the spinal cord. The threat of anterior compression may exist in the case of inadequate backward movement, which would lead to an unsatisfactory outcome.4 In addition to complications such as C5 root palsy and cervical axial pain, the high incidence of late neurological deterioration postoperatively, which may be caused by cervical instability, kyphosis change, and progression of OPLL after the operation, also should be resolved.5,6

No guideline has been developed for the treatment of cervical oppressive myelopathy due to cervical OPLL. This meta-analysis was performed with the purpose of estimating the clinical effect of ACCF vs LAMP for the treatment of cervical OPLL.

Materials and Methods

Search Strategy

Four databases (PubMed, Embase, Cochrane Library, and the Cochrane Central Register of Controlled Trials) were comprehensively reviewed for articles published from January 1990 to October 2017 that compared the clinical effect of ACCF vs LAMP for the treatment of cervical oppressive myelopathy due to OPLL. No language restriction was set. Search terms used were as follows: (1) ventral OR anterior OR ventral approach OR anterior approach OR anterior cervical corpectomy and fusion OR ACCF OR corpectomy OR anterior decompression and fusion OR anterior decompression; (2) dorsal OR posterior OR dorsal approach OR posterior approach OR laminoplasty OR LAMP OR posterior decompression; (3) cervical OR myelopathy OR cervical myelopathy OR stenosis OR cervical stenosis OR cervical canal stenosis OR cervical spinal stenosis; (4) OPLL OR ossification of the posterior longitudinal ligament OR calcification of the posterior longitudinal ligament OR ossified posterior longitudinal ligament OR calcific posterior longitudinal ligament; and (1) and (2) and (3) and (4). All reference lists were scanned and manually searched to identify additional potentially relevant studies. Titles and abstracts of all retrieved articles were independently scanned by 2 reviewers (R.Q., W.S.), and full-text copies of all relevant articles were then acquired.

Inclusion Criteria

Inclusion criteria were as follows: nonrandomized cohort or randomized controlled studies involving patients with cervical myelopathy secondary to OPLL; intervention purpose being to evaluate the clinical effect of ACCF compared with LAMP; and outcome indicators of pre-operative and postoperative Japanese Orthopaedic Association (JOA) score, neurofunctional recovery rate, complication and reoperation rates, and the incidence of late neurological deterioration.

Exclusion Criteria

Patients with cervical myelopathy due to trauma, tumor, or disk herniation, a history of cervical surgery, other anterior or posterior or combined anteroposterior approach, and follow-up of less than 1 year were excluded. Further, review articles, case reports, animal studies, and noncomparative studies were excluded.

Data Extraction

The authors extracted the following from the included studies: study design; study location; patient demographics; surgical procedure; number of surgical segments; follow-up time; mean canal occupying ratio preoperatively; and primary outcome measures (preoperative JOA score, JOA score at final follow-up, neurofunctional recovery rate, and incidence of complication and reoperation).

Subgroup Analysis

The authors implemented subgroup analysis according to the preoperative canal occupying ratio. Subgroup A represented a mean preoperative canal occupying ratio of less than 50%, whereas subgroup B represented a mean canal occupying ratio of 50% or greater.

Data Analysis

All statistical analyses were performed using RevMan version 5.3 software (The Cochrane Collaboration, Oxford, United Kingdom). Data not directly acquired about standard deviation were estimated using sample size and range.7 Heterogeneity of included studies was calculated using the chi-square test and quantified by calculating the I2 statistic. For the pooled effects, weighted mean difference (WMD) or standard mean difference was used for calculating the continuous variables because of the consistency of measurement unit, while odds ratio or risk ratio was used for the dichotomous variables. In this meta-analysis, the continuous variables were represented by WMD and 95% confidence intervals and the dichotomous variables were represented by odds ratios and 95% confidence intervals. Only P<.05 and I2≥50% were considered to be statistically significant. In addition, when P<.05 and I2≥50%, the authors chose the random effects model; when P≥.05 or I2<50%, the fixed effects model was used.

Results

Search Results

The process of obtaining relevant studies is shown in Figure 1. In total, 1768 studies were acquired through electronic and manual searching. Eight articles6,8–14 were included in the meta-analysis.

The process for identifying relevant studies.

Figure 1:

The process for identifying relevant studies.

Quality Assessment and Baseline Characteristics

There was 1 prospective cohort study and 7 retrospective cohort studies. All included studies were relatively low quality according to the GRADE scale (Table 1).15 These 8 studies had a total of 595 patients, with 317 in the ACCF group and 278 in the LAMP group. Baseline characteristics of the included studies are presented in Table 2.

Quality Evaluation of the 8 Included Studies According to the GRADE Scale

Table 1:

Quality Evaluation of the 8 Included Studies According to the GRADE Scale

Baseline Characteristics of the 8 Included Studiesa

Table 2:

Baseline Characteristics of the 8 Included Studies

Clinical Outcome

Preoperative JOA Score. These 8 studies provided the preoperative JOA score in the form of mean±standard deviation. The preoperative JOA score was slightly lower in the ACCF group compared with the LAMP group in subgroup A (P<.01, WMD, −0.39 [range, −0.49 to −0.29]; heterogeneity: chi-square=2.60, df=2, P=.27, I2=23%). No obvious difference was observed in preoperative JOA score between the 2 groups in subgroup B (P=.31, WMD, 0.25 [range, −0.23 to 0.72]; heterogeneity: chi-square=3.88, df=5, P=.57, I2=0%; Figure 2).

Weighted mean difference of the preoperative Japanese Orthopaedic Association score between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; IV, inverse variance; SD, standard deviation.

Figure 2:

Weighted mean difference of the preoperative Japanese Orthopaedic Association score between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; IV, inverse variance; SD, standard deviation.

Postoperative JOA Score. These 8 studies also provided the postoperative JOA score. No statistically significant difference was detected in the postoperative JOA score between the ACCF group and the LAMP group in subgroup A (P=.19, WMD, 0.67 [range, −0.33 to 1.67]; heterogeneity: tau2=0.47, chi-square=4.81, df=2, P=.09, I2=58%). However, the ACCF group presented a higher postoperative JOA scores than the LAMP group in subgroup B (P<.01, WMD, 2.16 [range, 1.10 to 3.21]; heterogeneity: tau2=1.26, chi-square=23.70, df=5, P=.0002, I2=79%; Figure 3).

Weighted mean difference of the postoperative Japanese Orthopaedic Association score between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; IV, inverse variance; SD, standard deviation.

Figure 3:

Weighted mean difference of the postoperative Japanese Orthopaedic Association score between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; IV, inverse variance; SD, standard deviation.

Recovery Rate. These 8 studies provided the recovery rate of neurological function. No obvious statistical difference was found in the neurological recovery rate between the 2 groups in subgroup A (P=.07, WMD, 11.49 [range, −1.02 to 24.00]; heterogeneity: tau2=102.43, chi-square=32.70, df=2, P<.01, I2=94%). However, in subgroup B, the ACCF group had a significantly higher neuro-functional recovery rate than the LAMP group (P<.01, WMD, 29.06 [range, 21.92 to 36.21]; heterogeneity: tau2=36.37, chi-square=11.35, df=5, P=.04, I2=56%; Figure 4). The above information indicated that the neurofunctional recovery rate was similar in the 2 groups when the preoperative canal occupying ratio was less than 50%. However, when the preoperative canal occupying ratio was 50% or greater, the recovery rate of neurological function was significantly better in the ACCF group compared with the LAMP group.

Weighted mean difference of the neurological recovery rate between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; IV, inverse variance; SD, standard deviation.

Figure 4:

Weighted mean difference of the neurological recovery rate between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; IV, inverse variance; SD, standard deviation.

Complications. Six of the 8 studies (401 patients—227 in the ACCF group and 174 in the LAMP group) provided surgical complications. No statistically significant difference was found in the complication rate between the 2 groups in both subgroups (subgroup A: P=.25, WMD, 1.67 [range, 0.70 to 4.00]; heterogeneity: chi-square=3.14, df=1, P=.08, I2=68%; subgroup B: P=.14, WMD, 1.58 [range, 0.85 to 2.92]; heterogeneity: chi-square=3.53, df=3, P=.32, I2=15%; Figure 5). Although the 2 groups had a similar complication rate, the major complications were cerebrospinal fluid leakage (8.78%) and dysphagia/dysphonia (6.83%) in the ACCF group vs a high incidence of axial neck pain (12.99%) and C5 root palsy (4.55%) in the LAMP group (Table 3).

Odds ratio of the complication rate between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; M-H, Mantel–Haenszel.

Figure 5:

Odds ratio of the complication rate between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; M-H, Mantel–Haenszel.

Complications Observed in the 2 Groups

Table 3:

Complications Observed in the 2 Groups

Reoperation. Four studies (142 patients—68 in the ACCF group and 74 in the LAMP group) provided the reoperation rate. The forest plots indicated that there was no significant difference in reoperation rate between the 2 groups (P=.13, WMD, 2.43 [range, 0.78 to 7.56]; Figure 6). No statistical heterogeneity was detected via the chi-square test.

Odds ratio of the reoperation rate in subgroup B between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; M-H, Mantel-Haenszel.

Figure 6:

Odds ratio of the reoperation rate in subgroup B between the anterior cervical corpectomy with fusion (ACCF) group and the laminoplasty (LAMP) group. Abbreviations: CI, confidence interval; M-H, Mantel-Haenszel.

Discussion

Anterior cervical corpectomy with fusion and LAMP are 2 conventional surgical procedures for the treatment of cervical oppressive myelopathy secondary to OPLL. However, which procedure provides a superior clinical effect remains controversial. Several meta-analyses have been published16–18 comparing the clinical effect between the anterior and the posterior approaches for the treatment of cervical OPLL. However, the current meta-analysis had the following highlights: (1) included studies were as comprehensive as possible; (2) clinical effects were compared between ACCF and LAMP; (3) subgroup analysis was performed strictly according to the mean preoperative canal occupying ratio, with subgroup A representing the mean preoperative canal occupying ratio of less than 50% and subgroup B representing the mean preoperative canal occupying ratio of 50% or greater; and (4) a relatively satisfactory conclusion was reached.

Eight cohort studies with adequate methodological quality were included in this meta-analysis. The authors implemented subgroup analysis according to the mean preoperative canal occupying ratio to decrease plausible confounding effects. The forest plots indicated that the postoperative JOA score and the neurofunctional recovery rate were similar between the 2 groups when the mean preoperative canal occupying ratio was less than 50%. However, when the mean preoperative canal occupying ratio was 50% or greater, ACCF led to a much better postoperative JOA score and neurofunctional recovery rate than LAMP.

Hirabayashi et al19 first introduced the computational method of postoperative neurofunctional recovery rate, with recovery rate=(postoperative JOA score-preoperative JOA score)/(17-preoperative JOA score)×100%. Various studies have reported that the neurofunctional recovery rate after ACCF was better than that after LAMP.8–11 On the basis of further research in this field, some authors thought that the anterior approach led to a much better neurological function recovery rate than the posterior approach for cervical OPLL when the preoperative canal occupying ratio was greater than 50% or 60%.6,8–10,13 Subgroup analysis of the neurological function recovery rate in the current study supported the above-mentioned conclusion. Regarding ACCF, although it seems that direct anterior decompression is feasible by resecting the ossified objects, one must consider technical difficulties, inadequate depression, iatrogenic neurologic damage, and other surgery-related complications, such as dural tear/cerebrospinal fluid leakage, dysphagia/dysphonia, and implant dislocation.2,20 Some authors have reported that anterior decompression for cervical oppressive myelopathy secondary to OPLL could lead to a high incidence of cerebrospinal fluid leakage.21,22 Furthermore, although the ACCF group had a complication rate similar to that of the LAMP group, Table 3 indicates that the most prevalent complication in the ACCF group was cerebrospinal fluid leakage (8.78%). In some cases with OPLL clinging to the dural sac, a new surgical technique called the floating method was performed to protect the spinal cord and prevent dural tear.23 A specific indicator named the “double-layer” signal was observed on preoperative bone window computed tomography axial views and used to judge whether the ossified mass was attached to the dural sac.24 Moreover, ACCF has been found to lead to longer operative time and more intraoperative blood loss due to its technical difficulty.9,10,16,17

Hirabayashi et al25 designed a novel form of posterior approach for cervical OPLL in the late 1970s. It was described as open-door LAMP and modified by many scholars in practice. Although LAMP seems to be safer and to have less surgical trauma than the anterior approach, its drawback is that the clinical effect depends on the backward movement of the spinal cord. Also, constant threat of anterior compression would exist in the case of inadequate movement, which might lead to an unsatisfactory recovery of neurological function.4 In addition, a prerequisite for LAMP is sufficient cervical lordosis. Fujimori et al10 reported that preoperative cervical lordosis of 20° or greater could be essential if LAMP were used to successfully treat cervical thick OPLL. Some authors have used an indicator called the K-line, which could comprehensively assess both preoperative cervical alignment and the canal occupying ratio.26 Moreover, the complications after LAMP mostly manifested as C5 root palsy and axial neck pain, which need to be resolved. Unfortunately, the exact pathogenesis has been unclear. Duetzmann et al27 reported that LAMP had a high incidence of C5 root palsy and axial neck pain. Table 3 indicates that the LAMP group had a high incidence of axial neck pain (12.99%) and C5 root palsy (4.55%). Delayed neurological deterioration was also observed in the LAMP group in 4 of the included studies,6,11,12,14 with an incidence rate as high as 11.11% (11 of 99 patients in the LAMP group). Cervical kyphotic deformity usually occurred in the patients who underwent LAMP. It was reported that the C2–C7 Cobb angle measured on lateral radiograph had significantly decreased after LAMP at the final follow-up.6,10,27 Further, some authors have considered the instability of the cervical segment at the thickest OPLL a potential threat to the neurofunctional recovery after LAMP.14 Also, biomechanical analysis indicated that stress distribution increased with progression of kyphosis deformity after posterior decompression, which might induce delayed neurological deterioration.28

Progression of OPLL was also observed in patients treated with ACCF or LAMP.6 After at least 3 years of follow-up, Hayashi et al29 reported that the growth of OPLL after LAMP was observed in 9 of 35 patients classified as segmental type, 9 of 24 classified as mixed type, and 6 of 7 classified as continuous type. It was generally known that progression of OPLL may induce late neurological deterioration, but it may also contribute to the postoperative stabilization of the cervical spine.30

Given the above, both risks and clinical benefits should be comprehensively considered when determining surgical strategy. Further, the current study had some limitations. First, all studies in this meta-analysis were published in English, which might have led to a potential publication bias. Second, all included studies were nonrandomized, and their quality was not high. Third, various surgical indications and technologies in different treatment centers made clinical heterogeneity inevitable. Finally, the duration of follow-up differed among the included studies, perhaps affecting the results.

Conclusion

On the basis of this meta-analysis, the authors concluded that ACCF had a significantly better postoperative JOA score and neurological recovery rate than LAMP when the mean preoperative canal occupying ratio was 50% or greater. They therefore recommend ACCF for the treatment of cervical OPLL with a preoperative canal occupying ratio of 50% or greater. However, in cases with a mean preoperative canal occupying ratio of less than 50%, no statistically significant difference was detected in the postoperative JOA score and the neurological function recovery rate between ACCF and LAMP. Therefore, on the basis of clinical effectiveness and security, the authors prefer LAMP for the treatment of cervical OPLL when the preoperative canal occupying ratio is less than 50%. Finally, given the limitations of this meta-analysis, a well-designed, prospective, randomized controlled trial should be performed to draw a more convincing conclusion.

References

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  25. Hirabayashi K, Toyama Y, Chiba K. Expansive laminoplasty for myelopathy in ossification of the longitudinal ligament. Clin Orthop Relat Res. 1999;359:35–48. doi:10.1097/00003086-199902000-00005 [CrossRef]
  26. Fujiyoshi T, Yamazaki M, Kawabe J, et al. A new concept for making decisions regarding the surgical approach for cervical ossification of the posterior longitudinal ligament: the K-line. Spine (Phila Pa 1976). 2008;33(26):e990–e993. doi:10.1097/BRS.0b013e318188b300 [CrossRef]
  27. Duetzmann S, Cole T, Ratliff JK. Cervical laminoplasty developments and trends, 2003–2013: a systematic review. J Neurosurg Spine. 2015;23(1):24–34. doi:10.3171/2014.11.SPINE14427 [CrossRef]
  28. Nishida N, Kanchiku T, Kato Y, et al. Biomechanical analysis of cervical myelopathy due to ossification of the posterior longitudinal ligament: effects of posterior decompression and kyphosis following decompression. Exp Ther Med. 2014;7(5):1095–1099. doi:10.3892/etm.2014.1557 [CrossRef]
  29. Hayashi M, Ogino T, Itoh T, Takei H, Hashimoto J, Ohshima Y. The progress of OPLL after cervical laminoplasty: at least 3 years follow-up. Spinal Surg. 1997;11(1):61–66. doi:10.2531/spinalsurg.11.61 [CrossRef]
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Quality Evaluation of the 8 Included Studies According to the GRADE Scale

Study (Year)Risk of BiasIndirectnessImprecisionPublication BiasLarge EffectPlausible Residual ConfoundingTotalQuality of Evidence
Kim et al8 (2015)−10NA−100−2Very low
Liu et al9 (2013)−10NA−100−2Very low
Sakai et al6 (2012)a−10NA−100−1Very low
Fujimori et al10 (2014)−10NA−100−2Very low
Tani et al11 (2002)−10NA−100−2Very low
Chen et al12 (2011)−10NA−100−2Very low
Chen et al13 (2012)−10NA−100−2Very low
Masaki et al14 (2007)−10NA−100−2Very low

Baseline Characteristics of the 8 Included Studiesa

Study (Year)Study DesignStudy LocationSurgical ApproachSample SizeMean (SD or Range) Age, ySex, M/F, No.Mean (SD or Range) Surgical Segments, No.Mean (SD or Range) Follow-up, mo
Kim et al8 (2015)RetrospectiveSouth KoreaACCF7157.3 (35–76)51/20NA48 (12–68)
LAMP6456.4 (35–76)49/15NA41 (24–64)
Liu et al9 (2013)RetrospectiveChinaACCF68 (subgroup A: 22; subgroup B: 46)54.4 (12.8)36/32NA≥60
LAMP59 (subgroup A: 20; subgroup B: 39)57.9 (9.5)25/34NA≥60
Sakai et al6 (2012)ProspectiveJapanACCF2059.5 (9.3)NA3.1 (1–5)≥60
LAMP2258.4 (9.6)NA4.5 (4–5)≥60
Fujimori et al10 (2014)RetrospectiveJapanACCF1255.6 (7.8)7/53.3 (0.9)118.8 (49.2)
LAMP1558.7 (9.1)13/25.4 (1.2)122.4 (68.4)
Tani et al11 (2002)RetrospectiveJapanACCF1462 (11)11/33.5 (1)49 (34)
LAMP1266 (6)9/34 (1.2)50 (43)
Chen et al12 (2011)RetrospectiveChinaACCF2257.2 (43–71)14/83.23≥48
LAMP2554.2 (32–66)16/9≥3≥48
Chen et al13 (2012)RetrospectiveChinaACCF9148.7 (1.4)63/282.7 (0.2)≥48
LAMP4146.3 (2.5)33/84.1 (0.2)≥48
Masaki et al14 (2007)RetrospectiveJapanACCF1951.8 (6.6)14/52.9 (0.9)≥12
LAMP4062.6 (10.3)30/104.6 (0.5)≥12

Complications Observed in the 2 Groups

ComplicationNo. (%)

ACCF (N=205)LAMP (N=154)
Cerebrospinal fluid leakage18 (8.78)2 (1.30)
Dysphagia/dysphonia14 (6.83)0
Central neurological dysfunction6 (2.93)0
Implant dislocation3 (1.46)0
Hematoma2 (0.98)2 (1.30)
Pseudarthrosis1 (0.49)0
C5 palsy2 (0.98)7 (4.55)
Axial neck pain020 (12.99)
Authors

The authors are from the Department of Orthopedics (RQ), Gaoyou People's Hospital Affiliated to Soochow University, Gaoyou; the Medical College of Nantong University (WS, BQ, KY), Nantong; the Department of Orthopedics (WS, BQ, JH, CX, CC, KY, FZ, XC), Affiliated Hospital of Nantong University, Nantong; Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair (JH, CC, FZ, XC), Nantong; and the Department of Orthopedics (PZ), Gaoyou Hospital of Integrated Traditional Chinese and Western Medicine, Gaoyou, Jiangsu, China.

Drs Qin, Sun, and Qian contributed equally to this work and should be considered as equal first authors.

The authors have no relevant financial relationships to disclose.

Correspondence should be addressed to: Xiaoqing Chen, MD, Department of Orthopedics, Affiliated Hospital of Nantong University, No 20 Xisi Rd, Chongchuan District, Nantong, 226001, Jiangsu, China ( xq.c@live.com).

Received: January 27, 2018
Accepted: July 05, 2018
Posted Online: April 09, 2019

10.3928/01477447-20190403-04

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