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      Is correction of segmental kyphosis necessary in single-level anterior cervical fusion surgery? An observational study

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          This study was conducted to determine whether sagittal lordotic alignment and clinical outcomes could be improved by the correction of segmental kyphosis after single-level anterior cervical discectomy and fusion (ACDF) surgery.

          Patients and methods

          We retrospectively reviewed patients who underwent single-level ACDF surgery in our hospital between January 2014 and February 2017. Basic characteristics of patients included age at surgery, gender, diagnosis, duration of symptoms, and location of target level. Pre- and postoperative radiographs at the 6-month follow-up were used to evaluate the following parameters, such as segmental angle, C2–C7 angle, T1 slope, and C2–C7 sagittal vertical axis (SVA). Postoperative clinical outcomes were assessed by the Neck Disability Index and VAS. According to the segmental angle of postoperative radiographs, patients were divided into noncorrection group and correction group.


          A total of 181 patients (99 males and 82 females) were analyzed in our study. There were 32 patients in the noncorrection group and 149 patients in the correction group. There was no significant difference in demographic and clinical data between the two groups before surgery. However, patients in the correction group showed larger C2–C7 angle and lower C2–C7 SVA after surgery in comparison with those in the noncorrection group. Besides, changes in the segmental angle were positively correlated with changes in C2–C7 angle and negatively correlated with changes in C2–C7 SVA.


          Surgical correction of segmental kyphosis in single-level cervical surgery contributed to balanced cervical alignment in comparison with those without satisfactory correction. However, we could not demonstrate that the correction of segmental alignment is associated with a better recovery in clinical outcomes.

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          Most cited references 19

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          Factors affecting sagittal malalignment due to cage subsidence in standalone cage assisted anterior cervical fusion.

          Fusion of cervical spine in kyphotic alignment has been proven to produce an acceleration of degenerative changes at adjacent levels. Stand-alone cages are reported to have a relatively high incidence of implant subsidence with secondary kyphotic deformity. This malalignment may theoretically lead to adjacent segment disease in the long term. The prospective study analysed possible risk factors leading to cage subsidence with resulting sagittal malalignment of cervical spine. Radiographic data of 100 consecutive patients with compressive radiculo-/myelopathy due to degenerative disc prolapse or osteophyte formation were prospectively collected in those who were treated by anterior cervical discectomy and implantation of single type interbody fusion cage. One hundred and forty four implants were inserted altogether at one or two levels as stand-alone cervical spacers without any bone graft or graft substitute. All patients underwent standard anterior cervical discectomy and the interbody implants were placed under fluoroscopy guidance. Plain radiographs were obtained on postoperative days one and three to verify position of the implant. Clinical and radiographic follow-up data were obtained at 6 weeks, 3 and 6 months and than annually in outpatient clinic. Radiographs were evaluated with respect to existing subsidence of implants. Subsidence was defined as more than 2 mm reduction in segmental height due to implant migration into the adjacent end-plates. Groups of subsided and non-subsided implants were statistically compared with respect to spacer distance to the anterior rim of vertebral body, spacer versus end-plate surface ratio, amount of bone removed from adjacent vertebral bodies during decompression and pre- versus immediate postoperative intervertebral space height ratio. There were 18 (18%) patients with 19 (13.2%) subsided cages in total. No patients experienced any symptoms. At 2 years, there was no radiographic evidence of accelerated adjacent segment degeneration. All cases of subsidence occurred at the anterior portion of the implant: 17 cases into the inferior vertebra, 1 into the superior and 1 into both vertebral bodies. In most cases, the process of implant settling started during the perioperative period and its progression did not exceed three postoperative months. There was an 8.7 degrees average loss of segmental lordosis (measured by Cobb angle). Average distance of subsided intervertebral implants from anterior vertebral rim was found to be 2.59 mm, while that of non-subsided was only 0.82 mm (P < 0.001). Spacer versus end-plate surface ratio was significantly smaller in subsided implants (P < 0.001). Ratio of pre- and immediate postoperative height of the intervertebral space did not show significant difference between the two groups (i.e. subsided cages were not in overdistracted segments). Similarly, comparison of pre- and postoperative amount of bone mass in both adjacent vertebral bodies did not show a significant difference. Appropriate implant selection and placement appear to be the key factors influencing cage subsidence and secondary kyphotisation of box-shaped, stand-alone cages in anterior cervical discectomy and fusion. Mechanical support of the implant by cortical bone of the anterior osteophyte and maximal cage to end-plate surface ratio seem to be crucial in the prevention of postoperative loss of lordosis. Our results were not able to reflect the importance of end-plate integrity maintenance; the authors would, however, caution against mechanical end-plate damage. Intraoperative overdistraction was not shown to be a significant risk factor in this study. The significance of implant subsidence in acceleration of degenerative changes in adjacent segments remains to be evaluated during a longer follow-up.
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            Cage subsidence does not, but cervical lordosis improvement does affect the long-term results of anterior cervical fusion with stand-alone cage for degenerative cervical disc disease: a retrospective study.

            Clinical outcomes of the stand-alone cage have been encouraging when used in anterior cervical discectomy and fusion (ACDF), but concerns remain regarding its complications, especially cage subsidence. This retrospective study was undertaken to investigate the long-term radiological and clinical outcomes of the stand-alone titanium cage and to evaluate the incidence of cage subsidence in relation to the clinical outcome in the surgical treatment of degenerative cervical disc disease.
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              Clinical adjacent-segment pathology after anterior cervical discectomy and fusion: results after a minimum of 10-year follow-up.

              Anterior cervical discectomy and fusion using cervical plates has been seen as effective at relieving cervical radiculopathy and myelopathy symptoms. Although it is commonly used, subsequent disc degeneration at levels adjacent to the fusion remains an important problem. However, data on the frequency, impact, and predisposing factors for this pathology are still rare.

                Author and article information

                Ther Clin Risk Manag
                Ther Clin Risk Manag
                Therapeutics and Clinical Risk Management
                Therapeutics and Clinical Risk Management
                Dove Medical Press
                19 December 2018
                : 15
                : 39-44
                [1 ]Department of Orthopedics, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, China, sdghgk@ 123456126.com
                [2 ]Department of Emergency, The Second Hospital of Tangshan City, Tangshan, Hebei 063000, China
                Author notes
                Correspondence: Lingde Kong, Department of Orthopedics, The Third Hospital of Hebei Medical University, 139 Ziqiang Road, Shijiazhuang, Hebei 050051, China, Tel +86 150 3211 1276, Fax +86 311 8860 2007, Email sdghgk@ 123456126.com

                These authors contributed equally to this work

                © 2019 Lu et al. This work is published and licensed by Dove Medical Press Limited

                The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

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