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      Cervical sagittal alignment as a predictor of adjacent-level ossification development

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          To explore the role of cervical sagittal alignment in the occurrence of adjacent-level ossification development (ALOD) in patients who underwent anterior cervical discectomy fusion with self-locking stand-alone polyetheretherketone cage, and the relationship between cervical sagittal alignment and clinical outcomes.


          Because of its advantages, anterior cervical plating systems have been used as the classic surgical method in the treatment of patients with cervical disc herniation. However, the proximity (<5 mm) of the plate to the adjacent disc space has proven to be a critical risk factor for ALOD. How cervical sagittal alignment influences the development of ALOD is unknown and its role in ALOD needs clarification.

          Patients and methods

          One hundred and eighteen adults who underwent anterior cervical discectomy fusion with self-locking stand-alone polyetheretherketone cage for cervical radiculopathy or myelopathy between December 2013 and December 2015 were retrospectively recruited. Of these, 15 patients developed ALOD and 103 patients did not, representing two groups for comparison. The cervical sagittal parameters were measured, including C2–C7 Cobb angle (Cobb), fused segment angle, cervical tilt (CT), T1 slope (T1S) and C2–C7 sagittal vertical axis. Clinical outcomes and efficacy were evaluated using a visual analog scale, Japanese Orthopedic Association (JOA) score and neck disability index (NDI) score before and after surgery.


          There were no significant differences in patient demographics between the two groups. Cobb value ( P<0.05), CT ( P<0.05) and T1S ( P<0.05) were significantly different between the two groups, while fused segment angle ( P>0.05) and C2–C7 sagittal vertical axis ( P>0.05) showed no difference. Compared with preoperative scores, improvement was seen in postoperative visual analog scale, JOA and NDI scores at each time point ( P<0.05). However, the postoperative scores at 24 months in the NO-ALOD group indicated greater improvements compared with the ALOD group ( P<0.05). There were significant correlations between Cobb and CT ( r=0.607, P<0.05) and CT and T1S ( r=0.681, P<0.05). Also, T1S was significantly correlated with clinical outcomes (JOA: r=0.689, P<0.05; NDI: r=−0.710, P<0.05).


          Maintaining a lordotic cervical sagittal alignment was related to a lower risk of ALOD and improved clinical outcomes.

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          Most cited references 20

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          The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion.

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            Donor site morbidity after anterior iliac crest bone harvest for single-level anterior cervical discectomy and fusion.

            This retrospective, questionnaire-based investigation evaluated iliac crest bone graft (ICBG) site morbidity in patients having undergone a single-level anterior cervical discectomy and fusion (ACDF) procedure performed by a single surgeon (T.J.A.). To evaluate acute and chronic problems associated with anterior ICBG donation, particularly long-term functional outcomes and impairments caused by graft donation. Anterior cervical discectomy and fusion procedures frequently use autologous anterior ICBG to facilitate osseous union. Although autologous ICBG offers several advantages over alternative grafting materials, donor site morbidity can be significant. Acute and chronic complications of donor sites have been reported, yet there are currently no reports of long-term functional outcomes after autologous anterior ICBG donation after single-level ACDF. A questionnaire was mailed to 187 consecutive patients who were retrospectively identified to have undergone autologous anterior ICBG harvest for single-level ACDF between 1994 and 1998. The questionnaire divided items into symptomatic (acute and chronic) and functional assessments. Patients answered yes, no, or not applicable; pain was assessed with a Visual Analogue Scale (VAS). Surveys were completed either by mail or follow-up telephone interview by 134 patients (71.6%). Average follow-up was 48 months (range, 24-72 months). Acute symptoms were reported at the following rates: ambulation difficulty, 50.7%; extended antibiotic usage, 7.5%; persistent drainage, 3.7%; wound dehiscence, 2.2%; and incision and drainage, 1.5%. The chronic symptom questionnaire demonstrated a high degree of satisfaction with the cosmetic result (92.5%). Pain at the donor site was reported by 26.1% of patients with a mean VAS score of 3.8 in 10, and 11.2% chronically use pain medication. Twenty-one patients (15.7%) reported abnormal sensations at the donor site, but only 5.2% reported discomfort with clothing. A unique functional assessment revealed current impairments at the following rates: ambulation, 12.7%; recreational activities, 11.9%; work activities, 9.7%; activities of daily living, 8.2%; sexual activity, 7.5%; and household chores, 6.7%. A large percentage of patients report chronic donor site pain after anterior ICBG donation, even when only a single-level ACDF procedure is performed. Moreover, long-term functional impairment can also be significant. Patients should be counseled regarding these potential problems, and alternative sources of graft material should be considered.
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              Kyphotic malalignment after anterior cervical fusion is one of the factors promoting the degenerative process in adjacent intervertebral levels.

              The aim of this study was to determine whether postoperative malalignment of the cervical spine after anterior interbody fusion surgery promotes degenerative changes in the neighboring intervertebral discs. Forty-two patients who underwent anterior interbody fusion surgery for cervical spondylosis and disc herniation (34 men, 8 women) were followed for an average of 9.8 years. The average age at surgery was 50.2 years. Twenty-three patients underwent a single-level fusion, 17 underwent two-level fusion, and 2 had three levels fused. The Japanese Orthopaedic Association cervical myelopathy score, with a normal score 17 points, was 11.7 before surgery and 14.9 at follow-up. Neurological status was significantly improved postoperatively, and the improvement was preserved thereafter in most cases (paired t-test, P<0.001). Degenerative changes were evident on radiological examination in the levels adjacent to the fused segment in 21 of the 42 (50%) patients. Eight of these 21 patients demonstrated neurological deterioration caused by an adjacent disc lesion. A total of 43% of the patients with adjacent-level degeneration had malalignment of the cervical spine, such as kyphosis or sigmoid curvature. In addition, degenerative change in adjacent intervertebral levels was observed in 77% of kyphoses of the fused segment. These were statistically significant (Fisher exact method, P<0.05, P<0.04, respectively). Our findings suggest that one of the factors promoting degenerative change in adjacent intervertebral levels after anterior cervical fusion for degenerative disorders is postoperative kyphotic change in the cervical spine and the fused segment.

                Author and article information

                J Pain Res
                J Pain Res
                Journal of Pain Research
                Journal of Pain Research
                Dove Medical Press
                20 July 2018
                : 11
                : 1359-1366
                Department of Orthopaedic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China, fanjingol@ 123456126.com , caiwhspine@ 123456sina.com
                Author notes
                Correspondence: Jin Fan, Department of Orthopaedic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China, Email fanjingol@ 123456126.com
                Weihua Cai, Department of Orthopaedic Surgery, The First Affliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Gulou Qu, Nanjing, Jiangsu 210029, China, Email caiwhspine@ 123456sina.com

                These authors contributed equally to this work

                © 2018 Liu 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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