Postoperative Cervical Kyphosis Research Articles

Effects of intraoperative hinge fracture on postoperative cervical spine alignment in double door cervical laminoplasty

Introduction Hinge fracture and cervical kyphosis are known complications of cervical laminoplasty. Prior literatures on hinge fracture focused mainly on laminoplasty performed using the open-door technique. In this study we aim to assess the effect of intraoperative hinge fracture on postoperative cervical spine alignment in cervical laminoplasty performed using the double door technique. Methods This study recruited patients who received double door cervical laminoplasty from January 2014 to December 2022. The diagnosis, demographic data, preoperation and postoperation cervical spine alignment of the patients with intraoperative hinge fracture were compared with patients withouintraoperative hinge fracture. Cervical spine alignment was measured using C2–7 Cobb's angle on neutral lateral cervical spine X ray. Results Nine patients with intraoperative hinge fracture and 51 patients without intraoperative hinge fracture were recruited into the study. There was no statistically significant difference in age, sex, diagnosis and preoperative cervical spine alignment between the patients with and without intraoperative hinge fracture. Significant difference was found in the postoperation cervical spine alignment (1.9 ± 15.5° vs 9.7 ± 13.6°, p = .044) and change in cervical spine alignment (−12.9 ± 12.1° vs −4.0 ± 10.0, p = .02) between patients with and without intraoperative hinge fracture. Conclusions In double door cervical laminoplasty, intraoperative hinge fracture is associated with development of postoperative cervical kyphosis.

Postoperative Changes of Spinopelvic Sagittal Parameters After Cervical Laminoplasty for Cervical Spondylotic Myelopathy.

A retrospective analysis of prospectively collected data. To investigate postoperative changes of spinopelvic sagittal parameters after laminoplasty for cervical spondylotic myelopathy (CSM) accompanying postoperative cervical kyphotic deformity or cervical regional sagittal imbalance. To the best of our knowledge, no study has been reported concerning postoperative changes of spinopelvic sagittal parameters accompanying postoperative deterioration of cervical sagittal alignment or balance after cervical laminoplasty. Forty-five CSM patients without preoperative cervical kyphosis who underwent laminoplasty were included. None of the 45 patients had a medical history of previous spine surgery, hip joint surgery, or knee joint surgery. The patients were divided into 2 groups (kyphosis and lordosis groups) according to postoperative C2-7 angle, and they were also divided into 2 other groups (imbalance and balance groups) according to postoperative C1-7 sagittal vertical axis. Postoperative changes (Δ) of T1 slope (T1S), thoracic kyphosis, thoracolumbar kyphosis (TLK), lumbar lordosis (LL), Pelvic tilt, and C7 sagittal vertical axis were measured comparing lateral radiographs of the whole spine in the standing position taken at 1 year postoperatively with those before surgery. Both T1S and TLK significantly decreased after cervical laminoplasty in the kyphosis group compared with the lordosis group. On the other hand, both T1S and TLK increased significantly, and LL significantly decreased after surgery in the imbalance group compared with the balance group. At 1 year after laminoplasty for CSM, both T1S and TLK significantly decreased accompanying postoperative cervical kyphotic deformity as a compensatory action for postoperative cervical kyphosis to maintain the global sagittal balance of the spine, whereas both T1S and TLK increased significantly, and LL significantly decreased accompanying postoperative cervical reginal sagittal imbalance which resulted in postoperative forward inclination of the whole spine.

Preoperative Range of Motion in Extension May Influence Postoperative Cervical Kyphosis After Laminoplasty.

Retrospective observational study. The objective of this study was to investigate factors associated with cervical kyphosis after laminoplasty. Many factors are reportedly associated with the deterioration of cervical curvature after laminoplasty, including cervical lordosis angle, cervical spine range of motion (ROM), T1 slope, and C2-C7 sagittal vertical axis. Postlaminoplasty kyphosis or deterioration of cervical curvature is likely caused by multiple factors. There is currently no consensus on these issues. Data of patients treated with laminoplasty for degenerative cervical myelopathy at our institution during 2008-2018 were reviewed. The following variables were collected for each patient: age and sex; follow-up time; surgery involving C3 (yes or no); surgery involving C7 (yes or no); distribution of segments operated on; number of laminae operated on; flexion, extension, and total ROM; cervical lordotic angle; longitudinal distance index; curvature index; C2-C7 sagittal vertical axis; and T1 slope. Logistic regression analysis was used to assess possible risk factors for postoperative kyphosis. Receiver operating characteristic curves were constructed to determine the cutoff values of risk factors. The study cohort comprised 151 patients. Logistic regression analysis indicated that sex, number of laminae operated on, and preoperative extension ROM were significantly associated with postoperative cervical kyphosis ( P <0.05). There was significantly greater postoperative kyphosis in women than in men; the more segments operated on, the greater the risk of postoperative kyphosis, and the larger the preoperative extension ROM, the lower the risk of postlaminoplasty kyphosis. Receiver operating characteristic curve analysis showed that the cutoff value for preoperative extension ROM is 22.1°. Preoperative extension ROM may be associated with the development of postoperative kyphosis. The cutoff value of preoperative extension ROM that suggested the prospect of postoperative kyphosis in our sample was 22.1°.

Comparison of C2 dome-like laminectomy with C2 partial laminectomy for upper cervical ossification of the posterior longitudinal ligament.

To compare surgical outcomes of C2 dome-like laminectomy with C2 partial laminectomy in patients with ossification of the posterior longitudinal ligament (OPLL) up to the C2 level and above. 32 patients underwent surgical treatment for OPLL up to C2 and were divided into: C2 dome-like laminectomy group (C2-DOM group, n = 16) and C2 partial laminectomy group (C2-PL group, n = 16). The cervical curvature (CCI), dura width at C2/3, Japanese orthopedic association (JOA) score, recovery rate (RR), neck disability index (NDI) score, and visual analogue scale (VAS) score were evaluated and compared preoperatively and postoperatively at 1 month, 3 months, 6 months, 1 year, and annually thereafter. The JOA score and NDI significantly improved at the final follow-up in both groups with no significant intergroup differences. There were no significant differences in preoperative dura width at C2/3 and VAS between the two groups. At the final follow-up, dura width at C2/3 in the C2-PL group was significantly larger than the C2-DOM group, while the VAS of C2-DOM group was significantly lower than C2-PL group. The CCI in both groups decreased compared with before surgery, and there was no significant difference in CCI between the two groups. C2-DOM is less demolitive and reduces postoperative neck pain, while C2-PL can achieve more adequate decompression without increasing the risk of postoperative cervical kyphosis.

Preliminary Results of Instantaneous Centre of Rotation Change after Thoracic Instrumentation in Adolescent Idiopathic Scoliosis Patients.

The instantaneous centre of rotation (ICR) is the centre of motion with zero velocity where a rigid body moves in a particular plane. ICR, as a dynamic measurement, gives more accurate results in terms of quality and quantity of the vertebral motions compared to range of motion (ROM). We aimed to determine the effect of thoracic instrumentation on cervical movement of adolescent idiopathic scoliosis (AIS) patients who had undergone thoracic level instrumentation by measuring pre-operative and post-operative ICR change in a pilot study. A total of 25 AIS patients were included in this study. C4-C5 and C6-C7 segmental ICR were determined by pre-operative and post-operative cervical flexion-extension radiographs. In addition, cervical sagittal parameters and global sagittal parameters were investigated. There was no statistically significant change in ICR location post-operatively in both x and y coordinates at C4-C5 segment (p: 0.326 and p: 0.946, respectively) and C6-C7 segment (p: 0.209, p: 0.086, respectively). There was a positive correlation between LCL and C4-C5 ICR y coordinate (r: 0.481), but not with C6-C7 ICR y coordinate (r: -0.2, p: 0.398). T5-T12 kyphosis decreased (p: 0.002) and T1 pelvic angle (0.003), SVA (0.02) and sacral slope (0.049) increased significantly post-operatively. T1S was correlated with LCL (r: 0.595, p: 0.002), T5-T12 kyphosis (r: 0.423, p: 0.035), SVA (r: 0.658, p<0.001) and C2-C7 SVA (r: 0.416, p: 0.039). The ICR for cervical region was not changed post-operatively in AIS patients with thoracic instrumentation. There was no relationship found between the development of post-operative cervical kyphosis or lordosis and ICR, which represents the quality and quantity of intervertebral motion. The T1 vertebra plays a key role for cervical, thoracic, and global parameters interaction.

Impact of C3 Involvement on Postoperative Kyphosis Following Cervical Laminoplasty: A Comparison Between High and Low T1 Slope

The goal of the present study was to investigate the impact of C3 involvement on the postoperative kyphosis following cervical laminoplasty in patients with high and low T1S. The data from ossification of the posterior longitudinal ligament patients who had undergone laminoplasty between January 2016 and December 2019 were retrospectively reviewed. Patients were divided into low-and high-T1S groups according to preoperative T1S, and the postoperative alignment change was compared between the groups. The relationships between postoperative cervical kyphosis and preoperative variables, including gender, C3 laminoplasty, T1S, cervical lordosis (CL), C2-7 Sagittal Vertical Axis, and T1S minus CL (T1S-CL) were investigated. Eighty-six patients were divided into 2 groups above and below median preoperative T1S (23.70). There were thirty-three patients (38.3%) in low-T1S group and fifty-three patients (61.7%) in high-T1S group. Twenty-three patients (26.7%) were performed with C3 involved laminoplasty. C3 laminoplasty (odds ratio [OR], 9.67; 2.82-33.16; P=0.000), high T1S (OR, 4.89; 1.54-15.49; P=0.007), and mismatched T1S-CL (OR, 5.96; 1.83-19.43; P=0.003) were significantly associated with postoperative kyphosis. In high-T1S group, the loss of CL was significant (P=0.017) when C3 laminoplasty was performed, whereas, in low-T1S group, the C3 laminoplasty did not show the statistically significant difference. (P=0.194). C3 laminoplasty, mismatched T1S-CL, and high T1S were found to increase the risk of postoperative kyphosis following cervical laminoplasty. Patients with high T1 slope tended to exhibit a greater loss of CL when the laminoplasty was performed extending to C3 segment.

Transiency of postoperative cervical kyphosis seen after surgical correction of sagittal malalignment in adult spinal deformity patients.

ObjectiveIn this study, we evaluated factors affecting changes in cervical lordosis after deformity correction and during follow-up period in adult spinal deformity (ASD) patients with severe sagittal imbalance.MethodsSeventy-nine patients, with an average age of 71.6 years, who underwent long-segment fixation from T10 to S1 with sacropelvic fixation were included. We performed a comparative analysis of the radiographic parameters after surgery (Post) and at the last follow-up (Last). We calculated the Pearson’s correlation coefficient and performed multilinear regression analysis to predict independent parameters for Post and Last cervical lordosis (CL), T1 slope (T1S), and thoracic kyphosis (TK).ResultsHyperlordotic changes of -23.3° in CL before surgery was reduced to -7° after surgery, and Last CL had increased to -15.3°. T1S was reduced from 27° before surgery to 14.4° after surgery and had increased to 18.8° at the last follow-up. Through multilinear regression analysis, we found that Post CL and T1S were more significantly affected by the amount of LL correction (p = .045 and .049). The effect of Last T1S was significantly associated with the Last CL; the effect of Last TK, with the Last T1S; and the effect of Post PI-LL, with the Last TK (p < .05).ConclusionThe postoperative kyphotic change in CL in ASD patients with preoperative cervical hyperlordosis is not permanent and is affected by drastic LL correction and SVA restoration. To achieve spinopelvic harmony proportional to the difference in LL relative to PI, TK becomes modified over time to increase T1S and CL, in an effort to achieve optimal spine curvature.

Prediction of angular kyphosis after cervical laminoplasty using radiologic measurements

Angular kyphosis is an important complication after cervical laminoplasty. Previous reports have suggested that T1 slope (T1s) and extension function (EF) have key roles in kyphosis, and no different radiologic measuments which affects postoperative kyphosis were seen between ossification of the posterior longitudinal ligament (OPLL) or cervical spondylotic myelopathy (CSM). We tried to find preoperative radiologic measurements predicting angular kyphosis after laminoplasty according to disease entities. We retrospectively analyzed 133 patients with OPLL or CSM who underwent expansive laminoplasty. Preoperative neutral and extension C2-7 cobb angle (CA), T1s, C2-7 sagittal vertical axis, and C2-7 slope angle (SA) were measured. EF of C2-7 CA and C2-7 SA was defined as extension CA/SA minus neutral CA/SA. Significant angular kyphosis was defined as LCL less than −10° after surgery. Mean loss of lordosis was −3.23, and 16.5% of patients showed significant kyphosis. Preoperative EF-CA, EF-SA, and T1s were found to be predictive for angular kyphosis by Pearson correlation analysis. The receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) of radiologic measurements could not reach 0.7. In patients with OPLL, the AUC of preoperative neutral CA was 0.716. However, in patients with CSM ROC curve analysis revealed that EF-CA and EF-SA could predict the significant angular kyphotic changes. Examining OPLL and CSM separately, preoperative radiologic measurements were found to influence postoperative cervical kyphosis, respectively. However, preoperative C2-7 neutral CA in OPLL patients and both EF-CA and EF-SA in CSM patients could predict significant angular kyphosis after cervical laminoplasty.

Predictors of poor outcome in cervical spondylotic myelopathy patients underwent anterior hybrid approach: focusing on change of local kyphosis

ObjectiveThis study was a retrospective multivariable analysis for risk factors of poor outcome in patients who underwent anterior hybrid approach, and discussed the causes of worsening of postoperative local alignment.MethodsA total of 86 patients with progressive spinal cord compression and local kyphosis underwent an anterior hybrid approach (ACDF+ACCF), between June 2011 and June 2017. We evaluated clinical outcome by the Japanese Orthopaedic Association (JOA) score and recovery rate. Patients were divided into two groups according to the worsening and improving of postoperative local alignment. Multivariate logistic regression analysis was applied to the evaluation of risk factors. Mann-Whitney U test, independent t test, and chi-squared test were performed for the comparison of local kyphosis between postoperative and last follow-up.ResultsThere were twenty patients who had a recovery rate of less than 50%. Advance age, longer duration of symptoms, bigger T1 slope angle, and lower change of local kyphosis angle were significantly associated with a poor clinical outcome by multivariate logistic regression analysis. The cause of worsening of postoperative local alignment had T1 slope, C2–7 sagittal vertical axis (SVA), adjacent segment degeneration (ASD), and implant subsidence.ConclusionsThe change of local kyphosis was a predictor of clinical outcome after the hybrid approach. Furthermore, postoperative ASD, implant subsidence, T1 slope, and C2–7 Cobb were associated with recurrence of postoperative cervical kyphosis.

Which Factors Affect Postoperative Cervical Kyphosis after Laminoplasty for Cervical Spondylotic Myelopathy?

Which Factors Affect Postoperative Cervical Kyphosis after Laminoplasty for Cervical Spondylotic Myelopathy?

91. Can the proposed posterior ligament-bone injury classification and severity score predict the failure of anterior-only surgery for subaxial cervical facet dislocations?

BACKGROUND CONTEXT The approach selection for subaxial cervical fracture dislocations (SCFD) is controversial. While spinal surgeons increasingly prefer a single anterior approach, the complication of postoperative cervical kyphosis is worrisome. Hence, identification of suitable candidates requiring a second posterior reconstruction is necessary, thus preventing the failure of anterior-only surgery in patients with SCFD. PURPOSE To introduce a novel classification and scoring system called the posterior ligament-bone injury classification and severity (PLICS) score and verify whether this system can be generally utilized for the treatment of the SCFD to predict the failure of anterior-only surgery. STUDY DESIGN/SETTING A retrospective cohort study. PATIENT SAMPLE A total of 394 patients with SCFD who underwent anterior decompression, reduction, and fusion between January 2002 and December 2017 in one center were retrospectivelyenrolled in the study. The inclusion criteria included: 1. the preoperative magnetic resonance imaging (MRI) detected facture dislocation accompanying with an extruded disc, which deformed the dural sac beyond the line between the postero-inferior corner of cranial vertebrae and the postero-superior corner of caudal vertebrae; 2. the clinical level of neural dysfunction corresponds to the segment of reconstruction without the requirement of an extensive posterior decompression; 3. the reduction can be achieved under an attempt at the awake skull traction preoperatively or via anterior approach after the removal of herniated disc intraopertively. The exclusion criteria included: reduction can't be by preoperative skull traction, or by an anterior approach intraoperatively; the patients obtained a posterior reconstruction surgery when the intramedullary edema may extend beyond the segment of dislocation; severe traumatic cervical spondylolisthesis (over grade 3); the patients are accompanying by ankylosing spondylitis. OUTCOME MEASURES Clinical outcomes with respect to neck pain and function were recorded for each patient according to visual analog score (VAS) and the Neck Disability Index (NDI). We paired the equal number of patients between successful and unsuccessful groups to compare the difference in the clinical outcome. The American Spinal Injury Association (ASIA) impairment scale was recorded at each follow-up interval. Additionally, lateral radiography computed tomography (CT) and MRI were also recommended. METHODS Patients were divided into successful and unsuccessful groups according to whether failure of internal fixation was observed during follow-up. PLICS is based on the injury severity of the ligament-bone structure of three elements. Anatomically, the posterior column of cervical spine can be subdivided into three-column structure, including bilateral facet joints and the outside joint capsules, and posterior spinous processes and the attached ligament structures, so-called posterior ligamentous complex, including the supraspinal ligament and interspinous ligament. In this score system, a specific point value (0 - 3) is assigned to a particular variable within each element reflective of the severity of injury and its contribution to stability of posterior column of cervical spine. The preoperative PLICS score of all patients are recorded respectively. RESULTS Among 354 patients, 89.8% fulfilled the follow-up. Fifteen patients (4.2%) experienced hardware failure and progressive cervical kyphosis at the postoperative follow-up. The patients were divided into successful (15 patients) and unsuccessful (339 patients) groups. The average VAS score in the satisfactory group decreased from 6.7+0.8 to 1.3+0.6. The average VAS score in the unsatisfactory group decreased from 4.9+0.8 to 0.3+0.5. The average NDI score at the12-month follow-up was statistically low in the satisfactory group (6.2+2.1 vs 15.5+3.8, P= .028). It is worth noting that, except for only one patient with a PLICS score of 6, the PLICS score for the other 14 patients who experienced postoperative hardware failure was >7. However, the PLICS score for the other 339 patients (except for 2 cases) who obtained satisfactory radiological outcome was CONCLUSIONS When a PLICS score >7 is accompanied by severe lateral mass fracture, the risk of postoperative failure after an anterior-only reconstruction is high and supplemental posterior strengthening can be considered. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Does Preoperative T1 Slope and Cervical Lordosis Mismatching Affect Surgical Outcomes After Laminoplasty in Patients with Cervical Spondylotic Myelopathy?

To assess whether preoperative T1 slope and cervical lordosis mismatching affect the surgical outcomes of patients with cervical spondylotic myelopathy (CSM) after laminoplasty. A total of 85 patients with CSM who underwent unilateral open-door laminoplasty between January 2013 and May 2017 were retrospectively reviewed. Based on preoperative T1 slope and C2-C7 lordosis matching, the patients were divided into 2 groups: the match group and the mismatch group. The T1 slope minus C2-C7 lordosis (T1S-CL) <20° was defined as matching. Radiographic parameters included T1 slope, C2-C7 lordosis, C2-C7 sagittal vertical axis (SVA), and T1S-CL. Clinical outcomes were based on the Neck Disability Index (NDI) and Japanese Orthopedic Association (JOA) scores. The preoperative T1S-CL had significant correlation with T1 slope (r= 0.283), C2-C7 lordosis (r= -0.611), and C2-C7 SVA (r= 0.331). At the final follow-up, patients in the mismatch group had a higher incidence of postoperative cervical kyphosis (P= 0.007) and C2-C7 SVA >40 mm (P= 0.043). The mismatch group also had greater △C2-C7 lordosis (P= 0.028), △C2-C7 SVA (P=0.042), and △T1S-CL (P= 0.044). Comparison of clinical outcomes revealed that patients in the match group had better NDI and JOA recovery (P < 0.05). T1S-CL is a clinically relevant parameter for surgical decision making because patients with T1S-CL mismatching are more likely to have postoperative kyphotic alignment changes and cervical sagittal imbalance. Laminoplasty might not be a suitable option for patients with T1S-CL mismatching.

The time course of cervical alignment after cervical expansive laminoplasty: Determining optimal cut-off preoperative angle for predicting postoperative kyphosis.

Retrospective Cohort studyTo analyze cervical lordosis angle (CLA) change after cervical expansive laminoplasty (CEL) over time, and to determine optimal cut-off angle for predicting postoperative kyphosisPostoperative development of sagittal malalignment after laminoplasty is associated with neurological dysfunction and neck pain. However, there is no information on the serial CLA change over time and cut-off angle for predicting postoperative kyphosisThe Cobb angle between C2 and C7 in a series of lateral cervical X-rays in the neutral position was retrospectively reviewed for 36 months. And, the effect of time on CLA after CEL and the risk factors associated with postoperative cervical kyphosis (Cobb's angle ≤0°) were analyzed. Also, the optimal cut-off angle for predicting postoperative kyphosis was determined.A total of 110 cases of CEL for cervical myelopathy were enrolled from February 2005 to May 2010. The mean cervical alignment changed from 12.3 ± 10.4° (mean ± standard deviation [SD]) at the preoperative evaluation to 8.2 ± 11.6°, 10.6 ± 10.1°, 9.1 ± 10.0°, 8.4 ± 11.2°, 8.5 ± 10.5°, 8.1 ± 9.9°, and 8.7 ± 10.1° at 1, 3, 6, 12, 18, 24, and 36 postoperative months, respectively. The cervical lordosis showed statistically significant decreased at the 1st month, then the lordotic angle was partially restored at the 3rd, and 6th, and then no significant changes after the 6th. The only risk factor for kyphosis development was the preoperative CLA. The optimal cut-off preoperative angle for predicting postoperative kyphosis was 8.5°.The decrease of CLA after expansive laminoplasty peaked in the 1st month. Some of the lordotic angles were restored in the 3rd and 6th months, before reaching a plateau after the 6th month. The optimal cut-off preoperative angle for predicting postoperative kyphosis was 8.5°.Level of Evidence of their study: Level 4.

Differences in Postoperative Changes of Cervical Sagittal Alignment and Balance After Laminoplasty Between Cervical Spondylotic Myelopathy and Cervical Ossification of the Posterior Longitudinal Ligament.

Study Design:Retrospective cohort study.Objectives:To compare postoperative changes of cervical sagittal alignment (CSA) and cervical sagittal balance (CSB) after laminoplasty between cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL) and to examine impacts of these radiologic changes on neurologic outcomes.Methods:A total of 168 consecutive patients with CSM (CSM group) and 51 consecutive patients with OPLL (OPLL group) were included. As indicators of CSA and CSB, the C2-7 angle and C1-C7 sagittal vertical axis (SVA) were, respectively, measured before surgery and at 2-year follow-up. Neurologic status was assessed using the Japanese Orthopaedic Association score before surgery and at 2-year follow-up.Results:Whereas both postoperative loss of C2-7 angle and increase of C1-C7 SVA were significantly greater in the elderly subgroup of the CSM group, patient age did not significantly affect these changes in the OPLL group. Preservation of C7 maintained C1-C7 SVA at postoperative 2 years only in the CSM group. Postoperative cervical kyphosis and sagittal imbalance significantly decreased neurologic improvement in the CSM group but not in the OPLL group.Conclusions:Elderly patients with CSM have significantly greater postoperative loss of lordosis and increase in C1-C7 SVA than nonelderly patients, and both postoperative kyphotic deformity and sagittal imbalance significantly deteriorate neurologic recovery. On the other hand, although patients with OPLL, irrespective of patient age and preservation of C7, have significantly more loss of lordosis and increase in C1-C7 SVA than CSM patients, neither postoperative kyphotic deformity nor sagittal imbalance significantly deteriorates neurologic recovery in OPLL patients.

Small sagittal vertical axis accompanied with lumbar hyperlordosis as a risk factor for developing postoperative cervical kyphosis after expansive open-door laminoplasty.

OBJECTIVE Preoperative positive cervical sagittal imbalance and global sagittal imbalance are risk factors for postoperative cervical kyphosis after expansive open-door cervical laminoplasty (ELAP). The purpose of this study was to investigate the relationship between the incidence of postoperative cervical kyphosis after ELAP and the preoperative global sagittal spinal alignment in patients with cervical spondylotic myelopathy (CSM) without spinal sagittal imbalance. METHODS Among 84 consecutive patients who underwent ELAP for CSM at the authors' hospital, 43 patients without preoperative cervical kyphosis (C2-7 angle ≥ 0°) and spinal sagittal imbalance (C2-7 sagittal vertical axis [SVA] ≤ 80 mm and C-7 SVA ≤ 95 mm) were included in the study. The global spinal sagittal parameters were measured on lateral whole-spine standing radiographs preoperatively and at 1 year postoperatively. The difference in preoperative global sagittal spinal alignment between the postoperative cervical lordosis group and the cervical kyphosis group was analyzed. RESULTS The incidence of postoperative cervical kyphosis after ELAP was 25.6% (11 of 43 cases). Thirty-two patients (16 men and 16 women; mean age 67.7 ± 12.0 years) had lordosis, and 11 (7 men and 4 women; mean age 67.2 ± 9.6 years) had kyphosis. The preoperative C-7 SVA and pelvic incidence minus lumbar lordosis (PI-LL) in the kyphosis group were significantly smaller than those in the lordosis group (p < 0.05). The smaller C-7 SVA accompanied by a small PI-LL, the "truncal negative offset," led to postoperative cervical kyphosis due to posterior structural weakening by ELAP. CONCLUSIONS In patients with CSM without preoperative cervical and global spinal sagittal imbalance, a small SVA accompanied by lumbar hyperlordosis is the characteristic alignment leading to postoperative cervical kyphosis after ELAP.

Growth and alignment of the pediatric subaxial cervical spine following rigid instrumentation and fusion: a multicenter study of the Pediatric Craniocervical Society.

OBJECTIVE The long-term effects of surgical fusion on the growing subaxial cervical spine are largely unknown. Recent cross-sectional studies have demonstrated that there is continued growth of the cervical spine through the teenage years. The purpose of this multicenter study was to determine the effects of rigid instrumentation and fusion on the growing subaxial cervical spine by investigating vertical growth, cervical alignment, cervical curvature, and adjacent-segment instability over time. METHODS A total of 15 centers participated in this multi-institutional retrospective study. Cases involving children less than 16 years of age who underwent rigid instrumentation and fusion of the subaxial cervical spine (C-2 and T-1 inclusive) with at least 1 year of clinical and radiographic follow-up were investigated. Charts were reviewed for clinical data. Postoperative and most recent radiographs, CT, and MR images were used to measure vertical growth and assess alignment and stability. RESULTS Eighty-one patients were included in the study, with a mean follow-up of 33 months. Ninety-five percent of patients had complete clinical resolution or significant improvement in symptoms. Postoperative cervical kyphosis was seen in only 4 patients (5%), and none developed a swan-neck deformity, unintended adjacent-level fusion, or instability. Of patients with at least 2 years of follow-up, 62% demonstrated growth across the fusion construct. On average, vertical growth was 79% (4-level constructs), 83% (3-level constructs), or 100% (2-level constructs) of expected growth. When comparing the group with continued vertical growth to the one without growth, there were no statistically significant differences in terms of age, sex, underlying etiology, surgical approach, or number of levels fused. CONCLUSIONS Continued vertical growth of the subaxial spine occurs in nearly two-thirds of children after rigid instrumentation and fusion of the subaxial spine. Failure of continued vertical growth is not associated with the patient's age, sex, underlying etiology, number of levels fused, or surgical approach. Further studies are needed to understand this dichotomy and determine the long-term biomechanical effects of surgery on the growing pediatric cervical spine.

Cervical Kyphotic Deformity after Laminoplasty in Patients with Cervical Ossification of Posterior Longitudinal Ligament with Normal Sagittal Spinal Alignment

Background Preoperative cervico-thoracic kyphosis and cervical regional positive imbalance are the risk factors for postoperative cervical kyphosis after expansive laminoplasty (ELAP). However, the relationship between preoperative global sagittal spinal alignment and postoperative cervical kyphosis in patients with cervical ossification of the posterior longitudinal ligament (OPLL) is unclear. The purpose of this study was to investigate the relationship between the onset of postoperative cervical kyphosis after ELAP and the preoperative global spinal sagittal alignment in patients with OPLL with normal sagittal spinal alignment. Methods Sixty-nine consecutive patients without preoperative cervical kyphosis who underwent ELAP for OPLL and cervical spondylotic myelopathy (CSM) were enrolled. The global sagittal alignment radiography preoperatively and 1 year postoperatively were examined. The subjects were divided into a postoperative cervical lordosis group (LG) or a kyphosis group (KG) at 1 year postoperatively. The preoperative global sagittal spinal alignment between LG and KG in CSM and OPLL was compared. Results The occurrence of cervical kyphosis after ELAP was 7 of 27 cases (25.9%) in OPLL and 13 of 42 cases (31.0%) in CSM. In patients with CSM in the KG, C7 the sagittal vertical axis (SVA) was smaller than in the LG. In patients with cervical OPLL in the KG, C2-C7 angle, C2-C7 SVA, and thoracic kyphosis (TK) were smaller than those in the LG. In OPLL, the age of the KG was younger than that of LG; however, this was not a significant difference in CSM. Conclusion In patients with cervical OPLL without preoperative global spinal sagittal imbalance, preoperative small C2-C7 angle, C2-C7 SVA, TK, and younger age were typical characteristics of postoperative cervical kyphosis after ELAP.

The Predictable Factors of the Postoperative Kyphotic Change of Sagittal Alignment of the Cervical Spine after the Laminoplasty.

ObjectiveLaminoplasty is an effective surgical method for treating cervical degenerative disease. However, postoperative complications such as kyphosis, restriction of neck motion, and instability are often reported. Despite sufficient preoperative lordosis, this procedure often aggravates the lordotic curve of the cervical spine and straightens cervical alignment. Hence, it is important to examine preoperative risk factors associated with postoperative kyphotic alignment changes. Our study aimed to investigate preoperative radiologic parameters associated with kyphotic deformity post laminoplasty.MethodsWe retrospectively reviewed the medical records of 49 patients who underwent open door laminoplasty for cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL) at Pusan National University Yangsan Hospital between January 2011 and December 2015. Inclusion criteria were as follows: 1) preoperative diagnosis of OPLL or CSM, 2) no previous history of cervical spinal surgery, cervical trauma, tumor, or infection, 3) minimum of one-year follow-up post laminoplasty with proper radiologic examinations performed in outpatient clinics, and 4) cases showing C7 and T1 vertebral body in the preoperative cervical sagittal plane. The radiologic parameters examined included C2–C7 Cobb angles, T1 slope, C2–C7 sagittal vertical axis (SVA), range of motion (ROM) from C2–C7, segmental instability, and T2 signal change observed on magnetic resonance imaging (MRI). Clinical factors examined included preoperative modified Japanese Orthopedic Association scores, disease classification, duration of symptoms, and the range of operation levels.ResultsMean preoperative sagittal alignment was 13.01° lordotic; 6.94° lordotic postoperatively. Percentage of postoperative kyphosis was 80%. Patients were subdivided into two groups according to postoperative Cobb angle change; a control group (n=22) and kyphotic group (n=27). The kyphotic group consisted of patients with more than 5° kyphotic angle change postoperatively. There were no differences in age, sex, C2–C7 Cobb angle, T1 slope, C2–C7 SVA, ROM from C2–C7, segmental instability, or T2 signal change. Multiple regression analysis revealed T1 slope had a strong relationship with postoperative cervical kyphosis. Likewise, correlation analysis revealed there was a statistical significance between T1 slope and postoperative Cobb angle change (p=0.035), and that there was a statistically significant relationship between T1 slope and C2–C7 SVA (p=0.001). Patients with higher preoperative T1 slope demonstrated loss of lordotic curvature postoperatively.ConclusionLaminoplasty has a high probability of aggravating sagittal balance of the cervical spine. T1 slope is a good predictor of postoperative kyphotic changes of the cervical spine. Similarly, T1 slope is strongly correlated with C2–C7 SVA.

Circumferential fusion for severe post surgical cervical kyphosis

Cervical kyphosis-though a common occurrence after surgery and other conditions like trauma, infections, etc., is usually restricted to around 20-40°. It is more common in children. Angulations of more than 70-80° are exceedingly uncommon and present more treatment challenges. We discuss here the management of a 14-year-old child with a severe postoperative cervical kyphotic angulation of 92°. The child presented 10 months after surgery for a C3-C4 intramedullary cyst with neck deformity and near tetraplegic state. He underwent a combined anterior-posterior approach for correction after a trial of skull traction. Six months after the surgery, the child was ambulatory with almost total correction of the deformity. Surgical correction of postoperative cervical kyphosis usually involves a posterior approach for small angles and an anterior approach for larger angulations. The combined anterior-posterior approach is preferred for severe angulations or for those cases not correctable by a single approach. A purely posterior approach may be the only option for those cases where the anterior approach is impossible.

Clinical and radiological results of total disc replacement in the cervical spine with preoperative reducible kyphosis

To investigate the clinical and radiological results of total disc replacement (TDR) in the cervical spine with preoperative reducible kyphosis, and discuss when TDR is indicated for the patients with preoperative kyphosis. Fifty-two patients who underwent single-level cervical TDR from June 2008 to May 2010 were included in this study. TDR was indicated for patients with preoperative lordosis or reducible kyphosis, and the patients were divided into a lordotic group (preoperative global angle of ≥0°) and kyphotic group (preoperative global angle of <0°). Clinical results were evaluated using the Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS) score and Neck Disablity Index (NDI). For radiological evaluation, the global and functional spinal unit (FSU) angles and the global and FSU range of motion were measured preoperatively and postoperatively. The mean NDI in the kyphotic group was significantly higher than that in the lordotic group preoperatively and at sixmonths postoperatively, but the groups showed no significant differences in JOA score, VAS score and NDI at the two year follow-up. The mean global and FSU angles in the kyphotic group were significantly lower than those in the lordotic group preoperatively and at sixmonths postoperatively, but they gradually improved postoperatively. The differences lost significance at the two year follow-up. Postoperative cervical kyphosis had adverse effects on the NDI after TDR. Artificial discs, symptom relief, and neck functional exercises may contribute to correction of preoperative reducible kyphosis at different stages after cervical TDR. Preoperative reducible kyphosis should not be an independent contraindication for cervical TDR.