C2-C7 SVA Research Articles

Preoperative Factors on Loss of Range of Motion after Posterior Cervical Foraminotomy.

Background and Objectives: Posterior cervical foraminotomy (PCF) aims to resolve cervical radiculopathy while preserving range of motion (ROM). However, its effectiveness in maintaining ROM is uncertain. This study investigates the changes in ROM after PCF and identifies preoperative factors that influence ROM reduction post surgery. Materials and Methods: This retrospective cohort study included patients treated at our hospital from August 2016 to September 2021. Clinical outcomes were assessed using the visual analog scale (VAS) for neck and arm pain and the neck disability index (NDI). Radiological outcomes included the segmental angle (SA), cervical angle (CA), C2-C7 SVA, Pfirrmann grade, extent of facetectomy, foraminal stenosis, and ROM. Patients were categorized into two groups based on segmental ROM changes: decreased (Group D) and maintained (Group M). Radiological and clinical outcomes were compared between the groups. Univariate and multivariate regression analyses were performed to identify risk factors for ROM loss after PCF. Results: 76 patients were included: 34 in Group D and 42 in Group M, with no demographic differences. Preoperatively, Group D had significantly larger flexion segmental and cervical angles than Group M (segmental, p < 0.001; cervical, p = 0.001). Group D also had a higher Pfirrmann grade (p = 0.014) and more bony bridge formations (p = 0.004). While no significant differences were observed in arm pain VAS and NDI scores, Group D exhibited worse neck pain VAS at the last follow-up (p = 0.03). Univariate linear regression indicated that preoperative segmental ROM (p < 0.001, B = 0.82) and bony bridge formation (p = 0.046, B = 5.33) were significant predictors of ROM loss post PCF. Conclusions: Patients with higher preoperative flexion angles and Pfirrmann grades at the operative level are at an increased risk for ROM loss and neck pain and often exhibit bony bridge formation. Accounting for these factors can improve surgical planning and patient outcomes.

Comparison of radiological and clinical outcomes of cervical laminoplasty versus lateral mass screw fixation in patients with ossification of the posterior longitudinal ligament

PurposeThis study aimed to compare cervical sagittal parameters and clinical outcomes between patients undergoing cervical laminoplasty(CL) and those undergoing lateral mass screw fixation(LMS).MethodsWe retrospectively studied 67 patients with multilevel ossification of the posterior longitudinal ligament (OPLL) of the cervical spine who underwent lateral mass screw fixation (LMS = 36) and cervical laminoplasty (CL = 31). We analyzed cervical sagittal parameters (C2-7 sagittal vertical axis (C2-7 SVA), C0-2 Cobb angle, C2-7 Cobb angle, C7 slope (C7s), T1 slope (T1s), and spino-cranial angle (SCA)) and clinical outcomes (visual analog scale [VAS], neck disability index [NDI], Japanese Orthopaedic Association [JOA] scores, recovery rate (RR), and minimum clinically significant difference [MCID]). The cervical sagittal parameters at the last follow-up were analyzed by binary logistic regression. Finally, we analyzed the correlation between the cervical sagittal parameters and each clinical outcome at the last follow-up after surgery in both groups.ResultsAt the follow-up after posterior decompression in both groups, the mean values of C2-C7 SVA, C7s, and T1s in the LMS group were more significant than those in the CL group (P ≤ 0.05). Compared with the preoperative period, C2-C7 SVA, T1s, and SCA gradually increased, and the C2-C7 Cobb angle gradually decreased after surgery (P < 0.05). The improvement in the JOA score and the recovery rate was similar between the two groups, while the improvement in the VAS-N score and NDI score was more significant in the CL group (P = 0.001; P = 0.043). More patients reached MCID in the CL group than in the LMS group (P = 0.036). Binary logistic regression analysis showed that SCA was independently associated with whether patients reached MCID at NDI postoperatively. SCA was positively correlated with cervical NDI and negatively correlated with cervical JOA score at postoperative follow-up in both groups (P < 0.05); C2-7 Cobb angle was negatively correlated with cervical JOA score at postoperative follow-up (P < 0.05).ConclusionCL may be superior to LMS in treating cervical spondylotic myelopathy caused by OPLL. In addition, smaller cervical SCA after posterior decompression may suggest better postoperative outcomes.

Comparative Analysis of Postoperative Sagittal Balance in Expansive Open-Door Laminoplasty versus Laminectomy with Fusion for Multilevel Ossification of Posterior Longitudinal Ligament: A Retrospective Study.

BACKGROUND This single-center study included 80 patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL) and aimed to compare postoperative sagittal balance following treatment with expansive open-door laminoplasty (LP) vs total laminectomy with fusion (LF). MATERIAL AND METHODS Data of 80 patients with multilevel OPLL treated with LP vs LF between January 2017 and January 2022 were retrospectively analyzed. The basic data, cervical sagittal parameters, and clinical outcomes of the patients were counted in the preoperative and postoperative periods, and complications were recorded. Forty patients underwent LP and 40 underwent LF. Cervical sagittal parameters were compared between and within the 2 groups. Clinical outcomes and complications were compared between the 2 groups. RESULTS At last follow-up, the postoperative C2-C7 Cobb angel, T1 slope (T1S), and C7 slope (C7S) were significantly higher in the LF group than in the LP group (P<0.001). C2-C7 SVA (cSVA) was slightly higher in the LF group (P>0.05) and significantly higher in the LP group (P<0.05). The incidence of postoperative complications in the LP group was significantly lower than in the LF group (P=0.02). The postoperative scores on the Visual Analog Scale (VAS), Neck Disability Index (NDI), and Japanese Orthopedic Association (JOA) were significantly improved in both groups (P<0.001). CONCLUSIONS Both procedures had good outcomes in neurological improvement. After posterior surgery, the cervical vertebrae all showed a tilting forward. Compared to LP, LF may change cervical balance in Cobb angel, T1S. LF has better efficacy in improving cervical lordosis compared with LP. Patients with high T1 slope after surgery may has more axial pain.

A Novel Cervical Sagittal Classification for Asymptomatic Population Based on Cluster Analysis.

Cross-sectional study. To propose a novel cervical sagittal classification for asymptomatic people so as to deepen the understanding of cervical sagittal alignment. Cervical spine sagittal morphology varies in people. There is a lack of widely-accepted cervical sagittal classification method. In all, 183 asymptomatic subjects were included. A series of global and segmental cervical sagittal parameters were measured. Subjects with cervical lordosis (CL)<0 degrees were incorporated directly into the kyphosis (K) group. For subjects with CL ≥0 degrees, a two-step cluster analysis was used to arrive at the optimal number of clusters. The results of the expressions for the subtypes were derived by graphing. The 60 randomly selected lateral cervical spine films were evaluated by 4 spine surgeons at 4-week intervals using our classification method, the Toyama classification method and the Donk classification method. The 3 classification methods' reliability was expressed by the intra-group correlation coefficient (ICC), and convenience was expressed by the measuring time. Finally, the distribution of 4 subtypes was depicted, and sagittal parameters were compared among subtypes. Four subtypes of the cervical spine were suggested: Large lordosis (LL): CL≥-1.5×T1 slope (TS)+70°; Small lordosis (SL): -1.5×TS+50°≤CL<-1.5×TS+70°; Straight (S): 0°≤CL<-1.5×TS+50°; and K: CL<0°. The measuring time for our classification method was significantly less than the Toyama classification method (P<0.001). Our classification method showed high inter-observer reliability (ICC=0.856) and high to excellent intra-observer reliability (ICC between 0.851 and 0.913). SL was the most common type (37.7%). Men had more LL type and women had more S type and K type. The proportion of S and K increased with age. Cervical sagittal parameters were significantly different among the subtypes except for C4 vertebral body (VB) angle (P=0.546), C2-C7 SVA (P=0.628) and NT (P=0.816). We proposed a novel cervical sagittal classification for an asymptomatic population, which proved to be simple to implement with satisfactory reliability.

Cervical Sagittal Alignment and Related Factor Analysis and Prediction Model in Patients Undergoing Revision Surgery After Anterior Cervical Fusion.

Patients with myelopathy or radiculopathy commonly undergo anterior cervical fusion surgery (ACFS), which has a notable failure rate on occasion. The goal of this study was to compare revision and nonrevision surgery patients in cervical sagittal alignment (CSA) subsequent to ACFS; additionally, to identify the best CSA parameters for predicting clinical outcome after ACFS; and furthermore, to create an equation model to assist surgeons in making decisions on patients undergoing ACFS. The data of 99 patients with symptomatic cervical myelopathy/radiculopathy who underwent ACFS were analyzed. Patients were divided into group A (underwent revision surgery after the first surgery failed) and group B (underwent only the first surgery). We measured and analyzed both preoperative and postoperative CSA parameters, including C2 slope, T1 slope, cervical lordosis C2-C7 (CL), C2-C7 sagittal vertical axis (C2C7 SVA), occiput-C2 lordosis angle (C0-C2), and chin brow vertical angle, and we further computed the correlation between the CSA parameters and created a prediction model. The (T1S-CL)-C2S mismatch differed significantly between groups A and B ([9.95 ± 9.95] 0 , [3.79 ± 6.58] 0 , P < 0.05, respectively). A significant correlation was observed between C2 slope and T1CL in group B relative to group A postoperatively (R 2 = 0.42 versus R 2 = 0.09, respectively). Compared with group B, patients in group A had significantly higher C2C7SVA values, more levels of fusion, and more smokers. The sensitivity, specificity, accuracy, and discrimination of the model were, respectively, 73.5%, 84%, 78.8%, and 85.65%. The causes of revision surgery in cervical myelopathic patients after anterior cervical corpectomy and fusion/anterior cervical diskectomy and fusion are multifactorial. (T1S-CL)-C2S mismatch and high C2C7SVA are the best cervical sagittal parameters that increase the odds of revision surgery, and the effect is more enhanced when comorbidities such as smoking, low bone-mineral density, and increased levels of fusion are taken into account.

Cervical Sagittal Balance: Impact on Clinical Outcomes and Subsidence in Anterior Cervical Discectomy and Fusion.

Degenerative disease of the cervical spine leads to sagittal imbalance, which may affect treatment results. The purpose of this study was to evaluate changes in selected cervical sagittal balance parameters and their effects on subsidence and clinical outcomes of the procedure. This study encompassed a total of 95 evaluated patients who underwent anterior cervical discectomy and fusion (ACDF). Selected cervical sagittal balance parameters were assessed using lateral projection X-rays: C2-C7 spinal vertical axis (C2-C7 SVA), spinocranial angle (SCA), C7 slope, C2-C7 lordosis, and the segmental Cobb angle. Measurements were collected the day before, the day after, and 12 months after surgery. Changes in clinical parameters was assessed using the VAS and NDI scales. Subsidence was defined as a loss of intervertebral height of more than 30% of the baseline value. Among all the assessed parameters, only the C2-C7 SVA demonstrated a statistically significant difference between the groups with and without subsidence: 26.03 vs. 21.79 [mm], with p = 0.0182, preoperatively and 27.80 vs. 24.94 [mm], with p = 0.0449, on the day after surgery, respectively. We conclude that higher preoperative and postoperative C2-C7 SVA values might contribute to an elevated risk of implant subsidence. Furthermore, both the SCA and C7 slope could conceivably influence the clinical outcome, respectively impacting pain, as assessed by the VAS and the disability, as evaluated through the NDI scale.

Comparative effectiveness and functional outcome of C3 & C7 dome-hybrid open-door laminoplasty with traditional unilateral open-door laminoplasty for cervical spondylotic myelopathy

ObjectiveThe C3 & C7 dome-hybrid open-door laminoplasty was proven to be an effective treatment for multi-levels cervical spondylotic myelopathy (CSM). However, its superiority over traditional unilateral open-door laminoplasty (UOLP) remains questionable, and no studies have compared the efficacy of this technique with traditional UOLP. This study aimed to compare the effectiveness of C3 & C7 dome-hybrid open-door laminoplasty with traditional UOLP in treating multi-levels CSM.MethodsA retrospective study of multi-levels CSM with laminoplasty was performed, including 35 cases of traditional UOLP and 27 cases of C3 & C7 dome-hybrid open-door laminoplasty. Radiographic evaluation parameters and clinical outcomes were recorded to evaluate the surgical effectiveness.ResultsThere was no significant difference in demographic baseline parameters. At the final follow-up, the C2–C7 Cobb angle of the modified group was significantly greater than that of the traditional group (p = 0.026). Meanwhile, the C2–C7 SVA of the modified group was significantly smaller than that of the traditional group (p = 0.009). Clinical outcomes such as VAS, NDI, and SF-12 scores, improved significantly in the modified group compared to the traditional group, while the JOA scores had no significant difference in both groups. There was no significant difference in the overall rate of complications between the two groups.ConclusionBoth techniques have satisfactory outcomes in treating multi-levels CSM. Comparing with traditional UOLP, C3 & C7 dome-hybrid open-door laminoplasty has a greater superiority in reducing postoperative neck pain and maintaining the cervical sagittal alignment. It is proven to be a feasible management for patients with multi-levels CSM.

Adult spinal deformity patients revised for pseudarthrosis have comparable two-year outcomes to those not undergoing any revision surgery.

This study aimed to evaluate whether adult spinal deformity patients undergoing revision for symptomatic pseudarthrosis have comparable two-year outcomes as patients who do not experience pseudarthrosis. Patients whose indexed procedure was revision for pseudarthrosis (pseudo) were compared with patients who underwent a primary procedure and did not have pseudarthrosis by 2Y post-op (non-pseudo). Patients were propensity-matched (PSM) based on baseline (BL) sagittal alignment, specifically C7SVA and CrSVA-Hip. Key outcomes were 2Y PROs (SRS and ODI) and reoperation. All patients had a minimum follow-up period of two years. A total of 224 patients with min 2-year FU were included (pseudo = 42, non-pseudo = 182). Compared to non-pseudo, pseudo-patients were more often female (P = 0.0018) and had worse BL sagittal alignment, including T1PA (P = 0.02], C2-C7 SVA [P = 0.0002], and CrSVA-Hip [P = 0.004]. After 37 PSM pairs were generated, there was no significant difference in demographics, BL and 2Y alignment, or operative/procedural variables. PSM pairs did not report any significantly different PROs at BL. Consistently, at 2Y, there were no significant differences in PROs, including SRS function [3.9(0.2) vs 3.7(0.2), P = 0.44], pain [4.0 (0.2) vs. 3.57 (0.2), P = 0.12], and ODI [25.7 (5.2) vs 27.7 (3.7), P = 0.76]. There were no differences in 1Y (10.8% vs 10.8%, P > 0.99) and 2Y (13.2% vs 15.8%, P = 0.64) reoperation, PJK rate (2.6% vs 10.5%, P = 0.62), or implant failure (2.6% vs 10.5%, P = 0.37). Notably, only 2 patients (5.4%) had recurrent pseudarthrosis following revision. Kaplan-Meier curves indicated that patients undergoing intervention for pseudarthrosis had comparable overall reoperation-free survival (log-rank test, χ2 = 0.1975 and P = 0.66). Patients undergoing revision for pseudarthrosis have comparable PROs and clinical outcomes as patients who never experienced pseudarthrosis. Recurrence of symptomatic pseudarthrosis was infrequent.

Do Cervical Parameters Increase the Risk of Thoracic Spinal Stenosis in Patients with Cervical Spinal Stenosis?

The diagnosis and treatment of tandem stenosis have been widely discussed. However, studies on concurrent cervical and thoracic spinal stenosis are rare in the literature. This study was aimed to investigate the risk factors for thoracic spinal stenosis (TSS) in patients with cervical spinal stenosis (CSS). This retrospective cohort study assessed the risk factors for TSS in 162 patients who were diagnosed with CSS. Patients were divided into TSS (n=45) and non-TSS (n=117) groups. We retrospectively analyzed clinical characteristics and radiographic parameters, including age, gender, body mass index, ossification of the cervical posterior longitudinal ligament (OPLLc), hypertrophy of cervical ligamentum flavum (HLFc), cervical stenosis segments, and cervical sagittal parameters. Cervical sagittal parameters were measured on T2-weighted magnetic resonance imaging (MRI), including C2-7 Cobb angle (Cobb), cervical tilt (CT), T1 slope (T1S), thoracic inlet angle (TIA), C2-C7 sagittal vertical axis (C2-C7 SVA) and cervical curvature. Two groups showed significant differences in OPLLc, HLFc, cervical stenosis segments, and TIA. The receiver operating characteristic curves (ROC) demonstrated that the optimal threshold for TIA was 68.25. In multivariate logistic regression analysis, OPLLc (OR=4.403,95% CI=1.782-10.880,P=0.001), HLFc (OR=4.849,95% CI=1.995-11.782,P<0.001) and TIA>68.25 ° (OR=2.555,95%CI=1.044-6.251,p=0.040) were independent risk factors for TSS. Moreover, the multi-index ROC curve demonstrated that the area under the curve for predicted probability was 0.799 (p<0.001). Routine thoracic MRI assessment is strongly recommended in CSS patients with OPLLc, HLFc, and enlarged TIA to screen for neglected but vital thoracic disease.

K-line tilt as a novel potential risk factor for cervical Modic change: a retrospective study

BackgroundCervical sagittal parameters are important parameters that reflect the mechanical stress in the sagittal plane of the cervical spine and are an important basis for predicting the clinical status and prognosis of patients. Although it has been confirmed that there is a significant correlation between cervical Modic changes and some sagittal parameters. However, as a newly discovered sagittal parameter, there is no report on the relationship between the K-line tilt and the Modic changes of cervical spine.MethodsA retrospective analysis was performed for 240 patients who underwent cervical magnetic resonance imaging scan for neck and shoulder pain. Among them, 120 patients with Modic changes, namely the MC(+) group, were evenly divided into three subgroups of 40 patients in each group according to different subtypes, namely MCI subgroup, MCII subgroup and MCIII subgroup. One hundred twenty patients without Modic changes were included in MC(−) group. We measured and compared the sagittal parameters of cervical spine among different groups, including K-line tilt, C2–C7 sagittal axial vertical distance (C2–C7 SVA), T1 slope and C2–7 lordosis. Logistic regression was used to analyse the risk factors of cervical Modic changes.ResultsThe K-line tilt and C2–7 lordosis were significantly different between MC(+) group and MC(−) group (P < 0.05). The K-line tilt greater than 6.72° is a risk factor for Modic changes in cervical spine (P < 0.05). At the same time, the receiver operating characteristic curve showed that this change had moderate diagnostic value when the area under the curve was 0.77.ConclusionThis study shows that the K-line tilt greater than 6.72° is a potential risk factor for Modic changes in cervical spine. When the K-line tilt is greater than 6.72°, we should be alert to the occurrence of Modic changes.Trial registration number: 2022ER023-1.

428 Accomplishing Realignment Goals Withstands the Test of Time: The Outcomes of a Prospective Consecutively Enrolled Single-Center Adult Cervical Deformity Series With Minimum 5-Year Follow-Up

INTRODUCTION: Adult cervical deformity(CD) realignment has shown promising short-term and two-year clinical results, but longer-term outcomes of CD surgery remain unclear. METHODS: Operative CD patients&gt;18 years eligible for 5-year (5Y) follow-up were included. Optimal thresholds for C2 Slope and T1 Slope by Passfall et al were assessed. Student’s t-test, paired t-test, binary and multivariable logistic regression analyses were used to evaluate the clinical, radiographic, and complications outcomes of the five-year eligible cohort. RESULTS: 58 patients were enrolled from 2012 to 2017(54.5±10.3 years,57% female, BMI: 30.0 ± 7.3 kg/m2, 16% osteoporosis), and underwent surgical correction (levels fused: 5.2 ± 2.6, EBL: 772 ± 672 mL, operative time: 372 ± 139 min, LOS: 5.9 ± 8.1 days). By surgical approach, 13.8% anterior-only, 51.7% posterior-only, 34.5% combined. 53% had previous cervical surgery, 41% a fusion. The most common UIV was C3, LIV was T1. By three months (3M), patients improved in cervical lordosis, C2-C7 SVA (cSVA), and T1 Slope(all p &lt;.02), but not C2 Slope or TS-CL (both p&gt;.5). The cohort significantly improved from baseline (BL) to 2Y in NDI, NRS-Neck, and EQ-5D(all P&lt;.02). From 2Y to last follow-up, patients did not improve in mJOA or NDI, but did in EQ-5D (0.441 to 0.509) and NRS-Neck (5.9 to 5.0, both p&lt;.05). There were 14(24.1%) cases of DJK, 6 were distal junctional failure (10.3%), and 17(29.3%) underwent reoperation. Patients corrected below the T1 Slope threshold of 26.5° and maintained at last follow-up experienced DJK less often(OR: 0.1,[0.02-0.74]). Patients corrected below the C2 Slope threshold of 10° and maintained at last follow-up experienced no DJK, DJF or reoperations. CONCLUSIONS: Although complications including distal junctional failure and reoperation remain prevalent, correction of cervical deformity and achievement of realignment targets results in notable clinical and radiographic improvement with most patients achieving favorable outcomes by two years, with further improvement seen until last follow-up.

Axial superior facet slope may determine anterior or posterior atlantoaxial displacement secondary to os odontoideum and compensatory mechanisms of the atlantooccipital joint and subaxial cervical spine

ObjectiveTo introduce novel parameters in determining directions of os odontoideum (OO) with atlantoaxial displacement (AAD) and compensations of cervical sagittal alignment after displacement.MethodsAnalysis was performed on 96 cases receiving surgeries for upper cervical myelopathy caused by OO with AAD from 2011 to 2021. Twenty-four patients were included in the OO group and divided into the OO-anterior displacement (AD) group and the OO-posterior displacement (PD) group by displacement. Seventy-two patients were included as the control (Ctrl) group and divided into Ctrl-positive (Ctrl-P) group and Ctrl-negative (Ctrl-N) group by axial superior facet slope (ASFS) in a neutral position. ASFS, the sum of C2 slope (C2S) and axial superior facet endplate angle (ASFEA), was measured and calculated by combining cervical supine CT with standing X-ray. Cervical sagittal parameters were measured to analyse the atlantoaxial facet and compensations after AAD.ResultsAtlas inferior facet angle (AIFA), ASFS, and ASFEA in Ctrl-P significantly differed from OO-AD.C0-C1, C1-C2, C0-C2, C2-C7, C2-C7 SVA, and C2S in Ctrl-P significant differed from the OO-AD group. C2-C7 SVA and C2S in Ctrl-N significantly were smaller than the OO-PD group. C1-C2 correlated with C0-C1 and C2-C7 negatively in the OO group. Slight kyphosis of C1-C2 in OO-AD was compared with lordosis of C1-C2 in Ctrl-P, inducing increased extension of C0-C1 and C2-C7. Mildly increased lordosis of C1-C2 in OO-PD was compared with C1-C2 in Ctrl-N, triggering augmented flexion of C0-C1 and C2-C7.ConclusionASFS was vital in determining directions of OO with AAD and explaining compensations. ASFS and ASFEA could provide pre- and intraoperative guidelines.Key Points• ASFS may determine the directions and compensatory mechanisms of AAD secondary to OO.• ASFS could be achieved by the sum of ASFEA and C2S.

Prevalence of sleep disturbance in patients with cervical radiculopathy and an analysis of risk factors: a cross-sectional study.

Previous research has shown that many patients with musculoskeletal diseases suffer from sleep disturbances. However, the sleep quality of patients with cervical radiculopathy (CR) has yet to be fully investigated. This study aims to investigate the prevalence and status of sleep disturbances in patients with CR and identify the mechanisms and risk factors associated with this condition. We conducted a cross-sectional study of patients diagnosed with CR. The Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) were used to evaluate the sleep quality of patients and determine whether patients experience sleep disturbances. In addition, we analyzed the clinical and radiological risk factors of sleep disturbance and determined the key risk factors related to sleep disturbance by multivariable analysis. According to specific inclusion and exclusion criteria, 186 patients with CR were finally included, with a mean age of 59.1 ± 14.3years, of which 113 (60.8%) were female. Sleep disturbance was defined as a PSQI score ≥ 6 and was identified in 56.5% of patients (105/186). By performing multivariate analysis, we determined that sleep disturbance was closely related to the female gender, a higher Beck Depression Inventory (BDI) score, a reduction in cervical mobility, an increase in C2-C7 sagittal vertical axis (C2-C7 SVA), and severe asymmetry of the paravertebral muscle at C5 and C6 levels. In this study, we identified the high prevalence and potential high-risk factors of sleep disturbance in patients with CR. Clinicians should closely evaluate and monitor such patients and consider appropriate treatment strategies. IV.

Restore cervical sagittal alignment by cervical disc arthroplasty and systematic total bilateral uncuscectomy in severe spondylosis: A prospective study

IntroductionSevere spondylosis is common and represents contraindication to achieve cervical disc arthroplasty (CDA). Research questionIs it possible to restore cervical sagittal alignment using an adequate prosthetic model and performing systematic bilateral total uncuscectomy (or uncinectomy), even in cases of severe spondylosis ? Material and methodsWe propose a prospective clinical and radiological study comparing the evolution of preoperative and postoperative cervical sagittal balance 1 year after the interposition of a prosthesis with mobile bearing and systematic total uncuscectomy. VAS for brachialgia and cervicalgia, NDI, Odom's criteria, C2–C7 Cobb angle, C2–C7 SVA, T1 slope, C2 slope, C1–C2 Cobb angle, and segmental Cobb angle were analyzed preoperatively and 1 year postoperatively. Results73 patients for a total of 129 levels treated were analyzed. Patients showed significant improvements in VASb, VASc, NDI, and Odom's criteria one year after surgery without clinical differences in the severe spondylosis subgroup (41 patients for 77 levels treated). Our results showed an increase in the C2–C7 Cobb angle postoperatively and a better correlation between T1 slope and C2–C7 Cobb angle postoperatively than preoperatively. Postoperative radiological results were similar between the spondylosis and non-spondylosis subgroups. However preoperative C2–C7 Cobb angle and preoperative ROM were lower in the severe spondylosis subgroup. Discussion and conclusionThis study showed the possibility of restoring cervical sagittal balance by performing cervical disc arthroplasty with systematic uncuscectomy, even in cases of severe spondylosis. Moreover, we propose a simplified mathematical formula to preoperatively evaluate the lack of angulation to restore sagittal cervical alignment.

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.

P113. At what point does degenerative become deformity: when good outcomes necessitate sagittal correction in adult cervical deformity surgery

BACKGROUND CONTEXT Current radiographic thresholds have shown inconsistent correlation with clinical outcomes. However, it has not been determined at what point in presenting deformity does sagittal correction tremendously improve clinical outcomes following cervical deformity surgery. PURPOSE Define baseline thresholds in cervical parameters that, when exceeded, benefit dramatically from surgical correction to achieve ideal clinical outcomes. STUDY DESIGN/SETTING Retrospective. PATIENT SAMPLE A total of 290 ACD patients. OUTCOME MEASURES Clinical outcomes, radiographic alignment. METHODS CD patients with baseline (BL) and 2-year (2Y) data included. Parameters assessed: C2 slope (C2S), C2-C7 Lordosis, C2-C7 SVA (cSVA), T1 Slope (T1S), TS-CL. Outcomes: Virket al Good Clinical Outcome (GCO): [Meeting 2 of 3: 1) an NDI>20 or meeting MCID, 2) mJOA >=14), 3) an NRS-Neck<=5 or improved by 2 or more points from baseline]. Binary logistic regression assessed each parameter to determine if correction was more likely needed to achieve GCO. Conditional inference tree (CIT) run machine learning analysis generated baseline thresholds for each parameter, above which, correction was necessary to achieve GCO. RESULTS Included: 105 CD patients. There were 57 (54%) of patients achieving GCO by 2Y. Correction was necessitated when baseline C2S was above 20° (OR: 6.8, [1.6-28.9]; p=.01) and when baseline C2-C7 Lordosis was below 10° (OR: 16, [2.4-107.5]; p=.004). Patients presenting with a cSVA above 20 mm more often achieved clinical success when corrected (74.2% vs 0.0%, p<.001). A baseline T1 slope above 23° was 16 times more likely to reach GCO with correction than those below this threshold (p=.005). TS-CL more likely required correction to reach GCO when above 26° at baseline (OR: 7.0, [1.7-29.1]; p=.007). When assessing patients above both the cSVA and C2S threshold versus the remaining cohort, these patients more likely met GCO when corrected in either parameter (OR: 22.5, [3.3-152.0]; p=.001). CONCLUSIONS Our study highlighted the importance of correction and the threshold at which it dramatically impacts clinical success. These new thresholds delineate patients obtaining superior benefit for sagittal correction and may better increase the utility gained from surgical intervention for cervical deformity. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Current radiographic thresholds have shown inconsistent correlation with clinical outcomes. However, it has not been determined at what point in presenting deformity does sagittal correction tremendously improve clinical outcomes following cervical deformity surgery. Define baseline thresholds in cervical parameters that, when exceeded, benefit dramatically from surgical correction to achieve ideal clinical outcomes. Retrospective. A total of 290 ACD patients. Clinical outcomes, radiographic alignment. CD patients with baseline (BL) and 2-year (2Y) data included. Parameters assessed: C2 slope (C2S), C2-C7 Lordosis, C2-C7 SVA (cSVA), T1 Slope (T1S), TS-CL. Outcomes: Virket al Good Clinical Outcome (GCO): [Meeting 2 of 3: 1) an NDI>20 or meeting MCID, 2) mJOA >=14), 3) an NRS-Neck<=5 or improved by 2 or more points from baseline]. Binary logistic regression assessed each parameter to determine if correction was more likely needed to achieve GCO. Conditional inference tree (CIT) run machine learning analysis generated baseline thresholds for each parameter, above which, correction was necessary to achieve GCO. Included: 105 CD patients. There were 57 (54%) of patients achieving GCO by 2Y. Correction was necessitated when baseline C2S was above 20° (OR: 6.8, [1.6-28.9]; p=.01) and when baseline C2-C7 Lordosis was below 10° (OR: 16, [2.4-107.5]; p=.004). Patients presenting with a cSVA above 20 mm more often achieved clinical success when corrected (74.2% vs 0.0%, p<.001). A baseline T1 slope above 23° was 16 times more likely to reach GCO with correction than those below this threshold (p=.005). TS-CL more likely required correction to reach GCO when above 26° at baseline (OR: 7.0, [1.7-29.1]; p=.007). When assessing patients above both the cSVA and C2S threshold versus the remaining cohort, these patients more likely met GCO when corrected in either parameter (OR: 22.5, [3.3-152.0]; p=.001). Our study highlighted the importance of correction and the threshold at which it dramatically impacts clinical success. These new thresholds delineate patients obtaining superior benefit for sagittal correction and may better increase the utility gained from surgical intervention for cervical deformity.

P104. Crossing the bridge from degeneration to deformity: when good outcomes necessitate sagittal correction in adult spinal deformity surgery

BACKGROUND CONTEXT Patients with less severe adult spinal deformity undergo surgical correction and often achieve good clinical outcomes. However, it is not well understood how much clinical improvement is due to sagittal correction. PURPOSE Derive baseline thresholds in radiographic parameters that, when exceeded, result in dramatic clinical improvement from surgical correction. STUDY DESIGN/SETTING Retrospective. PATIENT SAMPLE A total of 689 ASD patients. OUTCOME MEASURES Radiographic alignment, clinical outcomes (ODI SCB). METHODS ASD patients with BL and 2-year (2Y) data included. Parameters assessed: SVA, PI-LL, PT, T1PA, L4-S1 Lordosis, C2-C7 SVA (cSVA), C2-T3 and C2 Slope (C2S). Outcomes: Good Outcome (GO): [Meeting either: 1) SCB for ODI by 2Y (change greater than 18.8), or 2) ODI 4.5 by 2Y. Binary logistic regression assessed each parameter to determine if correction was more likely needed to achieve GO. Conditional inference tree (CIT) run machine learning analysis generated baseline thresholds for each parameter, above which, correction was necessary to achieve GO. RESULTS Included: 447 ASD patients. There were 223 (50%) patients achieving GO by 2 years. Binary logistic regression analysis demonstrated correction of all 5 thoracolumbar parameters (SVA, T1PA, PI-LL, PT, L4-S1) were more often needed to achieve GO (all p.001). Of patients with baseline T1PA above 20°, 95% required correction to meet Good Outcome (95% vs 54%, p.001). CIT-generated thresholds were significant for each parameter, with a baseline C2 slope above 15° necessitating correction more often to obtain clinical success (OR: 8.1, [4.1-16.2]; p.001). CONCLUSIONS Our study highlights there is a tipping-point beyond which sagittal correction has an exponential influence on clinical improvement, reflecting the line where deformity becomes a significant contributor to disability. These new thresholds delineate patients suitable for sagittal correction, as opposed to conventional treatment of degenerative disc processes. Adherence to these benchmarks may improve the utility gained from surgical intervention for degenerative conditions and deformity. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Patients with less severe adult spinal deformity undergo surgical correction and often achieve good clinical outcomes. However, it is not well understood how much clinical improvement is due to sagittal correction. Derive baseline thresholds in radiographic parameters that, when exceeded, result in dramatic clinical improvement from surgical correction. Retrospective. A total of 689 ASD patients. Radiographic alignment, clinical outcomes (ODI SCB). ASD patients with BL and 2-year (2Y) data included. Parameters assessed: SVA, PI-LL, PT, T1PA, L4-S1 Lordosis, C2-C7 SVA (cSVA), C2-T3 and C2 Slope (C2S). Outcomes: Good Outcome (GO): [Meeting either: 1) SCB for ODI by 2Y (change greater than 18.8), or 2) ODI 4.5 by 2Y. Binary logistic regression assessed each parameter to determine if correction was more likely needed to achieve GO. Conditional inference tree (CIT) run machine learning analysis generated baseline thresholds for each parameter, above which, correction was necessary to achieve GO. Included: 447 ASD patients. There were 223 (50%) patients achieving GO by 2 years. Binary logistic regression analysis demonstrated correction of all 5 thoracolumbar parameters (SVA, T1PA, PI-LL, PT, L4-S1) were more often needed to achieve GO (all p.001). Of patients with baseline T1PA above 20°, 95% required correction to meet Good Outcome (95% vs 54%, p.001). CIT-generated thresholds were significant for each parameter, with a baseline C2 slope above 15° necessitating correction more often to obtain clinical success (OR: 8.1, [4.1-16.2]; p.001). Our study highlights there is a tipping-point beyond which sagittal correction has an exponential influence on clinical improvement, reflecting the line where deformity becomes a significant contributor to disability. These new thresholds delineate patients suitable for sagittal correction, as opposed to conventional treatment of degenerative disc processes. Adherence to these benchmarks may improve the utility gained from surgical intervention for degenerative conditions and deformity.

Evaluation of dynamic spinal alignment changes and compensation using three-dimensional gait motion analysis for dropped head syndrome

BACKGROUND CONTEXTDynamic kinematic evaluation of spino-pelvic alignment during gait using three-dimensional (3D) motion analysis has been proposed for adult spinal thoracolumbar deformity. That is because conventional full-spine radiographs cannot be used to evaluate dynamic factors. However, dynamic changes in spino-pelvic alignment during gait for dropped head syndrome (DHS) have not been studied using this approach. PURPOSE: This study aimed to assess the dynamic changes in spinal-pelvic alignment during gait in patients with DHS using 3D motion analysis. STUDY DESIGNRetrospective review of collected radiographic and kinematic data. PATIENT SAMPLENineteen DHS patients with neck pain and/or anterior gaze disturbance. OUTCOME MEASURESStatic spino-pelvic radiological alignment, dynamic spino-pelvic kinematic parameters and electromyogram (EMG) data. METHODSCenter of gravity of the head - C7 sagittal vertical axis (CGH-C7 SVA), C2-C7 SVA, T1 slope; cervical lordosis (CL), C7SVA, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT) and pelvic incidence (PI) were assessed using full-spine radiographs in a standing position to assess static spino-pelvic alignment. The 3D gait motion analysis was conducted during gait. Dynamic kinematic parameters were divided into spinal segments: cervical (C-), thoracic (T-), lumbar (L-) and pelvis (P-). Each spinal segment coronal angle to the pelvic angle, each spinal segment sagittal angle to the pelvic angle and pelvic sagittal angle to the horizontal axis were assessed as dynamic spino-pelvic kinematic parameters. Trunk and lower limb muscle activity during gait were assessed using wireless surface EMG analysis. Dynamic spino-pelvic kinematic variables and muscle activity were compared between the first walking lap and the final lap during gait analysis. The change in dynamic kinematic parameters was correlated with static radiological alignment and electromyographic muscular activity change. RESULTSCervical and thoracic anterior tilt increased significantly after an extended period of walking, indicating that dropped head worsened during gait. An increase of cervical anterior tilt during walking was significantly associated with decreased muscle activity in the cervical paraspinal muscles (r=-0.463, P<.05) and latissimus dorsi (r=-0.763, p<.01). Furthermore, significant correlations were found between a change in thoracic sagittal angle to pelvic angle and C7SVA (r=0.683, p<.01) and LL (r=-0.475, p<.05). This means that a larger C7SVA and smaller LL were associated with increased thoracic anterior tilt during gait. CONCLUSIONSThe 3D motion analysis for DHS showed that cervical and thoracic anterior tilt significantly increased after extended walking, resulting in worsening of dropped head. Decreased muscle activity of the neck extensor muscles during gait suggests insufficient neck extensor muscle endurance, which was associated with increased cervical anterior tilt. A greater increase in the thoracic anterior tilt during gait was found in DHS patients with a larger C7SVA and smaller LL due to insufficient thoracolumbar compensation for the dropped head. Correction of the cervical spine alone would not be sufficient to improve dropped head in cases with increased thoracic anterior tilt during gait. The results suggest that C7SVA and LL are crucial parameters in the surgical strategy for DHS.

Effects of combined adjustable Halo-pelvic fixation brace on cervical spine alignment in patients with severe rigid spinal deformity

ObjectiveTo evaluate the effect of continuous traction with a combined adjustable Halo-pelvic fixation brace on the cervical spine alignment in patients with severe rigid spinal deformity and analyze its related factors.MethodsWe conducted a retrospective cohort study of 21 patients with severe rigid spinal deformity treated in our department between 2015 and 2019. All subjects received combined adjustable Halo-pelvic fixation brace traction before secondary orthopedic surgery. The influence of the Halo-pelvic fixation brace on the cervical spine alignment was evaluated by measuring the parameters of lateral cervical X-ray at three time points: before traction, at the end of traction, and 6 months after orthopedic surgery. The correlation between parameter changes and total traction duration was analyzed to explore factors influencing cervical alignment.ResultsThe C2L-C7L angle was 22.40 ± 15.91° before traction, which decreased to 5.91 ± 6.78° at the end of traction but increased to 14.51 ± 10.07° after orthopedic surgery (BT vs ET p < 0.005, ET vs AOS p < 0.005, BT vs AOS p < 0.005). Accordingly, C2L-C7U angle, C2L-C6L angle, C2L-C6U angle, C2L-C5L angle, C7 or T1 slope, C2-C7 SVA, SCA, C2-T1 Ha, C0 slope, and C0-C2 angle also changed similarly to C2L-C7L angle. Furthermore, moderate correlation was observed between C2L-C7L angle and total traction volume (r = 0.563, p = 0.008) and SCA and traction duration (r = 0.525, p = 0.015). However, no significant correlation was found between other cervical alignment parameters and total traction volume and traction duration.ConclusionsThe continuous traction of a combined adjustable Halo-pelvic fixation brace can affect the cervical spine alignment of patients with severe rigid spinal deformity and straighten the physiological curvature of the cervical spine. However, the sagittal alignment gradually recovers after the traction, without any adverse effects on the orthopedic surgery and global balance after the operation; therefore, this apparatus is worthy of wide application.

Bridging the cervicothoracic junction during posterior cervical laminectomy and fusion for the treatment of multilevel cervical ossification of the posterior longitudinal ligament: a retrospective case series

BackgroundThe purpose of this study was to investigate the surgical efficacy of crossing the cervicothoracic junction during posterior cervical laminectomy and fusion for the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL).MethodsFrom October 2009 to October 2017, 46 consecutive patients with multilevel cervical OPLL underwent posterior cervical laminectomy and crossing the cervicothoracic junction fusion were obtained in the study. Their medical records were retrospectively collected. Cervical lordosis and cervical sagittal balance were used to assess radiographic outcomes. Japanese Orthopedic Association (JOA), axial symptom, C5 root palsy, blood loss, and operation time were used to assess clinical outcomes. The mean follow-up period was 20.7 ± 8.3 months.ResultsThe operation time was 205.2 ± 39.8 min and the intraoperative blood loss was 352.2 ± 143.7 ml. Analysis of the final follow-up data showed significant differences in JOA score (P < 0.01), C2-C7 lordosis angle (P < 0.01), and C2-C7 SVA (P < 0.01). CT confirmed that grafted bone was completely fused in all patients and progression of OPLL was observed in two patients (4.3%) at final follow-up. No adjacent segment disease (ASD) or instrument failure occurred in any patients.ConclusionsCervical laminectomy and crossing the cervicothoracic junction fusion are effective and safe methods to treat multilevel cervical OPLL. Randomized controlled studies compared constructs ending at cervical vertebrae or thoracic vertebrae are needed to confirm these results.