Cervical radiographic parameters in 1- and 2-level anterior cervical discectomy and fusion

Application and Advantages of the Trans-Unco-Discal (TUD) Approach for Cervical Spondylotic Myelopathy and Radiculopathy: Classification and Modification of Surgical Technique Based on the Location of Spinal Cord and/or Nerve Root Compression

Purpose: We assess the application and advantages of modifying the trans-unco-discal (TUD) approach which we underwent for cervical myelo-radiculopathy. We present the surgical techniques of the modified TUD approach. Materials and Methods: The material was 180 cases where anterior cervical decompression (ACD) was performed by the modified TUD approach. We classified the material into four groups based on the location of the nerve root and/or spinal cord compression: I, compression of the root at intervertebral foramen (IVF); II, compression of the posterior margin of the vertebral body; III, compression of the IVF and posterior margin of the vertebral body; IV, compression of the bilateral IVF and posterior margin of the vertebral body. We applied the modified TUD approach to these four types. We present the surgical procedures and techniques for the modified TUD approach. The Japanese orthopedic association (JOA) score and neuroradiological alignment were examined. Results: The improvement rate of the JOA score was 78.4% at 6 months post-surgery and 77.5% in the most recent examinations. By the modified TUD approach, compressive lesions of the spinal cord and/or nerve roots were removed, and good alignment was acquired and sustained. Conclusions: ACD by the modified TUD approach safely achieved appropriate decompression for the spinal cord and/or nerve roots, and the patients had a high improvement rate and good alignment. Complications were less common than with other surgical procedures. If the TUD approach and endoscopic approaches can be combined, their application to new area is anticipated.

A Comparison between Structural Allografts and Polyetheretherketone Interbody Spacers Used in Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis

Among interbody implants used during anterior cervical discectomy and fusion (ACDF), structural allografts and polyetheretherketone (PEEK) are the most used spacers. Currently, no consensus has been established regarding the superiority of either implant, with US surgeons preferring structural allografts, whereas UK surgeons preferring PEEK. The purpose of this systematic review (level of evidence, 4) was to compare postoperative and patient-reported outcomes between the use of structural allografts PEEK interbody spacers during ACDF. Five electronic databases (PubMed, Embase, Scopus, Web of Science, and Cochrane) were searched for articles comparing the usage of structural allograft and PEEK interbody spacers during ACDF procedures from inception to April 10, 2023. The searches were conducted using the keywords "Spine," "Allograft," and "PEEK" and were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Subsequent quality and sensitivity analyses were performed on the included studies. Nine studies involving 1,074 patients were included. Compared with the PEEK group, the structural allograft group had comparable rates of postoperative pseudoarthrosis (p=0.58). However, when stratified according to the number of levels treated, the 3-level ACDF PEEK group was 3.45 times more likely to have postoperative pseudoarthrosis than the structural allograft group (p=0.01). Subsequent postoperative outcomes (rate of subsidence and change in the preoperative and postoperative segmental disc heights) were comparable between the PEEK and structural allograft groups. Patient-reported outcomes (Visual Analog Scale [VAS] of neck pain and Neck Disability Index [NDI]) were comparable. This study showed that for 3-level ACDFs, the use of structural allografts may confer higher fusion rates. However, VAS neck pain, NDI, and subsidence rates were comparable between structural allografts and PEEK cages. In addition, no significant difference in pseudoarthrosis rates was found between PEEK cages and structural allografts in patients undergoing 1- and 2-level ACDFs.

Comparison of Perioperative Complications After Anterior-Posterior Versus Posterior-Anterior-Posterior Cervical Fusion: A Retrospective Review of 153 Consecutive Cases

BACKGROUND

Although published data support the utilization of circumferential fusion to treat select cervical spine pathologies, it is unclear whether the posterior-anterior-posterior (PAP) fusion has increased risks compared with the anterior-posterior fusion.

OBJECTIVE

To evaluate the differences in perioperative complications between the 2 circumferential cervical fusion approaches.

METHODS

One hundred fifty-three consecutive adult patients who underwent single-staged circumferential cervical fusion for degenerative pathologies from 2010 to 2021 were retrospectively reviewed. Patients were stratified into the anterior-posterior ( n = 116) and PAP ( n = 37) groups. The primary outcomes assessed were major complications, reoperation, and readmission.

RESULTS

Although the PAP group was older ( P = .024), predominantly female ( P = .024), with higher baseline neck disability index ( P = .026), cervical sagittal vertical axis ( P = .001), and previous cervical operation rate ( P < .00001), the major complication, reoperation, and readmission rates were not significantly different from the 360° group. Although the PAP group had higher urinary tract infection ( P = .043) and transfusion ( P = .007) rates, higher estimated blood loss ( P = .034), and longer operative times ( P < .00001), these differences were insignificant after the multivariable analysis. Overall, operative time was associated with older age (odds ratio [OR] 17.72, P = .042), atrial fibrillation (OR 158.30, P = .045), previous cervical operation (OR 5.05, P = .051), and lower baseline C1 - 7 lordosis (OR 0.93, P = .007). Higher estimated blood loss was associated with older age (OR 1.13, P = .005), male gender (OR 323.31, P = .047), and higher baseline cervical sagittal vertical axis (OR 9.65, P = .022).

CONCLUSION

Despite some differences in preoperative and intraoperative variables, this study suggests both circumferential approaches have comparable reoperation, readmission, and complication profiles, all of which are high.

Radiographic Outcomes Following ACDF With Hyperlordotic Implants to Achieve Cervical Anterior Column Realignment

BACKGROUND

Degenerative disc disease and progressive sagittal malalignment can both contribute to degenerative cervical myelopathy and radiculopathy. For patients with symptoms refractory to conservative management, anterior cervical discectomy and fusion (ACDF) is a thoroughly vetted intervention shown to improve pain and disability measures. Hyperlordotic implants can also help restore cervical sagittal balance through anterior column realignment (ACR).

METHODS

A consecutive bi-institutional series of patients who underwent ACDF with hyperlordotic polyetheretherketone (PEEK) implants between 2014 and 2016 was reviewed. All included patients underwent ACDF between C3 and C7 inclusive of a hyperlordotic PEEK cervical implant (>10° lordosis), and had ≥12 months of radiographic follow-up. Lateral radiographs were analyzed to compare pre- and postoperative cervical parameters.

RESULTS

Forty-six patients were included (mean age, 58.0 years; male, 35%). Mean body mass index was 28.3 kg/m2, and mean radiographic follow-up 14.4 months. Overall, cervical lordosis increased from -7.8° preoperatively to -14.8° postoperatively and to -15.7° at last follow-up (P < 0.001). Additionally, the mean segmental lordosis of ACR levels treated increased from -0.2° preoperatively to -4.8° postoperatively (P < 0.001), but no significant change was observed at last follow-up. Lastly, improvement in segmental lordosis was seen at both postoperative time points at the C3-C4 (P = 0.002 and P = 0.005, respectively), C4-C5 (P < 0.001 and P < 0.001, respectively), and C5-C6 levels (P < 0.001 and P < 0.001, respectively).

CONCLUSIONS

Our study demonstrates that hyperlordotic PEEK implants used for ACR effectively contribute to restoration of cervical lordosis in patients undergoing ACDF, potentially reducing the need for additional posterior surgery.

Radiographic Parameters in Cervical Myelopathy: Review of Current Literature

STUDY DESIGN

This was a narrative review.

OBJECTIVES

Provide a comprehensive review of radiographic alignment parameters and their effect on procedure selection, surgical decision-making, and clinical outcomes for the treatment of cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA

The use of radiographic parameters to predict prognosis and surgical outcomes in patients with CSM is an evolving field given the complex presentation of patients with this condition.

METHODS

A literature search was conducted using PubMed for surgical treatment of CSM, with an emphasis on cervical radiographic parameters and clinical outcomes.

RESULTS

The principal goals of spine surgery can be broken down into decompression, stabilization, and restoration of alignment. The principle of restoring balance takes careful preoperative planning and attention to radiographic parameters including cervical lordosis, C2-C7 sagittal vertical axis, neck tilt, thoracic inlet angle, T1 slope, K-line, and modified K-line. Surgical interventions for CSM include anterior cervical discectomy and fusion, posterior cervical fusion, or laminoplasty and careful consideration of radiographic measures guide surgical decision-making is essential to ensure optimal outcomes.

CONCLUSION

Utilization of key radiographic parameters in surgical planning and decision-making allows surgeons to optimize clinical outcomes for CSM.

LEVEL OF EVIDENCE

Level V.

Comparison of 3-level anterior cervical discectomy and fusion and open-door laminoplasty in cervical sagittal balance: A retrospective study

Objective

To compare the clinical efficacy and radiological outcomes of 3-level anterior cervical discectomy and fusion (ACDF) and open-door laminoplasty (LP).

Methods

A total of 74 patients from January 2017 to January 2020 were enrolled in this retrospective study. There were two groups. Group A (30 cases) received 3-level ACDF, while Group B (44 cases) received open-door LP. Clinical evaluation included perioperative parameters, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores. Radiological evaluation included cervical curve depth (CCD), C2–7 angle, C2–7 sagittal vertical axis (cSVA), C7 slope (C7S), and T1 slope (T1S).

Results

Perioperative parameters such as blood loss, drainage volume after surgery, and hospital stay of patients in Group A were significantly less than those in Group B (P < .001). NDI scores decreased and JOA scores increased significantly after surgery in both groups (P < .05). There was a significant difference in both scores postoperatively and at 1 month after surgery between the two groups (P < .05). CCD and C2–7 angle of Group A increased significantly postoperatively at 1 month after surgery and at final follow-up (FFU) (P < .05). There was a significant difference in CCD and the C2–7 angle between the two groups postoperatively at 1 month after surgery and at FFU (P < .05). T1S increased significantly in Group A postoperatively and at 1 month after surgery (P < .05).

Conclusion

3-level ACDF and open-door LP achieved favorable clinical outcomes and ACDF benefited patients in the early stage of rehabilitation. Compared with open-door LP, 3-level ACDF had advantages of reconstructing cervical lordosis with increased CCD and C2–7 angle.

Cervical Alignment Analysis Comparing Two-Level Cervical Disc Arthroplasty with Anterior Cervical Discectomy and Fusion with Anterior Plate Fixation

OBJECTIVE

This study assesses cervical alignments after 2-level cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) with anterior plate fixation.

METHODS

Eighty-two patients who underwent 2-level CDA or ACDF in 2014-2019 were identified. Cervical alignment parameters were compared between the 2 cohorts. Subgroup analyses were performed to determine factors that differentiate alignment outcomes between the 2 procedures.

RESULTS

Although both cohorts achieved significant focal lordosis (FL) and overall cervical lordotic (CL) gains, CDA cohorts achieved significantly greater 12-month FL gain (P = 0.022). However, in a multivariate analysis controlling for preoperative variables, FL gain was no longer significant. Although the CDA cervical sagittal vertical axis (cSVA) significantly improved at 3 (P = 0.030) and 12 (P = 0.007) months, these improvements were not superior to the ACDF cSVA. Male patients undergoing CDA achieved greater 12-month CL gain. Patients undergoing CDA with body mass index >25 kg/m² achieved greater 12-month FL gain. Patients undergoing CDA with symptom duration >12 months achieved greater FL gain at 3 and 12 months. Patients undergoing CDA with high baseline T1 slope or cSVA achieved greater 12-month cSVA reduction. Clinical outcomes were comparable between the 2 cohorts. Unlike the ACDF group, CL gain in the CDA group was significantly correlated with the cSVA reduction, which was associated with significant improvement in the Neck Disability Index, arm pain, and 12-Item Short-Form Mental Component Scores. Heterotopic ossification was not found to significantly affect patient outcome and cervical alignment in both cohorts.

CONCLUSIONS

ACDF and CDA are viable options for 2-level degenerative disc disease in carefully selected patients. Both approaches produced equivalent postoperative alignment changes in a 2-level operation.

The Impact of Upper Cervical Spine Alignment on Patient-reported Outcome Measures in Anterior Cervical Decompression and Fusion

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

To determine the extent to which the upper cervical spine compensates for malalignment in the subaxial cervical spine, and how changes in upper cervical spine sagittal alignment affect patient-reported outcomes.

SUMMARY OF BACKGROUND DATA

Previous research has investigated the relationship between clinical outcomes and radiographic parameters in the subaxial cervical spine following anterior cervical discectomy and fusion (ACDF). However, limited research exists regarding the upper cervical spine (occiput to C2), which accounts for up to 40% of neck movement and has been hypothesized to compensate for subaxial dysfunction.

MATERIALS AND METHODS

Patients undergoing ACDF for cervical radiculopathy and/or myelopathy at a single center with minimum 1-year follow-up were included. Radiographic parameters including cervical sagittal vertical axis, C0 angle, C1 inclination angle, C2 slope, Occiput-C1 angle (Oc-C1 degrees), Oc-C2 degrees, Oc-C7 degrees, C1-C2 degrees, C1-C7 degrees, and C2-C7 degrees cervical lordosis (CL) were recorded preoperatively and postoperatively. Delta (Δ) values were calculated by subtracting preoperative values from postoperative values. Correlation analysis as well as multiple linear regression analysis was used to determine relationships between radiographic and clinical outcomes. Alpha was set at 0.05.

RESULTS

A total of 264 patients were included (mean follow-up 20 mo). C2 slope significantly decreased for patients after surgery (Δ=-0.8, P =0.02), as did parameters of regional cervical lordosis (Oc-C7 degrees, C1-C7 degrees, and C2-C7 degrees; P <0.001, <0.001, and 0.01, respectively). Weak to moderate associations were observed between postoperative CL and C1 inclination ( r =-0.24, P <0.001), Oc-C1 degrees ( r =0.59, P <0.001), and C1-C2 degrees ( r =-0.23, P <0.001). Increased preoperative C1-C2 degrees and Oc-C2 degrees inversely correlated with preoperative SF-12 Mental Composite Score (MCS-12) scores ( r =-0.16, P =0.01 and r =-0.13, P =0.04). Cervical sagittal vertical axis was found to have weak but significant associations with Short Form-12 (SF-12) Physical Composite Score (PCS-12) ( r =-0.13, P =0.03) and MCS-12 ( r =0.12, P =0.05).

CONCLUSION

No clinically significant relationship between upper cervical and subaxial cervical alignment was detected for patients undergoing ACDF for neurological symptoms. Upper cervical spine alignment was not found to be a significant predictor of patient-reported outcomes after ACDF.

LEVEL OF EVIDENCE

Level III.

The Effect of Anterior Cervical Discectomy and Fusion Procedure Duration on Patient-Reported Outcome Measures

OBJECTIVE

To determine whether operative duration of anterior cervical discectomy and fusion (ACDF) significantly affects patient-reported outcome measures (PROMs) 90 days after surgery and at 1-year follow-up.

METHODS

Patients who underwent primary 1-level to 4-level ACDF were retrospectively identified. Demographic data and PROMs were collected through chart review. Patients were split into short, medium, and long tertiles based on procedure duration. PROM surveys were administered preoperatively as baseline measurements, at initial follow-up (between 60 and 120 days postoperatively), and at 1 year postoperatively. Outcomes included Neck Disability Index, Short-Form 12 Physical Component Score (PCS-12), Short-Form 12 Mental Component Score, visual analog scale (VAS) neck score, and VAS arm score.

RESULTS

Significant short-term improvements were found across all groups for all PROMs. All groups showed long-term improvements in Short-Form 12 Mental Component Score, PCS-12, Neck Disability Index, VAS neck score, and VAS arm score, with the exception of the medium-duration group in PCS-12 (P = 0.093). On multivariate analysis, short-duration procedures predicted better improvement in VAS neck score (β = -1.01; P = 0.012) and VAS arm score (β = -1.38; P = 0.002) compared with long-duration procedures, whereas medium-duration procedures resulted in better improvement in VAS arm score (β = -1.00; P = 0.011). Further, short and medium duration was a predictor of decreased length of hospital stay (β = -0.67, P = 0.001 and β = -0.59, P = 0.001, respectively) compared with long-duration procedures.

CONCLUSIONS

All groups improved after ACDF regardless of surgical duration. Further, surgical duration was not a predictor of differing improvement in physical function or disability.

Analyzing the Significance of T1 Slope minus Cervical Lordosis in Patients with Anterior Cervical Discectomy and Fusion Surgery

Objective

Accurate measurement of T1 slope (a component of T1s minus cervical lordosis [CL]) is often constrained by anatomical limitations. In this situation, efforts should be made to find the exact meaning of T1s-CL and whether there are any alternatives to it.

Methods

We enrolled 117 patients who received two-level anterior cervical discectomy and fusion (ACDF). Occipital slope, C2 slope (C2s), C7 slope (C7s), T1, O-C2 angle (O-C2A), C2-7 angle (C2-7A), O-C7 angle (O-C7A), T1s-CL, C7-T1 angle (C7-T1A), and C2-7 sagittal vertical axis were measured. We determined 16° (T1s-CL) as the reference point for dividing subjects into the mismatch group and the balance group, and a comparative analysis was performed.

Results

The mean value of C7-T1A was constantly maintained within 2.6° peri-operatively. In addition, C2s and T1s-CL showed the same absolute change (Δ|0.8|°). The mean values of T1s-CL of the mismatch and balance groups were 23.0° and 7.6°, respectively. The five factors with the largest differences between the two groups were as follows : C2s (Δ13.3°), T1s-CL (Δ15.4°), O-C2A (Δ8.7°), C2-7A (Δ14.7°), and segmental angle (Δ7.9°) before surgery. Only four factors showed statistically significant change between the two groups after ACDF : T1s-CL (Δ4.0° vs. Δ0.2°), C2s (Δ3.2° vs. Δ0.7°), O-C2A (Δ2.6° vs. Δ1.3°), C2-7A (Δ6.3° vs. Δ1.3°). A very strong correlation between T1s-CL and C2s was also found (r=|0.88–0.96|).

Conclusion

C2s itself may be the essential key to represent T1s-CL. The amounts and directions of change of these two factors (T1s-CL and C2s) were also almost identical. The above phenomenon was re-confirmed once again through the correlation analysis.

Etiology and treatment of cervical kyphosis: state of the art review-a narrative review

Objective

To provide state of the art review regarding cervical kyphosis.

Background

Cervical spine kyphosis has been increasingly common due to the growing elderly population. Clinicians should comprehensively understand its symptoms, biomechanics, etiology, radiographic evaluation, classification, and treatment options and complications of each treatment. Comprehensive review will help clinicians improve the management for patients with cervical kyphosis.

Methods

The available literature relevant to cervical kyphosis was reviewed. PubMed, Medline, OVID, EMBASE, and Cochrane were used to review the literature.

Conclusions

This article summarizes current concepts regarding etiology, evaluation, surgical treatment, complications and outcomes of cervical kyphosis. Major etiologies of cervical kyphosis include degenerative, post-laminectomy, and ankylosing spondylitis. Clinical presentations include neck pain, myelopathy, radiculopathy, and problems with horizontal gaze, swallowing and breathing. Cervical lordosis, C2-7 sagittal vertical axis, chin-brow to vertical angle, and T1 slope should be evaluated from upright lateral 36-inch film. The most widely used classification system includes a deformity descriptor and 5 modifiers. A deformity descriptor provides a basic grouping of the deformity consisting of five types, cervical, cervicothoracic, thoracic, coronal cervical deformity, and cranio-vertebral junction deformity. The 5 modifiers include C2-7 sagittal vertical axis, chin-brow to vertical angle, T1 slope minus cervical lordosis, myelopathy based on modified Japanese Orthopaedic Association score, and SRS-Schwab classification for thoracolumbar deformity. Current treatment options include anterior discectomy and fusion, anterior osteotomy, Smith-Peterson osteotomy, pedicle subtraction osteotomy, or a combination of these based on careful preoperative evaluation.

Does Cervical Alignment Matter? The Effect of 2-level Anterior Cervical Discectomy and Fusion on Sagittal Alignment and Patient-reported Outcomes

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

This study aimed to determine the change in cervical sagittal balance following 2-level anterior cervical discectomy and fusion (ACDF) and whether the degree of change was associated with improvement in patient-reported outcomes (PROs).

SUMMARY OF BACKGROUND DATA

Sagittal balance in cervical spine surgery has been recognized as an important surgical goal. However, its influence on clinical outcomes following anterior decompressive procedures remains debatable.

MATERIALS AND METHODS

Patients who underwent primary 2-level ACDF for cervical spondylotic radiculopathy and/or myelopathy were identified from an institutional spine registry. Radiographic measurements were done preoperatively, postoperatively, and at minimum 24 months follow-up. Measurements comprised segmental lordosis (SL), C2-C7 cervical lordosis (CL), C2-C7 sagittal vertical axis, C7 slope (C7S), T1 slope (T1S) and C7 slope minus cervical lordosis (C7S-CL). Disk heights were measured preoperatively and postoperatively. PROs including the Neck Disability Index, Short Form-36, and Visual Analog Scale for neck pain and arm pain were collected preoperatively and at 24 months postoperatively.

RESULTS

In total, 90 patients were included. Mean follow-up was 58.6±22.9 months. Significant improvement in all PROs was achieved at 24 months (P<0.05). SL was -1.2±8.2 degrees preoperatively, increased to 5.2±5.9 degrees postoperatively (P<0.001), and decreased to 1.2±6.2 degrees at follow-up (P=0.005). CL was 8.5±12.5 degrees preoperatively, increased to 10.8±12.4 degrees postoperatively (P=0.018), and maintained at 10.9±11.2 degrees at follow-up (P=0.030). Sagittal vertical axis, C7S, T1S, and C7S-CL did not change significantly. Significant increases in disk heights were achieved postoperatively (P<0.001). Fusion rate was 98.9% at follow-up. PROs were not related to radiologic measurements. Maintaining or increasing CL or SL was not related to a greater degree of improvement in PROs.

CONCLUSIONS

Two-level ACDF restored segmental and global CL, but changes in cervical sagittal alignment did not correlate with the magnitude of improvement in PROs. Adequate decompression with solid fusion remains fundamental to achieving good clinical outcomes in patients with degenerative cervical disease.

How do C2 tilt and C2 slope correlate with patient reported outcomes in patients after anterior cervical discectomy and fusion?

BACKGROUND/CONTEXT

C2 tilt and C2 slope are quick and easy measurements to obtain on lateral radiographs and may be used to determine overall cervical sagittal alignment; however, the influence of these measurements on patient outcomes has not been well established in literature.

PURPOSE

To determine if C2 tilt and/or C2 slope predict patient outcomes better compared with conventional radiographic measures after an anterior cervical discectomy and fusion (ACDF).

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

A total of 249 patients who underwent 1 to 3 level ACDF to address radiculopathy and/or myelopathy at a single academic institution between 2011 and 2015 were identified. Patients with less than 1 year of follow-up were excluded.

OUTCOME MEASURES

Patient Reported Outcomes: Neck Disability Index (NDI), Physical Component Score-12 (PCS-12), and Mental Component Score (MCS-12), Visual Analog Score (VAS) Neck and Arm scores Cervical radiographic measurements: C2 tilt, C2 slope, C2-C7 lordosis, cervical SVA, T1 slope, T1 slope minus cervical lordosis (TS-CL), and C2-C7 ROM METHODS: Pearson correlation tests were performed to assess for significant associations between radiographic measurements and patient outcomes. Multiple linear regression models were developed adjusting for demographics and radiographic parameters to determine which factors were predictive of patient outcomes.

RESULTS

C2 tilt and TS-CL correlated with all postoperative physical outcome scores (NDI, PCS-12, VAS Neck and ARM; p<.05), however no association was seen between C2 slope and postoperative outcomes. After accounting for the presence of subaxial deformity, C2 tilt and TS-CL remained strongly correlated to patient outcome scores. With multiple linear regression, C2 tilt was a significant predictor for NDI, whereas TS-CL was a significant predictor for PCS-12, VAS Neck and VAS Arm.

CONCLUSIONS

C2 tilt significantly correlated with well-described conventional cervical parameters as well as postoperative physical outcomes measures, especially NDI, on multivariate analysis. C2 tilt may provide an easy and practical tool for predicting physical outcomes after ACDF.

The Effect of Anterior Cervical Discectomy and Fusion on Cervical Sagittal Vertical Axis and Lordosis with Minimum 2-Year Follow-Up

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) can induce lordosis and improve cervical sagittal vertical axis (SVA), but multilevel ACDF may inadvertently increase cervical SVA because of insufficient lordosis induction.

METHODS

Patients who underwent 1-, 2-, or ≥3-level ACDF in the subaxial spine with minimum 2-year follow up were retrospectively studied. C2-C7 Cobb angle (lordosis), cervical SVA, and T1 slope were measured preoperatively, immediately postoperatively, and at last follow-up.

RESULTS

Inclusion criteria were met by 127 patients. There were no differences in baseline demographics among 1-, 2-, and ≥3-level ACDF groups. Mean follow-up was 43.7 months (range, 24-142 months). Increase of cervical SVA immediately postoperatively was 1.94 mm, -1.44 mm, and 7.25 mm for 1-, 2-, and ≥3-level ACDF (P = 0.041) and at last follow-up was 2.97 mm, 0.70 mm, and 9.32 mm for 1-, 2-, and ≥3-level ACDF (P = 0.026). At last follow-up, 2-level ACDF patients had the greatest decrease in T1 slope (-0.43°) compared with increase of 2.71° for 1-level and 2.84° for ≥3-level patients (P = 0.028). In all 3 groups, segmental (ACDF levels) lordosis, cervical SVA, and T1 slope did not decrease from immediate postoperative to last follow-up. Only 2-level ACDF maintained C2-7 lordosis (2.16°) compared with loss of lordosis in 1-level (-0.84°) and ≥3-level (-2.00°) ACDF (P = 0.008) at last follow-up. Linear regression analysis showed that T1 slope had no relationship with correction of cervical SVA (P = 0.5310) but had a significant correlation with Cobb angle loss of C2-C7 lordosis (P = 0.0016).

CONCLUSIONS

Compared with 1- and 2-level ACDF, ≥3-level ACDF resulted in significant increase of cervical SVA and loss of overall lordosis. Compared with 1- and ≥3-level ACDF, 2-level ACDF had the greatest ability to maintain lordosis. T1 slope had a significant correlation with loss of C2-C7 lordosis after ACDF.

Reciprocal change of occipitocervical parameters after anterior cervical discectomy and fusion

To evaluate the reciprocal changes in occipitocervical parameters according to the recovery of cervical lordosis (CL) after anterior cervical discectomy and fusion (ACDF) in patients with sagittal imbalance. Sixty-five cases that underwent ACDF were followed. They were divided according to the recovery of the CL: Group 1 (ΔCL > 5°, 30 cases) and Group 2 (ΔCL < 5°, 35 cases). The following parameters were measured: occiput-cervical inclination (OCI), CL, occiput-C2 angle (OC2A), distance between external occipital protuberance and spinous process of C2 (OC2D), distance between spinous processes of C2 and C7 (C27D), and shortest distance between the plumb line of C2 body and posterosuperior corner of C7 (C27SVA). Overall, all parameters changed significantly after ACDF. Preoperative CL and preoperative C27D showed a correlation with ΔCL. ΔCL was negatively correlated with ΔC27D and ΔC27SVA. In Group 1, CL increased from − 2.60 ± 1.88° to 11.57 ± 1.83°, OC2A decreased from 23.96 ± 2.05° to 19.87 ± 1.36°, OC2D increased from 82.96 ± 1.48 mm to 86.50 ± 1.81 mm, C27D decreased from 95.61 ± 2.66 mm to 87.01 ± 2.50 mm, and C27SVA decreased from 24.14 ± 2.20 mm to 17.06 ± 2.14 mm. In Group 2, only OCI decreased significantly after ACDF. ACDF can increase CL postoperatively in patients with cervical sagittal imbalance. Patients with significant CL recovery after ACDF showed a reciprocal change in occipitocervical parameters. (OC2A, OC2D).

Titanium-interlayer mediated hydroxyapatite coating on polyetheretherketone: a prospective study in patients with single-level cervical degenerative disc disease

BACKGROUND

Currently, there are limited reports regarding investigation of the biological properties of polyetheretherketone (PEEK) coated with titanium (Ti) and hydroxyapatite (HA) in human. The objective of this study is to evaluate the in vivo response of the PEEK cages coated with Ti and HA versus uncoated PEEK cages after anterior cervical discectomy and fusion (ACDF) in patients with single-level cervical degenerative disc disease (CDDD).

METHODS

Twenty-four patients with PEEK cages coated with Ti and HA (PEEK/Ti/HA group) were matched one-to-one with patients with uncoated PEEK cages (PEEK group) based on age, gender, and operative segment. All patients had been followed up for more than 2 years. Radiological assessments included intervertebral height (IH), C2-7 angle (C2-7a), segmental alignment (SA), and fusion rate. Clinical parameters included Visual Analogue Scale (VAS) and Japanese Orthopedic Association (JOA) scores.

RESULTS

There was no statistical difference in SA, IH, and C2-7a between the two groups before and after surgery and all these parameters were restored postoperatively. The fusion rate of PEEK/Ti/HA group was significantly higher than PEEK group at 3-month post-operation (87.5% vs. 62.5%). At the last follow-up, the fusion rate of the both groups achieved 100%. The VAS and JOA scores were comparable between two groups and improved postoperatively.

CONCLUSIONS

In patients with single-level ACDF, PEEK cage coated with Ti and HA provided a higher fusion rate than uncoated PEEK cage at 3-month post-operation, while both two cages could achieve solid osseous fusion at the last follow up. Compared with the uncoated PEEK cage, PEEK/Ti/HA cage yielded similar favorable segmental and overall cervical lordosis, IH, and clinical outcomes after the surgery.

The importance of preoperative T1 slope for determining proper postoperative C2-7 Cobb's angle in patients undergoing cervical reconstruction

BACKGROUND

This study aimed to explore the relationship among different cervical sagittal parameters in asymptomatic volunteers and the correlation between surgical efficacy and difference of presumed and actual postoperative C2-7 Cobbs's angle (C2-7COBB), which was calculated based on preoperative T1 slope (T1S) in patients undergoing cervical reconstruction.

METHODS

In total, 158 inpatients with cervical spondylosis and 274 asymptomatic volunteers were retrospectively reviewed. Cervical sagittal parameters, such as C2-7COBB, T1S, thoracic inlet angle (TIA), and neck tilt (NT), were compared. Then, the correlation among these parameters was analyzed in asymptomatic volunteers, and a regression equation between T1S and C2-7COBB was established and used to analyze the correlation among the Japanese Orthopaedic Association (JOA) score improvement, the sagittal parameters, and the difference between presumed and actual postoperative C2-7COBB in patients after cervical reconstruction.

RESULTS

The mean T1S, C2-7COBB, and TIA were significantly decreased in patients (P < 0.01). T1S and NT had a strong correlation with TIA (P < 0.01). T1S demonstrated a moderate correlation with C2-7COBB in asymptomatic volunteers (r = 0.569, P < 0.01). A regression equation had been established as C2-7COBB = 0.742 × T1S - 0.866. The mean C2-7COBB and JOA score improved significantly (P < 0.05) postoperatively. Moreover, the JOA improvement rate showed a significant negative correlation with the difference in the presumed and actual postoperative C2-7COBB (r = - 0.696, P < 0.01).

CONCLUSION

Our study successfully established a regression equation for calculating postsurgical C2-7COBB based on the correlation between T1S and C2-7COBB in asymptomatic volunteers. The regression equation could be used for guiding surgeons to accomplish an ideal postsurgical C2-7COBB for patients with cervical spondylosis.

Anterior Reconstruction Techniques for Cervical Spine Deformity

Cervical spine deformity is an uncommon yet severely debilitating condition marked by its heterogeneity. Anterior reconstruction techniques represent a familiar approach with a range of invasiveness and correction potential-including global or focal realignment in the sagittal and coronal planes. Meticulous preoperative planning is required to improve or prevent neurologic deterioration and obtain satisfactory global spinal harmony. The ability to perform anterior only reconstruction requires mobility of the opposite column to achieve correction, unless a combined approach is planned. Anterior cervical discectomy and fusion has limited focal correction, but when applied over multiple levels there is a cumulative effect with a correction of approximately 6° per level. Partial or complete corpectomy has the ability to correct sagittal deformity as well as decompress the spinal canal when there is anterior compression behind the vertebral body. If pathoanatomy permits, a hybrid discectomy-corpectomy construct is favored over multilevel corpectomies. The anterior cervical osteotomy with bilateral complete uncinectomy may be necessary for angular correction of fixed cervical kyphosis, and is particularly useful in the midcervical spine. A detailed understanding of the patient's local anatomy, careful attention to positioning, and avoiding long periods of retraction time will help prevent complications and iatrogenic injury.

Cervical sagittal parameters were closely related to Neck Disability Index score after anterior cervical decompression and fusion

Background

ACDF treatment of CSM is currently recognized as a surgical method with reliable efficacy. However, the cervical radiographic findings in a certain group of patients showed that the symptoms were not completely relieved. This study will investigate the relationship between cervical parameters and prognoses after ACDF surgery.

Methods

This study collected cases of CSM treated with ACDF in Zhongda Hospital from May 2014 to June 2018. The investigators recorded gender, age, cervical sagittal parameters, fusion segment, BMI, symptom duration, and NDI score. To compare the changes of parameters after surgery and explore the correlation between each factor and NDI score.

Results

Generally, cervical lordosis increased and TS-CL decreased after surgery and during follow-up. Postoperative T1S, SVA and SCA decreased significantly compared to preoperative. T1S was positively correlated with CL (r = 0.245), SVA (r = 0.184), and negatively correlated with SCA (r = − 0.314) and NT (r = − 0.222). The last follow-up NDI score was positively correlated with T1S (r = 0.689), SVA (r = 0.155), TS-CL (r = 0.496), and age (r = 0.194), while negatively correlated with SCA (r = − 0.142). A linear regression model was established with the following formula: NDI = 0.809 × (T1S) − 0.152 × (CL) + 1.962 × (Sex) + 0.110 × (Age). T1S (B = 0.205, P < 0.001), CL (B = − 0.094, P = 0.041), and NT (B = 0.142, P = 0.023) were independent risk factors that affected whether the last follow-up NDI score was greater than preoperative.

Conclusions

In ACDF treatment of CSM, there exists a close correlation between cervical sagittal parameters and NDI scores. T1S, CL, sex, and age were linearly dependent on NDI scores. The increase of T1S, NT, and the decrease of CL were risk factors that affected follow-up NDI score greater than preoperative. Reducing T1S is beneficial to clinical recovery.

Impact of the Inclusion of C2 in Posterior Cervical Fusions for Cervical Myelopathy on Sagittal Cervical Alignment

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine the impact of including C2 in posterior fusions on radiographic parameters of cervical alignment in cervical spondylotic myelopathy.

SUMMARY OF BACKGROUND DATA

Despite the use of posterior instrumentation and arthrodesis after cervical laminectomy, loss of lordosis and the development of kyphosis are prevalent. Inadequate cervical lordosis and other measures of sagittal cervical alignment have been shown to correlate with disability, general health scores, and severity of myelopathy. The role of C2 in the posterior tension band, which maintains sagittal alignment, differs from the subaxial spine, as it is the insertion point for erector spinae muscles that play a critical role in maintaining posture.

PATIENTS AND METHODS

This study compares the radiographic outcomes of sagittal balance between 2 cohorts of patients who underwent posterior cervical decompression and fusion for cervical myelopathy over a 12-year period at a single institution. Demographic and surgical characteristics were collected using the electronic medical record of patients undergoing posterior cervical fusions (PCF) which included the axis [axial fusion (AF)] and those that were subaxial fusions (SAF). Radiographic measurements included preopertaive and postoperative C2-C7 lordosis (CL), C2-C7 sagittal vertical axis (SVA), and T1 slope (T1S).

RESULTS

After review of the electronic medical records, 229 patients were identified as having PCF and decompression for treatment of myelopathy. One hundred sixty-seven patients had AF, whereas 62 had SAF. PCF resulted in loss of CL in both cohorts. Although there was no statistical difference in postoperative CL, there was a significant increase in SVA (P<0.001) and T1S (P<0.001) with AF.

CONCLUSIONS

PCF often result in loss of lordosis. When compared with SAF, inclusion of C2 into the fusion construct may result in worsened sagittal balance, increasing the SVA and T1S.

Half of Unplanned Readmissions Following One or Two-Level Anterior Cervical Decompression and Fusion Are Unrelated to Surgical Site

MINI: In this study we analyze rates of readmission, and the timing and reasons for readmission after one to two level anterior cervical decompression and fusion. Among 18,833 patients who underwent anterior cervical decompression and fusion, 3% were readmitted to the hospital within 30 days. 39.5% of readmissions were for reasons related to surgical site.

STUDY DESIGN

Retrospective review of a national database.

OBJECTIVE

In this study we analyze rates of readmission, and the timing and reasons for readmission after one to two level anterior cervical decompression and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

The safety profile of ACDF has been previously described with readmission rates typically between 2% and 4%. However no studies have investigated the primary diagnoses driving readmission, and whether these diagnoses are related to the surgical site.

METHODS

Demographics, comorbidities, and procedural characteristics were collected for all patients undergoing one or two-level ACDF for degenerative indications identified by Current Procedural Terminology (CPT) coding in the National Surgical Quality Improvement Program (NSQIP) database. The incidence of 30-day complications and readmissions was calculated, and the reasons for readmission as well as the timing of readmission were reviewed. Multivariate logistic regression analyses were performed to identify risk factors associated with complications or readmissions within 30 days of surgery.

RESULTS

Eighteen thousand eight hundred thirty three patients underwent ACDF (15,464 single-level and 3369 two-level, mean age 53.7 yrs, standard deviation [SD]: 11.6; 50% male). Postoperative complication rate of was 4.3% in two-level fusions and 3.5% in single-level fusion (P = 0.027). Five hundred sixty nine unplanned readmissions were identified (3.0%), of which 39.5% were related to the surgical site and 49.7% were unrelated to the surgical site (10.5% unknown cause of readmission). The most frequent reason for 30-day readmission was pneumonia (9.3%, mean time to readmission of 11.3 d) followed by dysphagia (7.4%, 6.3 d), and acute postoperative pain (7.2%, 11.4 d).

CONCLUSION

In this nationwide analysis of 18,833 ACDF cases, 3.0% of patients were readmitted within 30 days, of which at least 49.7% were for reasons unrelated to the surgical site.

LEVEL OF EVIDENCE

3.

Transient Dorsal Column Dysfunction After Extreme Cervical Deformity Correction: Report of 3 Cases

BACKGROUND

Chin-on-chest kyphotic cervical deformity can be debilitating. Surgical deformity correction serves to decompress neural elements and restore lordosis. This can be achieved through multiple osteotomies with instrumentation and fusion, sometimes requiring a staged approach. Such procedures carry a high risk of neurologic injury. Here we present examples of transient neurologic dysfunction not previously reported in the common literature.

CASE DESCRIPTION

The authors present 3 patients who underwent extreme cervical deformity correction for chin-on-chest deformity. Deformity correction in all cases was obtained through multiple osteotomies with multilevel cervicothoracic posterior instrumentation and arthrodesis. On postoperative examination, all 3 patients developed transient ataxia, dysmetria, and decreased proprioception in all 4 extremities-examination findings consistent with dorsal column dysfunction. All symptoms resolved within 2-3 weeks postoperatively.

CONCLUSIONS

Incomplete spinal cord syndromes such as posterior cord syndrome can be caused by compression or stretching of the ascending dorsal spinal tracts. Considering the large degree of correction obtained, we hypothesize the resulting shortening of the dorsal columns as the pathomechanism. Providers should be aware, and patients should be counseled preoperatively that these symptoms may occur. If these symptoms are present postoperatively, appropriate diligence is warranted with the understanding that these deficits may be transient.

Applicability of cervical sagittal vertical axis, cervical lordosis, and T1 slope on pain and disability outcomes after anterior cervical discectomy and fusion in patients without deformity

OBJECTIVE

Understanding what influences pain and disability following anterior cervical discectomy and fusion (ACDF) in patients with degenerative cervical spine disease is critical. This study examines the timing of clinical improvement and identifies factors (including spinal alignment) associated with worse outcomes.

METHODS

Consecutive adult patients were enrolled in a prospective outcomes database from two academic centers participating in the Quality Outcomes Database from 2013 to 2016. Demographics, surgical details, radiographic data, arm and neck pain (visual analog scale [VAS] scores), and disability (Neck Disability Index [NDI] and EQ-5D scores) were reviewed. Multivariate analysis was used.

RESULTS

A total of 186 patients were included, and 48.4% were male. Their mean age was 55.4 years, and 45.7% had myelopathy. Preoperative cervical sagittal vertical axis (cSVA), cervical lordosis (CL), and T1 slope values were 24.9 mm (range 0-55 mm), 10.4° (range -6.0° to 44°), and 28.3° (range 14.0°-51.0°), respectively. ACDF was performed at 1, 2, and 3 levels in 47.8%, 42.0%, and 10.2% of patients, respectively. Preoperative neck and arm VAS scores were 5.7 and 5.4, respectively. NDI and EQ-5D scores were 22.1 and 0.5, respectively. There was significant improvement in all outcomes at 3 months (p < 0.001) and 12 months (p < 0.001). At 3 months, neck VAS (3.0), arm VAS (2.2), NDI (12.7), and EQ-5D (0.7) scores were improved, and at 12 months, neck VAS (2.8), arm VAS (2.3), NDI (11.7), and EQ-5D (0.8) score improvements were sustained. Improvements occurred within the first 3-month period; there was no significant difference in outcomes between the 3-month and 12-month mark. There was no correlation among cSVA, CL, or T1 slope with any outcome endpoint. The most consistent independent preoperative factors associated with worse outcomes were high neck and arm VAS scores and a severe NDI result (p < 0.001). Similar findings were seen with worse NDI and EQ-5D scores (p < 0.001). A significant linear trend of worse NDI and EQ-5D scores at 3 and 12 months was associated with worse baseline scores. Of the 186 patients, 171 (91.9%) had 3-month follow-up data, and 162 (87.1%) had 12-month follow-up data.

CONCLUSIONS

ACDF is effective in improving pain and disability, and improvement occurs within 3 months of surgery. cSVA, CL, and T1 slope do not appear to influence outcomes following ACDF surgery in the population with degenerative cervical disease. Therefore, in patients with relatively normal cervical parameters, augmenting alignment or lordosis is likely unnecessary. Worse preoperative pain and disability were independently associated with worse outcomes.

The change of cervical sagittal parameters plays an important role in clinical outcomes of cervical spondylotic myelopathy after multi-level anterior cervical discectomy and fusion

BACKGROUND

Cervical sagittal parameters were closely related with clinical outcomes after multi-level ACDF. Our purpose was to evaluate the clinical outcomes and cervical sagittal parameters in patients with MCSM after ACDF and to identify the risk factors of poor clinical outcomes.

MATERIAL AND METHODS

ACDF was performed in 89 patients with MCSM. Based on average JOA recovery rate, patients were divided good-outcome group (group GO) and poor-outcome group (group PO). The cervical sagittal parameters including Cobb angle, SVA, T1S, cranial tilt and cervical tilt were measured. Multivariate logistic regression was used to identify risk factors.

RESULTS

Fifty-four patients (60.67%) were divided into group GO, while 35 patients (39.33%) were divided into group PO. Cobb angle, SVA and T1S was corrected from preoperative average 11.80° ± 9.63°, 23.69 mm ± 11.69 mm and 24.43° ± 11.78° to postoperative average 15.08° ± 9.05°, 18.79 mm ± 10.78 mm and 26.92° ± 11.94° respectively (p < 0.001). △Cobb angle (p = 0.008) and △SVA (p = 0.009) showed significantly statistical differences between two groups. Longer symptom duration, lower preoperative JOA score, smaller △Cobb angle and larger △SVA were identified as risk factors of poor clinical outcomes.

CONCLUSION

Multi-level ACDF is an effective surgical method to treat patients with MCSM. However, long duration of preoperative symptoms, lower preoperative JOA score, smaller △Cobb angle and larger △SVA are risk factors for poor outcomes in patients with MCSM after ACDF. Sagittal parameters should be paid attention to in surgery.

Clinical and radiological results comparison of allograft and polyetheretherketone cage for one to two-level anterior cervical discectomy and fusion: A CONSORT-compliant article

BACKGROUND

Recently, many kinds of cages for cervical fusion have been developed to avoid the related complications caused by tricortical iliac crest graft. The existing literature has reported the excellent clinical efficacy and superior fusion rate. However, various types of cages have their own disadvantages. Which bone graft material is the best choice for cage with the fewest complications? At present, there is still no conclusion.

METHODS

By reviewing patients with 1 to 2-level cervical degenerative disease in our hospital with a novel cage made of allograft or polyetheretherketone (PEEK), we evaluated the efficacy and reliability of the new cage in anterior cervical discectomy and fusion (ACDF). From 2015 to 2016, a prospective review of 58 and 49 consecutive cases with spondylotic radiculopathy or myelopathy undergoing ACDF using allograft (group A) and PEEK (group B) cage were performed. The follow-up ranged from 12 to 40 months. Intraoperative index, clinical outcome and complications were recorded. Radiographs evaluated segmental and overall cervical lordosis, the height of the intervertebral space, interbody height ratio (IHR), cage positioning, and fusion state.

RESULTS

A total of 134 cages were implanted. Compared to preoperatively, the visual analog scale (VAS) and neck disability index (NDI) were reduced postoperatively without any change during the subsequent follow-up in both groups. There was no migration or extrusion of the cages at the latest follow-up. There were 2 and 4 patients suffering dysphagia respectively. In both groups, the intervertebral height, IHR, segmental and overall cervical lordosis were significantly greater than pre-operation (P < .05) and were maintained at the last follow-up, but were not statistically significant (P > .05). The allograft group achieved a fusion rate of 100% (58/58) according to CT scans at 3 months post-operation, while PEEK group was 91.8% (45/49), which reached 95.9% (47/49) at 6 months and 100% at 12 months. In addition, the fusion state was maintained in all patients at the last follow-up.

CONCLUSION

Our data showed that the new allograft cage is superior to the PEEK cage in providing a high fusion rate and fewer complications after 1-level and 2-level ACDF procedures. It may represent an excellent alternative to other cages.

Comparison of Adjacent Segment Degeneration, Cervical Alignment, and Clinical Outcomes After One- and Multilevel Anterior Cervical Discectomy and Fusion

Objective

This study aimed to assess the influence of a fused segment on cervical range of motion (ROM) and adjacent segmental kinematics and determine whether increasing number of fusion levels causes accelerated adjacent segment degeneration (ASD) after anterior cervical discectomy and fusion (ACDF).

Methods

A total of 165 patients treated with ACDF were recruited for assessment, and they were divided into 3 groups based on the number of fusion levels. Radiological measurements and clinical outcomes included visual analogue scale (VAS) and Neck Disability Index (NDI) assessed preoperatively and at ≥2 years of follow-up.

Results

ASD occurred in 41 of 165 patients who underwent ACDF (1-level, 12 of 78 [15.38%]; 2-level, 14 of 49 [28.57%]; 3-level, 15 of 38 [39.47%]; p=0.015) at final follow-up (mean, 31.9 months). Significant differences were found in reduction of global ROM based on the number of fusion levels (p<0.001). The upper adjacent segment ROM increased over time (p=0.004); however, lower segment ROM did not. Three-level ACDF did not obtain greater amounts of lordosis than did 1- or 2-level ACDF (p=0.003). Postoperative neck VAS scores and NDI were significantly higher for 3-level ACDF than for 1- or 2-level ACDF (p=0.033 and p=0.001).

Conclusion

ASD occurred predominantly in multilevel cervical fusion, more frequently in the upper segment of the prior fusion and as the number of fusion levels increased. Patients who underwent multilevel fusion had greater reduction of global ROM and increased compensatory motion at the upper adjacent segment. Three-level ACDF did not appear to restore cervical lordosis significantly compared with 1- or 2-level arthrodesis.

Sagittal Alignment Outcomes in Lordotic Cervical Spine: Does Three-Level Anterior Cervical Discectomy and Fusion Outperform Laminoplasty?

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

To compare the radiological outcomes between three-level anterior cervical discectomy and fusion (ACDF) and plate-only open-door laminoplasty (LAMP) in patients with lordotic cervical spine.

SUMMARY OF BACKGROUND DATA

Both three-level ACDF and LAMP are important surgical methods for multilevel cervical spondylotic myelopathy, but the cervical sagittal alignment outcomes and the lordosis preserving abilities between the two specific approaches have not been carefully compared.

METHODS

Sixty patients, all of whom had lordotic cervical spines and underwent three-level ACDF (n = 22) or LAMP (n = 38) for the treatment of multilevel cervical spondylotic myelopathy, were prospectively studied. Upright neutral cervical lateral radiographs were assessed preoperatively, at 3 days after surgery, and at the last follow-up (1.5 years). The primary radiological outcomes are C2-7 Cobb angle, and the secondary outcomes include C2-7 sagittal vertical axis , disc height, Harrison angle, and Ishihara index. The relationship between preoperative parameters and follow-up outcomes were assessed.

RESULTS

Preoperative cervical sagittal alignment parameters were similar between the two groups. Patients in the ACDF group obtained larger C2-7 Cobb angles than those the LAMP group early after surgery. However, the lordosis in the ACDF group decreased significantly during follow-up, leading to similar outcomes between the two groups. The lordosis-preserving ability of ACDF is significantly poorer than that of LAMP. Secondary radiological parameters also showed similar trends. In both groups, the preoperated Ishihara index was significantly related to follow-up C2-7 Cobb angles. For patients with Ishihara index less than 20, ACDF is more likely to produce a larger C2-7 Cobb angled at the time of follow-up.

CONCLUSION

In patients with lordotic cervical spine, the sagittal alignment outcomes of the two approaches were similar, and the lordosis-preserving ability was poorer in ACDF. Further research should focus on the factors related to the lordosis-preserving ability of multilevel ACDF.

LEVEL OF EVIDENCE

3.

[Correlation analysis between C 7 slope and cervical sagittal parameters in short segment anterior cervical discectomy with fusion]

OBJECTIVE

To elucidate the relationship between preoperative C 7 slope (C 7S) and sagittal parameters in anterior cervical discectomy with fusion (ACDF) by imaging.

METHODS

A retrospective analysis of 54 patients (24 males and 30 females) with ACDF for cervical spondylosis between January 2012 and January 2017 was performed. The age ranged from 23 to 71 years (mean, 46.6 years). There were 29 cases of cervical spondylotic radiculopathy and 25 cases of cervical spondylotic myelopathy. The disease duration ranged from 3 to 48 months, with an average of 16.8 months. In the 55 patients, 44 were single-segment ACDF and 10 were double-segment ACDF. Sagittal parameters of cervical spine were measured on cervical X-ray films before operation and at last follow-up, including C 2-7 Cobb angle, C 2-7 sagittal vertical axis (C 2-7 SVA), C 7S, and segment Cobb angle (SCobb), and the changes of C 2-7 Cobb angle (the difference between the last follow-up and the preoperative angle) were calculated. Pearson correlation was used to analyze the correlation between the parameters before operation and at last follow-up. According to the preoperative median value of C 7S (15°), the patients were divided into group A (C 7S<15°) and group B (C 7S≥15°). The sagittal parameters before and after operation were compared between the two groups.

RESULTS

All the 54 patients were followed up 6-45 months (mean, 15.5 months). At last follow-up, C 7S, C 2-7 Cobb angle, C 2-7 SVA, and SCobb angle were significantly improved when compared with preoperative values ( P<0.05). Correlation analysis showed that the preoperative C 7S and SCobb angles were significantly correlated with C 2-7 Cobb angle and C 2-7 SVA ( P<0.05), but there was no significant correlation between C 7S and SCobb angle ( r=0.049, P=0.724). There was a significant correlation between C 7S, C 2-7 Cobb angle, and SCobb angle at last follow-up ( P<0.05), but there was no significant correlation between C 7S and SCobb angles and C 2-7 SVA ( P>0.05). According to the median value of preoperative C 7S, 28 patients in group A had C 7S of (11.82±3.60)°, while 26 patients in group B had C 7S of (20.77±4.09)°. There was no significant difference in gender and age between the two groups ( P>0.05). The preoperative C 2-7 Cobb angle and C 2-7 SVA in group A were significantly lower than those in group B ( P<0.05). There was no significant difference between preoperative SCobb angle and group B ( t=0.234, P=0.816). There were no significant differences in C 2-7 Cobb angle, C 2-7 SVA, and SCobb angle between group A and group B at last follow-up ( P>0.05). However, the change of C 2-7 Cobb angle in group A was significantly higher than that in group B ( t=2.321, P=0.024).

CONCLUSION

Preoperative C 7S≥15° group has more physiological lordosis before operation, but its postoperative cervical curvature changes less, while ACDF is more conducive to correct the preoperative C 7S<15 ° cervical curvature.

Obesity does not impact clinical outcome but affects cervical sagittal alignment and adjacent segment degeneration in short term follow-up after an anterior cervical decompression and fusion

BACKGROUND CONTEXT

Obesity increases complications and cost following spine surgery. However, the impact on sagittal alignment and adjacent segment degeneration (ASD) after anterior cervical decompression and fusion is less understood.

PURPOSE

To compare clinical and radiographic outcomes after anterior cervical decompression and fusion between obese and nonobese patients.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

In all, 467 patients that underwent an anterior cervical decompression and fusion procedure from January 2008 through December 2015 were assessed. Surgery indications were radiculopathy, myelopathy, or myeloradiculopathy that had failed nonoperative treatments. Exclusion criteria included patients who had postoperative follow-up less than 6 months. Of 467 patients originally identified, 399 fulfilled the inclusion and exclusion criteria.

OUTCOME MEASURES

The following patient-reported outcomes were obtained: Neck Disability Index and Visual Analog Scale scores for the neck and arm pain. Radiographic assessments included: C2-C7 lordosis, T1 angle, levels fused, sagittal vertical axis (SVA), fusion mass lordosis, proximal and distal adjacent segment lordosis, ASD, and presence of fusion.

METHODS

Plain radiographs were performed preoperatively, immediately postoperatively, and final follow-up. Demographic information was collected on all patients. Baseline patient characteristics were compared using chi-squared analysis and independent sample t tests for categorical and continuous data, respectively. For analysis, patients were divided into 4 groups based on obesity stratification as defined by Center for Disease Control: body mass index (BMI) <25 kg/m² (normal weight), BMI≥25 kg/m² to <30 kg/m² (overweight), ≥30 kg/m² to <35 kg/m² (Class I obesity), BMI≥35 kg/m² to <40 kg/m² (Class II obesity), and BMI≥40 kg/m² (Class III obesity). Additionally, obese (≥30 kg/m²) and nonobese (<30 kg/m²) patients were compared in a separate analysis. Multivariate analysis was used to compare clinical and radiographic outcomes among all BMI classes, as well as between BMI≥30 kg/m² versus BMI<30 kg/m² study groups. Multivariate analyses controlled for differences in baseline patient characteristics and included age, sex, smoking, American Society of Anesthesiologists Physical Status Score, diabetes mellitus, and number of levels.

RESULTS

Of the 399 patients assessed, 97 were identified as normal weight, 157 as overweight, 81 with Class I obesity, 45 with Class II obesity, and 19 with Class III obesity. On multivariate analysis, despite having similar SVA measurements on preoperative radiographs, increase in BMI was associated with increase in postoperative SVA (p=0.041) along with significantly larger SVA in immediate postoperative (p=0.004) and final follow-up radiographs (p=0.003) for patients with BMI≥30 kg/m² versus BMI<30 kg/m². Furthermore, patients with BMI≥30 kg/m² had smaller preoperative (p=0.012), immediate postoperative (p=0.017), and final lordosis (p<0.001) in addition to smaller immediate postoperative (p=0.025) and final fusion segment lordosis (p=0.015) and smaller preoperative (p=0.024) and final distal lordosis (p=0.021) compared with patients with BMI<30 kg/m². Additionally, greater BMI was associated with lower final Visual Analog Scale neck scores (p=0.008). Radiographic early ASD rates were higher in patients BMI≥30 kg/m² versus BMI<30 kg/m² (p=0.028).

CONCLUSIONS

Overall, obese patients who underwent anterior cervical decompression and fusion had similar patient-reported outcomes compared with nonobese patients but had worse radiographic parameters and higher rates of ASD development compared with nonobese patients. This underscores the importance of patient selection and surgical approach for both patient populations.

[Effect of anterior cervical discectomy and decompression with different fusion segments on sagittal spine-pelvis balance]

Objective

To explore the effect on sagittal spine-pelvis balance of different fusion segments in anterior cervical discectomy and fusion (ACDF).

Methods

The clinical data of 326 patients with cervical spondylotic myelopathy, treated by ACDF between January 2010 and December 2016, was retrospectively analysed. There were 175 males and 151 females with an average age of 56 years (range, 34-81 years). Fusion segments included single segment in 69 cases, double segments in 85 cases, three segments in 90 cases, and four segments in 82 cases. Full spine anterolateral X-ray films were performed before operationand at 12 months after operation. The spine-pelvis parameters of fusion segments were measured and compared. The parameters included C 0-2 Cobb angle, C 2-7 Cobb angle, C 2-7 sagittal vertical axis (C 2-7 SVA), T 1 slope (T 1S), thoracic inlet angle (TIA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), C 7 sagittal vertical axis (C 7 SVA), T 1 pelvic angle (TPA). The Japanese Orthopaedic Association (JOA) score of cervical spine and visual analogue scale (VAS) scores of pain of cervical spine and upper extremity were compared before operation and at 12 months after operation. Pearson correlation analysis was performed on LL, PI, SS, C 7 SVA, and TPA before and after operation to evaluate the changes of spine-pelvis fitting relationship after ACDF.

Results

All 326 patients were followed up 12-32 months (mean, 18.5 months). During the follow-up period, internal fixator was in place, and no spinal cord nerve or peripheral soft tissue injury was found. JOA scores and cervical VAS scores improved significantly at 12 months after operation ( P<0.05), no significant difference was found in VAS scores of upper extremity when compared with preoperative scores ( P>0.05). The preoperative cervical VAS scores and the postoperative JOA scores at 12 months had significant differences between groups ( P<0.05). At 12 months after operation, there was no significant difference in sagittal spine-pelvis parameters in the single segment group compared with preoperative ones ( P>0.05); but the C 0-2 Cobb angle, C 2-7 Cobb angle, C 2-7 SVA, T 1S, TIA, C 7 SVA, and TPA in the double segments, three segments, and four segments groups were significant larger than preoperative ones ( P<0.05). The C 0-2 Cobb angle, C 2-7 Cobb angle, T 1S, C 7 SVA, and TPA among 4 groups had significant differences before operation and at 12 months after operation ( P<0.05). At 12 months after operation, the changes of C 7 SVA and TPA in the double segments, three segments, and four segments groups were significantly larger than those in the single segment group ( P<0.05). PI had positive correlations with LL and SS before and after operation in 4 groups ( P<0.05).

Conclusion

Normal fitting relationship between lumbar spine and pelvis in physiological state also exists in patients with cervical spondylotic myelopathy, and ACDF can not change this specific relationship. In patients with cervical spondylotic myelopathy, the sagittal spine-pelvis sequence do not change after ACDF single-level fusion, while the sagittal spine-pelvis balance change after double-level and multi-level fusion.

Anterior cervical corpectomy and fusion : Spinal cord compression caused by buckled ligamentum flavum

Anterior cervical corpectomy and fusion (ACCF) is a commonly performed surgical procedure for cervical spondylotic myelopathy (CSM). Various complications associated with ACCF have been reported; however, spinal cord compression caused by buckling of the ligamentum flavum (LF) after ACCF has not yet been well recognized. This article describes the case of a 59-year-old man who underwent ACCF at C5 for treatment of CSM. Although numbness and weakness of the upper extremities were relieved 2 weeks after the operation, gait imbalance persisted and worsened at 7 months. Magnetic resonance imaging (MRI) performed at 12 months revealed buckling of the LF into the spinal canal at the C5/6 level, compressing the spinal cord; moreover, high signal intensity in the spinal cord was observed beneath the buckling area on T2-weighted images. The secondary laminoplasty at C5 and C6 was performed 13 months after primary surgery and MRI showed that the spinal canal was widened at the C5 and C6 levels and the spinal cord was decompressed.

Cervical Spine Deformity-Part 2: Management Algorithm and Anterior Techniques

A sound operative plan based on solid understanding of the pathology and biomechanics is the most important part of cervical deformity correction. Many different surgical options exist for operative management of cervical spine deformities. However, selecting the correct approach that ensures the optimal clinical outcome can be challenging and often controversial. In Part 2 of this three-part review series, we discuss the pre-operative planning, management algorithm, and anterior surgical techniques for cervical deformity correction.

Differences in Cervical Sagittal Alignment Changes in Patients Undergoing Laminoplasty and Anterior Cervical Discectomy and Fusion

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) and laminoplasty (LP) are the most commonly performed procedures for degenerative cervical spondylosis. Cervical sagittal alignment (CSA) has recently been studied as an important predictor of clinical and radiological outcomes. The data from previous studies are insufficient for analysis using the recently designed CSA parameters, T1 slope (T1s), and T1s minus cervical angle (T1sCA).

METHODS

We retrospectively collected data from patients who underwent ACDF and LP from January 2013 to May 2016. The CSA parameters included CA, sagittal vertical axis, T1s, and T1sCA. T1sCA values were used to evaluate the preoperative cervical balance (T1sCA>20°: imbalance). Clinical results were evaluated using the neck disability index (NDI) and recovery rate (RR) according to the Japanese Orthopedic Association scoring system.

RESULTS

We analyzed the data of 72 patients (ACDF, n=39; LP, n=33). Imbalance on ACDF was associated with an increase in CA (balance: preoperative [PRE], 15.64° → follow-up [F/U], 15.74°, p=0.953; imbalance: PRE, -1.14° → F/U, 8.045°, p=0.008), whereas balance on LP was associated with a significant decrease in CA (balance: PRE, 16.26°→ F/U, 11.59°, p=0.009; imbalance: PRE, 5.36°→ F/U, 2.38°, p=0.249). No significant difference was found in the RR and NDI changes in the ACDF group based on balance, but a significant difference was found in RR in the LP group (balance: 61.65%±19.88%, imbalance: 46.90%±15.71%, p=0.046).

CONCLUSION

We found a significant difference in postoperative alignment in cases of ACDF and LP according to preoperative cervical sagittal balance. The postoperative clinical results of the LP group were more affected by F/U alignment than by the degree of alignment change.

A Lower T1 Slope as a Predictor of Subsidence in Anterior Cervical Discectomy and Fusion with Stand-Alone Cages

Objective

Preoperative parameters including the T1 slope (T1S) and C2–C7 sagittal vertical axis (SVA) have been recognized as predictors of kyphosis after laminoplasty, which is accompanied by posterior neck muscle damage. The importance of preoperative parameters has been under-estimated in anterior cervical discectomy and fusion (ACDF) because there is no posterior neck muscle damage. We aimed to determine whether postoperative subsidence and pseudarthrosis could be predicted according to specific parameters on preoperative plain radiographs.

Methods

We retrospectively analyzed 41 consecutive patients (male: female, 22: 19; mean age, 51.15±9.25 years) who underwent ACDF with a stand-alone polyether-ether-ketone (PEEK) cage (>1 year follow-up). Parameters including SVA, T1S, segmental angle and range of motion (ROM), C2–C7 cervical angle and ROM, and segmental inter-spinous distance were measured on preoperative plain radiographs. Risk factors of subsidence and pseudarthrosis were determined using multivariate logistic regression.

Results

Fifty-five segments (27 single-segment and 14 two-segment fusions) were included. The subsidence and pseudarthrosis rates based on the number of segments were 36.4% and 29.1%, respectively. Demographic data and fusion level were unrelated to subsidence. A greater T1S was associated with a lower risk of subsidence (p=0.017, odds ratio=0.206). A cutoff value of T1S<28° significantly predicted subsidence (sensitivity: 70%, specificity: 68.6%). There were no preoperative predictors of pseudarthrosis except old age.

Conclusion

A lower T1S (T1S<28°) could be a risk factor of subsidence following ACDF. Surgeons need to be aware of this risk factor and should consider various supportive procedures to reduce the subsidence rates for such cases.

An assessment of the most reliable method to estimate the sagittal alignment of the cervical spine: analysis of a prospective cohort of 138 cases

OBJECTIVE

Although there is increasing recognition of the importance of cervical spinal sagittal balance, there is a lack of consensus as to the optimal method to accurately assess the cervical sagittal alignment. Cervical alignment is important for surgical decision making. Sagittal balance of the cervical spine is generally assessed using one of two methods; namely, measuring the angle between C-2 and C-7, and drawing a line between C-2 and C-7. Here, the best method to assess sagittal alignment of the cervical spine is investigated.

METHODS

Data from 138 patients enrolled in a randomized controlled trial (Procon) were analyzed. Two investigators independently measured the angle between C-2 and C-7 by using Harrison's posterior tangent method, and also estimated the shape of the sagittal curve by using a modified Toyama method. The mean angles of each quantitative assessment of the sagittal alignment were calculated and the results were compared. The interrater reliability for both methods was estimated using Cronbach's alpha.

RESULTS

For both methods the interrater reliability was high: for the posterior tangent method it was 0.907 and for the modified Toyama technique it was 0.984. For a lordotic cervical spine, defined by the modified Toyama method, the mean angle (defined by Harrison's posterior tangent method) was 23.4° ± 9.9° (range 0.4°–52.4°), for a kyphotic cervical spine it was −2.2° ± 9.2° (range −16.1° to 16.9°), and for a straight cervical spine it was 10.5° ± 8.2° (range −11° to 36°).

CONCLUSIONS

An absolute measurement of the angle between C-2 and C-7 does not unequivocally define the sagittal cervical alignment. As can be seen from the minimum and maximum values, even a positive angle between C-2 and C-7 could be present in a kyphotic spine. For this purpose, the modified Toyama method (drawing a line from the posterior inferior part of the vertebral body of C-2 to the posterior upper part of the vertebral body of C-7 without any measurements) is a better tool for a global assessment of cervical sagittal alignment.

Clinical trial registration no.: ISRCTN41681847 (https://www.isrctn.com)

The relationship between changes of cervical sagittal alignment after anterior cervical discectomy and fusion and spino-pelvic sagittal alignment under roussouly classification: a four-year follow-up study

Background

Anterior cervical discectomy and fusion (ACDF) is widely used in the treatment of cervical degenerative disease; however, the variation of cervical sagittal alignment changes after ACDF has been rarely explored. The purpose of this study is to determine the relationship between changes of cervical sagittal alignment after ACDF and spino-pelvic sagittal alignment under Roussouly classification.

Methods

A cohort of 133 Chinese cervical spondylotic patients who received ACDF from 2011 to 2012 was recruited. All patients were categorized with Roussouly Classification. Lateral X-ray images of global spine were obtained, and preoperative and postoperative parameters were measured and analyzed, including C2–C7 angles (C2–C7), C0–C7 angles (C0–C7), external auditory meatus (EAM) tilt, sacral slope (SS), thoracic kyphosis (TK), lumbar lordosis (LL), spinal sacral angles (SSA), Superior adjacent inter-vertebral angle (SAIV), inferior adjacent inter-vertebral angle (IAIV) and et al. The Wilcoxon signed-rank test was used for intragroup comparisons preoperatively and at postoperative 48 months.

Results

Among the parameters, C2–C7 and C0–C7 showed significant increase, while EAM TK, and IAIV decreased significantly. In type I, EAM and TK decreased significantly, however SS showed a significant increase; in type II, TK showed a significant decrease, but SSA showed a significant increase; in type III, a significant increase of C0–C7 was observed with a significant decrease in EAM, nevertheless, LL, SS and SSA showed significant decreases; and in type IV, C2–C7 showed a significant increase and EAM decreased significantly. The percentage of lordotic alignment in cervical spine increased, which was presenting in type I, III and IV. Nevertheless, the amount of patients with straight cervical alignment increased in type II.

Conclusion

The backward movement of head occurs is the compensatory mechanism in cervical sagittal alignment modifications after ACDF. The compensatory alteration of spino-pelvic sagittal alignment varied in different Roussouly type.

Can segmental mobility be increased by cervical arthroplasty?

OBJECTIVE

Many reports have successfully demonstrated that cervical disc arthroplasty (CDA) can preserve range of motion after 1- or 2-level discectomy. However, few studies have addressed the extent of changes in segmental mobility after CDA or their clinical correlations.

METHODS

Data from consecutive patients who underwent 1-level CDA were retrospectively reviewed. Indications for surgery were medically intractable degenerative disc disease and spondylosis. Clinical outcomes, including visual analog scale (VAS)–measured neck and arm pain, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores, were analyzed. Radiographic outcomes, including C2–7 Cobb angle, the difference between pre- and postoperative C2–7 Cobb angle (ΔC2–7 Cobb angle), sagittal vertical axis (SVA), the difference between pre- and postoperative SVA (ΔSVA), segmental range of motion (ROM), and the difference between pre- and postoperative ROM (ΔROM), were assessed for their association with clinical outcomes. All patients underwent CT scanning, by which the presence and severity of heterotopic ossification (HO) were determined during the follow-up.

RESULTS

A total of 50 patients (mean age 45.6 ± 9.33 years) underwent a 1-level CDA (Prestige LP disc) and were followed up for a mean duration of 27.7 ± 8.76 months. All clinical outcomes, including VAS, NDI, and JOA scores, improved significantly after surgery. Preoperative and postoperative ROM values were similar (mean 9.5° vs 9.0°, p > 0.05) at each indexed level. The mean changes in segmental mobility (ΔROM) were −0.5° ± 6.13°. Patients with increased segmental mobility after surgery (ΔROM > 0°) had a lower incidence of HO and HO that was less severe (p = 0.048) than those whose ΔROM was < 0°. Segmental mobility (ROM) was significantly lower in patients with higher HO grade (p = 0.012), but it did not affect the clinical outcomes. The preoperative and postoperative C2–7 Cobb angles and SVA remained similar. The postoperative C2–7 Cobb angles, SVA, ΔC2–7 Cobb angles, and ΔSVA were not correlated to clinical outcomes after CDA.

CONCLUSIONS

Segmental mobility (as reflected by the mean ROM) and overall cervical alignment (i.e., mean SVA and C2–7 Cobb angle) had no significant impact on clinical outcomes after 1-level CDA. Patients with increased segmental mobility (ΔROM > 0°) had significantly less HO and similarly improved clinical outcomes than those with decreased segmental mobility (ΔROM < 0°).