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

Shin, Jae‐Gook

doi:10.14245/ns.1938166.083

Cited by 47 publications

(53 citation statements)

References 36 publications

(57 reference statements)

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“…Orthopedic surgeons use the terminology compensation for additional joint motion found in joints adjacent to a surgical fusion. Several biomechanical studies have documented a mechanism by which adjacent unfused levels compensate for the loss of cervical range of motion (ROM) in fused levels [ 19 ]. The compensation is perceived as a new ability for further cervical single joint motion; however, the compensation may be pre-existing surplus motion of the adjacent joints.…”

Section: Discussionmentioning

confidence: 99%

The global end-ranges of neck flexion and extension do not represent the maximum rotational ranges of the cervical intervertebral joints in healthy adults - an observational study

et al. 2021

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Background In clinical diagnosis, the maximum motion of a cervical joint is thought to be found at the joint’s end-range and it is this perception that forms the basis for the interpretation of flexion/extension imaging studies. There have however, been representative cases of joints producing their maximum motion before end-range, but this phenomenon is yet to be quantified. Purpose To provide a quantitative assessment of the difference between maximum joint motion and joint end-range in healthy subjects. Secondarily to classify joints into type based on their motion and to assess the proportions of these joint types. Study design This is an observational study. Subject sample Thirty-three healthy subjects participated in the study. Outcome measures Maximum motion, end-range motion and surplus motion (the difference between maximum motion and end-range) in degrees were extracted from each cervical joint. Methods Thirty-three subjects performed one flexion and one extension motion excursion under video fluoroscopy. The motion excursions were divided into 10% epochs, from which maximum motion, end-range and surplus motion were extracted. Surplus motion was then assessed in quartiles and joints were classified into type according to end-range. Results For flexion 48.9% and for extension 47.2% of joints produced maximum motion before joint end-range (type S). For flexion 45.9% and for extension 46.8% of joints produced maximum motion at joint end-range (type C). For flexion 5.2% of joints and for extension 6.1% of joints concluded their motion anti-directionally (type A). Significant differences were found for C2/C3 (P = 0.000), C3/C4 (P = 0.001) and C4/C5 (P = 0.005) in flexion and C1/C2 (P = 0.004), C3/C4 (P = 0.013) and C6/C7 (P = 0.013) in extension when comparing the joint end- range of type C and type S. The average pro-directional (motion in the direction of neck motion) surplus motion was 2.41° ± 2.12° with a range of (0.07° -14.23°) for flexion and 2.02° ± 1.70° with a range of (0.04°-6.97°) for extension. Conclusion This is the first study to categorise joints by type of motion. It cannot be assumed that end-range is a demonstration of a joint’s maximum motion, as type S constituted approximately half of the joints analysed in this study.

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Section: Discussionmentioning

confidence: 99%

The global end-ranges of neck flexion and extension do not represent the maximum rotational ranges of the cervical intervertebral joints in healthy adults - an observational study

et al. 2021

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“…However, the decrease in adjacent segment foraminal motion observed for fusion, while an increase was observed for ADR at the long term follow up, was contradictory to our hypothesis and to the widely-held notion that development of adjacent segment disease is associated with increased motion at the adjacent level in compensation for immobilization of the index level in fusion. One possible explanation is that with spinal fusion, motion at adjacent segments is characterized by an initial period of hypermobility as found in shorter-term studies (1–2 years post-operative) [ 29 , 33 , 34 ], followed by degenerative changes that decrease mobility in the long-term [ 35 ]. Degenerative changes to any structure contributing to the geometry of neural foramina, such as the disc and the facet joint, may be involved in the development of hypomobility [ 36 , 37 ]; however, changes to these structures were not examined in this study to substantiate this argument.…”

Section: Discussionmentioning

confidence: 99%

Dynamic foraminal dimensions during neck motion 6.5 years after fusion and artificial disc replacement

et al. 2020

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Objective To compare changes in foraminal motion at two time points post-surgery between artificial disc replacement (ADR) and anterior cervical discectomy and fusion (ACDF). Methods Eight ACDF and 6 ADR patients (all single-level C5-6) were tested at 2 years (T1) and 6.5 years (T2) post-surgery. The minimum foraminal height (FH.Min) and width (FW.Min) achieved during neck axial rotation and extension, and the range of these dimensions during motion (FH.Rn and FW.Rn, respectively) were measured using a biplane dynamic x-ray system, CT imaging and model-based tracking while patients performed neck axial rotation and extension tasks. Two-way mixed ANOVA was employed for analysis. Results In neck extension, significant interactions were found between year post-surgery and type of surgery for FW.Rn at C5-6 (p<0.006) and C6-7 (p<0.005), and for FH.Rn at C6-7 (p<0.01). Post-hoc analysis indicated decreases over time in FW.Rn for ACDF (p<0.01) and increases in FH.Rn for ADR (p<0.03) at the C6-7 adjacent level. At index level, FW.Rn was comparable between ACDF and ADR at T1, but was smaller for ACDF than for ADR at T2 (p<0.002). In axial rotation, differences were found between T1 and T2 but did not depend on type of surgery (p>0.7). Conclusions Changes were observed in the range of foraminal geometry at adjacent levels from 2 years to 6.5 years post-surgery that were different between ACDF and ADR for neck extension.

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“…Therefore, spine surgeons always need to bear in mind the possibility of ASD and consequent fusion extension. Fusion should be decided not only by considerations of current pathology but also of overall spinal column structure, and the proper fusion site should be determined based on careful medical history-taking and physical and radiologic evaluations 30) .…”

Section: Discussionmentioning

confidence: 99%

The Risk Factors of Early and Late-Onset Adjacent Segment Degeneration after Thoracolumbar Fusion Surgery

Kim

Ryu

et al. 2020

Nerve

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Adjacent segment degeneration (ASD) is a long-term complication that can occur after thoracolumbar fusion surgery. This study was undertaken to determine the risk factors of earlyonset ASD. Methods: We retrospectively reviewed patients who underwent thoracolumbar fusion at our institute for lumbar disease from January 2008 to December 2018. Potential risk factors examined included radiologic factors such as postoperative sagittal alignment, preexisting disc degeneration, and facet degeneration. For the analysis, patients were dichotomized based on times to ASD, that is, <1 year (the early group) and ≥1 year (the late group). Results: During the 11-year study period, 693 patients underwent thoracolumbar fusion, and 92 (13.28%) patients developed ASD; 34 (4.9%) during the first postoperative year and 58 (8.4%) at more than 1 year after surgery. The proportion of patients with a longer fusion length was greater in the early group (p=0.0045). Postoperative lumbar lordosis (LL; p=0.0007) and sagittal vertical axis (SVA) (p=0.009) values were significantly different in the 2 groups, sacral slope (SS; p<0.05) was smaller in the early group, and pelvic tilt (PT; p=0.03) was larger in the early group. However, pelvic incidence (PI; p=0.72) was no different in the 2 groups. Conclusion: The risk factors of early-onset ASD after thoracolumbar fusion surgery were confirmed to be the degree of fusion length and LL after surgery. SVA was found to possibly contribute to early-onset ASD. Although PI was similar in the 2 study groups, SS and PT were significantly different. So when you perform spinal fusion surgery, you should minimize fusion length and consider sagittal alignment.

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

Cited by 47 publications

References 36 publications

The global end-ranges of neck flexion and extension do not represent the maximum rotational ranges of the cervical intervertebral joints in healthy adults - an observational study

The global end-ranges of neck flexion and extension do not represent the maximum rotational ranges of the cervical intervertebral joints in healthy adults - an observational study

Dynamic foraminal dimensions during neck motion 6.5 years after fusion and artificial disc replacement

The Risk Factors of Early and Late-Onset Adjacent Segment Degeneration after Thoracolumbar Fusion Surgery

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