Influence of the Number of Cervical Fusion Levels on Cervical Spine Motion and Health-Related Quality of Life

Upper Instrumented Vertebrae, Number of Levels Fused, and Plate Morphology Do Not Affect Severity of Chronic Dysphagia After Anterior Cervical Spine Surgery

BACKGROUND

Disordered swallowing, or dysphagia, is the most common complication after anterior cervical spine (ACS) surgery. Many operative factors are associated with development of dysphagia. The aim of this study was to explore how number of levels instrumented, specific levels fused, and plate morphology affect chronic dysphagia after ACS surgery.

METHODS

Consecutive patients referred to a tertiary center for otolaryngology evaluation for chronic dysphagia after ACS surgery between 2012 and 2017 were enrolled. Basic demographic data were obtained. Plain radiographs were reviewed for number of levels fused, upper instrumented vertebrae, and plate morphology. Plate morphology was categorized as a closed, small window, large window, or no profile plate. The 10-item Eating Assessment Tool (EAT-10) was used to assess dysphagia severity.

RESULTS

Of 171 patients referred for dysphagia, 126 met inclusion criteria; 54% were female, with a mean age of 63 years (range, 32-88 years). Mean EAT-10 score was 18.5 ± 10.1. Mean time from spine surgery to videofluoroscopic swallow study for dysphagia was 58.3 months. Mean number of levels fused was 2.2 ± 0.9. There were no significant differences in EAT-10 scores in single-level versus multilevel fusion (19.0 vs. 18.4, P = 0.76) as well as with regard to upper instrumented vertebrae or plate morphology.

CONCLUSIONS

In this series of patients with chronic dysphagia following ACS surgery, the severity of dysphagia as measured by the EAT-10 was not affected by upper instrumented vertebrae, number of levels fused, or plate morphology.

Minimally Invasive Full‐endoscopic Posterior Cervical Foraminotomy and Discectomy: Introducing a Simple and Useful Localization Technique of the “V” Point

Objective

Conventional localization technique of V point for full‐endoscopic posterior cervical foraminotomy and discectomy (FPCD) required repeated fluoroscopies, especially in patients with short and thick necks. To address this issue, the present study aimed to introduce a new localization technique of V point, and further evaluate its efficacy.

Methods

A K‐wire was inserted and fixed at the pedicle eye under A/P fluoroscopy, then a working channel was established quickly along with it. Thirty‐four patients who underwent minimally invasive FPCD assisted by the new technique were included in this study. The clinical and radiological data were collected and analyzed, including radiation dose, operative time, positioning time, visual analog scale (VAS) for neck and arm pain, neck disability index (NDI) scores, Cobb angle of operative level and range of motion of the cervical spine.

Results

All operations were performed successfully, and no iatrogenic nerve or vascular injury occurred. None of the patients needed to be transferred to open surgery or revision surgery. The mean radiation dose was found to be1.68 ± 0.36 mSv. The mean positioning time observed was 10.68 ± 5.42 min and the average operation time was 81.18 ± 10.87 min. The operation time significantly declined as the number of patients increased. A significant difference in operation time between the first (96.22 ± 10.36 min) and last quartile (75.00 ± 3.84 min) of cases was observed (t = 4.82, P < 0.001). The VAS scores for neck and arm pain, and NDI scores were significantly improved after surgery (P_VAS−Neck<0.0001, P_VAS−Arm<0.0001, P_NDI<0.0001). Based on MacNab criteria, the excellent plus good rate was 91.17%. The Cobb angle of operative level and range of motion of the cervical spine were significantly improved postoperatively (t = 2.846, P_OA = 0.015; t = 2.232, P_ROM−CA = 0.026).

Conclusion

The new image‐assisted V point localization technique is simple and useful with little radiation exposure and short positioning time. FPCD assisted by the new technique could be a safe and effective alternative on properly selected patients.

Patients With Preoperative Cervical Deformity Experience Similar Clinical Outcomes to Those Without Deformity Following 1-3 Level Anterior Cervical Decompression and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim was to compare the outcomes of patients with incompletely corrected cervical deformity against those without deformity following short-segment anterior cervical decompression and fusion for clinically significant radiculopathy or myelopathy.

SUMMARY OF BACKGROUND DATA

Cervical deformity has increasingly been recognized as a driver of disability and has been linked to worse patient-reported outcomes measures (PROMs) after surgery.

METHODS

Patients 18 years or above who underwent 1-3 level anterior cervical decompression and fusion to address radiculopathy and/or myelopathy at a single institution between 2014 and 2018 with at least 1 year of PROMs were reviewed. Patients were categorized based on cervical deformity into 2 groups: sagittal vertebral axis (cSVA) ≥40 mm as the deformity group, and cSVA <40 mm as the nondeformity group. Patient demographics, surgical parameters, preoperative and postoperative radiographs, and minimum 1-year PROMs were compared.

RESULTS

Of the 230 patients, 191 (83%) were in the nondeformity group and 39 (17%) in the deformity group. Patients with deformity were more likely to be male (69.2% vs. 40.3%, P<0.001) and have a greater body mass index (32.8 vs. 29.7, P=0.028). The deformity group had significantly greater postoperative cSVA (44.2 vs. 25.1 mm, P<0.001) but also had significantly greater ∆cSVA (-4.87 vs. 0.25 mm, P=0.007) than the nondeformity group. Both groups had significant improvements in visual analog scale arm, visual analog scale neck, Short-Form 12 Physical Component Score, and neck disability index (NDI) (P<0.001). However, the deformity group experienced significantly greater ∆NDI and ∆mental component score (MCS)-12 scores (-19.45 vs. -11.11, P=0.027 and 7.68 vs. 1.32, P=0.009).

CONCLUSIONS

Patients with preoperative cervical sagittal deformity experienced relatively greater improvements in NDI and MCS-12 scores than those without preoperative deformity. These results suggest that complete correction of sagittal alignment is not required for patients to achieve significant clinical improvement.

LEVEL OF EVIDENCE

III.

Cervical Sagittal Alignment: Literature Review and Future Directions

Cervical alignment as a concept has come to the forefront for spine deformity research in the last decade. Studies on cervical sagittal alignment started from normative data, and expanded into correlation with global sagittal balance, prognosis of various conditions, outcomes of surgery, definition and classification of cervical deformity, and prediction of targets for ideal cervical reconstruction. Despite the recent robust research efforts, the definition of normal cervical sagittal alignment and cervical spine deformity continues to elude us. Further, many studies continue to view cervical alignment as a continuation of thoracolumbar deformity and do not take into account biomechanical features unique to the cervical spine that may influence cervical alignment, such as the importance of musculature connecting cranium-cervical-thoracic spine and upper extremities. In this article, we aim to summarize the relevant literature on cervical sagittal alignment, discuss key results, and list potential future direction for research using the '5W1H' framework; "WHO" are related?, "WHY" important?, "WHAT" to evaluate and "WHAT" is normal?, "HOW" to evaluate?, "WHEN" to apply sagittal balance?, and "WHERE" to go in the future?

Cervical Disc Arthroplasty: Rationale and History

Biomechanical studies have demonstrated that cervical fusion results in increased motion and intradiscal pressures at adjacent levels. Cervical disc arthroplasty (CDA) is an alternative treatment for cervical radiculopathy and myelopathy resulting from degenerative disc disease. By maintaining segmental motion, surgeons hope to avoid some of the primary drawbacks of anterior cervical discectomy and fusion (ACDF), such as pseudoarthrosis and adjacent segment disease. First introduced in the 1960s, CDA has evolved over the years with changes to implant geometry and materials. Early devices produced suboptimal outcomes, but more recent generations of implants have shown long-term outcomes rivaling or even surpassing those of ACDF. In this article, the rationale for CDA as well as the history of such devices is reviewed.

One-Level Versus 2-Level Treatment With Cervical Disc Arthroplasty or Fusion: Outcomes Up to 7 Years

Background

Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) have been used to treat degenerative disc disease at single as well as multiple cervical levels. This study compares the safety and efficacy of 1-level versus 2-level CDA and ACDF.

Methods

In total, 545 and 397 patients with degenerative disc disease were studied in 1-level and 2-level Food and Drug Administration (FDA)-approved clinical trials, respectively: CDA (n = 280 and 209), ACDF (n = 265 and 188). Data from these studies were used to compare 1- versus 2-level procedures: the propensity score method was used to adjust for potential confounding effects, and adjusted mean outcome safety and efficacy scores at 2 and 7 years postsurgery were compared between 1-level and 2-level procedures within treatment type.

Results

One-level and 2-level procedures had similar rates of improvement in overall success and patient-reported outcomes scores for both CDA and ACDF. There were no statistical differences in rates of implant-related adverse events (AEs) or serious implant-related AEs between 1-level and 2-level CDA. The 7-year rate of implant-related AEs was higher for 2-level than 1-level ACDF (27.7% vs 18.9%, P ≤ .036), though the rates of serious implant-related AEs between ACDF groups did not differ significantly. Secondary surgery rates were not statistically different between 1-level and 2-level procedures (CDA or ACDF) at the index or adjacent levels at 2 or 7 years. Grade IV heterotopic ossification at 7 years was reported in 4.6% of 1-level CDA patients and 8.6%/7.3% at the superior/inferior levels, respectively, of 2-level CDA patients.

Conclusions

One- and 2-level CDA appear equally safe and effective in the treatment of cervical degenerative disc disease. Two-level ACDF appears to be as effective as 1-level ACDF but with a higher rate of some AEs at long-term follow-up.

Level of Evidence

2.

Clinical Trials

clinicaltrials.gov: NCT00667459, NCT00642876, and NCT00637156.

Anterior Cervical Discectomy and Fusion Outcomes over 10 Years: A Prospective Study

STUDY DESIGN

Prospective cohort study with >10-year follow-up.

OBJECTIVE

To assess the long-term, >10-year clinical outcomes of anterior cervical discectomy and fusion (ACDF) and to compare outcomes based on primary diagnosis of disc herniation, stenosis or advanced degenerative disc disease (DDD), number of levels treated, and preexisting adjacent level degeneration.

SUMMARY OF BACKGROUND DATA

ACDF is a proven treatment for patients with stenosis and disc herniation and results in significantly improved short- and intermediate-term outcomes. Motion preservation treatments may result in improved long-term outcomes but need to be compared to long-term ACDF outcomes reference.

METHODS

Patients who had disc herniation, stenosis, and DDD and underwent ACDF with or without decompression were prospectively enrolled and followed for a minimum of 10 years with outcome assessment at various intervals. All 159 consecutive patients had autogenous tricortical iliac crest bone graft and plate instrumentation used. Outcomes included visual analog scale for neck and arm pain. pain drawing, Oswestry Disability Index, and self-assessment of procedure success. Preoperative adjacent-level disc degeneration, pseudarthrosis, and secondary operations were analyzed.

RESULTS

For all diagnostic groups, significant outcomes improvement was seen at all follow-up periods for all scales relative to preoperative scores. Outcomes were not related to age, gender, number of levels treated, and minimally to preexisting degeneration at the adjacent level. The use of narcotic pain medication decreased substantially. Neurological deficits almost all resolved. Patient self-reported success ranged from 85% to 95%. Over the long term, additional surgery for pseudarthrosis (10%) occurred in the early follow-up period, and for adjacent segment degeneration (21%), which occurred linearly during the >10-year follow-up period.

CONCLUSION

ACDF leads to significantly improved outcomes for all primary diagnoses and was sustained for >10 years' follow-up. Secondary surgeries were performed for pseudarthrosis repair and for symptomatic adjacent-level degeneration.

LEVEL OF EVIDENCE

2.

Reliability and validity of CODA motion analysis system for measuring cervical range of motion in patients with cervical spondylosis and anterior cervical fusion

The aim of the present study was to evaluate the reliability of the Cartesian Optoelectronic Dynamic Anthropometer (CODA) motion system in measuring the cervical range of motion (ROM) and verify the construct validity of the CODA motion system. A total of 26 patients with cervical spondylosis and 22 patients with anterior cervical fusion were enrolled and the CODA motion analysis system was used to measure the three-dimensional cervical ROM. Intra- and inter-rater reliability was assessed by interclass correlation coefficients (ICCs), standard error of measurement (SEm), Limits of Agreements (LOA) and minimal detectable change (MDC). Independent samples t-tests were performed to examine the differences of cervical ROM between cervical spondylosis and anterior cervical fusion patients. The results revealed that in the cervical spondylosis group, the reliability was almost perfect (intra-rater reliability: ICC, 0.87–0.95; LOA, −12.86–13.70; SEm, 2.97–4.58; inter-rater reliability: ICC, 0.84–0.95; LOA, −13.09–13.48; SEm, 3.13–4.32). In the anterior cervical fusion group, the reliability was high (intra-rater reliability: ICC, 0.88–0.97; LOA, −10.65–11.08; SEm, 2.10–3.77; inter-rater reliability: ICC, 0.86–0.96; LOA, −10.91–13.66; SEm, 2.20–4.45). The cervical ROM in the cervical spondylosis group was significantly higher than that in the anterior cervical fusion group in all directions except for left rotation. In conclusion, the CODA motion analysis system is highly reliable in measuring cervical ROM and the construct validity was verified, as the system was sufficiently sensitive to distinguish between the cervical spondylosis and anterior cervical fusion groups based on their ROM.

Débridement and Reconstruction Improve Postoperative Sagittal Alignment in Kyphotic Cervical Spinal Tuberculosis

BACKGROUND

Cervical spinal tuberculosis is relatively common in some developing countries. It erodes vertebrae and discs, which sometimes results in cervical kyphosis and myelopathy. However, to our knowledge, no studies have evaluated improvements to patient-reported outcomes among patients who undergo surgical cervical sagittal realignment after kyphotic cervical spinal tuberculosis has been treated by débridement and reconstruction.

QUESTIONS/PURPOSES

(1) Can a spine with kyphotic cervical spinal tuberculosis be returned to normal alignment and fused successfully? (2) Will patient-reported outcomes be improved with this intervention? (3) Are patient-reported outcomes correlated with realignment?

METHODS

Forty-six patients with kyphotic cervical spinal tuberculosis were evaluated in this retrospective study. We generally performed surgery on patients with this condition when patients with cervical spinal tuberculosis presented with cervical kyphosis with or without neurologic deficits. Patients who did not meet these criteria were treated with other surgical procedures during the study period. Study patients were evaluated with cervical imaging, patient-reported outcomes questionnaires (Neck Disability Index [NDI], and the Japanese Orthopaedic Association [JOA] score), and physical examinations. Scores were collected by fellows preoperatively and at followup. No patient died during the followup. The mean followup was 26.8 months (range, 20-35 months). Preoperative and 2-year followup radiologic parameters were measured, including C0-2 Cobb angle, C2-7 Cobb angle, C2-7 sagittal vertical axis, center of gravity (CG) to C7 sagittal vertical axis (CG-C7 sagittal vertical axis), thoracic inlet angle, T1 slope, and neck tilt. The correlations between cervical alignment and the NDI and JOA score were analyzed. Factors correlated with the NDI and JOA score improvements were identified by multiple stepwise regression analysis. CT was used to assess bone fusion after surgery.

RESULTS

All 46 patients showed bone fusion on CT scans. The preoperative C0-2 Cobb angle improved after surgery (mean difference, 5.0°; 95% CI, 2.3°-7.7°; p = 0.0068), as did C2-7 Cobb angle (mean difference, -33°; 95% CI, -35° to -31°; p = 0.0074), C2-7 sagittal vertical axis (mean difference, -28 mm; 95% CI, -30 mm to -26 mm; p = 0.0036), CG-7 sagittal vertical axis (mean difference, -26 mm; 95% CI, -28 mm to -24 mm; p = 0.0049), T1 slope (mean difference, 6.0°; 95% CI, 3.7°-8.3°; p = 0.0053) and the thoracic inlet angle (mean difference, 8.0°; 95% CI, 3.7°-12°; p = 0.0072). With the numbers available, the neck tilt angle did not improve (mean difference, -0.2°; 95% CI, -1.0° to 0.6°; p = 0.079). The preoperative NDI of 34 ± 5.1 decreased to 17 ± 4.6 (p = 0.0096) at followup. Improvements in NDI were correlated with the magnitude of correction of the cervical deformities, including C0-2 Cobb angle (r = -0.357, p = 0.007), C2-7 Cobb angle (r = 0.410, p = 0.002), T1 slope (r = -0.366, p = 0.006, thoracic inlet angle (r = -0.376, p = 0.005), C2-7 sagittal vertical axis (r = 0.450, p = 0.001), and CG-C7 sagittal vertical axis (r = 0.361, p = 0.007). The JOA score improved to 13 ± 2.6 from 7.2 ± 1.9, which did not correlate with postoperative cervical realignment. After controlling for potential confounding variables like Cobb angles and T1 slope, we found C2-7 sagittal vertical axis was the most influential factor correlated with NDI improvement (r = 0.450, p = 0.002).

CONCLUSION

When treating kyphotic cervical spinal tuberculosis by débridement, decompression, and reconstruction, more attention should be drawn to realigning the cervical spine, in particular to restoring the C2-7 sagittal vertical axis. However, how best to restore the C2-7 sagittal vertical axis and cervical alignment in a kyphotic cervical spine needs further study.

LEVEL OF EVIDENCE

Level III, therapeutic study.