Postoperative C5 Palsy after Anterior or Posterior Decompression for Degenerative Cervical Myelopathy: A Subgroup Analysis of the Multicenter, Prospective, Randomized, Phase III, CSM-Protect Clinical Trial

STUDY DESIGN

Retrospective cohort study of prospectively accrued data.

OBJECTIVE

To evaluate a large, prospective, multicentre dataset of surgically-treated DCM cases on the contemporary risk of C5 palsy with surgical approach.

SUMMARY OF BACKGROUND DATA

The influence of surgical technique on postoperative C5 palsy after decompression for degenerative cervical myelopathy (DCM) is intensely debated. Comprehensive analyses are needed using contemporary data and accounting for covariates.

METHODS

Patients with moderate to severe DCM were prospectively enrolled in the multicenter, randomized CSM-Protect clinical trial and underwent either anterior or posterior decompression between Jan 31, 2012, to May 16, 2017. The primary outcome was the incidence of postoperative C5 palsy, defined as onset of muscle weakness by at least one grade in manual muscle test at the C5 myotome with slight or absent sensory disruption after cervical surgery. Two comparative cohorts were made based on anterior or posterior surgical approach. Multivariate hierarchical mixed-effects logistic regression was used to estimate odds ratios (OR) with 95% confidence intervals (CI) for C5 palsy.

RESULTS

A total of 283 patients were included, and 53.4% underwent posterior decompression. The total incidence of postoperative C5 palsy was 7.4% and was significantly higher in patients that underwent posterior decompression compared to anterior decompression (11.26% vs. 3.03%, P=0.008). After multivariable regression, posterior approach was independently associated with greater than four times the likelihood of postoperative C5 palsy (P=0.017). Rates of C5 palsy recovery were comparable between the two surgical approaches.

CONCLUSION

The odds of postoperative C5 palsy are significantly higher after posterior decompression compared to anterior decompression for DCM. This may influence surgical decision-making when there is equipoise in deciding between anterior and posterior treatment options for DCM.

LEVEL OF EVIDENCE

Therapeutic Level II.

Prospective Randomized Comparison of Minimally Invasive Tlif versus Open Tlif: Clinical Effectiveness and Restoration of Working Capacity in Railway Workers

STUDY DESIGN

Randomized Clinical Trial.

OBJECTIVE

To compare the clinical efficacy and restoration of working capacity after MI (minimally invasive)-TLIF and O (open)-TLIF in railway workers with lumbar degenerative disease.

METHODS

83 patients, who were indicated for two-level lumbar decompression and fusion were randomly assigned to one of two groups: group 1 (n = 44) had MI-TLIF procedure and group 2 (n = 39) had O-TLIF procedure. The functional status was assessed using SF-36, ODI and VAS for back and leg pain, preoperatively, at discharge, and at 3, 6, and 12 months postoperatively. MRI and CT were obtained 1-year follow-up. The percentage of patients who returned to work at 1-year, work intensity and the time to return to work post-operatively were analyzed.

RESULTS

At 1-year follow-up, the MI-TLIF group had significantly better ODI, VAS and SF-36 scores compared to the O-TLIF group. The postoperative MRIs revealed a statistically significantly less multifidus muscle atrophy in the MI group compared to the Open group. At 1-year follow-up, a comparable fusion ratio between MI group and Open group was recorded. After MI-TLIF procedure, depending on the workload, patients had a statistically significantly earlier return to work (P < .05) and statistically significantly higher return to work rate compared with the O-TLIF group (P < .05).

CONCLUSIONS

The use of two-level MI-TLIF in railway workers has made it possible to significantly improve long-term clinical results, reduce the risk of surgical complications, muscle atrophy and time to return to work compared to O-TLIF.

The incidence of reoperation for pseudarthrosis after cervical spine surgery

INTRODUCTION

Pseudarthrosis after cervical spine surgery represents an underreported and challenging complication. Using a large multi-center surgical database, we sought to: (1) report the incidence of cervical pseudarthrosis, (2) evaluate changes in rates of cervical pseudarthrosis, and (3) describe risk factors for suboptimal outcomes after cervical pseudarthrosis surgery.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database from 2012 to 2019 was used. The primary outcome was occurrence of a cervical fusion procedure with a prior diagnosis of pseudarthrosis. Fusion for pseudarthrosis was divided into anterior and posterior approaches. Post-operative complications were classified as major or minor. Prolonged LOS was defined as exceeding the 75th percentile for total hospital stay.

RESULTS

A total of 780 patients underwent cervical fusion for pseudarthrosis, and a significant increase in rates of surgery for pseudarthrosis was seen (0.25-1.2%, p < 0.001). The majority of cervical pseudarthrosis was treated with a posterior approach (66.5%). Postoperatively, 38 (4.9%) patients suffered a complication and 247 (31.7%) had a prolonged LOS. The three strongest risk factors for complications and extended LOS were > 10% weight loss preoperatively, congestive heart failure, and pre-operative bleeding disorder.

CONCLUSION

Results from a large multi-center national database revealed that surgery to treat cervical pseudarthrosis has increased from 2012 to 2019. Most pseudarthrosis was treated with a posterior approach. Reoperation to treat cervical pseudarthrosis carried risk, with 5% having complications and 32% having an extended LOS. These results lay the groundwork for a future prospective study to discern the true incidence of cervical pseudarthrosis and how to best avoid its occurrence.

Is neck pain treatable with surgery?

INTRODUCTION

Neck pain is one of the most common complaints in clinical practice and can be caused by a wide variety of conditions. While cervical spine surgery is a well-accepted option for radicular pain and myelopathy, surgery for isolated neck pain is controversial. The identification of the source of pain is challenging and subtle, and misdiagnosis can lead to inappropriate treatment. MATERIALS AND METHODS AND RESULTS: We conducted a thorough literature review to discuss and compare different causes of neck pain. We then supplemented the literature with our senior author's expert analysis of treating cervical spine pathology.

CONCLUSIONS

This study provides an in-depth discussion of neck pain and its various presentations, as well as providing insight into treatment strategies and diagnostic pearls that may prevent mistreatment of cervical spine pathology.

Simultaneous Versus Staged Surgery For Double Crush Syndrome Of Cervical Radiculopathy And Peripheral Nerve Compression At The Wrist: A Retrospective Single-Center Study

STUDY DESIGN

Retrospective single-center study.

OBJECTIVES

to evaluate the results of surgical treatment in patients with double crush syndrome associated with cervical radiculopathy and upper limb peripheral nerve compression after staged and simultaneous operations.

SUMMARY OF BACKGROUND DATA

Currently, choosing the optimal diagnostic and therapeutic modalities in treating patients with double crush syndrome remains unresolved.

METHODS

The study included 79 patients with double crush syndrome (cervical radiculopathy and syndrome of Guyon's canal or Carpal tunnel syndrome). Two independent groups were studied: In the Staged Group (n=35), we performed a cervical decompression with stabilization and peripheral nerve decompression at separate days due to ongoing clinical symptoms (average interval between interventions being 22 (18;26) days). In the Simultaneous Group (n=33), we performed both the cervical spine surgery, as well as the peripheral nerve procedures in one surgical session. Total operative time, estimate blood loss, length of hospitalization, complications and clinical data (NDI score, SF-36, VAS neck pain score, VAS arm pain score, Disabilities of Arm, Shoulder and Hand (DASH) score, Macnab scale) were compared. We used the Mann-Whitney (MW) test for intergroup comparisons, Wilcoxon criterion for dependent samples, and Fisher's exact test for binomial parameters.

RESULTS

There was a significantly lower operative time, duration of inpatient treatment and temporary disability in the Simultaneous Group (P=0.01, P=0.04 and P=0.006 respectively). Comparative analysis did not reveal significant intergroup differences using NDI, VAS and DASH (P>0.05), whereas, at discharge, significantly better clinical parameters were appreciated for the Simultaneous Group using SF-36 and Macnab scores (P=0.04 and P=0.03, respectively). At Last Follow-up, an intra-group analysis revealed comparable clinical effectiveness between the two approaches (P>0.05).

CONCLUSION

Comparison of the effectiveness of simultaneous and staged surgery revealed comparable long-term clinical outcomes. However, simultaneous surgery conveys clinically important advantages in terms of surgical time, anesthesia duration, length of hospitalization and patient disability.

LEVEL OF EVIDENCE

3.

AO Spine Guideline for the Use of Osteobiologics (AOGO) in Anterior Cervical Discectomy and Fusion for Spinal Degenerative Cases

STUDY DESIGN

Guideline.

OBJECTIVES

To develop an international guideline (AOGO) about the use of osteobiologics in anterior cervical discectomy and fusion (ACDF) for treating degenerative spine conditions.

METHODS

The guideline development process was guided by AO Spine Knowledge Forum Degenerative (KF Degen) and followed the Guideline International Network McMaster Guideline Development Checklist. The process involved 73 participants with expertise in degenerative spine diseases and surgery from 22 countries. Fifteen systematic reviews were conducted addressing respective key topics and evidence was collected. The methodologist compiled the evidence into GRADE Evidence-to-Decision frameworks. Guideline panel members judged the outcomes and other criteria and made the final recommendations through consensus.

RESULTS

Five conditional recommendations were created. A conditional recommendation is about the use of allograft, autograft or a cage with an osteobiologic in primary ACDF surgery. Other conditional recommendations are about the use of osteobiologic for single- or multi-level ACDF, and for hybrid construct surgery. It is suggested that surgeons use other osteobiologics rather than human bone morphogenetic protein-2 (BMP-2) in common clinical situations. Surgeons are recommended to choose 1 graft over another or 1 osteobiologic over another primarily based on clinical situation, and the costs and availability of the materials.

CONCLUSION

This AOGO guideline is the first to provide recommendations for the use of osteobiologics in ACDF. Despite the comprehensive searches for evidence, there were few studies completed with small sample sizes and primarily as case series with inherent risks of bias. Therefore, high-quality clinical evidence is demanded to improve the guideline.

The Relationship of Radiographic Parameters and Morphological Changes at Various Stages of Degeneration of the Lumbar Facet Joints: Cadaver Study

STUDY DESIGN

Cadaveric specimens.

OBJECTIVE

To perform a pathomorphological analysis of the degree of facet joint (FJ) degeneration utilizing fresh cadaveric models and correlating these structural changes with imaging findings.

METHODS

L1-L5 FSU including all tissue between the anterior longitudinal ligament to the posterior spinal structures were obtained on 28 patients at a mean of 5.7 hours post-mortem. The samples were fixed in an agar medium and CT and MRI were performed. The level of FJ degeneration was identified based on prior classifications Osteoarthritis Research Society International (OARSI), as was the facet angle and tropism. Pathomorphological assessment including articular cartilage cell density was performed according to prior established methodology.

RESULTS

Radiographically, a direct association was identified between FJ degeneration and patient age. Facet angle and tropism did not significantly vary by patient age. Pathomorphologically, there was a decrease in the cellular density of articular cartilage with increasing patient age. Similarly, there was a significant direct correlation between radiographic degree of degenerative changes in FJs with the age of cadavers and the degree of degeneration of FJs according to the morphological classification of OARSI, as well as a significant inverse correlation with cell density.

CONCLUSION

A comprehensive assessment of various signs of FJ degeneration using cadaveric material has established that, based on radiographic imaging, it is possible to assess the microstructural state of FJ, including at an early stage of the disease. This data may be useful for surgeons in guiding therapeutic strategies based on individual biometric parameters of the FJ.

An Algorithmic Roadmap for Surgical Management of Degenerative Cervical Myelopathy: A Narrative Review

Degenerative cervical myelopathy (DCM) is a leading cause of disability, with its surgical management being crucial for patient neurological outcomes. Given the varied presentations and severities of DCM, treatment options are diverse. Surgeons often face challenges in selecting the most appropriate surgical approach, as there is no universally correct answer. This narrative review aims to aid the decision-making process in treating DCM by presenting a structured treatment algorithm. The authors categorized surgical scenarios based on an algorithm, outlining suitable treatment methods for each situation. Four primary scenarios were identified based on the number of levels requiring surgery and K-line status: (1) K-line (+) and ≤ 3 levels, (2) K-line (+) and ≥ 3 levels, (3) K-line (-) and ≤ 3 levels, and (4) K-line (-) and ≥ 3 levels. This categorization aids in determining the appropriateness of anterior or posterior approaches and the necessity for fusion, considering the surgical levels and K-line status. The complexity of surgical situations and the diversity of treatment methods for DCM can be effectively managed by utilizing an algorithmic approach. Furthermore, surgical techniques that minimize stages and address challenging conditions could potentially enhance outcomes in DCM treatment.

Timing dependent synergies between motor cortex and posterior spinal stimulation in humans

Volitional movement requires descending input from motor cortex and sensory feedback through the spinal cord. We previously developed a paired brain and spinal electrical stimulation approach in rats that relies on convergence of the descending motor and spinal sensory stimuli in the cervical cord. This approach strengthened sensorimotor circuits and improved volitional movement through associative plasticity. In humans it is not known whether dorsal epidural SCS targeted at the sensorimotor interface or anterior epidural SCS targeted within the motor system is effective at facilitating brain evoked responses. In 59 individuals undergoing elective cervical spine decompression surgery, the motor cortex was stimulated with scalp electrodes and the spinal cord with epidural electrodes while muscle responses were recorded in arm and leg muscles. Spinal electrodes were placed either posteriorly or anteriorly, and the interval between cortex and spinal cord stimulation was varied. Pairing stimulation between the motor cortex and spinal sensory (posterior) but not spinal motor (anterior) stimulation produced motor evoked potentials that were over five times larger than brain stimulation alone. This strong augmentation occurred only when descending motor and spinal afferent stimuli were timed to converge in the spinal cord. Paired stimulation also increased the selectivity of muscle responses relative to unpaired brain or spinal cord stimulation. Finally, paired stimulation effects were present regardless of the severity of myelopathy as measured by clinical signs or spinal cord imaging. The large effect size of this paired stimulation makes it a promising candidate for therapeutic neuromodulation.

Revision Strategies for Cervical Disc Arthroplasty

STUDY DESIGN

Narrative review.

OBJECTIVE

To review indications and strategies for revision of cervical disc arthroplasty (CDA).

SUMMARY OF BACKGROUND DATA

No data were generated as part of this review.

METHODS

A narrative review of the literature was performed.

RESULTS

No results were generated as part of this review.

CONCLUSIONS

CDA is a proven, motion-sparing surgical option for the treatment of myelopathy or radiculopathy secondary to cervical degenerative disc disease. As is the case with any operation, a small percentage of CDA will require revision, which can be a technically demanding endeavor. Here we review available revision strategies and associated indications, a thorough understanding of which will aid the surgeon in finely tailoring their approach to varying presentations.

Laminectomy with Laminar Reconstruction for Resection of Intradural Tumors at the Thoracolumbar Junction: A Technical Note

OBJECTIVE

To introduce a new laminar reconstruction technique to treat primary spinal cord tumors.

METHODS

Laminectomy and laminoplasty techniques have been used to treat intradural spinal tumors. The advantage of laminectomy is its superior exposure of the spinal cord, whereas the advantage of laminoplasty is the reconstruction of the dorsal roof of the spine. In this technical note, we present a technique that combines a full laminectomy to maximize exposure, with a reconstructive technique to repair the lamina. This technique restores the posterior ligamentous complex to preserve spinal biomechanics.

RESULTS

In this illustrative case, a 55-year-old woman with severe back pain radiating to the right lower extremity was found to have an intradural tumor at the T12-L1 spinal level. Given the transitional level of the spine and potentially high biomechanical stresses on the posterior support structures, we used a T12 laminectomy to resect the tumor, followed by reconstruction using miniplates. The patient tolerated the surgery well, without any complications. She was discharged home and was doing well during the 3 months follow-up visit. Appropriate patient consent was obtained.

CONCLUSIONS

Laminectomy and laminar reconstruction allow maximum visualization and manipulation of the tumor, followed by restoration of the dorsal roof of the spinal ring, and is an effective technique for treating spinal cord tumors.

Do Grip Strength Dynamometer Readings Improve After Cervical Spine Surgery?

STUDY DESIGN

Retrospective, cohort study.

OBJECTIVES

Hand function can be difficult to objectively assess perioperatively. In patients undergoing cervical spine surgery by a single-surgeon, we sought to: (1) use a hand dynamometer to report pre/postoperative grip strength, (2) distinguish grip strength changes in patients with radiculopathy-only vs myelopathy, and (3) assess predictors of grip strength improvement.

METHODS

Demographic and operative data were collected for patients who underwent surgery 2015-2018. Hand dynamometer readings were pre/postoperatively at three follow-up time periods (0-3 m, 3-6 m, 6-12 m).

RESULTS

262 patients (mean age of 59 ± 14 years; 37% female) underwent the following operations: ACDF (80%), corpectomy (25%), laminoplasty (19%), and posterior cervical fusion (7%), with 81 (31%) patients undergoing multiple operations in a single anesthetic setting. Radiculopathy-only was seen in 128 (49%) patients, and myelopathy was seen 134 (51%) patients. 110 (42%) had improved grip strength by ≥10-lbs, including 69/128 (54%) in the radiculopathy-only group, and 41/134 (31%) in the myelopathy group. Those most likely to improve grip strength were patients undergoing ACDF (OR 2.53, P = .005). Patients less likely to improve grip strength were older (OR = .97, P = .003) and underwent laminoplasty (OR = .44, 95% CI .23, .85, P = .014). Patients undergoing surgery at the C2/3-C5/6 levels and C6/7-T1/2 levels both experienced improvement during the 0-3-month time range (C2-5: P = .035, C6-T2: P = .015), but only lower cervical patients experienced improvement in the 3-6-month interval (P = .030).

CONCLUSIONS

Grip strength significantly improved in 42% of patients. Patients with radiculopathy were more likely to improve than those with myelopathy. Patients undergoing surgery from the C2/3-C5/6 levels and the C6/7-T1/2 levels both significantly improved grip strength at 3-month postoperatively.

The Feasibility of Multiple Fixation Points in C2

STUDY DESIGN

Analysis using three-dimensional simulation software for spinal screw placement and computed tomographic scan images.

PURPOSE

To assess the feasibility of achieving multiple (three or four) screw fixation points in C2 vertebra by using a combination of pedicle and laminar screws.

OVERVIEW OF LITERATURE

Secure C2 fixation using multiple screws is required or beneficial in some unique cases. However, to the best of our knowledge, there have been no reports analyzing the feasibility of multiple screw fixation in C2.

METHODS

We used 1.0-mm interval computed tomographic scan images of 100 patients (50 men and 50 women) and screw trajectory simulation software. The diameter of all screws was set at 3.5 mm, considering its common usage in real surgery. The anatomical feasibility of placing both pedicle and laminar screws on the same side was evaluated. For all feasible sides, the three-dimensional distance between the screw entry points was measured.

RESULTS

In 85% of cases, both pedicle and laminar screws could be placed on both sides, allowing for the insertion of 4 screws. In 11% of cases, 2 screws could be placed on one side, while only 1 screw was feasible on the other side, resulting in the placement of 3 screws. In all 181 sides where both types of screws could be inserted, the distance between their entry points exceeded 16.1 mm, which was sufficient to prevent the collision between the screw heads.

CONCLUSIONS

C2 vertebra can accommodate three (11%) or four (85%) screws in 96% of cases.

How Knowledgeable Are Spine Surgeons Regarding EMG-NCS for Cervical Spine Conditions? An International Aospine Survey

STUDY DESIGN

Cross-sectional, international survey.

OBJECTIVES

To evaluate the knowledge of spine surgeons regarding the use of electromyography (EMG) and nerve conduction studies (NCS) for degenerative cervical spine conditions (DCC).

METHODS

All members of AO Spine International were emailed an anonymous survey to evaluate their clinical knowledge about the use of EMG and nerve conduction studies for DCC. Descriptive statistics were used to analyze the results, as well as to compare the answers among different groups of surgeons and assess demographic characteristics.

RESULTS

A total of 402 participants answered the survey, 91.79% were men from the 5 continents. There were 221 orthopedic surgeons (55.39%) and 171 neurosurgeons (42.86%), more than a half of them with a complete spinal fellowship (56.44%). The most common reasons that surgeons obtain the test is to differentiate a radiculopathy from a peripheral nerve compression (88.06%). As a group, the responding surgeons' knowledge regarding EMG-NCS was poor. Only 53.46% of surgeons correctly answered that EMG-NCS is unable to differentiate a C5 from a C6 radiculopathy. Only 23.47% of the surgeons knew that EMG-NCS are not able to diagnose a pre vs a post-fixed brachial plexus. Only 25% of the surgeons correctly answered a question regarding the test's ability to diagnose other neurological diseases.

CONCLUSIONS

We found that our respondents' knowledge regarding EMG-NCS for DCC was poor. Identifying the weak points of knowledge about EMG-NCS may help to educate surgeons on the indications for the test and the proper way to interpret the results.

Identification of Deep Cervical Fascial Layers During Anterior Cervical Spine Exposure

BACKGROUND

Anterior approaches to the cervical spine are among the most common exposures by which neurosurgeons and orthopedic surgeons access the prevertebral space and ultimately the cervical disk and vertebral bodies. There is a paucity of literature describing the microanatomic fascial planes of the neck with respect to anterior cervical approaches.

OBJECTIVE

To delineate the microanatomic connections of the cervical fascial planes pertinent to anterior cervical exposure.

METHODS

Using a cadaveric model, original illustrations, the Visible Human Project, and an original surgical video, we demonstrate a stepwise method for identifying the correct planes for anterior cervical exposure.

RESULTS

A step-by-step method for identifying the anterior cervical fascial planes intraoperatively is demonstrated.

CONCLUSION

A comprehensive understanding of anterior cervical microsurgical anatomy is vital for performing a methodical yet efficient approach to the prevertebral space while minimizing retraction and iatrogenic injury to the surrounding neurovascular structures.

Clinical and radiological outcomes of one-level cervical corpectomy with an expandable cage for three-column uncomplicated subaxial type «B» injures: a multicenter retrospective study

PURPOSE

To evaluate the clinical and radiological results of the operative management of three-column uncomplicated type «B» subaxial injures treated with a one-level cervical corpectomy with an expandable cage.

METHODS

This study included 72 patients with a three-column uncomplicated type «B» subaxial injures who met the inclusion criteria, underwent a one-level cervical corpectomy with an expandable cage at one of three neurosurgical departments between 2005 and 2020, and were followed up for clinical and radiological outcomes at a minimum 3-yr follow-up.

RESULTS

There was a decrease in the VAS pain score from an average of 80 mm to 7 mm (p = 0.03); a decrease in the average NDI score from 62 to 14% (p = 0.01); excellent and good outcomes according to Macnab's scale were 93% (n = 67/72). There was an average change in the cervical lordosis (Cobb method) from -9.10 to -15.40 (p = 0.007), without significant loss of lordosis (p = 0.27). There was no significant degeneration of the adjacent levels by 3 years post-op. The fusion rate, using the Cervical Spine Research Society criteria, was poor: it was 62.5% (n = 45/72), and using the CT criteria, it was 65.3% (n = 47/72). 15.4% patients (n = 11/72) suffered complications. Statistical difference between the fusion and pseudoarthrosis (according to X-ray criteria) subgroups showed that there were no statistically significant differences in the smoking status, diabetes, chronic steroid use, cervical injury level, subtypes of AO type B subaxial injuries and types of expandable cage systems.

CONCLUSIONS

One-level cervical corpectomy with an expandable cage, despite a poor fusion rate, can be considered a feasible and relatively safe method for treating three-column uncomplicated subaxial type «B» injures, with the benefit of immediate stability, anatomical reduction, and direct decompression of the spinal cord. While no one in our series had any catastrophic complications, we did note a high complication rate.

A standardized anesthetic/analgetic regimen compared to standard anesthetic/analgetic regimen for patients with high-risk factors undergoing open lumbar spine surgery: a prospective comparative single-center study

The objective of the study is to improve the results of patients undergoing lumbar spine surgery who are at high risk for anesthesia and/or surgical complications. Two independent groups were compared: the study group (SG, n = 40) (standardized neuroanesthetic protocol with multimodal analgesia) and the control group (CG, n = 40) (intravenous anesthesia based on propofol and fentanyl). The data were collected using prospective observation of early and long-term results of lumbar fusion. After 24 months, the level of functional state and quality of life were studied. Patients in the SG did not have statistically significant changes in intraoperative hemodynamics; the best indicators of cognitive functions were noted. The effectiveness of the SG compared with the CG was confirmed by a statistically significantly lower amount of perioperative opioid drugs required (p = 0.01) and a minimal level of incisional pain (p < 0.05). An intergroup comparison of the adverse effects of anesthesia revealed a significantly lower number in the SG (n = 4) compared to the CG (n = 16) (p = 0.004). The number of postoperative surgical complications was comparable (p = 0.72). Intergroup comparison showed improved ODI, SF-36, and the Macnab scale at 24 months after surgery in the SG compared to the CG (p < 0.05). Long-term clinical results correlated with the level of incisional pain in the first three postoperative days. Our standardized neuroanesthetic protocol ensured effective treatment of postoperative incisional pain, significantly decreased the perioperative use of opioids, reduced adverse anesthesia events, and improved long-term clinical results in patients with high risk factors for anesthetic complications who undergoing open lumbar spine surgery.

The Effect of Cervical Fusion on Functional Sagittal Spinal Alignment Based on the Inflection Point: Case Series Study

STUDY DESIGN

A retrospective radiologic study.

OBJECTIVE

The inflection point is the disc space between a lordotic and kyphotic segment of spine. To our knowledge, there has been no study evaluating changes in functional sagittal alignment determined by inflection points after cervical fusion surgery. The purpose is to identify changes in functional sagittal alignment after cervical fusion as determined by functional segments between cervicothoracic and thoracolumbar inflection points.

METHODS

Standing radiographs of the sagittal whole spine were taken in 62 patients who underwent cervical fusion procedures. We identified cervicothoracic and thoracolumbar inflection points in the sagittal plane and measured Cobb angles of resulting "functional" cervical, thoracic, and lumbar segments. We also measured the C2 and T1 sagittal vertical axis (SVA) distance to S1 and the anatomic cervical lordosis, thoracic kyphosis, lumbar lordosis, spinopelvic parameters, and T1 sagittal slope. We compared the pre- and post-op values.

RESULTS

The functional cervical segment and T1 sagittal slope increased postoperatively. C2 and T1 SVA distance to S1 decreased postoperatively. In patients with a single level fusion or lower instrumented vertebra (LIV) proximal or equal to C6, functional cervical segment, and anatomic cervical lordosis increased postoperatively. In those with multiple level fusion or LIV distal or equal to C7, the C2 SVA distance to S1 decreased postoperatively.

CONCLUSIONS

After cervical fusion surgery, functional cervical sagittal parameters determined by the inflection point improve without changes in the anatomic sagittal parameters. Postoperative changes in functional sagittal parameters were affected by the number of fused levels and LIV.

What Is the Impact of Surgical Approach in the Treatment of Degenerative Cervical Myelopathy in Patients With OPLL? A Propensity-Score Matched, Multi-Center Analysis on Inpatient and Post-Discharge 90-Day Outcomes

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

Provide a comparison of surgical approach in the treatment of degenerative cervical myelopathy in patients with OPLL.

METHODS

A national database was queried to identify adult (≥18 years) patients with OPLL, who underwent at least a 2-level cervical decompression and fusion for cervical myelopathy from 2012-2014. A propensity-score-matching algorithm was employed to compare outcomes by surgical approach.

RESULTS

After propensity-score matching, 627 patients remained. An anterior approach was found to be an independent predictor for higher inpatient surgical complications(OR 5.9), which included dysphagia:14%[anterior]vs.1.1%[posterior] P-value < 0.001, wound hematoma:1.7%[anterior]vs.0%[posterior] P-value = 0.02, and dural tear:9.4%[anterior]vs.3.2%[posterior] P-value = 0.001. A posterior approach was an predictor for longer hospital length of stay by nearly 3 days(OR 3.4; 6.8 days[posterior]vs.4.0 days[anterior] P-value < 0.001). The reasons for readmission/reoperation did not vary by approach for 2-3-level fusions; however, for >3-level fusions, patients with an anterior approach more often had respiratory complications requiring mechanical ventilation(P-value = 0.038) and required revision fusion surgery(P-value = 0.015).

CONCLUSIONS

The national estimates for inpatient complications(25%), readmissions(9.9%), and reoperations(3.5%) are substantial after the surgical treatment of multi-level OPLL. An anterior approach resulted in significantly higher inpatient surgical complications, but this did not result in a longer hospital length of stay and the overall 90-day complication rates requiring readmission or reoperation was similar to those seen after a posterior approach. For patients requiring >3-level fusion, an anterior approach is associated with significantly higher risk for respiratory complications requiring mechanical ventilation and revision fusion surgery. Precise neurological complications and functional outcomes were not included in this database, and should be further assessed in future studies.

Variation in Cervical Pedicle Morphology: Important Considerations for Posterior Cervical Procedures

BACKGROUND

Safe posterior cervical spine surgery requires in-depth understanding of the surgical anatomy and common variations. The cervical pedicle attachment site to the vertebral body (VB) affects the location of exiting nerve roots and warrants preoperative evaluation. The relative site of attachment of the cervical pedicle has not been previously described.

OBJECTIVE

To describe the site of the pedicle attachment to the VB in the subaxial cervical spine.

METHODS

Cervical spine computed tomography scans without any structural, degenerative, or traumatic pathology as read by a board-certified neuroradiologist during 2021 were reviewed. Multiplanar reconstructions were created and cross-registered. The pedicle's attachment to the VB was measured relative to the VB height using a novel calculation system.

RESULTS

Fifty computed tomography scans met inclusion criteria yielding 600 total pedicles between C3-T1 (100 per level). The average patient age was 26 ± 5.3 years, and 21/50 (42%) were female. 468/600 (78%) pedicles attached in the cranial third of the VB, 132/600 (22%) attached in the middle third, and 0 attached to the caudal third. The highest prevalence of variant anatomy occurred at C3 (36/100 C3 pedicles; 36%).

CONCLUSION

In the subaxial cervical spine, pedicles frequently attach to the top third of the VB, but significant variation is observed. The rate of variation is highest at C3 and decreases linearly with caudal progression down the subaxial cervical spine to T1. This is the first report investigating this morphological phenomenon.

Laminoplasty versus Laminectomy in the Treatment of Primary Spinal Cord Tumors in Adult Patients: A Systematic Review and Meta-analysis of Observational Studies

The present systematic review and meta-analysis was conducted to compare the safety and efficacy of the two approaches for primary spinal cord tumors (PSCTs) in adult patients (laminoplasty [LP] vs. laminectomy [LE]). LE is one of the most common procedures for PSCTs. Despite advantages of LP, it is not yet widely used in the neurosurgical community worldwide. The efficacy of LP vs. LE remains controversial. Adult patients over 18 years of age with PSCT at the level of the cervical, thoracic, and lumbar spine were included in the study. A literature search was performed in MEDLINE via PubMed, EMBASE, The Cochrane Library, and Google Scholar up to December 2021. Operation time, hospital stay, complications, and incidence of postoperative spinal deformity (kyphosis or scoliosis were extracted. A total of seven retrospective observational studies with 540 patients were included. There were no significant differences between LP and LE group in operation time (p =0.25) and complications (p =0.48). The LE group showed larger postoperative spinal deformity rate than the LP group (odds ratio, 0.47; 95% confidence interval [CI], 0.27-0.84; p =0.01). The LP group had a shorter hospital stay (standardized mean differences, -0.68; 95% CI, -1.03 to -0.34; p =0.0001) than the LE group. Both LP and LE have comparable operative times and total complications in the treatment of PSCT. LP was superior to LE in hospital stay and postoperative spinal deformity rate. However, these findings are limited by the very low quality of the available evidence. Randomized controlled trials are needed for further comparison.

Prevalence of lumbosacral transitional vertebra among 4816 consecutive patients with low back pain: A computed tomography, magnetic resonance imaging, and plain radiographic study with novel classification schema

Study Design

A retrospective single-center study.

Background

The prevalence of the lumbosacral anomalies remains controversial. The existing classification to characterize these anomalies is more complex than necessary for clinical use.

Purpose

To assessment of the prevalence of lumbosacral transitional vertebra (LSTV) in patients with low back pain and the development of clinically relevant classification to describe these anomalies.

Materials and Methods

During the period from 2007 to 2017, all cases of LSTV were preoperatively verified, and classified according to Castellvi, as well as O'Driscoll. We then developed modifications of those classifications that are simpler, easier to remember, and clinically relevant. At the surgical level, this was assessed intervertebral disc and facet joint degeneration.

Results

The prevalence of the LSTV was 8.1% (389/4816). The most common L5 transverse process anomaly type was fused, unilaterally or bilaterally (48%), to the sacrum and were O'Driscoll's III (40.1%) and IV (35.8%). The most common type of S1-2 disc was a lumbarized disc (75.9%), where the disc's anterior-posterior diameter was equal to the L5-S1 disc diameter. In most cases, neurological compression symptoms (85.5%) were verified to be due to spinal stenosis (41.5%) or herniated disc (39.5%). In the majority of patients without neural compression, the clinical symptoms were due to mechanical back pain (58.8%).

Conclusions

LSTV is a fairly common pathology of the lumbosacral junction, occurring in 8.1% of the patients in our series (389 out of 4,816 cases). The most common types were Castellvi's type IIA (30.9%) and IIIA (34.9%) and were O'Driscoll's III (40.1%) and IV (35.8%).

Postoperative MRI Visualization of the Cervical Spine Following Cervical Disc Arthroplasty: A Prospective Single-Center Comparison of a Titanium and Cobalt-Chromium Prosthesis

STUDY DESIGN

Prospective non-randomized single-center cohort study.

OBJECTIVES

To analyze the quality of postoperative magnetic resonance imaging of 2 structurally different cervical disc arthroplasty devices at the index and adjacent levels.

METHODS

A non-randomized, comparative, prospective, single-center study included 40 patients (23 men and 17 women) aged 32 (26-40) years. Two study groups were utilized: in the first (n = 20), a titanium prosthesis was used; in the second (n = 20), a cobalt-chromium implant was used. Evaluation of MRI studies before and after surgery was performed using sagittal and axial T2 weighted images by 2 specialists who were blinded to the prosthesis that was used. To determine the quality of an MRI image, the classification of Jarvik 2000, the radiological and orthopedic scales for assessing artifacts were used.

RESULTS

There was good-to-excellent inter-observer agreement for all of the MR parameters used for the titanium and satisfactory-to-good for the cobalt chromium group. The analysis of the quality of postoperative imaging using the Jarvik 2000 scale showed a statistically significant deterioration in MR images in the cobalt chromium group (P < 0.001), compared to the titanium (P = 0.091). Following a single-level total arthroplasty, the titanium group had better MRI images according to radiological and orthopedic scales (P < 0.001).

CONCLUSION

Titanium cervical disc arthroplasty devices result in superior postoperative MR imaging, as compared to cobalt chromium prostheses, as the latter significantly reduces image quality due to the pronounced ferromagnetic effect.

Intraoperative electrical stimulation of the human dorsal spinal cord reveals a map of arm and hand muscle responses

Although epidural stimulation of the lumbar spinal cord has emerged as a powerful modality for recovery of movement, how it should be targeted to the cervical spinal cord to activate arm and hand muscles is not well understood, particularly in humans. We sought to map muscle responses to posterior epidural cervical spinal cord stimulation in humans. We hypothesized that lateral stimulation over the dorsal root entry zone would be most effective and responses would be strongest in the muscles innervated by the stimulated segment. Twenty-six people undergoing clinically indicated cervical spine surgery consented to mapping of motor responses. During surgery, stimulation was performed in midline and lateral positions at multiple exposed segments; six arm and three leg muscles were recorded on each side of the body. Across all segments and muscles tested, lateral stimulation produced stronger muscle responses than midline despite similar latency and shape of responses. Muscles innervated at a cervical segment had the largest responses from stimulation at that segment, but responses were also observed in muscles innervated at other cervical segments and in leg muscles. The cervical responses were clustered in rostral (C4-C6) and caudal (C7-T1) cervical segments. Strong responses to lateral stimulation are likely due to the proximity of stimulation to afferent axons. Small changes in response sizes to stimulation of adjacent cervical segments argue for local circuit integration, and distant muscle responses suggest activation of long propriospinal connections. This map can help guide cervical stimulation to improve arm and hand function.NEW & NOTEWORTHY A map of muscle responses to cervical epidural stimulation during clinically indicated surgery revealed strongest activation when stimulating laterally compared to midline and revealed differences to be weaker than expected across different segments. In contrast, waveform shapes and latencies were most similar when stimulating midline and laterally, indicating activation of overlapping circuitry. Thus, a map of the cervical spinal cord reveals organization and may help guide stimulation to activate arm and hand muscles strongly and selectively.

Respiratory Compromise After Anterior Cervical Spine Surgery: Incidence, Subsequent Complications, and Independent Predictors

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Respiratory compromise (RC) is a rare but catastrophic complication of anterior cervical spine surgery (ACSS) commonly due to compressive fluid collections or generalized soft tissue swelling in the cervical spine. Established risk factors include operative duration, size of surgical exposure, myelopathy, among others. The purpose of this current study is to identify the incidence and clinical course of patients who develop RC, and identify independent predictors of RC in patients undergoing ACSS for cervical spondylosis.

METHODS

A large, prospectively-collected registry was used to identify patients undergoing ACSS for spondylosis. Patients with posterior cervical procedures were excluded. Baseline patient characteristics were compared using bivariate analysis, and multivariate analysis was employed to compare postoperative complications and identify independent predictors of RC.

RESULTS

298 of 52,270 patients developed RC (incidence 0.57%). Patients who developed RC had high rates of 30-day mortality (11.7%) and morbidity (75.8%), with unplanned reoperation and pneumonia the most common. The most common reason for reoperations were hematoma evacuation and tracheostomy. Independent patient-specific factors predictive of RC included increasing patient age, male gender, comorbidities such as chronic cardiac and respiratory disease, preoperative myelopathy, prolonged operative duration, and 2-level ACCFs.

CONCLUSION

This is among the largest cohorts of patients to develop RC after ACSS identified to-date and validates a range of independent predictors, many previously only described in case reports. These results are useful for taking preventive measures, identifying high risk patients for preoperative risk stratification, and for surgical co-management discussions with the anesthesiology team.

Minimally Invasive Transforaminal Lumbar Interbody Fusion (TLIF) Compared with Open TLIF for Acute Cauda Equina Syndrome: A Retrospective Single-Center Study with Long-Term Follow-Up

OBJECTIVES

In a retrospective study, we sought to compare the clinical efficacy and postoperative magnetic resonance imaging (MRI) scans of minimally invasive (MI) and open (O) transforaminal lumbar interbody fusion (TLIF) in the treatment of cauda equina syndrome (CES) caused by lumbar disc herniation.

METHODS

In total, 116 patients with CES associated with disc herniation underwent decompression and stabilization surgery from January 2005 to January 2020 in a single-center study, and data were collected and retrospectively analyzed. The patients were divided into the O-TLIF and the MI-TLIF group. The perioperative clinical data and MRI assessment were used to assess the efficacy of the respective surgical methods preoperatively and with a minimum follow-up of 30 months.

RESULTS

As expected, the O-TLIF group had statistically significantly longer surgery times and hospital stay, more bleeding, and perioperative surgical complications than the MI-TLIF group. At a minimum follow-up period of 30 months, the MI-TLIF group had significantly better Oswestry Disability Index, visual analog scale, and Short-Form-36, and neurologic CES symptoms than the O-TLIF group. The postoperative MRIs revealed a statistically significant difference in the multifidus muscle area in MI group compared with the O group.

CONCLUSIONS

In patients with acute CES caused by disc herniation, MI-TLIF, with decreased disruption of paravertebral tissues and postoperative pain syndrome, results in earlier mobilization and rehabilitation with better long-term clinical outcomes compared with O-TLIF.

Crossing the Cervico-Thoracic Junction in Long Posterior Cervical Fusions Reduces Caudal Adjacent Segment Pathology

STUDY DESIGN

Retrospective case control.

OBJECTIVES

The purpose of this study is to compare clinical outcomes and rates of symptomatic caudal adjacent segment pathology (ASP) in posterior cervical fusions (PCF) constructs with end-instrumented vertebrae in the cervical spine (EIV-C) to PCF constructs that end in the proximal thoracic spine (EIV-T).

METHODS

Retrospective review of 1714 consecutive cervical spinal fusion cases was done. Two groups were identified: 36 cervical end-instrumented vertebra patients (age56 ± 10 yrs) and 53 thoracic EIV patients (age 57 ± 9 yrs). Symptomatic ASP was defined as revision surgery or nerve root injection (or recommended surgery or injection) at the adjacent levels.

RESULTS

EIV-C patients had a significantly higher rate of caudal-level symptomatic ASP requiring intervention compared with EIV-T patients (39% vs 15%, p = 0.01). The development of caudal-level ASP was highest at C7 (41%), followed by C6 (40%). The overall complication rate and surgical revision rates, however, were similar between the groups. Neck Disability Index outcomes at 2 years postop were significantly better in the EIV-T group (24.5 vs. 34.0, p = 0.05).

CONCLUSIONS

Long PCF that cross the C-T junction have superior clinical outcomes and reduced rates of caudal breakdown, at the expense of longer fusions and higher EBL, with no increase in the rate of complications. Crossing the C-T junction affords protection of the caudal adjacent levels without adding significant operative time or morbidity.

Revision Anterior Cervical Disc Arthroplasty: A National Analysis of the Associated Indications, Procedures, and Postoperative Outcomes

STUDY DESIGN

Retrospective study.

OBJECTIVE

To examine the associated indications, procedures, and postoperative outcomes after revision ACDA.

METHODS

We utilized a national database to identify adult(≥18 years) patients who underwent either a primary ACDA or removal of ACDA over a 10-year period(2008-2017). An in-depth assessment of the reasons for revision surgery and the subsequent procedures performed after the removal of ACDA was done by using both Current Procedural Terminology(CPT) and International Statistical Classification of Diseases (ICD-9,10) coding.

RESULTS

From 2008 to 2017, a total of 3,350 elective, primary ACDA cases were performed. During this time, 69 patients had a revision surgery requiring the removal of ACDA. The most common reasons for revision surgery included cervical spondylosis(59.4%) and mechanical complications(27.5%). After removal of ACDA, common procedures performed included anterior cervical fusion with or without decompression(69.6%), combined anterior/posterior fusion/decompression (11.6%), and replacement of ACDA (7.2%). The indications for surgery did not vary significantly among the different procedures performed (p = 0.318). Patients requiring revision surgery for mechanical complications or those who underwent a combined surgical approach were at significantly higher risk for subsequent short-term complications (p<0.05).

CONCLUSION

Over a 10-year period, the rate of revision surgery for ACDA was low (2.1%). Nearly 90% of revision cases were due to either cervical spondylosis or mechanical complications. These indications for surgery did not vary significantly among the different procedures performed. These findings will be important during the shared-decision making process for patients undergoing primary or revision ACDA.

An Algorithmic Posterior Approach to the Treatment of Multilevel Degenerative Cervical Spine Disease: A Multicenter Prospective Study

BACKGROUND

The choice of surgical method for the treatment of multilevel degenerative cervical spine disease is based on the assessment of neurological symptoms and anatomical source of compression. However, such decision-making process remains complex and poorly defined.

PURPOSE

To analyze the effectiveness of an algorithmic posterior approach to the surgical treatment of patients with multilevel degenerative disease of the cervical spine based on the preoperative clinical and imaging parameters.

STUDY DESIGN

Prospective nonrandomized multicenter cohort study.

METHODS

The study included 338 patients with multilevel degenerative disease of the cervical spine. Two groups of patients were evaluated at 3 neurosurgical centers between 2015 and 2019. The prospective group (Group I, n = 214) consisted of patients who were treated using an algorithm to decide whether they should be treated with an instrumented arthrodesis or a nonfusion procedure. The control group (Group II, n = 124) consisted of patients who underwent posterior decompression with or without stabilization between 2007 and 2014. A total of 192 patients in Group I and 112 in Group II had more than 2 years of follow-up. Visual analog scale (VAS) neck pain, Neck Disability Index (NDI), MacNab and Nurick Scales were collected. Perioperative complications were identified.

RESULTS

At 2-year follow-up, Group I had significantly better clinical outcomes based on VAS neck pain score (P = 0.02), NDI score (P = 0.01), satisfaction with surgery on the MacNab Scale (P < 0.001), and outcome of surgery based on the Nurick Scale (P < 0.001). Complication rate was lower in Group I, 5.7% compared with 34.8% in Group II, P = 0.004.

CONCLUSIONS

The algorithmic posterior approach to the surgical treatment of patients with multilevel degenerative disease of the cervical spine resulted in significant improvement of functional outcomes and a decrease in complications at a minimum 2 years of follow-up.

LEVEL OF EVIDENCE: 2

Titanium versus polyetheretherketone versus structural allograft in anterior cervical discectomy and fusion: A systematic review

Introduction

Anterior cervical discectomy and fusion (ACDF) is a common procedure to address cervical spine pathology. The most common grafts used are titanium, polyetheretherketone (PEEK), or structural allograft. Comparison of fusion rate is difficult due to non-standardized methods of assessment. We stratified studies by method of fusion assessment and performed a systematic review of fusion rates for titanium, PEEK, and allograft.

Research question

Which of the common implants used in ACDF has the highest reported rate of fusion?

Materials and methods

An experienced librarian performed a five-database systematic search for published articles between 01/01/1990 and 08/07/2021. Studies performed in adults with at least 1 year of radiographic follow up were included. The primary outcome was the rate of fusion. Fusion criteria were stratified into 6 classes based upon best practices.

Results

34 studies met inclusion criteria. 10 studies involving 924 patients with 1094 cervical levels, used tier 1 fusion criteria and 6 studies (309 patients and 367 levels) used tier 2 fusion criteria. Forty seven percent of the studies used class 3–6 fusion criteria and were not included in the analysis. Fusion rates did differ between titanium (avg. 87.3%, range 84%–100%), PEEK (avg. 92.8%, range 62%–100%), and structural allograft (avg. 94.67%, range 82%–100%).

Discussion and conclusion

After stratifying studies by fusion criteria, significant heterogeneity in study design and fusion assessment prohibited the performance of a meta-analysis. Fusion rate did not differ by graft type. Important surgical goals aside from fusion rate, such as degree of deformity correction, could not be assessed. Future studies with standardized high-quality methods of assessing fusion, are required.

•

Anterior cervical discectomy and fusion (ACDF) is a common procedure to address cervical spine pathology.

•

The optimal graft type of promote fusion is unknown. The methods for assessing fusion are not standardized.

•

This is a systematic review comparing fusion rates for ACDF grafts after first stratified by method of fusion assessment.

•

Significant heterogeneity in study design and fusion assessment prohibited the performance of a meta-analysis; Fusion rate did not differ by graft type.

•

Future studies with standardized high-quality methods of assessing fusion, are required.

A Comparison of Various Surgical Treatments for Degenerative Cervical Myelopathy: A Propensity Score Matched Analysis

STUDY DESIGN

Retrospective Cohort.

OBJECTIVE

To compare the short-term outcomes for Laminoplasty, Laminectomy/fusion, and ACDF.

METHODS

We utilized a prospectively-collected, multi-center national database with a propensity score matching algorithm to compare the short-term outcomes for laminoplasty, laminectomy/fusion, and multi-level (>3) ACDF (with and without corpectomy). Bivariate analyses involved both chi-square/fisher exact test and t-test/ANOVA on perioperative factors. Multivariate analyses were performed to determined independent risk factors for short term outcomes.

RESULTS

546 patients remained after propensity score matching, with 182 patients in each cohort. ACDF required the longest operative time 188 ± 79 versus laminectomy/fusion (169 ± 75, p = 0.017), and laminoplasty (167 ± 66, p = 0.004). ACDF required the shortest hospital stay (LOS ≥ 2: ACDF 56.6%, laminoplasty 89.6%, laminectomy/fusion 93.4%, p < 0.05). ACDF had lower overall complications (ACDF 3.9%, laminoplasty 7.7%, laminectomy/fusion 11.5%, p < 0.05), mortality (ACDF 0%, laminoplasty 0.55%, laminectomy/fusion 2.2%, p < 0.05), and unplanned readmissions (ACDF 4.4%, laminoplasty 4.4%, laminectomy/fusion 9.9%, p < 0.05). No significant differences were seen in the other outcomes including DVT/PT, acute renal failure, UTI, stroke, cardiac complications, or sepsis. In the multivariate analysis, laminectomy/fusion (OR 17, reference: ACDF) and laminoplasty (OR10, reference: ACDF) were strong independent risk factors for LOS ≥ 2 days. Laminectomy/fusion (OR 3.2, reference: ACDF) was an independent predictor for any adverse events 30-days after surgery.

CONCLUSIONS

Laminectomy/fusion carries the highest risk for morbidity, mortality, and unplanned readmissions in the short-term postoperative period. Laminoplasty and ACDF cases carry similar short-term complications risks. ACDF is significantly associated with the longest operative duration and shortest LOS without an increase in individual or overall complications, readmissions, or reoperations.

Correlation between neurologic status and spinal injury at the Cervicothoracic Junction

BACKGROUND

With limited studies on spinal injuries occurring at the cervicothoracic junction, there is currently a knowledge gap regarding the correlation between morphology of injury and neurology and whether surgery provides a favorable neurological outcome. The primary objective was to determine whether the neurological deficit correlated with the severity of injury at this region of the spine.

METHODS

All patients with injuries at the cervicothoracic junction from December 2015 to December 2020 in a government trauma hospital were included. Patient demographics, characteristics of the injury, neurological score, imaging findings, surgery details and neurological outcomes were analyzed. All patients had a minimum follow up of 2 years.

RESULTS

Of the total 30 patients, 23 were male and 7 female with mean age 42.4 years. 90% had fall injuries with 76.7% sustaining AO type C injury and 10% with AO B2 injury.73.4% had injury at C6-C7 level followed by 13.3% , C7-T1. Only 16.7% patients presented with intact neurology. Plain x-rays failed to detect cervicothoracic junction, injuries in 63.3% patients. Posterior stabilization was performed in 56.7%. Neurological improvement was observed in 9 patients.

CONCLUSIONS

Though cervicothoracic junction injuries are uncommon, they are highly unstable injuries and difficult to diagnose by plain x-rays. These injuries also result in profound neurological deficit. Surgical stabilization of these injuries should be considered for a favorable neurological and functional outcome.

Does Cigarette Smoking Affect Cervical Laminoplasty Clinical and Radiologic Outcomes?

STUDY DESIGN

Retrospective review.

OBJECTIVE

This study aimed to investigate if smokers have both poorer early clinical and radiologic outcomes in cervical laminoplasty when compared with nonsmokers.

SUMMARY OF BACKGROUND DATA

Cigarette smoking had been reported to increase rates of pseudoarthrosis following spinal instrumentation with fusion.

METHODOLOGY

A retrospective review of all patients who underwent open-door cervical laminoplasty was performed. Nurick, neck pain visual analog scale, and neck disability index scores were reviewed. Cervical lordosis, range of motion (ROM), and intervertebral disc height were measured. The rates and reasons for revision surgery were recorded and classified according to the etiology of laminoplasty revision surgery.

RESULTS

Sixty patients were recruited, of which 20 patients (18 males, 2 females) were smokers and 40 patients (27 males, 13 females) were nonsmokers. There was no statistically significant difference between smokers and nonsmokers in preoperative and postoperative visual analog scale, neck disability index, and Nurick scores. A trend was noted toward a greater postoperative reduction in cervical lordosis (13±8 vs. 11±11 degrees). Furthermore, 41% of smokers versus 30% in nonsmokers had >10% loss of postoperative ROM, and 59% smokers versus 50% nonsmokers had >5% loss of postoperative ROM.Postoperative complications and intervertebral disc deterioration were similar in both groups. A higher reoperation rate was noted in smokers with 6 smokers (30%) as compared with 4 nonsmokers (10%), although this did not reach statistical significance. Among the smokers, 4 (20%) were because of cervical disease progression while 2 were technique related. In nonsmokers, all 4 (10%) were because of cervical disease progression.

CONCLUSION

This study showed that while there was a nonstatistically significant trend noted toward higher rates of revision surgery in smokers, the laminoplasty outcomes were not significantly poorer in smokers. In heavy smokers with multilevel cervical myelopathy, laminoplasty may be the treatment of choice over anterior spinal decompression and fusion where a high risk of pseudoarthrosis is anticipated.

Factors Affecting the Decision to Initiate Anticoagulation After Spine Surgery: Findings From the AOSpine Anticoagulation Global Initiative

STUDY DESIGN

Cross-sectional, international survey.

OBJECTIVES

To identify factors influencing pharmacologic anticoagulation initiation after spine surgery based on the AOSpine Anticoagulation Global Survey.

METHODS

This survey was distributed to the international membership of AOSpine (n = 3805). A Likert-type scale described grade practice-specific factors on a scale from low (1) to high (5) importance, and patient-specific factors a scale from low (0) to high (3) importance. Analysis was performed to determine which factors were significant in the decision making surrounding the initiation of pharmacologic anticoagulation.

RESULTS

A total of 316 spine surgeons from 64 countries completed the survey. In terms of practice-specific factors considered to initiate treatment, expert opinion was graded the highest (mean grade ± SD = 3.2 ± 1.3), followed by fellowship training (3.2 ± 1.3). Conversely, previous studies (2.7 ± 1.2) and unspecified guidelines were considered least important (2.6 ± 1.6). Patient body mass index (2.0 ± 1.0) and postoperative mobilization (2.3 ± 1.0) were deemed most important and graded highly overall. Those who rated estimated blood loss with greater importance in anticoagulation initiation decision making were more likely to administer thromboprophylaxis at later times (hazard ratio [HR] = 0.68-0.71), while those who rated drain output with greater importance were likely to administer thromboprophylaxis at earlier times (HR = 1.32-1.43).

CONCLUSION

Among our global cohort of spine surgeons, certain patient factors (ie, patient mobilization and body mass index) and practice-specific factors (ie, expert opinion and fellowship training) were considered to be most important when considering anticoagulation start times.

Identification of Anterior Cervical Spinal Instrumentation Using a Smartphone Application Powered by Machine Learning

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

The purpose of this study is to develop and validate a machine learning algorithm for the automated identification of anterior cervical discectomy and fusion (ACDF) plates from smartphone images of anterior-posterior (AP) cervical spine radiographs.

SUMMARY OF BACKGROUND DATA

Identification of existing instrumentation is a critical step in planning revision surgery for ACDF. Machine learning algorithms that are known to be adept at image classification may be applied to the problem of ACDF plate identification.

METHODS

A total of 402 smartphone images containing 15 different types of ACDF plates were gathered. Two hundred seventy-five images (∼70%) were used to train and validate a convolution neural network (CNN) for classification of images from radiographs. One hundred twenty-seven (∼30%) images were held out to test algorithm performance.

RESULTS

The algorithm performed with an overall accuracy of 94.4% and 85.8% for top-3 and top-1 accuracy, respectively. Overall positive predictive value, sensitivity, and f1-scores were 0.873, 0.858, and 0.855, respectively.

CONCLUSION

This algorithm demonstrates strong performance in the classification of ACDF plates from smartphone images and will be deployed as an accessible smartphone application for further evaluation, improvement, and eventual widespread use.Level of Evidence: 3.

The adjustable aiming device for caspar pin insertion in anterior cervical spine surgery

BACKGROUND

Creating a rectangular disc space is an important step during anterior cervical discectomy and fusion or cervical total disc replacement. The study aims to determine the accuracy of Caspar pin insertion by using a novel Adjustable Caspar Pin Aiming Device in anterior cervical procedures.

METHODS

Forty Caspar pins were placed using an Adjustable Caspar Pin Aiming Device in 20 human cadaveric cervical vertebral bodies from C3 to C7 after performing anterior discectomies. Accuracy of pin placement was assessed by lateral fluoroscopy, considering superior endplate slope (SE), inferior endplate slope (IE), Caspar pin slope (CP), and endplate-Caspar pin slope difference (SE/CP, IE/CP).

RESULTS

The mean superior endplate slope (SE), inferior endplate slope (IE), and Caspar pin slope (CP) were 10.82 ± 2.3°, 10.32 ± 3.2°, and 15.58 ± 7.9°, respectively. The average superior endplate-Caspar pin slope difference (SE/CP) and inferior endplate-Caspar pin slope difference (IE/CP) were 6.6 ± 0.8° and 7.7 ± 0.8°, respectively. The greatest slope difference was observed at the superior and inferior endplates of C3. No cervical endplate violations occurred.

CONCLUSION

Adjustable Caspar Pin Aiming Device allowed for a highly accurate Caspar pin placement with the average endplate-Caspar pin slope difference of less than 7.7°. It results in accurate placement of the superior and inferior Caspar pins parallel to the index vertebral endplates. Furthermore, it appears to facilitate the safe and effective insertion of Caspar pins for anterior cervical procedures.

Impact of Cervical Disc Arthroplasty vs Anterior Cervical Discectomy and Fusion on Driving Disability: Post Hoc Analysis of a Randomized Controlled Trial With 10-Year Follow-Up

BACKGROUND

Driving an automobile requires the ability to turn the neck laterally. Anecdotally, patients with multilevel fusions often complain about restricted turning motion. The purpose of this study was to compare the effectiveness of cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) on driving disability improvement at 10-year follow-up after a 2-level procedure.

METHODS

In the original randomized controlled trial, patients with cervical radiculopathy or myelopathy at 2 levels underwent CDA or ACDF. The driving disability question from the Neck Disability Index was rated from 0 to 5 years preoperatively and up to 10 years postoperatively. Severity of driving disability was categorized into "none" (score 0), "mild" (1 or 2), and "severe" (3, 4, or 5). Score and severity were compared between groups.

RESULTS

Out of 397 patients, 148 CDA and 118 ACDF patients had 10-year follow-up. Driving disability scores were not different between the groups preoperatively (CDA: 2.65; ACDF: 2.71, P = 0.699). Postoperatively, the scores in the CDA group were significantly lower than those in the ACDF group at 5 (0.60 vs 1.08, P ≤ 0.001) and 10 years (0.66 vs 1.07, P = 0.001). Mean score improvement in the CDA group was significantly greater than the ACDF group at 10-year follow-up (-1.94 vs -1.63, P = 0.003). The majority of patients reported severe driving disability (CDA: 56.9%, ACDF: 58.0%, P = 0.968) before surgery. After surgery, a greater proportion of patients in the CDA group had neck pain-free driving compared with the ACDF group at 5 (63.3% vs 41.8%, P < 0.001) and 10 years (61.8% vs 41.2%, P = 0.003).

CONCLUSION

In patients with cervical radiculopathy/myelopathy and 2-level disease, CDA provided greater improvements in driving disability as compared with ACDF at 10-year follow-up. This is the first report of its kind. This finding may be attributable to preservation of motion associated with CDA.

CLINICAL RELEVENCE

This study provides valuable information regarding the improvement of driving disability after both CDA and ACDF. It demonstrates that both procedures result in significant improvements, with CDA resulting in even better improvements than ACDF, up to 10 year follow-up.

LEVEL OF EVIDENCE: 3

Improving Assessment of Disease Severity and Strategies for Monitoring Progression in Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 4]

STUDY DESIGN

Narrative Review.

OBJECTIVE

To (i) discuss why assessment and monitoring of disease progression is critical in Degenerative cervical myelopathy (DCM); (ii) outline the important features of an ideal assessment tool and (iii) discuss current and novel strategies for detecting subtle deterioration in DCM.

METHODS

Literature review.

RESULTS

Degenerative cervical myelopathy is an overarching term used to describe progressive injury to the cervical spinal cord by age-related changes of the spinal axis. Based on a study by Smith et al (2020), the prevalence of DCM is approximately 2.3% and is expected to rise as the global population ages. Given the global impact of this disease, it is essential to address important knowledge gaps and prioritize areas for future investigation. As part of the AO Spine RECODE-DCM (Research Objectives and Common Data Elements for Degenerative Cervical Myelopathy) project, a priority setting partnership was initiated to increase research efficiency by identifying the top ten research priorities for DCM. One of the top ten priorities for future DCM research was: What assessment tools can be used to evaluate functional impairment, disability and quality of life in people with DCM? What instruments, tools or methods can be used or developed to monitor people with DCM for disease progression or improvement either before or after surgical treatment?

CONCLUSIONS

With the increasing prevalence of DCM, effective surveillance of this population will require both the implementation of a monitoring framework as well as the development of new assessment tools.

Establishing Diagnostic Criteria for Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 3]

STUDY DESIGN

Narrative review.

OBJECTIVES

To discuss the importance of establishing diagnostic criteria in Degenerative Cervical Myelopathy (DCM), including factors that must be taken into account and challenges that must be overcome in this process.

METHODS

Literature review summarising current evidence of establishing diagnostic criteria for DCM.

RESULTS

Degenerative Cervical Myelopathy (DCM) is characterised by a degenerative process of the cervical spine resulting in chronic spinal cord dysfunction and subsequent neurological disability. Diagnostic delays lead to progressive neurological decline with associated reduction in quality of life for patients. Surgical decompression may halt neurologic worsening and, in many cases, improves function. Therefore, making a prompt diagnosis of DCM in order to facilitate early surgical intervention is a clinical priority in DCM.

CONCLUSION

There are often extensive delays in the diagnosis of DCM. Presently, no single set of diagnostic criteria exists for DCM, making it challenging for clinicians to make the diagnosis. Earlier diagnosis and subsequent specialist referral could lead to improved patient outcomes using existing treatment modalities.

Laminectomy with instrumented fusion vs. laminoplasty in the surgical treatment of cervical ossification of the posterior longitudinal ligament: A multicenter retrospective study

Laminectomy with instrumented fusion (LF) has demonstrated better prevention of ossification of posterior longitudinal ligament (OPLL) growth compared to laminoplasty (LP). There remains uncertainty, however, as to which surgical approach is more beneficial with respect to clinical outcomes and complications. We retrospectively reviewed 273 cervical OPLL patients of more than 3 levels, from the two institutions' databases, who underwent LF or LP between January 1998 and January 2016. Each 273 patient (85 with LF, 188 with LP) was assessed for postoperative neurologic and radiologic outcomes, complications and reoperations. The mean length of follow-up was 40.11 months. There were baseline differences between cohorts. Overall, postoperative JOA recovery rate at last follow up was significantly better in the LP group with similar improvement in visual analog neck score. Postoperative C2-7 Cobb angle was decreased compared to baseline for both LF and LP cohorts, but there was no significant difference between groups. Complications occurred in 19 (22.35%) LF patients, and 11 (5.85%) LP patients, with higher incidence of C5 palsy and instrumentation failure in the LF group. Four LF patients (4.71%) and five LP patients (2.66%) underwent reoperation during the follow up period.

Return to golf after adult degenerative and deformity spine surgery: a preliminary case series of how surgery impacts golf play and performance

Background

Golf is a commonly played sport among older adults, and degenerative and/or deformity spine pathology can severely impact older individuals' ability to play golf. In a cohort of self-identified, avid golfers undergoing degenerative or deformity spine surgery, we report their: (I) presentation, (II) operative treatment, and (III) return-to-play (RTP) process.

Methods

A retrospective case series of self-identified, avid golfers undergoing spine surgery at a single institution from 2015-2019 was undertaken. Demographic, presenting, operative, RTP data, along with numerical rating scale (NRS) pain scores were collected. The first and full RTP time postoperatively, in addition to the following golf metrics: 18-hole rounds per month, handicap, and self-perceived effort/performance were obtained.

Results

A total of 6 golfers were included, 3 undergoing each degenerative and deformity operations. Mean age was 60 years, and 5 of 6 (83%) patients were female. All patients were self-identified, avid golfers with a mean experience of 31 years. Mean preoperative NRS back/neck pain was 9.7, which decreased to 0.8 postoperatively (P<0.001). Players undergoing smaller operations (lumbar fusion/cervical laminoplasty) returned to golf sooner than patients undergoing larger deformity corrections, with a mean first RTP of 4.3 months for degenerative patients vs. 9.7 months among deformity patients. All patients played either the same or more rounds of golf after surgery once they reached full RTP. The handicap of all players improved after surgery to better than before surgery, except for one high-level golfer with a handicap of 9 preoperatively that went to 15 postoperatively following an extensive revision deformity reconstruction.

Conclusions

All patients returned to playing golf at or more frequently than their preoperative status. Degenerative patients returned to play sooner than deformity patients. All patients performed at a higher level after surgery, except for one high-level golfer whose handicap worsened slightly. These data provide baseline information for future prospective studies of golfers undergoing spine surgery.

Surgical management of Diffuse Idiopathic Skeletal Hyperostosis (DISH) causing secondary dysphagia (Narrative review)

Objectives: To summarize the current evidence on surgical treatment for large bridging osteophytes of the anterior cervical spine from Diffuse Idiopathic Skeletal Hyperostosis (DISH). Overview of Literature: In the current review, the surgical treatment of secondary dysphagia from DISH was the most useful treatment. We propose a treatment algorithm for management of this condition because currently there are only case reports and retrospective studies available. Methods: Literature search was performed using the MeSH terms "Anterior Cervical Osteophyte," "Diffuse Idiopathic Skeletal Hyperostosis (DISH)," and "Dysphagia" and "Treatment" for articles published between January 2000 and February 2020. PubMed search identified 117 articles that met the initial screening criteria. Detailed analysis identified the 40 best matching articles, following which the full inclusion and exclusion criteria left 11 articles for this review. Results: Incidence of secondary dysphagia was associated with DISH in elderly patients (average 65 years). The major clinical findings were dysphagia or respiratory compromise, with the most common level of bridging osteophytes of the cervical spine at C3-C5. There were 10 articles on surgical treatment involving anterior cervical osteophytectomy without fusion, 1 for multilevel cervical oblique corpectomy, 1 for anterior cervical discectomy with fusion plus plate, and 1 for anterior cervical osteophytectomy with stand-alone PEEK cage or plus plate. All the cases resulted in significant improvement without recurrence, with only 1 case having post-operative complications. Follow-up duration was 3-70.3 months. Conclusions: Surgical intervention for anterior cervical osteophytectomy appears to result in improved outcomes. However, there could be disadvantages concerning cervical spine motion if cervical osteophytectomy with cervical discectomy and fusion (ACDF) plus plate system is done.

Multilevel anterior cervical osteotomies with uncinatectomies to correct a fixed kyphotic deformity associated with ankylosing spondylitis: technical note and operative video

Ankylosing spondylitis (AS) is an inflammatory disorder leading to ossification of joints and ligaments, resulting in autofusion throughout the spinal column. In patients with fixed, kyphotic cervical deformities, which cause an impaired horizontal gaze and severe neck pain, surgical intervention is warranted. Although several articles have described the anterior and/or posterior surgical treatments used to address the fixed kyphosis, few sources present the key operative steps and technical nuances. The purpose of this technical report was to provide detailed surgical steps, representative photographs, and an operative video demonstrating multilevel anterior cervical osteotomies, uncinatectomies, and a posterior osteotomy for the correction of a fixed cervical deformity secondary to AS.

Hybrid Anterior Cervical Discectomy and Fusion and Cervical Disc Arthroplasty: An Analysis of Short-Term Complications, Reoperations, and Readmissions

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Although cervical disc arthroplasty (CDA) has become a well-established and effective treatment for symptomatic cervical degeneration, many patients with multilevel disease are not good candidates for CDA at all levels. For such patients, hybrid surgery (HS)-a combination of adjacent anterior cervical discectomy and fusion (ACDF) and CDA-may be more appropriate. Given the novelty of HS and the relative dearth of studies adequately assessing short-term perioperative complications, this current study sought to assess the short-term morbidity profile of HS, differences in operative duration, length of stay (LOS), and readmission and reoperation rates and reasons relative to a 2-level ACDF cohort.

METHODS

All patients who underwent HS and 2-level ACDF were identified between 2011 and 2018 using a large, prospectively collected registry. Baseline patient characteristics and postoperative complications were compared using bivariate and/or multivariate analysis.

RESULTS

A total of 390 patients undergoing HS were identified. Two-level procedures were the most common (74.9%). Patients undergoing HS were more likely to be younger, male, and have fewer comorbidities. There were no differences between HS and 2-level ACDF in rates of any postoperative complication, transfusion, readmissions, and operative duration. However, HS had a decreased LOS (0.5 days), relative to a 2-level ACDF. HS patients had low rates of reoperation (1.28%) with 1 case for hematoma evacuation and another for revision CDA.

CONCLUSIONS

This study represents one of the largest cohorts of patients undergoing HS reported to date. Patients undergoing HS are not at increased risk of perioperative complications relative to a 2-level ACDF and may benefit from shorter LOS.

Cervical fusion for treatment of degenerative conditions: development of appropriate use criteria

BACKGROUND CONTEXT

High quality evidence is difficult to generate, leaving substantial knowledge gaps in the treatment of spinal conditions. Appropriate use criteria (AUC) are a means of determining appropriate recommendations when high quality evidence is lacking.

PURPOSE

Define appropriate use criteria (AUC) of cervical fusion for treatment of degenerative conditions of the cervical spine.

STUDY DESIGN/SETTING

Appropriate use criteria for cervical fusion were developed using the RAND/UCLA appropriateness methodology. Following development of clinical guidelines and scenario writing, a one-day workshop was held with a multidisciplinary group of 14 raters, all considered thought leaders in their respective fields, to determine final ratings for cervical fusion appropriateness for various clinical situations.

OUTCOME MEASURES

Final rating for cervical fusion recommendation as either "Appropriate," "Uncertain" or "Rarely Appropriate" based on the median final rating among the raters.

METHODS

Inclusion criteria for scenarios included patients aged 18 to 80 with degenerative conditions of the cervical spine. Key modifiers were defined and combined to develop a matrix of clinical scenarios. The median score among the raters was used to determine the final rating for each scenario. The final rating was compared between modifier levels. Spearman's rank correlation between each modifier and the final rating was determined. A multivariable ordinal regression model was fit to determine the adjusted odds of an "Appropriate" final rating while adjusting for radiographic diagnosis, number of levels and symptom type. Three decision trees were developed using decision tree classification models and variable importance for each tree was computed.

RESULTS

Of the 263 scenarios, 47 (17.9 %) were rated as rarely appropriate, 66 (25%) as uncertain and 150 (57%) were rated as appropriate. Symptom type was the modifier most strongly correlated with the final rating (adjusted ρ2 = 0.58, p<.01). A multivariable ordinal regression adjusting for symptom type, diagnosis, and number of levels and showed high discriminative ability (C statistic = 0.90) and the adjusted odds ratio (aOR) of receiving a final rating of "Appropriate" was highest for myelopathy (aOR, 7.1) and radiculopathy (aOR, 4.8). Three decision tree models showed that symptom type and radiographic diagnosis had the highest variable importance.

CONCLUSIONS

Appropriate use criteria for cervical fusion in the setting of cervical degenerative disorders were developed. Symptom type was most strongly correlated with final rating. Myelopathy or radiculopathy were most strongly associated with an "Appropriate" rating, while axial pain without stenosis was most associated with "Rarely Appropriate."

Cervical disc arthroplasty: What we know in 2020 and a literature review

Cervical disc arthroplasty (CDA) is a safe and effective option to improve clinical outcomes (e.g., NDI, VAS, and JOA) in degenerative cervical disc disease and compressive myelopathy. CDA's two main purported benefits have been that it maintains physiologic motion and thereby minimizes the biomechanical stresses placed on adjacent segments as compared to an ACDF. CDA might reduce the degeneration of adjacent segments, and the need for adjacent-level surgery. Reoperation rates of CDA have been reported to range from 1.8% to 5.4%, with a minimum 5-year follow-up. As the number of CDA procedures performed continues to increase, the need for revision surgery is also likely to increase. When performed skillfully in appropriate patients, CDA is an effective surgical technique to optimize clinical outcomes and radiological results. This review may assist surgical decision-making and enable a more effective and safer implementation of cervical arthroplasty for cervical degenerative disease.

The aiming device for cervical distractor pin insertion: a proof-of-concept, feasibility study

Background

Restoration of cervical lordosis after anterior discectomy and fusion is a desirable goal. Proper insertion of the vertebral distraction or Caspar pin can assist lordotic restoration by either putting the tips divergently or parallel to the index vertebral endplates. With inexperienced surgeons, the traditional free-hand technique for Caspar pin insertion may require multiple insertion attempts that may compromise the vertebral body and increase radiation exposure during pin localization. Our purpose is to perform a proof-of-concept, feasibility study to evaluate the effectiveness of a pin insertion aiming device for vertebral distraction pin insertion.

Methods

A Smith-Robinson approach and anterior cervical discectomy were performed from C3 to C7 in 10 human cadaveric specimens. Caspar pins were inserted using a novel pin insertion aiming device at C3-4, C4-5, C5-6, and C6-7. The angles between the cervical endplate slope and Caspar pin alignment were measured with lateral cervical imaging.

Results

The average Superior Endplate-to-Caspar Pin angle (SE-CP) and the average Inferior Endplate-to-Caspar Pin angle (IE-CP) were 6.2 ± 2.0° and 6.3 ± 2.2° respectively. For the proximal pins, the SE-CP and the IE-CP were 4.0 ± 1.1°and 5.2 ± 2.4° respectively. For the distal pins, the SE-CP and the IE-CP were 7.7 ± 1.4° and 6.2 ± 2.0° respectively. No cervical endplate violations occurred.

Conclusion

The novel Caspar pin insertion aiming device can control the pin entry points and pin direction with the average SE-CP and average IE-CP of 6.2 ± 2.0° and 6.3 ± 2.2°, respectively. The study shows that the average different angles between the Caspar pin and cervical endplate are less than 7°.