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Cervical alignment has become increasingly important in the planning of spine surgery. A relationship between the slope of T1 (T1S), the cervical lordosis (CL), and the overall cervical sagittal vertical axis (cSVA) has previously been demonstrated, but the exact nature of this relationship is poorly understood. In this study, we derive theoretical and empirical equations to better understand how T1S and CL affect cSVA. The first equation was developed on a theoretical basis using inherent trigonometric relationships of the cervical spine. By treating the cervical spine as the arc of a circumference, and by taking into account the cervical height (CH), the geometric relationship between theT1S, CL, and cSVA was described via a trigonometric identity utilizing a novel angle δ subtended by the CH and cSVA (δ = T1S-CL/2). The second equation was developed on an empiric basis by performing a multiple linear regression on data obtained from a retrospective review of a large multicenter deformity database. The theoretical equation determined that the value of cSVA could be expressed as: $cSVA\ = \ CH*{\rm{tan}}( {\pi /180*( {T1S - CL/2} )} )$. The empirical equation determined that value of cSVA could be expressed as: $cSVA=({1.1*T1} )\ - ( {0.43*CL} ) + 6.69$. In both, the sagittal alignment of the head over the shoulders is directly proportional to the T1S and inversely proportional to CL/2. These 2 equations may allow surgeons to better understand how the CL compensates for the T1S, to accurately predict the postoperative cSVA, and to customize cervical interbody grafts by taking into consideration each individual patient's specific cervical spine parameters., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: Global sagittal deformity is an established cause of disability. However, measurements of sagittal alignment are often ignored when patients present with symptoms localizing to the cervical or lumbar spine., Objective: To develop scoring scales to predict the risk of sagittal malalignment in patients with only cervical or lumbar spine radiographs., Methods: A retrospective review of a prospectively maintained multicenter adult spinal deformity database was performed. Primary outcome (sagittal malalignment) was defined as a C7 plumbline ≥ 50 mm. Two multivariate logistic regressions were performed using patient characteristics and measurements derived from cervical or lumbar radiographs as covariates. Point scores were assigned to age, body mass index (BMI), and lumbar lordosis or T1 slope by rounding their ß coefficients to the nearest integer., Results: Nine hundred seventy-nine patients were included, with 652 randomly assigned to the derivation cohort (used to build the score) and 327 comprising the validation set. Final cervical score for the primary outcome included BMI ≥ 25 (1 point), age ≥ 55 yr (2 points), and T1 slope ≥ 27o (2 points). Final lumbar score for the primary outcome included BMI ≥ 25 (1 point), age ≥ 55 yr (1 point), and lumbar lordosis ≥ 45o (-1 points). High scores for both the cervical and lumbar spine presented with high specificity and positive likelihood ratios of sagittal malalignment., Conclusion: We developed scoring scales to predict global sagittal malalignment utilizing clinical covariates and cervical or lumbar radiographs. Patients with high scores may prompt imaging with long-cassette plain films to evaluate for global sagittal imbalance., (Copyright © 2017 by the Congress of Neurological Surgeons)

Anterior cervical plate (ACP) failure is rarely addressed in the literature. In this retrospective, observational, longitudinal, cohort study, the objectives were to (1) identify incidences of in vivo biomechanical failure in commercially available, US Food and Drug Administration-approved ACP systems, (2) describe modes of failure, (3) suggest structural explanations for system failure, and (4) discuss complications and treatment of patients with failed ACP systems. Investigators retrospectively identified patients who underwent anterior cervical procedures followed by use of ACP as a fusion adjunct and showed evidence of ACP failure on plain radiographs. Components of the ACP system that led to failure were identified and examined. A total of 240 patients received ACP supplementation of anterior cervical fusion constructs during the 9.5-y study period. Evidence of ACP failure was noted in 7 patients (3.3%), and an eighth patient was referred for evaluation after ACP failure. Screw-plate interface failure occurred in all 8 cases. The biomechanical method by which the bone screw head was secured into the vertebral body, or against the ACP, the use of hybrid systems, the surgical technique selected, and host factors were used to determine the rate of failure. Concern for esophageal or other tissue injury often necessitated ACP removal. Screw-plate interface failure, which was found to be the most common mode of biomechanical ACP failure, may occur in hybrid constructs and in systems that do not create a rigid interface between the screw head and the ACP. Surgical technique and patient host factors may also influence the rate of biomechanical construct failure.

Background Context: Cervical spondylotic myelopathy is a degenerative condition of the cervical spine. Surgical decompression is considered the gold standard of treatment, yet multiple published studies failed to yield consistent clinical results. Properly designed clinical outcomes studies using physiological, functional, and self-reported measures have the ability to define the best intervention for this disease entity. Many validated outcomes measures for cervical spondylotic myelopathy already exist, ranging from the disease-specific Nurick grading scale to the generalized Short Form 36-item (SF-36) questionnaire., Purpose: To review the literature concerning outcome measurements for cervical spondylotic myelopathy., Conclusion: Future research must consistently use a broad array of outcome assessments to elucidate the correct utilization of surgical decompression for this disease entity.

Background Context: Iatrogenic injury to the vertebral artery during an anterior cervical decompression is a rarely mentioned but potentially catastrophic complication., Purpose: This study was designed to examine the incidence and management of iatrogenic vertebral artery injury (IVAI) in a large database., Study Design/setting: This was a retrospective study performed at a large teaching institution over a 7-year period (1994-2001)., Patient Sample: All anterior cervical spinal procedures performed for herniated or degenerative disc disease, or cervical spondylosis were identified, as were incidences of IVAI. Anterior cervical procedures performed for trauma, neoplasia, or infection were excluded from this study., Outcome Measures: Neurological and associated morbidity as well as mortality were recorded., Methods: Data were accessed through an institution-wide electronic medical record search through the operative reports of 10 spine surgeons. Hospital and clinical charts of IVAI cases were subsequently reviewed. Demographic data and intraoperative strategies for repair were recorded., Results: A total of 1,976 patients underwent anterior cervical spinal procedures in the review period. Six cases of IVAI were identified. In three of the six patients, arterial bleeding was controlled with hemostatic agents. Of these three, two suffered complications. The initial management of controlling arterial bleeding is by hemostatic agents; however, one must also consider repair or ligation. The remaining three patients were treated with primary repair or ligation, and no complications were noted., Conclusions: IVAI is a rare complication (0.3%) of anterior cervical procedures. The arterial bleeding can usually be controlled with topical hemostatic agents, but mortality may occur in instances where it cannot be adequately addressed in a timely fashion.

This retrospective, case-controlled pilot study was designed to examine the efficacy and safety of an implantable direct current bone growth stimulator (IDCBGS) as an adjunct to cervical arthrodesis in patients at high risk for nonunion after undergoing cervical fusion in region from the occiput to C3. Twenty patients underwent para-axial cervical arthrodesis (involving posterior spine fusion and instrumentation using standard surgical techniques) for the correction of instability. All were at high risk for nonunion due to advanced age, rheumatoid arthritis, prior failed fusion attempts, infection, or immunosuppressive drug use. An IDCBGS was used to augment the surgical procedure. The mean follow-up period was 19 months, and 16 patients were available for follow-up. Radiographic evidence of fusion was demonstrated in 15 of 16 patients (94%). After surgery, all patients demonstrated clinical stabilization, a resolution of symptoms in combination with an improvement in neurologic status, or both. The mean elapsed time before fusion occurred was 4.6 months. No neurologic complications related to cathode or generator placement were observed. The use of the stimulator as an adjunct to instrument- or non-instrument-assisted surgical fusion of the para-axial region in these high-risk patients appeared both safe and efficacious. Further investigation is warranted to define the possible role and clinical utility of the IDCBGS in selected patients requiring cervical fusion, particularly those at high risk for nonunion.

Background: Occipital condyle fractures (OCFs) have been reported in up to 4-16% of individuals suffering cervical spine trauma. The current management of OCF fractures relies on a rigid cervical collar for 6 weeks or longer. Here, we calculated the rate of acute and delayed surgical intervention (occipitocervical fusion) for patients with isolated OCF who were managed with a cervical collar over a 10-year period at a single institution. Methods: This was a retrospective analysis performed on all patients admitted to a Level 1 Trauma Center between 2008 and 2018 who suffered traumatic isolated OCF managed with an external rigid cervical orthosis. Radiographic imaging was reviewed by several board-certified neuroradiologists. Demographic and clinical data were collected including need for occipitocervical fusion within 12 months after trauma. Results: The incidence of isolated OCF was 4% (60/1536) for those patients admitted with cervical spine fractures. They averaged 49 years of age, and 58% were male falls accounted for the mechanism of injury in 47% of patients. Classification of OCF was most commonly classified in 47% as type I Anderson and Montesano fractures. Of the 60 patients who suffered isolated OCF that was managed with external cervical orthosis, 0% required occipitocervical fusion within 12 months posttrauma. About 90% were discharged, while the remaining 10% sustained traumatic brain/orthopedic injury that limited an accurate neurological assessment. Conclusion: Here, we documented a 4% incidence of isolated OCF in our cervical trauma population, a rate which is comparable to that found in the literature year. Most notably, we documented a 0% incidence for requiring delayed occipital-cervical fusions. [ABSTRACT FROM AUTHOR]