- Department of Neurosurgery, Desert Regional Medical Center, Palm Springs, California, United States.
- University of Texas Medical Branch at Galveston, Galveston, Texas, United States,
- School of Medicine, Anahuac Querétaro University, Santiago de Querétaro, México,
- College of Human Medicine, Michigan State University, East Lansing, Michigan, United States.
- William Beaumont School of Medicine, Oakland University, Rochester, Michigan, United States.
- School of Medicine, University of New Mexico, Albuquerque, New Mexico, United States.
School of Medicine, University of New Mexico, Albuquerque, New Mexico, United States.
DOI:10.25259/SNI_165_2021Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Brian Fiani1, Thao Doan2, Claudia Covarrubias3, Jennifer Shields4, Manraj Sekhon5, Alexander Rose6. Determination and optimization of ideal patient candidacy for anterior odontoid screw fixation. 19-Apr-2021;12:170
How to cite this URL: Brian Fiani1, Thao Doan2, Claudia Covarrubias3, Jennifer Shields4, Manraj Sekhon5, Alexander Rose6. Determination and optimization of ideal patient candidacy for anterior odontoid screw fixation. 19-Apr-2021;12:170. Available from: https://surgicalneurologyint.com/surgicalint-articles/10737/
Background: Odontoid process fractures are one of the most common spine fractures, especially in patients over age 70. There is still much controversy over the ideal candidate for anterior odontoid screw fixation (AOSF), with outcomes affected by characteristics such as fracture morphology, nonideal body habitus, and osteoporosis. Therefore, this systematic review seeks to discuss the optimal criteria, indications, and adverse postoperative considerations when deciding to pursue AOSF.
Methods: This investigation was conducted from experiential recall and article selection performed using the PubMed electronic bibliographic databases. The search yielded 124 articles that were assessed and filtered for relevance. Following the screening of titles and abstracts, 48 articles were deemed significant for final selection.
Results: AOSF is often utilized to treat Type IIB odontoid fractures, which has been shown to preserve atlantoaxial motion, limit soft-tissue injuries/blood loss/vertebral artery injury/reduce operative time, provide adequate osteosynthesis, incur immediate spinal stabilization, and allow motion preservation of C1 and C2. However, this technique is limited by patient characteristics such as fracture morphology, transverse ligament rupture, remote injuries, short neck or inability to extend neck, barrel chested, and severe spinal kyphosis, in addition to adverse postoperative outcomes such as dysphagia and vocal cord paralysis.
Conclusion: Due to the fact that odontoid fractures have a significant morbidity in elderly population, treatment with AOSF is generally recommended for this population with higher risk for nonoperative fusion. Considerations should be made to achieve fracture stability and fusion, while lowering the risk for operative and postoperative complications.
Keywords: Cervical fusion, Odontoid fracture, Odontoid screw fixation, Spinal fixation, Traumatic spinal injury
Anterior odontoid screw fixation (AOSF) is a cervical spine surgical procedure that usually utilizes an anteromedial approach to implement one or two screws for fusion of primarily Type II odontoid fractures.[
Approaches to intervention for odontoid fractures have varied from nonoperative management with cervical collar, Minerva, cervicothoracic orthoses, and halo orthosis to operative management such as AOSF or posterior atlantoaxial stabilization.[
However, different parameters must be considered for predicting success of fusion for Type 2 odontoid fractures utilizing the anterior screw fixation approach. For example, displacement <4 mm and those >6 mm have been associated with improved and lowered fusion rates, respectively.[
Determination of appropriate surgical candidates for AOSF must take into account many individual, clinical, and radiological features. Based on current literature, a proposed algorithm for the patient selection process [
Proposed algorithm for the patient selection process to guide treatment of odontoid fractures for use in conjunction with clinical judgment. *Criteria of instability: fracture age greater than or equal to 6 months post-injury, fracture comminution, concomitant disruption of transverse ligament, nonreducible or malaligned fracture, dens displacement greater than or equal to 6 mm, angulation greater than or equal to 10 degrees, or fracture gap greater than or equal to 2 mm. **Criteria for body habitus limitations: fixed cervical or thoracic kyphosis, short neck, or barrel-shaped chest imposing restrictions for proper patient positioning and anterior neck access in AOSF. AOSF, Anterior odontoid screw fixation.
Beyond age, other patient factors, such as comorbidities and functional dependence, bone quality, and especially body habitus, may influence medical suitability for surgery and postoperative outcome and, thus, should be considered when performing a clinical assessment to determine the best treatment approach for odontoid fractures. In patients with significantly reduced bone mineral density, strength, and healing potential, as seen in patients with severe osteoporosis, attaining adequate fixation and fusion are challenging and considered a contraindication given the high possibility for nonunion.[
Postoperative complications may occur as a result of surgical technique that has the potential to affect quality of life. Primarily, these are dysphagia or inability to swallow, as well as damage to the recurrent laryngeal nerve, causing dysphonia or vocal cord paralysis.[
Patients are placed under general anesthesia and positioned supine on the operating table. Anterior-posterior and lateral fluoroscopy are used to visualize the C2 vertebral body, odontoid process, and lateral masses of C1. Reduction is achieved using skull traction and flexion or extension maneuvers to position the head before stabilizing with a halter and assessing with fluoroscopy. The C5-6 level is identified and marked using the thyroid and cricoid cartilage preoperatively, then a transverse skin incision is made. The standard Smith-Robertson method is used to expose the prevertebral space by retracting the carotid sheath laterally and the trachea and esophagus medially. The anterior-inferior margin of C2 is exposed, and a Kirschner wire is drilled down the anterior-inferior edge of C2 to the midline of the dens on the opposite apical cortical bone using fluoroscopy. A guide wire is inserted centrally then a cannulated screw is inserted along the guide wire into the C2 body and posterior odontoid process. Fluoroscopy is used to confirm spinal stability.[
Careful selection of patients is necessary for surgery success. The integrity and grade of atlantal transverse ligament damage must be assessed, because atlantoaxial stability cannot be achieved with a single odontoid screw fixation if the ligament is damaged.[
Current available data have demonstrated that AOSF is a feasible treatment for Type II and shallow Type III odontoid fractures, providing immediate stabilization with high fusion rates and preserved C1-2 rotation [
Higher incidence of nonunion is observed in both fractures that are displaced by more than 6 mm, particularly posteriorly, as well as in geriatric patients.[
AOSF requires appropriate patient selection to minimize morbidity, maximize fusion rates, and avoiding reduction of range of motion. Because odontoid fractures have a significant morbidity in elderly population, treatment with AOSF is generally recommended for this population with higher risk for nonoperative fusion. Contraindications of anterior screw fixation mentioned in the literature include short neck, concomitant thoracic kyphosis, severe osteopenia, barrel chest deformity, disrupted transverse atlantoaxial ligament, and significant cervical kyphosis. Other factors that can be considered as contraindications include an unfavorable fracture plane angulation from anterior caudal to posterior rostral and inability to obtain an anatomical fracture reduction. Considerations should be made to achieve fracture stability and fusion, while lowering the risk for operative and postoperative complications especially those in relation to functionality and quality of life. Future studies, in particular randomized controlled trials and observational studies with larger patient sample size, should be conducted to further clarify appropriate patient selection and operative technique.
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