Anterior Odontoid Screw Fixation Research Articles

Surgeon Experience Is the Most Important Predictor of Case Failure Rate for Anterior Odontoid Screw Fixation: A Large Database Study.

Retrospective database analysis. Determine risk factors and failure rate of anterior odontoid screw fixation surgery. Anterior odontoid screw fixation (AOSF) stabilizes type II dens fractures while preserving cervical motion. Despite having potential advantages, AOSF's failure rate and factors contributing to failure remain unknown. We identified AOSF patients in the national claims database Pearldiver using CPT code 22318. Failure was defined as the requirement of supplementary posterior fusion surgery in the C1-C2 or occiput-C2 region after the AOSF. We considered potential predictors of failure including age, sex, Charlson Comorbidity Index (CCI), surgeon experience, history of osteoporosis, obesity, and tobacco use. Univariate comparison analysis and logistic regression were conducted to identify factors associated with the need for additional posterior surgery. For 2008 identified cases of AOSF, 249 cases (12.4%) required additional posterior fusion. Seventy-one of the 249 cases (28.5%) underwent revision surgery on the same day as the AOSF. Over 86% of revisions (215 cases) occurred within 200 days of the initial procedure. Posterior fusion rates are inversely correlated with surgeon experience, with the most experienced surgeons having a rate of 10.0%, followed by 11.5% for moderately experienced surgeons, and 15.0% for the least experienced surgeons. When comparing moderate and inexperienced surgeons to experienced surgeons, the odds ratios for posterior fusion were 1.18 (P>0.05) and 1.61 (P<0.006), respectively. Logistic regression revealed that both lesser experience (odds ratio=1.50) and osteoporosis (odds ratio=1.44) were the only factors significantly associated with failure (P<0.05). Our findings indicate a correlation between AOSF success and surgeon experience. While currently published results suggest higher success rates, most of this data originates from experienced surgeons and specialized centers, therefore, they may not accurately reflect the failure rate encountered in a more general practice setting. Level III.

Mortality in ASIA Impairment Scale grade A to D Patients With Odontoid Fracture and Magnetic Resonance Imaging Evidence of Spinal Cord Injury.

Odontoid fractures are common, often presenting in the elderly after a fall and infrequently associated with traumatic spinal cord injury (tSCI). The goal of this study was to analyze predictors of mortality and neurological outcome when odontoid fractures were associated with signal change on magnetic resonance imaging (MRI) at admission. Over an 18-year period (2001-2019), 33 patients with odontoid fractures and documented tSCI on MRI were identified. Mean age was 65.3 years (standard deviation [SD] = 17.2), and 21 patients were male. The mechanism of injury was falls in 25 patients, motor vehicle accidents in 5, and other causes in 3. Mean Injury Severity Score (ISS) was 40.5 (SD = 30.2), Glasgow Coma Scale (GCS) score was 13 (SD = 3.4), and American Spinal Injury Association (ASIA) motor score (AMS) was 51.6 (SD = 42.7). ASIA Impairment Scale (AIS) grade was A, B, C, and D in 9, 2, 3, and 19 patients, respectively. Mean intramedullary lesion length was 32.3 mm (SD = 18.6). The odontoid peg was displaced ventral or dorsal in 15 patients. Twenty patients had surgical intervention: anterior odontoid screw fixation in 7 and posterior spinal fusion in 13. Eleven (33.3%) patients died in this series: withdrawal of medical care in 5; anoxic brain injury in 4; and failure of critical care management in 2. Univariate logistic regression indicated that GCS score (p < 0.014), AMS (p < 0.002), AIS grade (p < 0.002), and ISS (p < 0.009) were risk factors for mortality. Multi-variate regression analysis indicated that only AMS (p < 0.002) had a significant relationship with mortality when odontoid fracture was associated with tSCI (odds ratio, 0.963; 95% confidence interval, 0.941-0.986).

Anterior Screw Fixation for Odontoid Fractures - A Case Series.

Fractures of the odontoid process are common cervical spine injuries, accounting for 10-20% of all cervical spine fractures. Anterior screw fixation of odontoid fractures is an osteosynthetic technique that can give immediate stability and preserve normal mobility. The study was conducted in Government Mohan Kumaramangalam Medical college in the period 2017-2020. Five patients with Anderson and D'Alonzo type II odontoid Fractures were included in the study. Through anterior approach, using a horizontal skin incision, a K wire is inserted from the inferior edge of C2 through the incision and impacted into the odontoid process. A cannulated screw with non-threaded proximal shaft is inserted and tightened firmly to allow the distal fragment to compress on the body of C2. All the patients were reviewed postoperatively at 3, 6, and 12 months. Out of the five patients, all the patients had successful anatomical union at the end of 16 weeks. No neurological sequelae were reported. Anterior screw fixation provides a reasonable approach to odontoid fractures. Posterior stabilization using multiple techniques has been described with good union rates but has several disadvantages. Anterior screw fixation provides direct fracture fixation without the need for bone grafts. In addition, it reduces post-operative discomfort and length of hospital stay. Anterior odontoid screw fixation was associated with relatively low complication rates and a high union rate in our study. We conclude that this shall be the preferred treatment method for Type II odontoid fractures.

A True Percutaneous Anterior Odontoid Screw Fixation: The Results of 42 Cases by a Single Surgeon

This study aimed to analyze a clinical series of odontoid fractures treated with true percutaneous anterior odontoid screws. The technique we used is different from the traditional approach of using blunt dissection to arrive at the anterior surface of the vertebral body. Between 2004 and 2021, forty-two patients underwent anterior screw fixation of the odontoid process using the true percutaneous technique without dissection among the fascial planes. Instead, we pressed from the medial border of the sternocleidomastoideus muscle with our second and third fingers to feel the vertebrae under the skin. Thus, the carotid artery is pushed laterally, the trachea-esophageal complex is moved medially, and when no esophagus, great vessels, etc., can be felt under our fingers; we have reached the anterior surface of the spine. Advancing the Jamshidi needle between the fingers causes it to pass only through the fascial layers. The absence of a gap between the dilatation tubes prevents any tissue from escaping into the tubes. We had no intraoperative complications, such as esophageal, tracheal, or carotid injury. One patient required screw revision. In total, 5 patients died during the follow-up period, and 3 were lost to follow-up. There was no residual neck pain in our cohort, and no instability was noted on flexion-extension radiographs, even in ten patients without solid bone fusion. True percutaneous anterior odontoid screw fixation is a safe and reliable procedure for treating odontoid fractures. The fibrous union of odontoid fractures provides as much stability as a solid bone fusion.

Reevaluation of a classification system: stable and unstable odontoid fractures in geriatric patients—a radiological outcome measurement

ObjectivesWe carried out a retrospective cohort study to differentiate geriatric odontoid fractures into stable and unstable and correlated it with fracture fusion rates. Results are based on the literature and on our own experience. The authors propose that the simple Anderson and D’Alonzo classification may not be sufficient for geriatric patients.MethodsThere were 89 patients ≥ 65 years who presented at our institution with type II and III odontoid fractures from 2003 until 2017 and were included in this study. Each patient was categorized with CT scans to evaluate the type of fracture, fracture gap (mm), fracture angulation (°), fracture displacement (mm) and direction (ventral, dorsal). Fractures were categorized as stable [SF] or unstable [UF] distinguished by the parameters of its angulation (< / > 11°) and displacement (< / > 5 mm) with a follow-up time of 6 months.SFs were treated with a semi-rigid immobilization for 6 weeks, UFs surgically—preferably with a C1–C2 posterior fusion.ResultsThe classification into SFs and UFs was significant for its angulation (P = 0.0006) and displacement (P < 0.0001). SF group (n = 57): A primary stable union was observed in 35, a stable non-union in 10, and an unstable non-union in 8 patients of which 4 were treated with a C1/2 fixation. The overall consolidation rate was 79%. UF group (n = 32): A posterior C1–C2 fusion was carried out in 23 patients, a C0 onto C4 stabilization in 7 and an anterior odontoid screw fixation in 2. The union rate was 100%. Twenty-one type II SFs (91%) consolidated with a nonoperative management (P < 0.001). A primary non-union occurred more often in type II than in type III fractures (P = 0.0023). There was no significant difference in the 30-day overall case fatality (P = 0.3786).ConclusionTo separate dens fractures into SFs and UFs is feasible. For SFs, semi-rigid immobilization provides a high consolidation rate. Stable non-unions are acceptable, and the authors suggest a posterior transarticular C1–C2 fixation as the preferred surgical treatment for UFs.Level of evidenceLevel III.

Full-Endoscopic Anterior Odontoid Screw Fixation: A Novel Surgical Technique.

ObjectiveFirst, to propose a novel minimally invasive technique of full‐endoscopic anterior odontoid fixation (FEAOF) that aims to reduce the risk of retropharyngeal approach (both open and percutaneous techniques) to anterior odontoid screw fixation. Second, to describe steps of the procedure and, lastly, to report the initial outcomes in patients treated with this novel technique.MethodsFour non‐consecutive patients who were diagnosed with a displaced odontoid fracture (Anderson‐D'Alonzo classification type II and Grauer subclassification type A or B) from 2019 to 2020 underwent surgical fixation by our novel technique for anterior odontoid screw fixation. A detailed technical approach of FEAOF for the surgical treatment of type II odontoid fractures was described, and the patients' outcomes based on postoperative radiographic results including computed tomography (CT), clinical outcome parameters including visual analogue scale (VAS) for neck pain both preoperatively and at postoperative follow‐up, and range of neck motion at the final follow‐up were reported.ResultsThe mean age was 33.5 years (24–41), three patients were male. The mean operative time was 93.75 min, and the mean blood loss was 7.5 ml. An immediate post‐operative thin‐sliced CT showed that all patients achieved satisfactory reduction and proper screw position. No screw malposition or penetration was found. At a 6‐month follow‐up, a thin‐sliced CT demonstrated solid bony union in every case. The mean VAS for neck pain was reduced from 6.5 to 0.6 at the 6‐months follow‐up. At the final follow‐up, all patients showed improvement in ranges of motion without any complications; however, one patient was lost to follow‐up.ConclusionsFEAOF is a feasible and effective option for treating type II odontoid fractures. The procedure is less invasive than other techniques and provides clear direct visualization of the involved structures.

O-Arm Assisted Anterior Odontoid Screw Fixation in Type II and Rostral Type III Odontoid Fractures: Single Center Surgical Series of 50 Patients.

Accuracy of screw placement is one of the important factors necessary for adequate union in odontoid fractures with malposition rates as high as 27.2% with standard techniques. To evaluate efficacy of intraoperative O-arm assistance in improving accuracy of anterior odontoid screw placement and clinco-radiological outcome in type II and III odontoid fractures. In this retrospective study, surgery consisted of anterior odontoid screw fixation under intraoperative O-arm assistance over 5 years. Demographical, clinical, radiological, operative details and postoperative events were retrieved from hospital database and evaluated for fusion and surgical outcome. 50 patients (Mean age 34.6 years, SD 14.10, range: 7-70 years; 44 males and 6 females) with Type II and Type III odontoid fracture underwent O-arm assisted anterior screw placement. The mean interval between injury and surgery was 12 days (range 1-65 days). Mean operating time was 132.2 min ± SD 33.56 with average blood loss of 93 ml. ±SD 61.46. With our technique, accurate screw placement was achieved in 100% patients. At the mean follow-up of 26.4 month (SD13.75), overall acceptable fusion rate was 97.8% with non-union in 2.2% patients. Morbidity occurred in two patients; one patient developed fixation failure while other patient had nonunion which was managed with posterior C1-C2 arthrodesis. We had surgical mortality in one patient due to SAH. So overall our procedure was successful in 94% patients and among patients whose follow-up was available, acceptable fusion rates of 97.8% were achieved. We conclude that use of intraoperative three-dimensional imaging using O-arm for anterior odontoid screw fixation improves accuracy and leads to improved radiological and clinical outcomes. It further enables us to extend the indications of odontoid screw fixation to selected complex Type II and rostral Type III odontoid fractures.

An experience with Goel-Harms C1-C2 fixation for type II odontoid fractures.

ABSTRACTObjective:Type II odontoid fractures need surgical stabilization for disabling neck pain and instability. Anterior odontoid screw fixation is a well-known technique. However, certain patients require posterior fixation. We present our surgical results and experiences with nine cases managed by the Goel-Harms technique.Materials and Methods:This is a retrospective review of nine patients operated on between January 2019 and December 2021 for Type II odontoid fractures with posterior fixation technique. Their clinical profile was collected from case files. The radiological data were retrieved from radiology archives. The indications for surgery were instability and refractory neck pain. The surgical decision for posterior fixation was guided by fracture morphology.Results:The mean age of presentation was 37.22 ± 9.85 years. Seven patients had Type II, and two had Type IIa odontoid fracture. All patients presented with unbearable neck pain. One patient had a quadriparesis. The fracture line was anterior-inferior sloping in six, posterior-inferior sloping in two, and transverse in one case. The anterior-posterior displacement of fracture ranged from 0 to 7 mm (mean 2.44 ± 2.18 mm). Partial transverse ligament tear without the Atlanto Axial Dislocation was present in three patients. The C1-C2 joint distraction was required in five cases. C1-C2 joint spacer was required in two cases. Following surgery, neck pain was relieved in all cases. Complete fracture alignment was achieved in eight patients. There were no postoperative complications. At the mean follow-up of 16.22 ± 9.61 months, there was no implant failure.Conclusions:Posterior C1-C2 fixation by the Goel-Harms technique is an excellent alternative to anterior fixation in selected cases.

Multi-holed biplane drill guide-assisted percutaneous anterior odontoid screw fixation.

The use of percutaneous anterior screw fixation for odontoid fractures has been widely reported. Because the anatomical characteristics of the odontoid and the screw occupy three-dimensional space, it is challenging to establish the screw trajectory quickly and correctly during the operation. The purpose of this study was to introduce a multi-holed biplane drill guide that can be used to optimize the guide needle trajectory in percutaneous anterior odontoid screw fixation. Twenty-one patients with type II or rostral type III odontoid fractures were treated with percutaneous anterior single screw fixation. Of these, 12 patients had an unsatisfactory initial guide needle position. A drill guide was used to provide a variety of guide needle tracks. All 12 patients successfully underwent guided screw placement without vascular or neurological complications. Postoperative X-ray and/or CT scans showed that the internal fixation position was satisfactory. At the end of the follow-up period, all patients exhibited bony union without loosening or fractures of the internal fixation. With the imperfect initial position of the guide needle as a reference, the multi-holed biplane drill guide can provide a variety of needle trajectory options in the sagittal and coronal planes for percutaneous anterior odontoid screw fixation. The operator can quickly obtain the ideal guide needle trajectory.

Determinants of health-related quality of life in patients with fracture of the axis vertebrae

The study is designed to evaluate quality of life and functional performance in patients with type II and III odontoid fracture treated with anterior odontoid screw fixation. We investigated the relationship between quality of life and: (1) the range of axial rotation of the cervical spine, (2) neck pain intensity, and (3) level of disability in these patients. The study involved 60 patients operated on for type II and III fractures with the use of direct osteosynthesis of the dens. Quality of life and functional performance were assessed using SF-36 Questionnaire and Neck Disability Index (NDI). The range of axial rotation was examined with the use of the Zebris ultrasound system while the intensity of pain with the use of the VAS Visual Analog Pain Scale. The subjects’ quality of life was poorer with respect to the mental dimension (32.3%) compared to the physical dimension (22.7%). Based on the NDI survey, the rate representing the patients’ functioning in daily life amounted to 13.7% which reflects mild limitations in functional abilities. It was shown that the range of axial rotation (both to the right and the left) was not related to the degree of disability of patients as measured by the NDI questionnaire. The model of regression was statistically significant for overall quality of life (F = 48.24 p < 0.001), as well as physical dimension (F = 45.1 p < 0.001). Quality of life indicators in SF-36 are decreased in patients operated for type II and III odontoid fracture and the mental dimension of the quality of life is significantly poorer than the physical one. More than half of the patients operated for type II and III odontoid fracture regained normal functioning, as assessed with the NDI questionnaire.

Anterior Odontoid Screw Fixation for Pediatric and Adolescent Odontoid Fractures: Single-Center Experience Over a Decade

Management of pediatric odontoid fractures is tricky and controversial. This study will enrich world literature with intricacies of anterior odontoid screw (OS) fixation in the pediatric population learned over the last decade. In this retrospective study, all patients with pediatric odontoid fracture who underwent anterior odontoid screw fixation from January 2010 to December 2019 were included and evaluated for surgical outcome. Thirteen patients were included in this study (mean age, 15 years; range, 6-18 years; male/female, 11:2; type II, 10; type IIA, 1; type III, 2). Common causes of injury were motor vehicle accidents (61.5%) followed by fall from height (38.5%) and all were acute fractures (2-30 days). Five patients had neurologic deficits. Accurate placement of screw was achieved in 92.3% of patients, including all 9 patients who used intraoperative O-arm. K wire migration during bicortical drilling resulted in neurovascular injury, with 1 mortality (7.7%). The remaining 12 patients were available for follow-up (mean, 36 months; range, 20-72 months) and all had preservation of neck movements. Successful OS fixation was achieved in 84.6% of patients, including 1 patient (7.7%) who had a fibrous union. One patient (8.3%) had nonunion because of migration of the screw head in the C2 body. Anterior odontoid screw fixation in the pediatric population provides good functional outcomes with instant fixation by direct osteosynthesis. However, the surgeon should be meticulous in the surgical approach and should achieve a lag effect. The surgeon should stop after engaging the outer cortex of the odontoid peg with K wire to avoid cranial migration. Intraoperative O-arm guidance is useful.

Anterior Odontoid Screw Fixation for C2 Fractures: Surgical Nuances, Complications, and Factors Affecting Fracture Union

Type II odontoid fractures are the commonest C2 fractures. The management of dens fractures remains controversial with various radiological and fracture morphological factors affecting the approach and outcomes. All cases of anterior odontoid screw fixation between 2010 and 2020 were retrospectively analyzed. Patients' clinical, radiological (type of fracture, orientation, displacement, and diastasis), operative (single vs. double screw) and follow-up records were documented. The postoperative imaging findings were classified into grades I (excellent), II (good), and III (poor) based on the anatomical alignment with the screw. Follow-up cervical computed tomography was reviewed for fracture union. A total of 49 patients with a mean age of 37.3 ± 13.8 years were included in the study. The average time from injury to surgery was 23.1 ± 22.2 days. The bicortical screw purchase and superoposterior odontoid tip breach significantly affected the postoperative alignment (P= 0.035 each). Fracture union was noted in 41 (83.7%) patients. The horizontal fracture displacement ≥2.5 mm (P= 0.02) and poor postoperative fracture alignment (P < 0.001) resulted in worse fracture union rates. Transient dysphagia was the commonest complication (n= 12), whereas screw breakout (n= 2) and pullout (n= 2) were other hardware-related complications. One patient underwent re-exploration for screw readjustment and 2 underwent posterior instrumentation. Anterior odontoid screw fixation is technically straightforward, less morbid, and preserves biomechanical cervical mobility, when compared with the posterior instrumentation. With careful patient selection, meticulous surgical planning, and intraoperative image-guided screw insertion, good fracture union outcomes can be obtained. In the current study, we were able to achieve stable fracture union in 83.7% patients.

Atlantoaxial Dislocation: Surgical Outcome following Anterior Retropharyngeal Approach to Odontoid with or without Fixation

Abstract Introduction Atlantoaxial dislocation (AAD) refers to a loss of stability between the atlas and axis vertebra. The conventional transoral approach and the anterior retropharyngeal approach (ARPA) are adequate for the upper cervical vertebral segments. This study was undertaken to evaluate the usefulness of the ARPA to the odontoid in patients of AAD. Materials and Methods The study was undertaken on 20 patients admitted in Nil Ratan Sircar Medical College and Hospital, Kolkata, India, with functional disability secondary to AAD. These patients underwent surgery through ARPA to odontoid with or without fixation. Patients were analyzed between October 2014 and September 2016. Results Maximum number of patients belonged to third decade of life. The male to female ratio was 1.5. The mean duration of symptoms was 10.86 months. Weakness of the upper and lower limbs predominated. About 65% patients had axial neck pain. Nine patients (45%) in total had difficulty in either bowel or bladder. Five patients presented with fracture odontoid and pannus formation of the odontoid process, while six had basilar invagination. One patient underwent anterior odontoid screw fixation and the other 19 patients underwent anterior retropharyngeal odontoidectomy with posterior fixation. Two patients expired in the present study. Most of the patients had improvement in Nurick grade during follow-up. Five patients had transient throat pain and dysphagia. Three patients had superficial surgical site infection. One patient had postoperative cerebrospinal fluid leak. Conclusion The ARPA to odontoid is a feasible approach for decompression and fixation of the odontoid in AAD cases.

Determination and optimization of ideal patient candidacy for anterior odontoid screw fixation.

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.

PICA injury secondary to anterior odontoid screw fixation: Case report of an exceptional complication

BackgroundOdontoid fracture is a common injury in the upper cervical spine that can sometimes be managed by anterior odontoid screw fixation. Case descriptionWe report the first case of iatrogenic postero-inferior cerebellar artery (PICA) injury while performing anterior odontoid screw fixation for a type II odontoid fracture in a 22-year-old man. Fisher grade 4 subarachnoid hemorrhage secondary to iatrogenic pseudoaneurysm formation was managed by the endovascular neuroradiologist. Odontoid fracture was then managed posteriorly using Harm's technique. Postoperative 12-month follow-up revealed good clinical and radiological results. CT scan showed fusion. Complete exclusion of the pseudo aneurysm with a mild stroke in the inferior left cerebellar hemisphere were noted on the MRI. There were no cerebellar ataxia or swallowing disorders. ConclusionTo the best of our knowledge, this is the first case report of iatrogenic PICA injury in anterior odontoid screw fixation. The patient was well managed in our institution within a multidisciplinary team. We recommend that surgical management of odontoid fractures should be performed in expert centres.

Endoscopic Anterior Odontoid Screw Fixation for the Odontoid Fracture: A Cadaveric Pilot Study.

Introduction:Anterior odontoid screw fixation technique for specific types of odontoid fracture has been proven to be an effective, yet challenging procedure because of threatened damage to the structures in the vicinity. There are few articles suggesting the role of percutaneous and endoscopic technique as an alternative approach to the standard microscopic way. This is the first cadaveric study using existing “EASY GO” endoscopic system-assisted odontoid screw placement.Study Design:This was a cadaveric study.Objective:The objective of the study is to use the endoscope as a safer minimally invasive approach than the standard microscopic anterior approach to odontoid.Methodology:This is a pilot study on 10 fresh-frozen formalin-fixed adult human cadavers. The cadaver was positioned in a way to simulate reduced odontoid fracture. Tubular dilators were used to dock at C2–3 disk space after identifying the landmarks through the microscopic method. The EASY GO endoscopic system was then introduced, and a handheld drill was used to mark the entry point and pass the K-wire through the planned trajectory.Results:No vascular or adjacent vital structures' injury was observed in any of the cadavers. The initial difficulty in attaining the alignment was overcome by the appropriate positioning of the scope.Conclusions:Endoscopic-assisted technique for odontoid screw fixation shall provide a minimally invasive, safe, and easy surgery.

A new tool in percutaneous anterior odontoid screw fixation

BackgroundPercutaneous anterior odontoid screw fixation for odontoid fractures remains challenging due to the complex anatomy of the craniocervical junction. We designed a new guide instrument to help with the placement of guide wire, which have achieved satisfying surgical results. The objective of this study is to evaluate the safety and efficacy of this new tool in percutaneous anterior odontoid screw fixation.MethodsTwenty-nine patients with odontoid fracture were retrospectively evaluated. All patients underwent percutaneous anterior odontoid screw fixation with the traditional guide instrument (n = 13) or the new guide instrument we designed (n = 16). The following clinical outcomes were compared between the two groups: operation time, radiograph times, incision length, blood loss, postoperative hospitalization, postoperative complications, bony union, fixation failure, and reoperation. Radiographs or CT scans were performed at 3, 6 and 12 months after surgery.ResultsThere were no significant differences in preoperative demographic data between the two groups. The operation time (56.62 ± 8.32 Vs 49.63 ± 7.47, P = 0.025) and radiograph times (26.54 ± 6.94 Vs 20.50 ± 5.02, P = 0.011) of the designed guide instrument group were significantly lower than those of the traditional guide instrument group. There were no significant differences in incision length (16.08 ± 3.07 Vs 15.69 ± 2.73, P = 0.720), blood loss (16.08 ± 4.96 Vs 17.88 ± 5.98, P = 0.393), postoperative hospitalization (7.15 ± 1.91 Vs 6.88 ± 2.36, P = 0.734), postoperative complications (7.7% Vs 12.5%, P = 1), and bony union (92.3% Vs 93.8%, P = 1) between the two groups. No fixation failure or reoperation occurred in either group.ConclusionsThe top of our designed guide instrument is a wedge-shaped tip with 30° inclination, which has a large contact area with the anterior surface of the cervical vertebra. According to our retrospective study, the guide instrument can reduce the operation time and radiograph times. It has potential clinical value, which needs further testing with a higher level of research design.

Can The Fracture Line of Type II Odontoid Fractures Come to A Neutral Position After Anterior Odontoid Screw Fixation without a Manipulation?

To examine whether there was an improvement in the displaced fracture line in the follow-up, in which Anterior odontoid screw fixation (AOSF) was performed without manipulation and to determine the "displacement angle range" in which AOSF was possible. A total of 11 patients with the diagnosis of type II odontoid fracture who underwent AOSF without manipulation were analyzed retrospectively. A control group of 30 cases was formed and odontoid related angle measurements were performed on cervical computed tomographies (CT) of the control group and the patients who were operated. In 6 of 7 cases in the posterior-displaced group along with all cases in the anterior-displaced group, it was determined that the displacement angles returned to the normal range in the 1st year follow-up. In 1 case having posterior displacement with posterior longitudinal ligament (PLL) damage, it was observed that the displacement angle improved to the normal range significantly, but the displacement continued. AOSF is a minimally invasive, safe and effective method in patients with displaced type II odontoid fracture, which is between the median odontoidobasal angle range of 100°-134°, whose PLL is preserved, and which cannot be manipulated.

Direct Anterior Screw Fixation for a Pediatric Odontoid Fracture with Associated Skull Fracture: A Case Report

The upper cervical spine remains the most susceptible region for spinal trauma in children, with odontoid fractures being the most common ones in this age group. Concomitant traumatic brain injuries or skull fractures can pose therapeutic challenges in such cases. We report a case of an 11-year-old boy who presented in the semiconscious state with a deep scalp laceration in the left frontoparietal region. A computed tomography (CT) scan revealed a depressed skull fracture requiring an emergency left frontoparietal decompressive craniectomy and an associated fracture of the odontoid process at the base with anterior displacement. Odontoid fractures usually heal well after immobilization, and the use of instrumented fusion is still debated in view of skeletal immaturity. The usual management of Halo vest could not be instituted in his case owing to the skull fracture, and a single cannulated screw fixation was done under fluoroscopic guidance. Direct operative fusion of the odontoid process has been described in younger children with apophyseal fractures, but the evidence of such procedures is rare in elder children with a fused odontoid process. This case report, thus, confirms the anterior odontoid screw fixation as an effective mode of treatment in children of the 7- to 12-year age group.

A Technique for the In Vivo Study of Three-dimensional Cervical Segmental Motion Characteristics After Anterior Screw Fixation for Odontoid Process Fractures.

Kinematics of the cervical spine was investigated using cone beam computed tomography (CBCT) images combined with three dimensions to three dimensions (3D-3D) registration technology in patients after anterior odontoid screw fixation (AOSF) surgery. The aim of this study was to investigate in vivo 3D cervical motion characteristics of patients who had undergone AOSF surgeries. AOSF surgery is a classic surgical method for the treatment of odontoid fracture, but there are few studies that investigated its effect on in vivo biomechanics of the cervical spine. Postoperative biomechanical characters of the atlantoaxial joint (C1-C2) and the caudal adjacent segment (C2-C3) have yet to be clarified. The study involved 14 patients subjected to a procedure of AOSF with lag screw. Subjects were matched with 14 healthy controls. All subjects underwent CBCT scanning of the cervical spine under seven functional positions. A 3D-3D registration was performed for each vertebra at each functional position to calculate the segmental motion characteristics. The ranges of motion (ROMs) of the C1-C2, C2-C3, and the overall cervical spine (C1-C7) for each of the functional positions were determined. The ROMs of the AOSF group were significantly (P < 0.05) smaller than the control group in flexion-extension positions for the C1-C2 (7.0°vs.11.0°), C2-C3 (3.7°vs.6.7°) and C1-C7 (43.3°vs.54.4°). The twisting ROM of the C1-C2 was 39.3° in the AOSF group and 65.7° in the control (P < 0.05), the bending ROM of the C2-C3 was 2.8° in the AOSF group and 8.9° in the control (P < 0.05). The twisting ROM of C1-C7 segment was 63.2° for the AOSF and 98.1° for the healthy control groups (P < 0.05). Although AOSF surgery reduced the flexion-extension ROMs of all investigated spinal segments, additionally, it reduced twisting ROMs of C1-C2 and C1-C7, but only lateral bending ROM of C2-C3, when compared with the control group. The data implied that the AOSF surgery would result in different biomechanics changes in the atlantoaxial segment and caudal adjacent segment. Longer-term follow-up studies of larger patient cohorts are necessary to evaluate the clinical outcomes of patients after the AOSF surgery.Level of Evidence: 3.