Reference ranges for atlantodental interval in adults and its variation with age and gender in a large series of subjects on multidetector computed tomography

Navigated Osteosynthesis for Unstable Atlas Fractures: Technical Note and Case Series

OBJECTIVE

Fractures of the atlas are typically considered stable or unstable based on the integrity of the transverse ligament. Whereas stable Jefferson burst fractures can be treated nonoperatively, unstable fractures with disruption of the transverse ligament often require surgical intervention. Atlas osteosynthesis has been proposed as a motion-preserving alternative to atlantoaxial fusion. Intraoperative navigation may facilitate safe placement of C1 instrumentation.

METHODS

Cases of patients with unstable atlas fractures treated with navigated osteosynthesis at a single level I trauma center were identified and retrospectively reviewed. Clinical presentation, surgical management, and postoperative outcomes were assessed.

RESULTS

Eight patients underwent navigated posterior atlas osteosynthesis for unstable C1 fractures between December 2015 and January 2024. All patients demonstrated injury to the transverse ligament (Dickman type I [n = 1] and type II [n = 7]). Patients were followed with serial radiographs showing preserved alignment, with no significant change in postoperative atlantodental interval at the most recent follow-up (+0.2 ± 0.87 mm [mean change ± standard deviation]; P = 0.53). Six patients obtained follow-up computed tomography, all of which demonstrated evidence of osseous union across fractures without hardware complication. No patients developed postoperative instability requiring fusion.

CONCLUSIONS

Atlas osteosynthesis is an attractive motion-preserving approach to the treatment of unstable atlas fractures, avoiding the morbidity of atlantoaxial fusion. Classically reserved for Jefferson fractures with Dickman type II transverse ligament injury, atlas osteosynthesis may also be a viable option for type I transverse ligament injuries. Intraoperative navigation can be particularly useful for screw placement in the setting of traumatically distorted anatomy with lateral mass displacement.

Morphometric analysis of atlas lateral mass in Down syndrome cases with relevance to surgical intervention

PURPOSE

Surgical stabilization of the Atlas vertebrae is indicated for severe atlantoaxial instability (AAI) in patients with Down syndrome (DS). This study aims to evaluate the morphological characteristics of the Atlas lateral mass (ALM) in patients with DS with regard to safe instrumentation for surgical stabilization and to compare them with non-syndromic group.

METHODS

This multicenter, retrospective, case-control study included age- and sex-matched patients with and without DS aged > 7 years with a cervical computed tomography (CT) scan. After three-dimensional CT reconstruction, nine parameters were evaluated for both groups. All included measurements were performed by a neuroradiologist who was blinded to clinical data.

RESULTS

Forty-three of 3,275 patients with DS were included in this study. Matching number of consecutive patients without DS were identified (mean age: 16 years). Patients with DS were significantly shorter than those without DS. Seven of nine parameters related to ALM were significantly lower in patients with DS than in those in the control group, including anterior wall height (AH), posterior wall height (PH), their ratio, and arch-ALM angle. On adjusting data for patient height, patients with DS had a smaller PH, lower PH/AH ratio, and steeper arch-ALM angle than the control group.

CONCLUSIONS

Patients with DS had a smaller posterior ALM wall and a steeper arch-ALM angle than the control group without DS. This information is important for surgical planning of safe posterior ALM exposure and safe instrumentation for surgical stabilization in patients with DS.

Three-dimensional computed tomography analysis of the atlanto-dental interval in a healthy Karachi population: a single-center retrospective cross-sectional study

Background

The atlantoaxial joint has a complex anatomical configuration and has a wide range of mobility. Traumatic, inflammatory, and neoplastic joint pathologies frequently affect this joint. The aim of this retrospective cross-sectional study was to evaluate the atlanto-dental intervals (ADI) in patients who underwent computed tomography (CT) scans of the neck and cervical spine in at a Tertiary Care Hospital in Karachi, Pakistan.

Methods

This was a retrospective cross-sectional study conducted at a tertiary care hospital in Karachi between 1 January 2021 and 31 December 2021, following approval from the hospital ethical review committee. Patients above the age of 15 who underwent CT scans were included, while individuals with a history of cervical trauma, infection, rheumatoid arthritis, or congenital anomalies, as well as those younger than 15 years old, were excluded. CT scans were performed using a multidetector scanner utilizing a standardized protocol. Sagittal and coronal images were reconstructed. ADI measurements, including anterior ADI (AADI), posterior ADI (PADI), and lateral ADI (LADI) on both sides, were determined using appropriate bone window settings. A radiologist with a minimum of 3 years of experience analyzed the CT scans.

Results

The mean age of the patients was 49.3±17.7 years (age range: 16-85 years). The mean AADI was 1.4±0.4 mm, with a range of 0.0-2.1 mm. The mean PADI was 19.1±1.9 mm, with a range of 13.8-24.6 mm. The mean left LADI measurement was 3.3±1.2 mm with a range of 1.2-10.0 mm, and the mean right LADI measurement was 3.2±1.1 mm with a range of 1.2-6.3 mm.

Conclusion

Our study examined the ADI in patients who underwent CT scans of the neck and cervical spine in Karachi. The findings provide valuable insights into the relationship between ADI measurements, age, and sex. These results contribute to our understanding of the anatomical variations in this region, which may aid in the diagnosis and management of cervical spine disorders.

Radiological Features in Type II Odontoid Fractures in Older Adults After High- and Low-Energy Trauma

STUDY DESIGN

Retrospective study.

OBJECTIVES

Although type II odontoid fractures mainly occur due to high-energy trauma (HET), the number of odontoid type II fractures after low-energy trauma (LET) in the elderly is on the rise. However, there is a paucity of conclusive evidence on the relationship between trauma mechanism and cervical spine alignment in the elderly population. Consequently, we examined cervical alignment and osteoporotic and osteoarthritic patterns in elderly individuals (aged ≥65 years) with type II odontoid fractures.

METHODS

We retrospectively assessed cervical spine alignment in 76 elderly individuals who experienced type II odontoid fractures after HET (n = 36) and LET (n = 40) between 2005 and 2020. Osteoporotic and osteoarthritic changes on computed tomography and cervical alignment parameters on sagittal plane radiographs were examined.

RESULTS

Moderate and severe osteoporosis of the dens-body junction and osteoarthritis of the atlanto-odontoid joint were more prevalent in the LET than the HET group (P<.005). The anterior atlantodental interval (ADI) was significantly smaller in the LET group than in the HET group (.7 [.7] millimeter vs 1.2 [.8] mm; P=.003). An ADI equal 0 mm indicative for anterior fusion of C1/C2 was present in 37.5% of patients of the LET group. The C0-C2 angle, C1-C2 lordosis, and C2-C7 sagittal vertical axis were significantly different (HET vs LET: 33.2 [7.2]° vs 41.6 [11.4]°, P=.005; 28.1 [7.0]° vs 34.0 [8.0]°, P=.002; and 16.1 [11.1] millimeter vs 27.1 [12.4] mm, P=.008; respectively).

CONCLUSION

Significantly higher rates of osteoporotic and degenerative changes were observed after LET. Furthermore, previous cervical malalignment represents a risk factor for type II odontoid fractures after LET.

The Effect of Prolonged Pre-Operative Halo Gravity Traction for Severe Spinal Deformities on the Cervical Spine Radiographs

STUDY DESIGN

Retrospective review of consecutive series.

OBJECTIVE

The study sought to assess the effect of prolonged pre-operative halo gravity traction (HGT) on the c-spine radiographs.

METHODS

Data of 37 pediatric and adult patients who underwent ≥ 12wks pre-op HGT prior to definitive spine surgery from 2013-2015 at a single site in West Africa was reviewed. Radiographic assessment of the c-spine including ADI, SVA and C2-C7 Lordosis were done at pre HGT and at 4 weekly intervals. Paired T-Test was performed to evaluate changes in these parameters during HGT.

RESULTS

37pts, 18/19 (F/M). Average age 18.2yrs. Diagnoses: 22 idiopathic, 6 congenital, 3 Post TB, 2 NM and 4 NF. Average duration of HGT: 125 days. Baseline coronal Cobb:130 deg, corrected 30% in HGT; baseline sagittal Cobb:146 deg, corrected 32% post HGT. Baseline ADI (3.17 ± 0.63 mm) did not change at 4wks (P > 0.05) but reduced at 8wks (2.80 ± 0.56 mm) and 12wks (2.67 ± 0.51 mm) post HGT (P < 0.05). Baseline HGT SVA (20.7 ± 14.98 mm) significantly improved at 4wks (11.55 ± 10.26 mm), 8wks (7.54 ± 6.78 mm) and 12wks (8.88 ± 4.5 mm) (P < 0.05). Baseline C2-C7 lordosis (43 ± 20.1 deg) reduced at 4wks (26 ± 16.37 deg), 8wks (17.8 ± 14.77 deg) and 12wks (16.7 ± 11.33 deg) post HGT (P < 0.05). There was no incidence of atlanto-axial instability on flexion extension radiographs at any interval.

CONCLUSION

Prolonged HGT, while providing partial correction of severe spine deformities, also appeared to have no adverse effect on atlanto-axial stability or cervical alignment. Therefore, HGT can be safely applied for several weeks in the preoperative management of severe spine deformities in pediatric/adult patients.

Plain roentgenographic and CT scan morphometric analysis of the anterior atlantodens interval (AADI) and posterior atlantodens interval (PADI) in the Indian population

Background:

The anterior atlantodental interval (AADI) and posterior atlantodental interval (PADI) on X-ray and computed tomography (CT) studies can both be used to gauge the risk and/or presence of neurological compression.

Methods:

This retrospective observational study was conducted at a tertiary care center in 116 patients with head injuries additionally warranting routine cervical X-ray and CT examinations.

Results:

The AADI averaged 1.36 ± 0.45 mm (X-ray) and 1.393 ± 0.47 mm (CT), while the mean PADI was 18.04 ± 2.44 mm (X-ray), and 18.07 ± 2.43 mm (CT). Notably, 93.96% of the total subjects had AADI below 2 mm. Further, 6.8% of patients with PADI =/<14 mm had no neurological deficits.

Conclusion:

No significant differences were observed for X-ray versus CT studies, measuring AADI and PADI. Therefore, X-rays should continue to prove reliable for assessing craniovertebral junction anatomy in emergency settings. Of interest, the normal upper limit of AADI on sagittal CT reconstructions should now be changed to 2 mm from the previously accepted upper limit of 3 mm.

Development and first application testing of a new protocol for CT-based stability evaluation of the injured upper cervical spine

PURPOSE

For trauma surgeons, the evaluation of the stability of the upper cervical spine may be demanding. The aim of this study was to develop a protocol for decision-making on upper cervical spine stability in trauma patients based on established parameters obtained by CT imaging as well as testing the protocol by having it applied by trauma surgeons.

METHODS

A structured literature search on upper cervical spine stability was performed. The best evaluated instability criteria in CT imaging were determined. Based on these parameters a protocol for stability evaluation of the injured upper cervical spine was developed. A first application testing was performed. In addition to the assessment of instability, the time required for the assessment was analyzed.

RESULTS

A protocol for CT-based stability evaluation of the injured upper cervical spine based on the current literature was developed and displayed in a flow chart. Testing of the protocol found the stability of the cervical spine was correctly assessed in 55 of 56 evaluations (98.2%). In one test run, a stable upper cervical spine was judged to be unstable. Further analysis showed that this case was based on a measurement error. The assessment time of CT-images decreased significantly during repeat application of the protocol (p < 0.0001), from 336 ± 108 s (first case) to 180 ± 30 s (fourth case).

CONCLUSION

The protocol can be applied quickly and safely by non-specialized trauma surgeons. Thus, the protocol can support the decision-making process in CT-based evaluation of the stability of the injured upper cervical spine.

Comparison of MR Ultrashort Echo Time and Optimized 3D-Multiecho In-Phase Sequence to Computed Tomography for Assessment of the Osseous Craniocervical Junction

BACKGROUND

To assess changes of the craniocervical junction (CCJ), computed tomography (CT) is considered the reference standard. Recent advances in bone depiction on magnetic resonance imaging (MRI) enable high-quality visualization of osseous structures. Consequently, MRI may serve as an alternative to CT, without the use of ionizing radiation.

PURPOSE

To compare two MRI sequences optimized for bone visualization to the CT reference standard in the assessment of the osseous CCJ.

STUDY TYPE

Prospective.

POPULATION/SUBJECTS

Twenty-seven decedents and five healthy volunteers.

FIELD STRENGTH/SEQUENCE

3T/ultrashort-echo time gradient echo (UTE) and optimized 3D-multiecho in-phase gradient echo sequences (FRACTURE).

ASSESSMENT

All decedents were scanned with both MRI sequences and CT. Three observers rated degeneration to obtain a score for the upper (atlanto-dental and left/right atlanto-occipital joint) and for the lower part of the CCJ (left and right atlanto-axial joint). Two reader rated the following quantitative parameters: basion-axial-interval, atlanto-dental-interval, atlanto-occipital-interval, Powers-ratio, and signal/contrast-to-noise-ratio. As a proof of concept, five healthy volunteers were scanned with both MRI sequences.

STATISTICAL TESTS

Degeneration was assessed on a Likert scale by three independent observers. Interrater and intermodality reliability were calculated using an intraclass correlation coefficient. To compare distance measurements between examination methods, a Friedman test, between-degenerative ratings, and a Kruskal-Wallis test were performed.

RESULTS

Degenerative ratings of the CCJ between MRI sequences and CT showed a good interrater and intermodality agreement. MRI sequences tended to underestimate the degree of degeneration compared to CT, and this became more marked with increasing degeneration severity. There were no significant relationships between distance measurements and the degree of degeneration (P_CT = 0.62, P_UTE = 0.64, P_FRACTURE = 0.67). The in vivo examination proved the feasibility of both MRI methods in a clinical setting.

DATA CONCLUSION

Quantitative and qualitative ratings on MR images were comparable to CT images; thus, MRI may be a valid alternative to CT assessing the CCJ.

LEVEL OF EVIDENCE

1.

TECHNICAL EFFICACY STAGE

3.

Upper cervical range of rotation during the flexion-rotation test is age dependent: an observational study

Background:

The flexion-rotation test (FRT) is widely used to detect movement dysfunction in the spinal segment C1/C2, especially in patients with cervicogenic headache. The current published literature indicates that range recorded during the FRT is not age dependent. This is questionable, considering the well documented relationship between aging and degeneration in the cervical spine and loss of cervical movement in older people. The present study therefore aims to examine the influence of age on FRT mobility, and to provide normative values for different age groups. An additional aim is to examine the influence of age on the ratio between lower and upper cervical rotation mobility.

Methods:

For this cross-sectional, observational study, healthy subjects aged from 18 to 90 years were recruited. The upper cervical range of rotation during the FRT was measured using a digital goniometer. Personal data including age, weight, height, and lifestyle factors were also assessed.

Results:

A total of 230 (124 male) healthy, asymptomatic subjects, aged between 18 and 87 years were included. Regression analysis showed that 27.91% (p < 0.0001) of the variance in FRT mobility can be explained by age alone, while 41.28% (p < 0.0001) of the variance in FRT mobility can be explained by age and total cervical range of motion (ROM). Normative values for different age decades were calculated using regression analysis. No significant influence of age on the ratio between ROM of lower and upper cervical rotation was found. There was no relevant impact of personal (gender, height, and weight) and lifestyle (smartphone and PC use) factors on ROM during the FRT.

Conclusion:

Upper cervical rotation mobility determined by the FRT correlates strongly with age; hence, the results of the FRT have to be interpreted taking into account the individual age of the tested subject. The ratio between lower and upper cervical rotation mobility is maintained in all age groups.

Anatomical evaluation of the craniovertebral junction on cone-beam computed tomography images

INTRODUCTION

There are many craniometric measurements that are used in evaluating craniovertebral junction (CVJ) pathologies such as basilar invagination, atlantoaxial dislocation and platybasia. Therefore, it is important to determine the normal reference range of the craniometric measurements. This study aims to determine the morphometric reference values of the bony structures in the CVJ from cone-beam computed tomography (CBCT) images of a group of South Eastern Anatolian population.

MATERIALS AND METHODS

The CBCT images of 300 individuals were retrospectively evaluated. 14 parameters on midsagittal and 2 parameters on the coronal plane were studied. The data were statistically evaluated.

RESULTS

Measurement results were found as follows; the distances between odontoid process (OP) and McGregor line as 0.31 ± 3.22 mm, OP and Chamberlain line 1.06 ± 3.22 mm, OP and McRae line 5.30 ± 1.59 mm, OP and Fischgold digastric line 8.70 ± 4.12 mm, OP and Fischgold bimastoid line - 5.15 ± 4.86 mm, length of McRae line 35.58 ± 2.52 mm, atlantodental interval 1.28 ± 0.48 mm, posterior atlantodental interval 19.54 ± 2.24 mm, basion axial interval 4.01 ± 1.83 mm, basion dental interval 4.92 ± 1.77 mm, length of Modified Ranawat line 28.66 ± 2.38 mm, length of Redlund-Johnell line 35.11 ± 4.09 mm, clivus canal angle 157.62° ± 11.85°, Welcher basal angle 130.83° ± 6.29°, craniocervical tilt 126.98° ± 12.24° and Powers ratio as 0.72 ± 0.06.

CONCLUSION

In this study, the morphometric values were evaluated according to age and gender in individuals who did not have any radiologic anomalies. The normal reference ranges may be useful for researchers who are researching pathology in this region. It is recommended to conduct further studies with different populations to determine the normal reference range.

The relationship between density variations of transverse ligament tubercles on multidetector computed tomography (MDCT) and age, gender, or laterality in a large cohort

BACKGROUND

Transverse ligament tubercles are unique structures that maintain the stability of the upper cervical spine. However, the density variations of tubercles in different clinical contexts or populations have not been carefully studied through multidetector computed tomography (MDCT).

PURPOSE

This study aimed to evaluate the relationship between density variations in the transverse ligament tubercles, as measured through multidetector computed tomography (MDCT), with age, gender, or laterality.

METHODS

A cohort of 339 Chinese patients that underwent MDCT in the head or neck were recruited. The patients were divided into eight age groups. The densities of the bilateral transverse ligament tubercles were classified through MDCT, and the potential relationship between the density of the tubercles and the age, gender, or laterality was analyzed.

RESULTS

Based on MDCT findings, four different density types of tubercles were identified (type 0-III). Our data suggest that the density of tubercles increased with age (χ² = 637.7, p < 0.05). However, the density of tubercles did not correlate with laterality (male: t = 0.217, p > 0.05, female: t = 1.448, p > 0.05) or gender (χ² = 5.706, p > 0.05).

CONCLUSIONS

The density of the transverse ligament tubercles, as measured through MDCT, shows a stereotyped dynamic pattern, i.e., it apparently increases with age, but neither gender nor laterality significantly contribute to these changes.

Cone beam computed tomography evaluation of the relationship between atlantodental interval and skeletal facial morphology in adolescents

Introduction

In the pediatric population, computed tomography examination of the upper cervical spine plays an important role in the diagnosis of neurological injuries involving that region. Due to the interconnected nature of the craniofacial structures, a structural change in one is expected to also cause changes in the other structures.

Objective

The aim of this study was to evaluate relationships between atlantodental interval, cervical vertebral morphology, and facial structure in healthy adolescents using cone beam computed tomography.

Methods

Thirty subjects aged 14–20 years (10 males, mean age: 17.2 years; 20 females, mean age: 17.9 years) were included in the study. The anterior, lateral and posterior atlantodental intervals, and vertical and anteroposterior dimensions of the first and second cervical vertebrae were evaluated from cone beam computed tomography images. Facial morphology was evaluated using 7 parameters on lateral cephalometric cone beam computed tomography images and 6 parameters on posteroanterior images. The Mann–Whitney U test and Wilcoxon test were used for statistical analyses.

Results

Comparisons between males and females showed that most parameters were larger in males, with significant differences in vertical facial dimensions (anterior lower face height: p = 0.05; anterior upper face height: p = 0.001), (distance between the most internal point of the frontozygomatic suture and midsagittal reference plane; p = 0.01), (the distance between the deepest point of the right alveolar maxillar process and midsagittal reference plane; p = 0.001), and C2 vertebral dimensions. The anterior and lateral atlantodental interval values correlated with maxilla position relative to the mandible angle, and the anterior atlantodental interval correlated with lower anterior facial height (p = 0.05). Dimensional measurements of the C1 and C2 vertebrae were correlated with both anterior facial heights and some posteroanterior parameters.

Conclusion

Sagittal, vertical, and transverse facial dimensions and positions were strongly associated with C1 and C2 vertebral dimensions, and the maxillomandibular relationship may affect atlantodental interval. Therefore, including craniofacial features in assessment of the atlantodental area and vertebral distances in adolescents may be beneficial.

The Managment of cervical spine abnormalities in children with spondyloepiphyseal dysplasia congenita: Observational study

Spondyloepiphyseal dysplasia congenita (SEDC) is an autosomal dominant disorder, characterized by disproportionate dwarfism with short spine, short neck associated with variable degrees of coxa vara. Cervical cord compression is the most hazardous skeletal deformity in patients with SEDC which requires special attention and management.Ten patients with the clinical and the radiographic phenotypes of spondyloepiphyseal dysplasia congenita have been recognized and the genotype was compatible with single base substitutions, deletions or duplication of part of the COL2A1 gene (6 patients out of ten have been sequenced). Cervical spine radiographs showed apparent atlantoaxial instability in correlation with odontoid hypoplasia or os-odontoideum.Instability of 8 mm or more and or the presence of symptoms of myelopathy were the main indications for surgery. Posterior cervical fusion from the occiput or C1-3, decompression of C1-2 and application of autorib transfer followed by halo vest immobilization have been applied accordingly.Orthopedic management of children with spondyloepiphyseal dysplasia congenita (SEDC) should begin with the cervical spine to avoid serious neurological deficits and or mortality.

Variation of bilateral transverse ligament tubercles with age and gender in a large series of subjects on multidetector computed tomography

BACKGROUND

The transverse ligament tubercles play an important role in maintaining the stability of upper cervical spine, but the variation of these tubercles with aging has not been studied systematically.

PURPOSE

To evaluate the variation of the height of the transverse ligament tubercles with respect to age and gender, and assess side-to-side differences on multidetector computed tomography (MDCT).

MATERIAL AND METHODS

A consecutive series of 291 Chinese patients undergoing a head or neck MDCT were divided into eight age groups. The bony anatomy of the atlas was displayed symmetrically by aligning the axial plane and the mean height of bilateral transverse ligament tubercles was measured. The height was correlated with age and gender and side-to-side differences were analyzed. Finally, the inter-observer performance was assessed.

RESULTS

No transverse ligament tubercles were seen in 51 cases (17.5%, 51/291) and unilateral transverse ligament tubercles were seen in two cases (0.7%, 2/291). Bilateral transverse ligament tubercles were observed in 238 cases (81.8%, 238/291). The average height of the left and right tubercles were 2.68 ± 1.58 mm and 2.68 ± 1.54 mm, respectively, with no significant side-to-side differences (t = 0.061, P > 0.05). The height was also similar in both genders (left: t = 0.497, P > 0.05, right: t = 0.730, P > 0.05). The height increased linearly with age (left: r = 0.513, P < 0.05, right: r = 0.516, P < 0.05). The inter-observer reliability was excellent.

CONCLUSION

The height of the transverse ligament tubercles on MDCT linearly increases with increasing age with no significant differences among the genders or the side measured.