Reference values of four measures of craniocervical stability using upright dynamic magnetic resonance imaging.

PURPOSE: To establish reference ranges for four most commonly used diagnostic measures of craniocervical instability (CCI) in three cervical sagittal positions. This necessitated development of a reliable measurement protocol using upright, dynamic MRI (udMRI), to determine differences in the extent of motion between positions, and whether age and sex correlate with these measures. MATERIALS AND METHODS: Deidentified udMRIs of 50 adults, referred for reasons other than CCI, were captured at three positions (maximal flexion, maximal extension and neutral). Images were analyzed, providing measures of basion-axial interval, basion-axial angle, basion-dens interval (BDI) and the Grabb-Oakes line (GOL) for all three positions (12 measures per participant). All measures were independently recorded by a radiologist and neurosurgeon to determine their reliability. Descriptive statistics, correlations, paired and independent t-tests were used. Mean (± 2 SD) identified the reference range for all four measures at each craniocervical position. RESULTS: The revised measurement protocol produced inter-rater reliability indices of 0.69-0.97 (moderate-excellent). Fifty adults' (50% male; mean age 41.2 years (± 9.7)) reference ranges for all twelve measures were reported. Except for the BDI and GOL when moving between neutral and full flexion, significant extents of movement were identified between the three craniocervical positions for all four measures (p ≤ 0.005). Only a minor effect of age was found. CONCLUSIONS: This is the first study to provide a rigorous standardized protocol for four diagnostic measures of CCI. Reference ranges are established at mid and ends of sagittal cervical range corresponding to where exacerbations of signs and symptoms are commonly reported.

CT diagnosis of pituitary abscess, suppurative meningitis, and atlanto-occipital septic arthritis in a pony.

A 15-year-old pony was presented for acute neurological signs. Neurological examination suggested a brainstem lesion, blood laboratory tests detected an active inflammatory process, and upper respiratory endoscopy identified a suppurative lesion at the dorsal aspect of the right guttural pouch. Computed tomography was performed and findings were consistent with pituitary abscess, meningitis, and atlanto-occipital joint septic arthritis. Imaging findings were confirmed based on cerebrospinal and synovial fluid cultures and necropsy. Computed tomography provided important information for identifying the cause of the patient's neurological signs and helped the owner make a final decision for euthanasia.

Normal Range of Movement During Rotation Stress Testing for the Alar Ligaments: An Observational Study.

OBJECTIVE: The purpose of this study was to determine the normal range of rotation occurring during rotation stress testing for alar ligament integrity and to ascertain whether rotation range on testing is affected by an individual's age. METHOD: In this observational study, 88 people aged 18 to 86 years old with no current neck problems or known risk factors for craniocervical instability underwent rotation stress testing for the alar ligaments. The test was performed in each direction in neutral, flexion, and extension, with the participant both sitting and supine. Rotation range was recorded using an electromagnetic movement tracking system. Range was assessed overall and then compared by 10-year age groups using analysis of variance. Reliability of measurements was assessed by intraclass correlation coefficient(2,1) and standard error of measurement. RESULTS: Mean angles of upper cervical rotation ranged between 10.91° (standard deviation 3.38°) to 16.12° (standard deviation 5.13°). Overall measured rotation ranged from 1.37° to 33.22°. Participants in older age groups generally displayed reduced rotation; however, the reduction was less than 4°. Reliability of rotation measurements was good to excellent, with the intraclass correlation coefficient ranging from 0.80 to 0.99. CONCLUSIONS: Normal range of rotation measured during stress testing for the alar ligament varied widely but did not exceed 33o. All values measured in this study fell below recommendations for ligament integrity. Age-related change was not clinically significant in the interpretation of this test in this asymptomatic population.

Radiological approach to basilar invagination type B: Reliability and accuracy.

OBJECTIVES: This study aims to determine the reliability of the radiological tests used in the diagnosis of basilar invagination (BI). METHODS: Patients diagnosed with type B basilar invagination, who had both magnetic resonance (MR) and computed tomography (CT) imaging between January 2014 and November 2019 were included in this retrospective reliability study. In this study, distance from odontoid apex to Chamberlain's line (OA-CL) was accepted as a reference method for the diagnosis. Forty-two BI cases and 79 controls were included. Three radiologists with different levels of experience individually evaluated OA-CL, Boogard's angle (BoA), clivo-axial angle (CXA), clivo-dens angle (CDA), and clivo-palate angle (CPA) on midsagittal CT and MR images. Statistical analysis was made with the intraclass correlation coefficient (ICC), t-test, and receiver operating characteristic (ROC) curve. RESULTS: The ICC for CT and MR were; 0.977-0.973 (OA-CL), 0.912-0.882 (BoA), 0.845-0.846 (CXA), 0.862-0.864 (CDA), and 0.762-0.747 (CPA) respectively (P < 0.001). The areas under the ROC curve were 0.977 (BoA), 0.832 (CXA), 0.852 (CDA), and 0.719 (CPA) (P < 0.001). The cut-off measures were ≥137.84° (BoA), ≤149.25° (CXA), ≤129.58° (CDA), and ≤61.83° (CPA). The diagnostic accuracies were 0.954 (BoA), 0.664 (CXA), 0.704 (CDA), 0.438 (CPA) (P < 0.001). CONCLUSIONS: OA-CL and BoA express excellent inter-rater agreement than CXA, CDA, and CPA, which are limited due to morphological variations and head spatial position. BoA is the second most reliable diagnostic test. CXA, CDA, should only be used for complementary information. CPA was found inadequate for the diagnosis of BI..

Occipital condyle defects assessed by radiography or CT can be a normal finding in foals.

Age of complete ossification of equine occipital condyles has not been published. Consequently, clinical significance of occipital condyle defects on radiographs or CT scans of young horses remains unknown. The goals of this single-center, retrospective, cross-sectional study were to characterize incidental occipital condyle defects and to define the age of complete ossification. The margin of occipital condyles was classified as regular or with defect(s). Analyses were made on 121 horses, including 106 radiographic and 19 CT studies showing the occipital condyles of horses less than 5 years of age obtained over 6 years in a referral hospital. Neurological signs and outcome were not associated with occipital defects. Horses with regular occipital condyles on radiographs had a median age of 974 days (median interquartile range = 707) compared with 47 days (interquartile range = 106) in the defect group. The odds of finding radiographically regular occipital condyles were 2.6% higher for each additional day of age (P = .011, 95% CI, 0.6-4.7%). In the CT group, univariate analyses demonstrated a significant effect of age on the aspect of occipital condyles (P = .016). Horses with regular occipital condyles were older (median age = 881 days; interquartile range = 1054) than horses with a defect (median age = 109 days, interquartile range = 318). All horses above 156 days (5.1 months) of age and 550 days (18.1 months) of age had regular occipital condyles on radiographic and CT images, respectively. This study describes occipital condyle defects as a potential normal finding in young horses and provides guidelines for interpretation of the occipital condyle ossification process.

The range of atlanto-occipital joint motion in cetaceans reflects their feeding behavior.

The cetaceans display a wide variety of lifestyles, especially with regard to their feeding behavior. However, the evolutionary process of the feeding behavior in cetaceans is still poorly understood, in part because reconstructing the feeding behavior of extinct taxa remains difficult. In cetaceans, cranium mobility relative to the trunk largely depends on the range of motion permitted by the atlanto-occipital joint, given the lack of flexibility of the cervical series. In this study, we examined 56 extant cetacean skeletal specimens from 30 species in 25 genera and nine families in order to investigate the relationships between anatomical traits and feeding behavior. Our results suggest that the range of dorso-ventral motion allowed by the atlanto-occipital joint (ROM) depends on prey habitat and the feeding technique of cetaceans. Cetaceans feeding on benthic/demersal prey had a relatively large ROM compared with those feeding on pelagic prey. In addition, ROM was largest in raptorial feeders, intermediate in suction feeders, and smallest in ram-filter feeders. Among raptorial feeders, ROM tended to be larger in taxa that facultatively tear off the prey's flesh compared with taxa that swallow their prey whole. Therefore, we conclude that ROM is a powerful tool to reliably reconstruct the feeding behavior of extinct cetacean taxa.

A morphometric study of the atlanto-occipital joint in adult patients with Chiari malformation type I.

BACKGROUND: There are many morphometric studies on Chiari malformation type I (CMI) patients, most of which focus on the posterior cranial fossa (PCF). Less attention has been paid to the atlanto-occipital joint. In this study, we aim to evaluate the morphological characteristics of the atlanto-occipital joint in CMI patients. MATERIALS AND METHODS: The cervical CT imaging data of adult patients diagnosed with CMI but without any bony malformation in craniovertebral junction (CVJ) who were treated by the authors between January 2014 and December 2019 were retrospectively analyzed. The equal number of sex and age-matched healthy individuals were included as the control group. The morphometric analysis was performed by measuring the length and depth of the atlanto-occipital joint, and the depth/length ratio was calculated to evaluate the curvature of the joint. RESULTS: A total of 47 patients (15 males and 32 females) were included. The mean age of patients was 47.49 ± 9.01 years (range 19-62 years). The mean depth/length ratio of the atlanto-occipital joint in CMI patients was 0.141 ± 0.065 (range 0.027 - 0.274), which was smaller than that of control individuals (0.228 ± 0.057, range 0.069 - 0.379). And the difference was statistically significant (p < .01). CONCLUSIONS: The atlanto-occipital joints in CMI patients are significantly flatter compared with those in healthy controls. This morphological variation could lead to differences of the atlanto-occipital stability between CMI patients and normal population, which may be related to the pathogenesis of CMI.

Quantification of anatomical variation at the atlanto-occipital articulation: morphometric resolution of commingled human remains within the repatriation documentation process.

Within many institutional collections are skeletal and mummified human remains representing a part of our species' adaptation and evolution to various biocultural environments. Archaeologically recovered individuals come from deep into our past, and possess information that provides insight into population history, genetics, diet, health and other questions relevant to all living peoples. Academic concerns have been raised regarding the reinterment of these collections due to the rise of the international repatriation movement, the passage of various laws and implementation of institutional policies. While all potential research questions cannot be anticipated, the proactive documentation of collections is one way to ensure primary data are maintained for future study. This paper explores developments in digitization technology that allow the archive of virtual copies of human remains, and an example of how anatomical and archaeological collections can be digitized towards pragmatic research goals. The anatomical variability of the human atlanto-occipital (AO) articular surfaces was studied using non-metric categorical shape, 2D measurement and 3D morphometric analyses to provide reference standards for the reassociation of individuals from commingled skeletal remains, such as found in some archaeological sites or forensic investigations including mass grave or mass disaster recovery scenes. Results suggest that qualitative shape observations and caliper-derived measurements of the articulating AO condyles tend to display significant sexual dimorphism and biological ancestry-related size and shape differences. Variables derived from a scanned 3D mesh, such as condylar angle and articular surface curvature, quantify biomechanical variation and display a stronger congruency within individuals. It is recommended that a two-stage approach involving initial screening and identification of possible reassociation candidates is accomplished with a linear osteometric approach, followed by 3D laser scanning of the candidate joint surfaces for morphometric analyses to confirm reassociations when destructive DNA typing is not allowed or otherwise impractical due to cost or other resource restrictions.

Clivopalate angle: a new diagnostic method for basilar invagination at magnetic resonance imaging.

OBJECTIVES: To investigate the diagnostic value of clivopalate angle (CPA) for basilar invagination (BI) at magnetic resonance imaging (MRI). METHODS: In this retrospective case-control study, CPA, clivodens angle (CDA), and clivoaxial angle (CXA) were measured on midsagittal MR images from 112 patients with BI (22 men; mean age, 43.9 years ± 13.1 years; range, 21-79 years) and 200 control subjects (57 men; mean age, 47.1 years ± 13.3 years; range, 20-80 years). Intraclass correlation coefficient (ICC), linear regression, Mann-Whitney U test, binary logistic regression, and receiver operating characteristic (ROC) curve were used for statistical analysis. RESULTS: Clivopalate angle showed better inter-observer agreement (ICC = 0.951) than CXA (0.867) or CDA (0.853). CPA significantly correlated with CXA (R = 0.811, p < 0.001) and CDA (R = 0.716, p < 0.001). Patients with BI had a significantly smaller CPA (45.9° ± 9.9°) than control subjects (61.9° ± 6.2°) (p < 0.001). With the optimal cutoff value of 53.5°, CPA had a sensitivity of 0.839 (94/112) and a specificity of 0.915 (183/200). The area under the ROC curve (AUC) was 0.937 (95% CI, 0.911-0.963) for CPA, which was similar to that of CXA (AUC, 0.957; 95% CI, 0.936-0.978) or CDA (AUC, 0.925; 95% CI, 0.892-0.957). The combination of CPA and CDA or CXA showed a higher diagnostic value than CDA or CXA alone. CONCLUSIONS: The diagnostic performance of CPA was similar to that of CXA or CDA, but CPA might be more reliable in evaluation of BI. CPA provided complementary information to CXA and CDA. KEY POINTS: • Clivopalate angle has a high diagnostic value for basilar invagination. • Clivopalate angle demonstrates high inter-reader agreement than does clivoaxial angle or clivodens angle. • Clivopalate angle provides complementary information to clivoaxial angle and clivodens angle.

Grisel's syndrome caused by Mycoplasma pneumoniae infection: a case report and review of the literature.

BACKGROUND: Grisel's syndrome is a non-traumatic subluxation of the atlantoaxial joints, which is caused by an inflammatory process involving the upper neck. Torticollis, neck pain, and reduced neck mobility are the main clinical signs of presentation. Predisposing factors are trauma, hyperlaxity of the transverse and alar ligaments of the atlantoaxial joints, and surgical interventions carried out in this area. Several viral and bacterial pathogens have been reported as causative events of Grisel's syndrome, including Epstein-Barr virus, Kawasaki disease, Streptococcus pyogenes, Staphylococcus aureus, and other infectious agents. Grisel's syndrome linked to Mycoplasma pneumoniae infection as the trigger has not previously been reported. Mycoplasma pneumoniae is a small prokaryotic microbe and a frequent etiologic factor of respiratory tract infections and, less frequently, of extrapulmonary body organs. The recognition of the Grisel's syndrome is based on clinical and neuroradiological investigations, and early diagnosis and specific treatment are crucial to the successful outcome of the disease. RESULTS: We report the case of an 8-year-old girl with Grisel's syndrome caused by an upper respiratory tract infection due to Mycoplasma pneumoniae. Diagnostic suspicion and treatment of Grisel's syndrome were established quickly by anamnestic and clinical data and confirmed by radiological findings. The girl was immediately treated with specific antibiotic therapy and cervical immobilization, thus preventing the most dangerous complications of the disorder. CONCLUSION: Mycoplasma pneumoniae, among the other infectious agents, may be cause of scute torticollis and Gresel's syndrome.

Reliability of Smartphone Inclinometry to Measure Upper Cervical Range of Motion.

CONTEXT: Assessment of upper cervical range of motion (UCROM) and mobility is commonly performed in the clinical setting for patients suffering from headache, neck pain, and vestibular dysfunction. Reliable and reproducible measurement of this motion is often difficult or too expensive to perform in the clinical setting. Smartphone applications using the device's internal gyroscope offer an easy and inexpensive means of measuring UCROM, but their reliability has not been reported in the literature. OBJECTIVE: To assess the reliability of an inclinometer application installed on 2 different devices (iPhone 6 [IP] and android [AN]) and to measure UCROM in a healthy population. DESIGN: Two examiners assessed passive UCROM. Each examiner was assigned to a specific smartphone, and a repeated-measures design consisting of 3 trials for each examiner-phone was performed. The order of testing was randomized, and the examiners were blinded to UCROM measures. SETTING: Laboratory. PARTICIPANTS: A total of 38 subjects (19 females and 19 males; age: 23.8 [1.2] y) without pain or injury to the neck or spine for at least 3 months. INTERVENTION: Each examiner passively flexed the head fully, rotated the head fully in 1 direction, and then in another. Peak rotation measures were recorded from each smartphone. Three trials were performed for each phone, with a 2-minute break between examiners/phones. MAIN OUTCOME MEASURES: Intraclass correlation coefficient using a 2-way mixed, absolute agreement model was obtained (1) between each examiner-phone and (2) within each examiner-phone for the measurements in each rotation direction. RESULTS: Interphone/examiner reliability comparing average peak and total UCROM for each device was excellent (.87, .81). Intraphone/examiner reliability, determined across 3 trials, was also excellent (AN right rot. = .91, AN left rot. = .96; IP right rot. = .98, IP left rot. = .95). CONCLUSION: UCROM can be reliably measured using a smartphone inclinometer application.

Transoral robotic-assisted surgery for the approach to anterior cervical spine lesions.

The Da Vinci robotic surgical system is increasingly being used by head and neck surgeons in transoral approaches for head and neck cancer. Our experience using the Da Vinci system for transoral robotic-assisted surgery (TORS) is presented. The feasibility of TORS for lesions involving the anterior portion of C1-C2 and the cranio-cervical junction has been evaluated from an anatomical viewpoint in a cadaveric laboratory. Two patients treated using the Da Vinci system to reach C1-C2 benign lesions are presented. The anatomical cadaveric study showed that this approach is safe and feasible. The first two cases which we describe confirmed the advantages of the Da Vinci system in the anterior approach to the cervical spine and allowed the limitations of this procedure to be assessed. TORS may be useful to reach anterior lesions of the cervical spine localized at the level of C1 and C2: first, for removal of small benign and well-delineated lesions; and second, for diagnostic purposes with biopsy of large lesions. Further studies and new instruments are needed to confirm the safety and results of this approach in terms of morbidity.

Effectiveness of intra-articular steroid injection for atlanto-occipital joint pain.

OBJECTIVES: The aims of this study were to evaluate the role of intra-articular joint injection for atlanto-occipital (AO) joint pain and to determine pain referral sites from that joint. DESIGN: Prospective observational study. METHOD: We evaluated 29 patients with chronic refractory neck pain and/or headache, and limited range of lateral bending with rotation at the AO joint on physical examination. Of the 24 patients who consented to undergo diagnostic injections, 20 patients had at least 50% relief from pain and underwent two AO intra-articular injections of mixture of local anesthetic and steroid approximately 1 week apart. Patients completed pain drawings, visual analog scales (VASs) for pain, and neck disability index (NDI) for level of function. Patients were evaluated for 2 months after the first injection. RESULT: There was headache in 14/20 (70%), posterior neck pain (PNP) in 20, and referred pain in 17 (85%). The average VAS values for headache, PNP, and other referred pains were reduced significantly from 5.64, 5.70, and 5.41, respectively, before treatments to 0.64, 2.30, and 1.71, respectively, two months after injection (P < 0.01). The average NDI value was reduced significantly from 39.95% at pretreatment to 20.40% at 2 months after treatment (P < 0.01). CONCLUSION: AO intra-articular steroid injection appears effective for the short-term control of chronic refractory pain arising from the AO joint.

Biomechanical effects of the transcondylar approach on the craniovertebral junction.

The transcondylar variation of the far-lateral, retrosigmoid approach is intended for pathologies in the anterolateral portion of the foramen magnum. That area is more clearly visualized when a fraction of the ipsilateral occipital condyle is removed. In this study, the biomechanical effect of this approach on occiput-C2 rotation was investigated. Our hypothesis was that the biomechanical characteristics are significantly altered following the transcondylar approach. Five human cadaveric upper cervical spine specimens (occiput-C7) were used in the study. Torsional moments were applied from zero to a maximum of 1.5 N m to the left and to the right using a mechanical testing machine. The resulting rotational motions of the O-C1, C1-2, and O-C2 segments were measured in the intact specimen and after a simulated right-sided transcondylar approach with resection of 2/3 of the condyle, confirmed by CT scanning and visual inspection. After the posterior two-thirds of the occipital condyle were removed, the neutral zone (NZ) increased 1.3° to the left and 2° to the right at C0-C1, and 7.4° to the left and 6.2° to the right at C1-2. The cumulative increase in NZ between O and C2 was 8.7° to the left and 8.2° to the right. The transcondylar approach also resulted in significant increases in range of motion (ROM) in axial rotation to both sides in all segments. ROM increased 2.8° to the left and 2.4° to the right between C0 and C1, 7.3° to the left and 5.4° to the right between C1 and C2, and 10.1° to the left and 7.8° to the right between CO and C2. Upon inspection, the area of the occipital condyle where the alar ligament attaches had been completely removed in three of the five specimens. Removing the posteromedial two-thirds of one occipital condyle alters the normal axial rotational movements of the craniovertebral junction on both sides. The insertion of the alar ligament can be inadvertently removed during condylar resection, and this could contribute to atlanto-axial instability. There is a biomechanical substrate to cranio-cervical instability following a transcondylar approach; these patients may need to be followed over several years to ensure it does not progress and necessitate occipito-cervical fusion.

Clinical characteristics of upper cervical spine injuries in children: a retrospective case series.

OBJECTIVE: Pediatric cervical spine injuries (CSI) can be devastating, and children < 8 years are particularly at risk for upper CSI given unique anatomical differences. Diagnosis of these injuries can be delayed due to variable clinical presentations and a paucity of existing literature. The authors aimed to characterize the spectrum of pediatric upper CSI. METHODS: This was a retrospective, single-center case series of trauma patients aged < 16 years who were assessed at a level I pediatric trauma center and diagnosed with upper CSI between 2000 and 2020. Patients were included if they had evidence of bony or ligamentous injury from the occiput to C2 on imaging or autopsy. Data were obtained from manual chart review and analyzed using descriptive statistics. RESULTS: In total, 502 patients were screened and 202 met inclusion criteria. Of these, 31 (15%) had atlanto-occipital (AO) joint distractions, 10 (5%) had atlanto-axial (AA) joint distractions, 31 (15%) had fractures of C1-2, and 130 (64%) had ligamentous injury without joint distraction. Of the patients with AO injury, 15 patients had complete dislocation. They presented as hemodynamically unstable with signs of herniation and 14 died (93%). In contrast, 16 had incomplete dislocation (subluxation). They usually had stable presentations and survived with good outcomes. Of the patients with AA injury, 2 had complete dislocation, presented with arrest and signs of herniation, and died. In contrast, 8 patients with subluxation mostly presented as clinically stable and all survived with little residual disability. The most common fractures of C1 were linear fractures of the lateral masses and of the anterior and posterior arches. The most common fractures of C2 were synchondrosis, hangman, and odontoid fractures. Overall, these patients had excellent outcomes. Ligamentous injuries frequently accompanied other brain or spine injuries. When these injuries were isolated, patients recovered well. CONCLUSIONS: Among upper CSI, AO and AA joint injuries emerged as particularly severe with high mortality rates. Both could be divided into complete dislocations or incomplete subluxations, with clear clinical differences and the former presenting with much more severe injuries. Lateral cervical spine radiography should be considered during resuscitation of unstable trauma patients to assess for these CSI subtypes. Fractures and ligamentous injuries were clinically heterogeneous, with presentations and outcomes depending on severity and associated injuries.

Traumatic atlanto-occipital dislocation with successfully bystander resuscitation after cardiopulmonary arrest: A case report.

This case report describes successful bystander cardiopulmonary resuscitation after a cardiopulmonary arrest due to a traffic accident, followed by early diagnosis and treatment of a traumatic atlanto-occipital dislocation, resulting in successful community reintegration.

Normative data on axial rotation of atlanto-occipital joint on 3 Tesla MRI using a simple and reliable method of calculation.

BACKGROUND: Various methods have been used to image and measure the normal range of axial rotation of the atlanto-occipital joint (AOJ), but a simple, precise, and reliable method is needed for everyday practice. PURPOSE: To generate normative ranges for AOJ rotation in various in-vivo positions and to investigate the reliability of a simple imaging method for measurement using routine high-field magnetic resonance imaging (MRI). MATERIAL AND METHODS: One hundred healthy volunteers were imaged on 3 T MRI with the AOJ in the center of the field of view. The scans were uniformly performed in seven different positions. The range of axial rotation was calculated by the angle between the craniofacial midline and the line linking the anterior and posterior tubercles of the atlas. The angle was defined as positive when it was angled right, and negative when it was angled left. The actual normative range of axial rotation was the difference between the angle in the supine neutral position and in the other positions. RESULTS: The normative axial rotation range of the AOJ in different positions was between -4.8° and +5.0°. The mean values of the actual rotation angles in the right supine position with maximum bending, the right supine position maximum rotation, and the right prostrate position maximum rotation were 0.1°, 1.70°, and 0.8°, respectively. The mean values of actual rotation angles in the left supine position with maximum bending, the left supine position with maximum rotation, and the left prostrate positive with maximum rotation were 0.1°, -1.7°, and -1.1°, respectively. The inter-observer reliability tested. CONCLUSION: A simple and reliable method of measurement on 3.0 T MRI demonstrated the normative axial rotation range of the AOJ in different positions to be between -4.8° and +5.0° and it was different from zero in neutral rotation. This method could be practically used to precisely diagnose AOJ rotary subluxation or dislocation.

Effect Sizes for Changes in Health and Well-Being Following Treatment With the One-To-Zero Technique in Individuals With Occipito-Atlantal Joint Dysfunction: A Repeated Measures Study.

Objectives: The purpose of this study was to determine effect sizes (ES) for changes in self-reported measures of musculoskeletal pain and dysfunction resulting from the one-to-zero method using a repeated measures study design. Methods: Twenty participants presenting with articular dysfunction of the occipito-atlantal (C0-C1) complex were treated using the one-to-zero method, a high-velocity low-amplitude thrust administered between the C0-C1 complex before treating other restrictive segments in a cephalocaudal direction. The participants completed online questionnaires using Google Forms that assessed aspects of the biopsychosocial model of pain at baseline and within a week after treatment. The questionnaires included the following: (1) Demographic and Health Behavior Survey; (2) Neck Bournemouth Questionnaire (NBQ) or Neck Disability Index (NDI); (3) Beck Anxiety Index (BAI); (4) Insomnia Severity Index (ISI); and (5) 36-Item Short Form Health Survey (SF-36). Paired t test or Wilcoxon signed ranks test was performed, dependent on normality. Cohen's d values were calculated for each questionnaire score (0.20 indicative of small; ≥0.50 medium; and ≥0.80 large ES). Results: The NDI, NBQ, BAI, and ISI had a large ES (all d ≥ 0.80). In the SF-36, 4 subscales had a small to near-medium ES, 1 subscale had a medium to near-large ES, and the remaining 2 had a large ES (d ≥ 0.80). The physical and mental component summary had a large (d = 0.88) and small ES (d = 0.35), respectively. Conclusion: The effect sizes suggest the one-to-zero treatment induces change in various aspects of the biopsychosocial model.

Anterior atlanto-occipital transarticular screw fixation: a biomechanical comparison with posterior fixation techniques.

OBJECTIVE: Atlanto-occipital instability is commonly treated with posterior fixation. However, in patients with congenital or acquired factors, posterior fixation may not be possible. For these situations, a novel anterior atlanto-occipital transarticular screw (AATS) fixation technique has been introduced recently. However, biomechanical study of this technique is lacking. This study was designed to evaluate the biomechanical stability of AATS fixation for the atlanto-occipital joint and compare it with conventional posterior occipitocervical fixation (POCF). METHODS: Six cadaveric specimens (occiput-C4) were tested in four conditions, including intact, injury, injury + AATS, and injury + POCF states. A pure moment of 1.5 Nm was applied to specimens in flexion, extension, lateral bending, and axial rotation. The range of motion (ROM) and neutral zone (NZ) were calculated and compared from the occiput to C1. RESULTS: The AATS fixation constrained ROMs to 0.4° in flexion (p < 0.001), 0.4° in extension (p < 0.001), 1.0° in lateral bending (p < 0.001), and 0.7° in axial rotation (p < 0.001) when compared with the injury state. In all directions, there was no statistically significant difference observed in ROMs and NZs between AATS fixation and POCF (p > 0.05). CONCLUSIONS: This study identified that the novel AATS fixation, as stand-alone anterior fixation, was equivalent to POCF in all directions. The results suggest that anterior transarticular screw fixation is a biomechanically effective salvage technique for posterior atlanto-occipital fixation, and may also serve as supplemental fixation.

Geometric and Inertial Properties of the Pig Head and Brain in an Anatomical Coordinate System.

Porcine models in injury biomechanics research often involve measuring head or brain kinematics. Translation of data from porcine models to other biomechanical models requires geometric and inertial properties of the pig head and brain, and a translationally relevant anatomical coordinate system (ACS). In this study, the head and brain mass, center of mass (CoM), and mass moments of inertia (MoI) were characterized, and an ACS was proposed for the pre-adolescent domestic pig. Density-calibrated computed tomography scans were obtained for the heads of eleven Large White × Landrace pigs (18-48 kg) and were segmented. An ACS with a porcine-equivalent Frankfort plane was defined using externally palpable landmarks (right/left frontal process of the zygomatic bone and zygomatic process of the frontal bone). The head and brain constituted 7.80 ± 0.79% and 0.33 ± 0.08% of the body mass, respectively. The head and brain CoMs were primarily ventral and caudal to the ACS origin, respectively. The mean head and brain principal MoI (in the ACS with origin at respective CoM) ranged from 61.7 to 109.7 kg cm2, and 0.2 to 0.6 kg cm2, respectively. These data may aid the comparison of head and brain kinematics/kinetics data and the translation between porcine and human injury models.