Isolated unilateral rupture of the alar ligament

Wong, Sui-To; Ernest, Kimberly; Fan, Grace; Zovickian, John; Pang, Dachling

doi:10.3171/2014.2.peds13527

Cited by 20 publications

(28 citation statements)

References 15 publications

(29 reference statements)

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“…Inter-fragmentary compression pressure alone cannot guarantee the biomechanical superiority of the Herbert screw compared with the cannulated lag screw. Second, clinically, greater inter-fragmentary compression pressure may not mean greater reduction of the fracture gap in odontoid process fixation, because, in humans, the dens is attached by many strong ligaments including apical and alar ligaments 12 , 26) . Furthermore, because there are so many risk factors of fusion failure of odontoid process fixation 2 , 3 , 11 , 15) , we must consider other factors for higher bone fusion rates after odontoid screw fixation.…”

Section: Discussionmentioning

confidence: 99%

Biomechanical Comparison of Inter-fragmentary Compression Pressures : Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation

Park

Kim

Sung

et al. 2017

J Korean Neurosurg Soc

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ObjectiveThe purpose of the present study was to compare inter-fragmentary compression pressures after fixation of a simulated type II odontoid fracture with the headless compression Herbert screw and a half threaded cannulated lag screw.MethodsWe compared inter-fragmentary compression pressures between 40- and 45-mm long 4.5-mm Herbert screws (n=8 and n=9, respectively) and 40- and 45-mm long 4.0-mm cannulated lag screws (n=7 and n=10, respectively) after insertion into rigid polyurethane foam test blocks (Sawbones, Vashon, WA, USA). A washer load cell was placed between the two segments of test blocks to measure the compression force. Because the total length of each foam block was 42 mm, the 40-mm screws were embedded in the cancellous foam, while the 45-mm screws penetrated the denser cortical foam at the bottom. This enabled us to compare inter-fragmentary compression pressures as they are affected by the penetration of the apical dens tip by the screws.ResultsThe mean compression pressures of the 40- and 45-mm long cannulated lag screws were 50.48±1.20 N and 53.88±1.02 N, respectively, which was not statistically significant (p=0.0551). The mean compression pressures of the 40-mm long Herbert screw was 52.82±2.17 N, and was not statistically significant compared with the 40-mm long cannulated lag screw (p=0.3679). However, 45-mm Herbert screw had significantly higher mean compression pressure (60.68±2.03 N) than both the 45-mm cannulated lag screw and the 40-mm Herbert screw (p=0.0049 and p=0.0246, respectively).ConclusionOur results showed that inter-fragmentary compression pressures of the Herbert screw were significantly increased when the screw tip penetrated the opposite dens cortical foam. This can support the generally recommended surgical technique that, in order to facilitate maximal reduction of the fracture gap using anterior odontoid screws, it is essential to penetrate the apical dens tip with the screw.

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Section: Discussionmentioning

confidence: 99%

Biomechanical Comparison of Inter-fragmentary Compression Pressures : Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation

Park

Kim

Sung

et al. 2017

J Korean Neurosurg Soc

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“…Interestingly, isolated rupture of the alar ligament has been managed conservatively with external immobilization, suggesting that other isolated ligamentous injuries may be treated with this approach [25]. Typically, unless frank AOD is seen on imaging, patients without neurological deficits may be treated conservatively [21, 26].…”

Section: Discussionmentioning

confidence: 99%

Traumatic Occipitocervical Distraction Injuries in Children: A Systematic Review

et al. 2019

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Background: Occipitocervical distraction injuries (OCDI) in children occur on a wide spectrum of severity, and decisions about treatment suffer from a lack of rigorous guidelines and significant inter-institutional variability. While clear cases of frank atlanto-occipital dislocation (AOD) are treated with surgical stabilization, the approach for less severe cases of OCDI is not standardized. These patients require a careful assessment of both radiographic and clinical criteria, as part of a complex risk-benefit analysis, to establish whether occipitocervical fusion (OCF) is indicated. Here, we performed a systematic review of the literature that describes traumatic OCDI in children < 18 years of age. Summary: We performed a systematic review, according to PRISMA guidelines, of children < 18 years of age presenting with traumatic etiologies of OCDI. We searched PubMed to identify papers congruent with these criteria. Exclusion criteria included (1) reports on atraumatic causes of OCDI and (2) studies with insufficient clinical and radiographic details on individual patients. We identified 16 reports describing a total of 144 patients treated for pediatric traumatic OCDI. Based on the synthesis of these findings and the collective experience of the authors, we present the demographic, clinical, and radiographic factors that underlie OC instability, which we hope will serve as components of a grading system in the future. We considered various clinical and radiographic findings including: (1) the mechanism of injury, (2) the patient’s age, (3) CT/CT angiography of head and neck findings and parameters, (4) MRI findings, and (5) neurological exam, for the purpose of determining the severity of the OCDI and offering treatment guidelines based on the summative risk of underlying OC instability. Key Messages: OCDI is a potentially devastating injury, especially in children. Although missing the diagnosis can have potentially catastrophic consequences, reverting to surgical fixation in less severe cases can subject children to unnecessary operative risk and permanently reduce their range of motion. After reviewing all the available reports of pediatric traumatic OCDI in the neurosurgical literature, we propose an outline of clinical and radiographic factors influencing underlying OC instability that could be incorporated into a grading scale to guide treatment. We hope this study stimulates discussion on the standardization of treatment for pediatric OCDI.

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“…Furthermore, clinical symptoms were reported in patients with WAD and AL signal alterations. [16][17][18]39 However, the clinical significance of these signal changes has been disputed since the 1990s: various MRI studies showed that there is a broad range of variations in interindividual signal intensity and morphology in AL, both in patients with WAD [36][37][38][39][40] and healthy volunteers. 23,24,29 As a cautionary note, MRI should generally be accompanied in WAD, and especially in suspected upper spinal instability, with multimodal imaging procedures depending on the clinical setting of the patient.…”

Section: Discussionmentioning

confidence: 99%

Signal changes of the alar ligament in a healthy population: a dispositional or degenerative consequence?

Wenz¹,

Kerl²,

Maros³

et al. 2015

SPI

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OBJECT The alar ligaments (ALs) are vital for stabilizing the craniocervical junction. In terms of morphology, their appearance varies and is visible on MRI. Dark signal of the AL on proton-density (PD)-weighted images is generally considered the norm, but the etiology of frequently observed signal hyperintensities is poorly understood. Using spectral fat suppression, signal hyperintensities can be differentiated into fat- and nonfat-related hyperintensities (NFH). Although signal hyperintensities have no evident association with whiplash-associated disorder, age-related degeneration has often been theorized. Therefore, this study investigates the signal intensities of the ALs on 3.0-T MRI with special reference to age. Expanding thereon, the authors investigated the relationship between signal hyperintensities and patient characteristics, such as height, weight, and sex. METHODS Sixty-six healthy volunteers were scanned using 3.0-T PD-weighted MRI, including spectral fat suppression of the craniocervical junction. The study population was separated into 2 groups (old vs young) using 2 approaches: dichotomization at the median age (40.0 years) and the calculated threshold (28.5 years) using receiver operating characteristics (ROC). The AL was independently characterized with respect to continuity, course, shape, signal intensity, and graduation of homogeneity by 2 experienced neuroradiologists. Signal intensity was differentiated into fat-related hyperintensity and NFH. Univariate and multivariate logistic regression models were employed to investigate the relationship between patient characteristics and signal intensities. RESULTS Two different AL patterns were observed: inhomogeneous (33.3%) and homogeneous (66.7%). The latter pattern was mostly surrounded by a small dark rim (56.8%). Fat could be identified in 15.9% of all ALs (21 of 132 patients), and NFH was identified in 17.4% of all ALs (23 of 132 patients). Here, 28.5 years was the preferred threshold, demonstrating a relatively high sensitivity for dichotomizing the population based on the ROC of NFH. The most relevant factor for having NFH was being older than the calculated threshold (odds ratio [OR] 3.420, p = 0.051). Fat-related hyperintensities occurred significantly more frequently in men than women (OR 0.110 and p = 0.007 for women; OR 9.075 and p = 0.007 for men). Height was the second most significant factor: for every 1-cm increase, the odds of having fat lesions increased by approximately 10% (OR 1.102; p = 0.017). CONCLUSIONS This study shows that AL signal hyperintensities are substantially influenced by age, sex, and height in healthy individuals. Regarding fat-related hyperintensities, the most relevant factors proved to be sex and height. The odds of detecting NFH increased almost significantly after a relatively young age (> 28.5 years) and were remarkably more frequent in individuals older than 28.5 years. The authors caution presumptions equating signal alterations with age-related deterioration. Instead, they suggest that dispositional factors such as sex and height are more relevant in the AL constitution. Signal alterations in ALs naturally occur in healthy symptom-free individuals, underscoring the importance of cautiously interpreting such lesions on posttraumatic MRI scans.

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Isolated unilateral rupture of the alar ligament

Cited by 20 publications

References 15 publications

Biomechanical Comparison of Inter-fragmentary Compression Pressures : Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation

Biomechanical Comparison of Inter-fragmentary Compression Pressures : Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation

Traumatic Occipitocervical Distraction Injuries in Children: A Systematic Review

Signal changes of the alar ligament in a healthy population: a dispositional or degenerative consequence?

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