5/13/2009 K S. C ontraindications BACKGROUND METHODS 2 METHODS 1 CRANIOVERTEBRAL INSTABILITY TESTING. DO THE TESTS REALLY REFLECT THE ANATOMY?

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1 CRANIOVERTEBRAL INSTABILITY TESTING. DO THE TESTS REALLY REFLECT THE ANATOMY? Peter Osmotherly 1 Prof Darren Rivett 1 A/Prof Susan Mercer 2 1. School of Health Sciences, The University of Newcastle, Australia 2. School of Biomedical Sciences, The University of Queensland, Australia C ontraindications R O C K S BACKGROUND Recommendations for screening for craniovertebral instability (CVI) Studies examining the validity of these ligament tests is lacking for most tests described Tests have been described based on published descriptions of the anatomy and biomechanics of the region (Aspinall 1990). Descriptions of ligamentous anatomy and role in controlling upper cervical movement is inconsistent and contradictory. No clinical stress test for CVI has ever been examined in a post-traumatic population METHODS 1 METHODS 2 Approach based on methodology of Dvorak et al (1988) 11 embalmed adult cadavers Specimens extending minimum occiput to C6 Divested of all muscle tissues Posterior wedge of approximately 140 cut from the occipital bone Posterior arch of the atlas, axis and included cervical segments resected 11 embalmed cadavers Specimens extending occiput to -3 Decalcified and embedded Serial slicing Stained Haematoxylin and Eosin Elastic Van Gieson Alcian Blue 1

2 METHODS 3 Alar ligaments 6 embalmed cadavers Specimens extending occiput to -3 MRI 4.6T magnet interfaced to an AVANCE spectrometer running ParaVision 4.0. A 3D RARE multiple spin echo sequence was used : TR = 2 sec, echo train length = 8, effective TE = 56, SW = Hz, Field-of-view = 80X80X45 mm, image matrix = 12X512X256, image resolution 156X0.156X0.176mm, total acquisition time= 18hr 24 min. Images were exported in DICOM format for analysis. Remain inconsistently described Classical descriptions Composed almost entirely of collagen fibres Role in limiting rotation Side bending stress test for the alar ligaments (Dvorak and Panjabi 1987) Current tests based almost exclusively on Dvorak and Panjabi (1987) Orientation Atlantal portion of the ligament Atlantal portion; Can it be tested? Does it have any significance? Mechanics Lateral flexion of the occiput is accompanied by immediate ipsilateral rotation of the axis under the atlas, i.e. Right lateral flexion is accompanied by right rotation of the axis under the atlas (or left rotation at the atlantoaxial joint). The rotation is the result of tension generated in the alar ligaments...\..\..\..\..\desktop\sidebending alar.mod Rotation stress test for alar ligaments RESULTS - ALAR LIGAMENTS Test is based on coupled motion alar ligaments prevent rotation as well as occipital lateral flexion. Patient position: Sitting Therapist position: Standing to side of patient Fixation: Thumb and index finger right hand hold spinous process. Left hand grasps cranium Stress: Left hand rotates head. No lateral flexion is permitted. Test is performed in neutral, flexion and extension. New Zealand Guidelines 2004 Interpretation: If alar ligament intact, no more than 20 degrees of rotation should be possible Origin either on the lateral or the posterolateral aspect of the upper one-third of the dens. Distance from the tip of the dens and the extent of attachment was subject to variation Fibres ran horizontally in seven specimens, with the remainder oriented cephalocaudally. Insertion consistently occurred onto the medial aspect of the occipital condyles. No atlantal portion was present in any specimen examined...\..\..\..\..\desktop\rotation alar.mod 2

3 Dens Transverse band of alar ligament Dens 3

4 Implications The broader spectrum of anatomical literature needs to be considered when designing clinical tests Orientation of the alar ligaments may be more horizontal than typically described The atlantal t l portion of the alar ligament should be considered an anatomical variant It should not be specifically tested Little or no functional significance A proportion of alar ligaments will not act to limit O-/2 rotation. Tectorial membrane The least explored of the passive stabilising structures of the craniovertebral region Usually described as arising from the posterior surface of the vertebral body of the second cervical vertebra Expands and broadens as it passes upwards, taking a funnel-shaped appearance Cephalad attachment of the tectorial membrane has been less consistently described Various reports of dissections published describing the tectorial membrane as a multilayered structure consisting of distinct t Fick (1904) Oda et al (1992) Cave (1933/34) Ross and Lamperti 2006 Zuckerman 1961 Recently challenged again by Tubbs et al (2006) Distraction testing for the Tectorial membrane. RESULTS TECTORIAL MEMBRANE Tectorial membrane limits flexion and distraction. Normal distraction should not exceed 1 to 2mm. Patient position: Supine with cervicothoracic junction flexed. (this removes the stabilizing effect of the ligamentum nuchea) Fixation: Gently grasp the neural arch and flex the cervicothoracic junction. Cup the occiput in your other hand Stress: perform a distraction If the response is negative, repeat the distraction test in craniovertebral flexion. Diagnostic validity: Not evaluated New Zealand Guidelines 2004 Each tectorial membrane was composed of 2 distinct layers; Superficial and deep Within these layers lay of ligament Superficial layer composed variably of 3 or 4 Deep layer consisting of 3..\..\..\..\..\Desktop\Tec membrane.mod 4

5 Central band Central band Lateral Lateral Superficial layer of the Tectorial membrane Deep central band Central band Deep lateral Lateral Deep layer of the Tectorial membrane Deep lateral Transverse ligament 5

6 Implications A more complex structure than has been described by most standard anatomical textbooks Strong similarity to the descriptions given by the older European anatomists Multilayered and composed of distinct of dense tissue Curve nature of the structure suggests that it may play a role in limiting craniocervical rotation International Mulligan Concept Conference 2009 Chicago 2 nd May 2009 CRICOS Provider 00109J 6