Dynamic Intervertebral Body Angle of the Lower Cervical Spine during Protracted Head Extension Using Measured by Fluoroscopy

Abstract

Abstract.[Purpose] To analyze dynamic lower cervical spine kinematics under neutral head extension (Ex) and protracted head extension (Pro-Ex) using fluoroscopy.[Method] The intervertebral body angle of the lower cervical spine of 8 healthy individual was analyzed using fluoroscopy during cervical extension with the head in the neutral (Ex) and protracted (Pro-Ex) positions.[Results] At maximum cervical extension position, we noted a significanly smaller value in the Pro-Ex position than in Ex position. During extension, the intervertebral body angle was significantly greater at C3-4 and less at C6-7 level in the Pro-Ex position compared to the Ex position in the initial phase. However, there was no significant difference in the intervertebral body angle between the two positions in final phase of extension. This shows greater extension movement C6-7 level in Pro-Ex.[Conclusion] The pro-Ex result showed less range of motion of extension. This suggests exaggerated hypermobility in the lower segments of the cervical spine, which might be implicated in early degenerative disease of the cervical spine.

Kinematic analysis of the lower cervical spine in the protracted and retracted neck flexion positions

“…Generally, degenerative changes frequently occur in lower segments 14 ) . Our previous study 7 ) showed that a protracted position during head extension also creates a higher ROM of the intervertebral body angle at the C5–6 and C6–7 levels. Considering these results, we assumed the Pro position is one of the strong reasons for degenerative changes in the C6–7 segments.…”

“…These images were analyzed using the LabVIEW software (National Instruments, Austin, TX, USA). For kinematic analysis, the intervertebral body angles were analyzed based on our previous study 7 ) . The intervertebral body angle is the angle between the midplane of the adjacent vertebral spine as described by Frobin et al 6 ) .…”

“…Acquisition of quantitative data from a normal person in pathological or recommended positions is the first step to understanding cervical spine diseases 6 ) . Recently, there have been a few studies about the neck flexion and extension motions 7 , 8 , 9 ) however, these studies are insufficiently related to the cervical vertebra kinematics in the neck flexion position with different head postures.…”

A Two Joint Neck Model to Identify Malposition of the Head Relative to the Thorax

“…The cervical spine has the largest mobility of all sectors of the human spine. Since the head moves with six degrees of freedom relative to the thorax, the cervical spine has six degrees of freedom [ 17 , 37 , 46 ]. The range of motion differs between directions.…”

Concurrent validity and reliability of a mobile tracking technology to measure angular and linear movements of the neck

“…The prototype 56 system was shown to be valid, although the reliability of the repositioning and upper cervical 57 flexion tests needs to be reconsidered. The anatomical and physiological characteristics of the cervical spine allow humans to rotate 65 and translate their head relative to the thorax in all directions (six degrees of freedom) 66 (Ordway et al, 1997;Park, 2015;Seo et al, 2013). Impairment of the neck is related to the 67 cervical range of motion (Ernst et al, 2015;Hall et al, 2010).…”