Kinematics of the Cervical Spine

Dunsker, Stewart B.; Colley, David P.; Mayfield, Frank H.

doi:10.1093/neurosurgery/25.cn_suppl_1.174

Cited by 18 publications

(15 citation statements)

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“…Cervical spine kinematics are commonly assessed using static, end-range of motion radiographs collected with the head in full flexion and full extension[1-5]. Previous studies have demonstrated significant inter-subject variability in intervertebral flexion-extension range of motion (ROM), ranging from 20% to 60% of the overall motion at each motion segment[4-8].…”

Section: Introductionmentioning

confidence: 99%

Continuous cervical spine kinematics during in vivo dynamic flexion-extension

Anderst¹,

Donaldson²,

Lee³

et al. 2014

The Spine Journal

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BACKGROUND CONTEXT A precise and comprehensive definition of “normal” in vivo cervical kinematics does not exist due to high inter-subject variability and the absence of mid-range kinematic data. In vitro test protocols and finite element models that are validated using only end range of motion data may not accurately reproduce continuous in vivo motion. PURPOSE The primary objective of this study was to precisely quantify cervical spine intervertebral kinematics during continuous, functional flexion-extension in asymptomatic subjects. The advantages of assessing continuous intervertebral kinematics were demonstrated by comparing asymptomatic controls with single-level anterior arthrodesis patients. STUDY DESIGN Cervical spine kinematics were determined during continuous in vivo flexion-extension in a clinically relevant age group of asymptomatic controls and a group of C5/C6 arthrodesis patients. PATIENT SAMPLE 6 single-level (C5/C6) anterior arthrodesis patients (average age: 48.8 ± 6.9 yrs; 1 M, 5 F; 7.6±1.2 mo. post-surgery) and 18 asymptomatic control subjects of similar age (average age: 45.6 ± 5.8 yrs; 5 M, 13 F). OUTCOME MEASURES The physiologic measure of continuous kinematic motion paths at each cervical motion segment (C2 to C7) during flexion-extension. METHODS Participants performed flexion-extension while biplane radiographs were collected at 30 images per second. A previously validated tracking process determined three-dimensional vertebral positions with sub-millimeter accuracy. Continuous flexion-extension rotation and anterior-posterior translation motion paths were adjusted for disc height and static orientation of each corresponding motion segment. This study was funded by NIH/NIAMS Grant #1R03AR056265 and The Cervical Spine Research Society 21st Century Development Grant. The authors have no potential financial conflict of interest biases related to this study. RESULTS Inter-subject variability in flexion-extension angle was decreased 15% to 46% and inter-subject variability in anterior-posterior translation was reduced 14% to 33% after adjusting for disc height and static orientation angle. Average inter-subject variability in continuous motion paths was 1.9° in flexion-extension and 0.6 mm in translation. Third-order polynomial equations were determined to precisely describe the continuous flexion-extension and anterior-posterior translation motion path at each motion segment (all R2 > .99). CONCLUSIONS A significant portion of the inter-subject variability in cervical kinematics can be explained by the disc height and the static orientation of each motion segment. Clinically relevant information may be gained by assessing intervertebral kinematics during continuous functional movement rather than at static, end range of motion positions. The fidelity of in vitro cervical spine mechanical testing protocols may be evaluated by comparing in vitro kinematics to the continuous motion paths presented.

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Section: Introductionmentioning

confidence: 99%

Continuous cervical spine kinematics during in vivo dynamic flexion-extension

Anderst¹,

Donaldson²,

Lee³

et al. 2014

The Spine Journal

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“…Intervertebral range of motion (ROM) is commonly determined in vivo using two-dimensional lateral radiographs, typically acquired at static full-flexion and full-extension positions 7,23–25 . These measurements have inherent limitations, including the high measurement variability associated with manual digitization 23,24,26,27 , the absence of dynamic loading, and the inability to assess motion out of the film plane.…”

Section: Introductionmentioning

confidence: 99%

“…These measurements have inherent limitations, including the high measurement variability associated with manual digitization 23,24,26,27 , the absence of dynamic loading, and the inability to assess motion out of the film plane. In order to improve our understanding of cervical spine kinematics, it has been suggested that three-dimensional (3D) measurements 7,28–32 be acquired during in vivo dynamic loading conditions 7,33–35 . An additional limitation of previous research has been the failure to assess the effects of arthrodesis on midrange kinematics, which make up the vast majority of activities of daily living 36,37 .…”

Section: Introductionmentioning

confidence: 99%

Longitudinal Study of the Six Degrees of Freedom Cervical Spine Range of Motion During Dynamic Flexion, Extension, and Rotation After Single-level Anterior Arthrodesis

Anderst

West

Donaldson

et al. 2016

Spine

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Study Design A longitudinal study using biplane radiography to measure in vivo intervertebral range of motion (ROM) during dynamic flexion/extension and rotation. Objective To longitudinally compare intervertebral maximal ROM and midrange motion in asymptomatic control subjects and single-level arthrodesis patients. Summary of Background Data In vitro studies consistently report that adjacent segment maximal ROM increases superior and inferior to cervical arthrodesis. Previous in vivo results have been conflicting, indicating that maximal ROM may or may not increase superior and/or inferior to the arthrodesis. There are no previous reports of midrange motion in arthrodesis patients and similar-aged controls. Methods Eight single-level (C5/C6) anterior arthrodesis patients (tested 7±1 months and 28±6 months post-surgery) and six asymptomatic control subjects (tested twice, 58±6 months apart) performed dynamic full ROM flexion/extension and axial rotation while biplane radiographs were collected at 30 images/s. A previously validated tracking process determined three-dimensional vertebral position from each pair of radiographs with sub-millimeter accuracy. The intervertebral maximal ROM and midrange motion in flexion/extension, rotation, lateral bending, and anterior-posterior translation were compared between test dates and between groups. Results Adjacent segment maximal ROM did not increase over time during flexion/extension or rotation movements. Adjacent segment maximal rotational ROM was not significantly greater in arthrodesis patients than in corresponding motion segments of similar-aged controls. C4/C5 adjacent segment rotation during the midrange of head motion and maximal anterior-posterior translation were significantly greater in arthrodesis patients than in the corresponding motion segment in controls on the second test date. Conclusions C5/C6 arthrodesis appears to significantly affect midrange, but not end-range, adjacent segment motions. The effects of arthrodesis on adjacent segment motion may be best evaluated by longitudinal studies that compare maximal and midrange adjacent segment motion to corresponding motion segments of similar-aged controls to determine if the adjacent segment motion is truly excessive.

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“…It is believed arthrodesis may lead to increased motion in adjacent vertebrae, resulting in overload [2][3][4][5][6] that leads to degeneration [4,[7][8][9][10][11][12] and potentially additional surgery [10,[13][14][15][16]. In an attempt to eliminate or minimize adjacent segment overload, several motion-preserving disk replacement devices have been recently developed [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Subject-Specific Inverse Dynamics of the Head and Cervical Spine During in Vivo Dynamic Flexion-Extension

Anderst¹,

Donaldson²,

Lee³

et al. 2013

Journal of Biomechanical Engineering

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The effects of degeneration and surgery on cervical spine mechanics are commonly evaluated through in vitro testing and finite element models derived from these tests. The objectives of the current study were to estimate the load applied to the C2 vertebra during in vivo functional flexion-extension and to evaluate the effects of anterior cervical arthrodesis on spine kinetics. Spine and head kinematics from 16 subjects (six arthrodesis patients and ten asymptomatic controls) were determined during functional flexionextension using dynamic stereo X-ray and conventional reflective markers. Subjectspecific inverse dynamics models, including three flexor muscles and four extensor muscles attached to the skull, estimated the force applied to C2. Total force applied to C2 was not significantly different between arthrodesis and control groups at any 10 deg increment of head flexion-extension (all p values ! 0.937). Forces applied to C2 were smallest in the neutral position, increased slowly with flexion, and increased rapidly with extension. Muscle moment arms changed significantly during flexion-extension, and were dependent upon the direction of head motion. The results suggest that in vitro protocols and finite element models that apply constant loads to C2 do not accurately represent in vivo cervical spine kinetics.

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Kinematics of the Cervical Spine

Cited by 18 publications

References 0 publications

Continuous cervical spine kinematics during in vivo dynamic flexion-extension

Continuous cervical spine kinematics during in vivo dynamic flexion-extension

Longitudinal Study of the Six Degrees of Freedom Cervical Spine Range of Motion During Dynamic Flexion, Extension, and Rotation After Single-level Anterior Arthrodesis

Subject-Specific Inverse Dynamics of the Head and Cervical Spine During in Vivo Dynamic Flexion-Extension

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