The Effects of the Degenerative Changes in the Functional Spinal Unit on the Kinematics of the Cervical Spine

Morishita, Yuichiro; Hida, Shinichi; Miyazaki, Masashi; Hong, Seongwon; Zou, Jun; Wei, Feng; Naito, Masatoshi; Wang, Jeffrey C.

doi:10.1097/brs.0b013e318166f059

Cited by 48 publications

(45 citation statements)

References 23 publications

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“…We previously demonstrated [15] that cervical cord compression greatly affected the sagittal segmental motion of the cervical spine. The sagittal segmental mobility at all levels was significantly reduced in the segments with severe cord compression when compared to those with no cord compression.…”

Section: Discussionmentioning

confidence: 99%

“…A comprehensive grading system for cervical disc degeneration was obtained by previously reported systems of classifying cervical intervertebral disc degeneration based on degenerative changes in the cervical functional spinal unit (FSU) [15]. Accordingly, T2-weighted sagittal images of 1,475 cervical intervertebral discs from 295 subjects were classified into four grades (Table 1) by the primary author and were judged eligible for inclusion in the study.…”

Section: Cervical Intervertebral Discmentioning

confidence: 99%

“…We defined cervical cord compression as the obliteration of the subarachnoid space in each segment resulting from compression due to disc herniation, osteophyte formation, or hypertrophy of the ligamentum flavum. Cervical cord compression in each segment was rated on a 3-point scale (range, 0-2), in which 0 indicated no cervical cord compression; 1, anterior or posterior cervical cord compression not affecting cord alignment; and 2, anterior or posterior cervical cord compression affecting cord alignment [15].…”

Section: Cervical Cord Compressionmentioning

confidence: 99%

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Cervical spinal canal stenosis: the differences between stenosis at the lower cervical and multiple segment levels

Morishita

Naito

Wang

2010

International Orthopaedics (SICOT)

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The lower cervical segments are commonly the level responsible for cervical spondylotic myelopathy; however, we rarely encounter stenosis at the upper cervical segment in a clinical setting. We assumed that there might be some differences between the pathogenetic mechanisms underlying the development of cervical canal stenosis at different segments. We performed positional MRI in the weight-bearing position for 295 consecutive symptomatic patients. All subjects were classified into four groups (A: normal; B: C3-4 stenosis; C: C5-6 stenosis; D: two-level cervical segments stenosis, stenosis at C3-4 and C5-6). Age, sagittal cervical canal diameter, cervical intervertebral disc degeneration, cervical cord compression, and cervical mobilities were evaluated for each group. Group B showed a narrow cervical spinal canal structure at the C3 to C4 pedicle levels, while groups C and D showed narrow structures at the C4 to C6 pedicle levels in the cervical spine. Additionally, the sagittal cervical canal diameters at all pedicle levels, except C7, in group D were significantly smaller than those observed in group C. We demonstrated the differences in the pathogenetic processes for the development of cervical spinal canal stenosis between C3-4, C5-6, and two-level cervical segments stenosis. Our results suggest that the developmental morphological structure of the cervical spinal canal plays an important role in the development of cervical canal stenosis at different segments. Moreover, individuals with sagittal cervical canal diameters of less than 13 mm may be exposed to an increased risk for future development of cervical spinal canal stenosis at the upper cervical segments following stenosis at the lower cervical segments.

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Section: Discussionmentioning

confidence: 99%

Section: Cervical Intervertebral Discmentioning

confidence: 99%

Section: Cervical Cord Compressionmentioning

confidence: 99%

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Cervical spinal canal stenosis: the differences between stenosis at the lower cervical and multiple segment levels

Morishita

Naito

Wang

2010

International Orthopaedics (SICOT)

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“…The mechanical loading of the disc is one of the main causes of its degeneration [1]. For chronic patients, the treatment regimen may range from conservative approach to surgical procedures, including fusion with and without instrumentation.…”

Section: Introductionmentioning

confidence: 99%

Parameters that effect spine biomechanics following cervical disc replacement

et al. 2011

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Total disc replacement (TDR) is expected to provide a more physiologic alternative to fusion. However, long-term clinical data proving the efficacy of the implants is lacking. Limited clinical data suggest somewhat of a disagreement between the in vitro biomechanical studies and in vivo assessments. This conceptual paper presents the potential biomechanical challenges affecting the TDR that should be addressed with a hope to improve the clinical outcomes and our understanding of the devices. Appropriate literature and our own research findings comparing the biomechanics of different disc designs are presented to highlight the need for additional investigations. The biomechanical effects of various surgical procedures are analyzed, reiterating the importance of parameters like preserving uncinate processes, disc placement and its orientation within the cervical spine. Moreover, the need for a 360°dynamic system for disc recipients who may experience whiplash injuries is explored. Probabilistic studies as performed already in the lumbar spine may explore high risk combinations of different parameters and explain the differences between ''standard'' biomechanical investigations and clinical studies. Development of a patient specific optimized finite element model that takes muscle forces into consideration may help resolve the discrepancies between biomechanics of TDR and the clinical studies.Factors affecting long-term performance such as bone remodeling, subsidence, and wear are elaborated. In vivo assessment of segmental spine motion has been, and continues to be, a challenge. In general, clinical studies while reporting the data have placed lesser emphasis on kinematics following intervertebral disc replacements. Evaluation of in vivo kinematics following TDR to analyze the quality and quantity of motion using stereoradiogrammetric technique may be needed.

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“…9,10,[12][13][14][15] Magnetic resonance im aging is the preferred radiological tool for diagnosing CSM because it not only anatomically depicts how the spinal cord is compressed but also reveals pathological changes in the spinal cord. However, it is difficult to make objective clinical assessments of CSM on the basis of radiological findings alone.…”

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confidence: 99%

Dynamic somatosensory evoked potentials to determine electrophysiological effects on the spinal cord during cervical spine extension

Morishita

Maeda

Ueta

et al. 2013

SPI

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Object The goal of this prospective study was to investigate somatosensory evoked potentials (SSEPs) during dynamic motion of the cervical spine and to evaluate the efficacy of analyzing dynamic SSEPs for predicting dynamic effects on the spinal cord in patients with cervical spondylotic myelopathy (CSM). Methods In total, 40 human subjects (20 CSM patients and 20 healthy volunteers as a control group) were examined prospectively using dynamic SSEPs with median nerve stimulation. The CSM patients showed cervical myelopathy due to cervical cord compression at the C4–5 segment. The SSEPs were examined with the cervical spine in a neutral position and at a 20° extension for 10 and 20 minutes. Changes in the N20 latency and amplitude were determined and analyzed. The authors defined the changes in the N20 latency and N20 amplitude between the neutral and extension positions of the cervical spine as percent latency and amplitude, respectively. Results In the CSM patients, SSEPs tended to deteriorate after cervical spine extension, and a statistically significant deterioration of the N20 amplitude after the extension was observed. Moreover, the percent latency and amplitude progressively increased during cervical spine extension in these patients. In the healthy controls, SSEPs tended to deteriorate with cervical spine extension, but these changes did not result in statistically significant differences. Moreover, in this group the percent latency and amplitude were almost identical during the extension. When the CSM patients and the healthy controls were compared, a significant difference in the percent amplitude was observed between the 2 groups during the cervical spine extension. Conclusions This study suggests the potential of dynamic SSEPs as a useful neurophysiological technique to detect the effect of dynamic factors on the pathogenesis of CSM.

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The Effects of the Degenerative Changes in the Functional Spinal Unit on the Kinematics of the Cervical Spine

Cited by 48 publications

References 23 publications

Cervical spinal canal stenosis: the differences between stenosis at the lower cervical and multiple segment levels

Cervical spinal canal stenosis: the differences between stenosis at the lower cervical and multiple segment levels

Parameters that effect spine biomechanics following cervical disc replacement

Dynamic somatosensory evoked potentials to determine electrophysiological effects on the spinal cord during cervical spine extension

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