Dimensions of the cervical neural foramen in conditions of spinal deformity: an ex vivo biomechanical investigation using specimen-specific CT imaging

Smith, Zachary A.; Khayatzadeh, Saeed; Bakhsheshian, Joshua; Harvey, Mike; Havey, Robert M.; Voronov, Leonard I.; Muriuki, Muturi; Patwardhan, Avinash G.

doi:10.1007/s00586-016-4409-4

Cited by 14 publications

(10 citation statements)

References 30 publications

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“…A novel test apparatus was designed to study the biomechanical consequences of cervical sagittal imbalance on the mechanics of the cervical spine. 8,9 The apparatus allows independent, controlled adjustment of the T1 tilt angle and anterior head offset relative to the base of the cervical spine (Fig. 1 left).…”

Section: Methodsmentioning

confidence: 99%

“…The motion and orientation of these lines and points during the test were determined using the specimen-specific anatomical and kinematic modeling technique. 7,8 Lordosis Angle C2-7 lordosis was the angle between anterior-posterior lines drawn on the superior surfaces of the C2 and C7 vertebral bodies. The same lines on C2 and C7 were used to determine C0-C7, C0-C2 lordosis.…”

Section: Measurementsmentioning

confidence: 99%

“…Specimen-specific anatomical and kinematic models were built for each specimen to facilitate analysis of the experimental data. 7,8 For this purpose, 5 aluminum radi-ABBREVIATIONS CSVA = cervical sagittal vertical axis.…”

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confidence: 99%

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Neutral cervical sagittal vertical axis and cervical lordosis vary with T1 tilt

Hofler

Muriuki

Havey

et al. 2020

Journal of Neurosurgery: Spine

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OBJECTIVEThe authors conducted a study to determine whether a change in T1 tilt results in a compensatory change in the cervical sagittal vertical axis (SVA) in a cadaveric spine model.METHODSSix fresh-frozen cadavers (occiput [C0]–T1) were cleaned of soft tissue and mounted on a customized test apparatus. A 5-kg mass was applied to simulate head weight. Infrared fiducials were used to track segmental motion. The occiput was constrained to maintain horizontal gaze, and the mounting platform was angled to change T1 tilt. The SVA was altered by translating the upper (occipital) platform in the anterior-posterior plane. Neutral SVA was defined by the lowest flexion-extension moment at T1 and recorded for each T1 tilt. Lordosis was measured at C0–C2, C2–7, and C0–C7.RESULTSNeutral SVA was positively correlated with T1 tilt in all specimens. After increasing T1 tilt by a mean of 8.3° ± 2.2°, neutral SVA increased by 27.3 ± 18.6 mm. When T1 tilt was reduced by 6.7° ± 1.4°, neutral SVA decreased by a mean of 26.1 ± 17.6 mm.When T1 tilt was increased, overall (C0–C7) lordosis at the neutral SVA increased from 23.1° ± 2.6° to 32.2° ± 4.4° (p < 0.01). When the T1 tilt decreased, C0–C7 lordosis at the neutral SVA decreased to 15.6° ± 3.1° (p < 0.01). C0–C2 lordosis increased from 12.9° ± 9.3° to 29.1° ± 5.0° with increased T1 tilt and decreased to −4.3° ± 6.8° with decreased T1 tilt (p = 0.047 and p = 0.041, respectively).CONCLUSIONSNeutral SVA is not a fixed property but, rather, is positively correlated with T1 tilt in all specimens. Overall lordosis and C0–C2 lordosis increased when T1 tilt was increased from baseline, and vice versa.

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Section: Methodsmentioning

confidence: 99%

Section: Measurementsmentioning

confidence: 99%

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Neutral cervical sagittal vertical axis and cervical lordosis vary with T1 tilt

Hofler

Muriuki

Havey

et al. 2020

Journal of Neurosurgery: Spine

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“…Even with adequate foraminotomies, if there is loss of disc height and consequently shortened foraminal height—a foraminotomy may not help when the cranial-caudal dimensions are further encroached by compression and extension. Increased thoracic kyphosis may also result in decreased foraminal area in the lower cervical spine, and predispose the patient to increased foraminal stenosis with further neck extension [ 6 ]. This can be avoided with the use of anterior interbody devices providing adequate indirect decompression and increasing the foraminal height prior to closing of a posteriorly-based osteotomy.…”

Section: Preoperative Planningmentioning

confidence: 99%

“…Increased thoracic kyphosis may also result in decreased foraminal area in the lower cervical spine, and predispose the patient to increased foraminal stenosis with further neck extension. 6 This can be avoided with the use of anterior interbody devices providing adequate indirect decompression and increasing the foraminal height prior to closing of a posteriorly-based osteotomy.…”

Section: Introductionmentioning

confidence: 99%

Anterior Reconstruction Techniques for Cervical Spine Deformity

et al. 2020

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Cervical spine deformity is an uncommon yet severely debilitating condition marked by its heterogeneity. Anterior reconstruction techniques represent a familiar approach with a range of invasiveness and correction potential-including global or focal realignment in the sagittal and coronal planes. Meticulous preoperative planning is required to improve or prevent neurologic deterioration and obtain satisfactory global spinal harmony. The ability to perform anterior only reconstruction requires mobility of the opposite column to achieve correction, unless a combined approach is planned. Anterior cervical discectomy and fusion has limited focal correction, but when applied over multiple levels there is a cumulative effect with a correction of approximately 6° per level. Partial or complete corpectomy has the ability to correct sagittal deformity as well as decompress the spinal canal when there is anterior compression behind the vertebral body. If pathoanatomy permits, a hybrid discectomy-corpectomy construct is favored over multilevel corpectomies. The anterior cervical osteotomy with bilateral complete uncinectomy may be necessary for angular correction of fixed cervical kyphosis, and is particularly useful in the midcervical spine. A detailed understanding of the patient's local anatomy, careful attention to positioning, and avoiding long periods of retraction time will help prevent complications and iatrogenic injury.

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