Are there typical localisations of lumbar disc herniations? A prospective study

Ebeling, U.; Reulen, H. J.

doi:10.1007/bf01400611

Cited by 102 publications

(63 citation statements)

References 21 publications

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“…First, posterolateral herniations, a term used widely in in vitro studies, correspond to intra or extraforaminal herniations clinically [39][40][41]. Such herniations are far less common than central posterior or mediolateral posterior herniations [14,16,21]. Second, a posterolateral protrusion or extrusion does not necessitate a posterolateral radial tear.…”

Section: Discussionmentioning

confidence: 99%

“…Using finite element analysis, Schmidt et al [11] found that under this same loading combination, flexion plus left axial rotation, the fibres of the inner right posterolateral annulus experience the largest shear strain. It is possible that the combination of flexion and torsion may act to drive a herniation posterolaterally, contributing to the radial tears and herniations that occur in this region, as documented in cadaveric studies [12,13] and clinical practice [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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The influence of torsion on disc herniation when combined with flexion

2010

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The role of torsion in the mechanical derangement of intervertebral discs remains largely undefined. The current study sought to investigate if torsion, when applied in combination with flexion, affects the internal failure mechanics of the disc wall when exposed to high nuclear pressure. Thirty ovine lumbar motion segments were each positioned in 2°axial rotation plus 7°fl exion. Whilst maintained in this posture, the nucleus of each segment was gradually injected with a viscous radioopaque gel, via an injection screw placed longitudinally within the inferior vertebra, until failure occurred. Segments were then inspected using micro-CT and optical microscopy in tandem. Five motion segments failed to pressurize correctly. Of the remaining 25 successfully tested motion segments, 17 suffered vertebral endplate rupture and 8 suffered disc failure. Disc failure occurred in mature motion segments significantly more often than immature segments. The most common mode of disc failure was a central posterior radial tear involving a systematic annulus-endplate-annulus failure pattern. The endplate portion of these radial tears often propagated contralateral to the direction of applied axial rotation, and, at the lateral margin, only those fibres inclined in the direction of the applied torque were affected. Apart from the 2°of applied axial rotation, the methods employed in this study replicated those used in a previously published study. Consequently, the different outcome obtained in this study can be directly attributed to the applied axial rotation. These inter-study differences show that when combined with flexion, torsion markedly reduces the nuclear pressure required to form clinically relevant radial tears that involve cartilaginous endplate failure. Conversely, torsion appears to increase the disc wall's resistance to radial tears that do not involve cartilaginous endplate failure, effectively halving the disc wall's overall risk of rupture.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The influence of torsion on disc herniation when combined with flexion

2010

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“…1,5,9,12,13 Cephalad involvement of L1 ± L2 or L2 ± L3 is rare except in An et al's study which noted an unusually high incidence of 28%. 4 …”

Section: Frequency and Location Of Far Lateral Discsmentioning

confidence: 99%

Foraminal and far lateral lumbar disc herniations: surgical alternatives and outcome measures

2002

Spinal Cord

168

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Far lateral disc herniations constitute 7 ± 12% of all disc herniations. They may be purely far lateral or extraforaminal in location, located beyond the pedicles, or may include intraforaminal and even intracanalicular components. Occurring predominantly at the L4 ± L5 and L3 ± L4 levels in almost equal numbers, they are occasionally noted at L5 ± S1. Clinical syndromes re¯ect compression of the superiorly exiting nerve root and ganglion; ie an L4 ± L5 far lateral disc produces a L4 root syndrome. Clinical complaints often include severe radicular pain accompanied by very positive mechanical signs; LaseÂ gue and reverse LaseÂ gue (femoral stretch test) maneuvers. Neurological de®cits, including motor, re¯ex, and sensory ®ndings, are seen over 75% of the time. Although conservative management is occasionally successful (10%), surgery is usually required. The extent of stenosis and attendant degenerative changes dictate whether laminectomy, hemilaminectomy or laminotomy are required along with one of several facet resection options; full facetectomy, the intertransverse approach, medial facetectomy, or an extreme lateral procedure. Postoperatively, patients' neurological outcomes based on both surgeon and patient based outcome measures (SF-36), were comparable for the dierent surgical procedures which had been based on the individual patient's pathology.

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“…Herniated disc fragments are known to migrate within the spinal canal in rostral, caudal, and lateral directions 6,14,22). Posterior epidural migration of herniated disc fragments are rare and most cases have been reported in lumbar region 2,4,5,8,12,17,19,20) .…”

Section: Introductionmentioning

confidence: 99%