The Biomechanics of Lumbar Facetectomy Under Compression-Flexion

Pintar, Frank A.; Cusick, Joseph F.; Yoganandan, Narayan; Reinartz, John; Mahesh, Mahadevappa

doi:10.1097/00007632-199207000-00013

Cited by 40 publications

(22 citation statements)

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“…In the present study this change in the length of the centrode, and thus the translational motion, was evident in all directions of motion. With the knowledge regarding the relationship of disc degeneration and ICR, 40,43 as well as column deficiency and ICR 7,17,26,39 on the one hand and the results of this study on the other, it appears that the ICR can have a diagnostic value in defining the source of segmental instability.…”

Section: The Icr and Ligament Failurementioning

confidence: 71%

“…A shift in the ICR away from the column of instability was also observed, which matches the results of previous experimental studies. 7,17,26,39 In flexion, the removal of all of the ligaments carried the ICR anteriorly and superiorly, toward the cen- ter of the disc. This result was also in agreement with a previous study, 5 which stated that the reduced posterior ligament stiffness was a passive factor causing upward and forward displacement of the ICR.…”

Section: The Icr and Ligament Failurementioning

confidence: 99%

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Instantaneous center of rotation behavior of the lumbar spine with ligament failure

Alapan

Demir

Kaner

et al. 2013

SPI

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Object The goal of this study was to investigate the effect of ligament failure on the instantaneous center of rotation (ICR) in the lower lumbar spine. Methods A 3D finite element model of the L4–5 segment was obtained and validated. Ligament failure was simulated by reducing ligaments in a stepwise manner from posterior to anterior. A pure bending moment of 7.5 Nm was applied to the model in 3 anatomical planes for the purpose of validation, and a 6-Nm moment was applied to analyze the effect of ligament failure. For each loading case, ligament reduction step, and load increment, the range of motion of the segment and the ICR of the mobile (L-4) vertebra were calculated and characterized. Results The present model showed a consistent increase in the range of motion as the ligaments were removed, which was in agreement with the literature reporting the kinematics of the L4–5 segment. The shift in the location of the ICR was below 5 mm in the sagittal plane and 3 mm in both the axial and coronal planes. Conclusions The location of the ICR changed in all planes of motion with the simulation of multiple ligament injury. The removal of the ligaments also changed the load sharing within the motion segment. The change in the center of rotation of the spine together with the change in the range of motion could have a diagnostic value, revealing more detailed information on the type of injury, the state of the ligaments, and load transfer and sharing characteristics of the segment.

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Section: The Icr and Ligament Failurementioning

confidence: 71%

Section: The Icr and Ligament Failurementioning

confidence: 99%

Instantaneous center of rotation behavior of the lumbar spine with ligament failure

Alapan

Demir

Kaner

et al. 2013

SPI

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“…The destabilization procedure was shown to effectively increase motion in the segment [14]. Recently, the destabilizing effect of facetectomy was also confirmed for loads other than pure bending moments [29]. A twolevel instability was chosen, because the injury for which the stabilization effect of an implant is tested should be specific for its intended application [26].…”

Section: Discussionmentioning

confidence: 99%

In vitro testing of a new transpedicular stabilization technique

et al. 1997

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The rigidity of a pedicle screw implant is a critical biomechanical variable in lumbar spinal fusions. Sufficient rigidity is required for integration of bone grafts and to promote healing. Osteopenia, stress shielding, and compensatory hypermobility have been described as consequences of excessive rigidity. Little is known about the biomechanical characteristics of "semirigid" compared to "rigid" implants. A new implant, whose rigidity can be varied by selection of different implant components, was tested in vitro under well-defined loading conditions. The three-dimensional load-displacement behavior of all lumbar vertebrae involved in or adjacent to the two-level fusion was evaluated for two fusion modifications: bilateral rigid and bilateral semirigid. Cyclic fatigue loading was subsequently carried out under realistic conditions and motion testing repeated. The rigid device reduced the motion of the L3-4 transfixed segment in the primary movement planes by 87.3% with respect to the intact spine value in flexion/extension (FE), 86.3% in lateral bending (LB), and 76.8% in axial rotation (AR). The semirigid device achieved a reduction in motion of 79.6% (FE), 82.7% (LB), and 51.7% (AR). The semirigid implant was particularly easy to insert, because no bending of rods or plates was necessary. The implants showed no loosening or breakage after the fatigue testing. The results are compared to other available systems and the underlying biomechanics discussed.

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“…However, a patient with a history of recent lumbar spinal fusion, for example, may not be one with whom you would want to introduce forceful spinal rotation. [47][48][49][50] This, of course, is a clinical decision that should be based on the culmination of evidence obtained from the entire consultation and assessment service visit, including outside records and imaging data. The TT may be used as a re-evaluation tool so that changes in clinical patterns can be documented and progress can be monitored, as indicated.…”

Section: Torsion Test Protocolmentioning

confidence: 99%