Spine
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A 3-dimensional finite element model of 2 lumbar motion segments (L4-L5 and L5-S1) was used to evaluate the sensitivity of lumbar total disc replacement (TDR) impingement to disc height distraction, spinal sagittal orientation, implant position, and implant lordosis. The models were implanted with a mobile-bearing TDR and exposed to simulated sagittally balanced erect posture. ⋯ The data from this study indicate that lumbar mobile-bearing TDR impingement is sensitive to disc height distraction, anterior-posterior position, implant lordosis, and spinal sagittal orientation. TDR impingement risk can be minimized by choosing an implant with an appropriate amount of lordosis, not overdistracting the disc space, and taking care not to place the implant too far anterior or posterior.
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Retrospective clinicoradiographic analysis. ⋯ With long fusions to the sacrum, one should anticipate more perioperative complications, a higher pseudarthrosis rate, and perhaps more revision surgery than short fusions. Short fusions may result in a more proximal junctional kyphosis, only rarely requiring revision surgery.
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This case report shows primary natural killer (NK)/T-cell lymphoma originating in the spine as the first case of successful treatment with autologous stem cell transplantation, along with case presentation and literature review. ⋯ Some primary NK/T-cell lymphomas that originate at sites other than the nasal cavity/nasopharynx do not present with typical clinical features and symptoms. A primary NK/T-cell lymphoma of the spine should be considered in the differential diagnosis of primary bone tumors. We report the first case of successful treatment with chemoradiotherapy and autologous stem cell transplantation in a patient with a primary spinal NK/T-cell lymphoma.
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Comparative Study
Host bone response to polyetheretherketone versus porous tantalum implants for cervical spinal fusion in a goat model.
In vivo assessment of polyetheretherketone (PEEK) and porous tantalum (TM) cervical interbody fusion devices in a goat model. ⋯ The TM implants supported bone growth into and around the implant margins better than the PEEK devices. TM's open cell porous structure facilitated host bone ingrowth and bone bridging through the device, which could be beneficial for long-term mechanical attachment and support in clinical applications.
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Finite element (FE) method was used to compare the biomechanics of L3-S1 lumbar spine with graded facetectomy before and after placement of Dynesys. ⋯ Partial facetectomy had a minimal effect on range of motion on the Dynesys-implanted segment. However, in the case of total facetectomy the motion increased by almost 40% in flexion and by 200% in axial rotation. The higher stresses applied to the screws in Dynesys in specific loadings may lead to higher risk of screw failure in Dynesys than in a generic rigid fixation construct.