The spine journal : official journal of the North American Spine Society
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Although the precise cause of heterotopic ossification (HO) remains unclear, it is certain that it increases with time. The reason why the reported occurrence rate has been given as a wider range is that there were no clinical reports that have addressed the occurrence rate based on the morphology and position. ⋯ Type 1 HO developed mostly in the posterior disc space. Type 2 HO was the dominant type in the anterior disc space. Type 3 HO developed only in the anterior disc space. It is certain that both Type 1 and Type 2 HOs are related to biomechanical stresses (compressive force for Type 1 HO and traction force for Type 2 HO). It is suggested that a cervical arthroplasty should be selected in terms of the implant level, hybrid conditions on the upper adjacent segment, disc design vulnerable to the pseudotranslation, the presence of preoperative ossification, and fitting implants to end plates to reduce the development of HO.
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Thoracic pedicle screw (TPS) constructs have improved curve correction measurements compared with hook and hybrid constructs in the treatment of adolescent idiopathic scoliosis (AIS), but the optimal implant density, or the number of screws per level, remains unknown in the treatment of flexible thoracic curves. ⋯ We identified no clinical, radiographic, perioperative, or complication-related advantage of constructs with higher TPS implant density in this patient cohort with flexible idiopathic scoliosis. Cost was significantly higher with HD constructs in comparison with LD constructs. Optimal implant density chosen by the surgeon should rely on a number of factors including curve magnitude and rigidity, bone density, and desired correction.
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It is suggested that the shape of the vertebral end plates may play a role in the development of abnormalities in the intervertebral disc. On midsagittal magnetic resonance images of the spine in patients with lumbar intervertebral disc herniation, a notable disproportion frequently exists between the end plates of two vertebrae to which the disc is attached. There is apparently no study in the literature examining possible association of this disproportion with development of disc herniation. ⋯ Difference of end plate is a significant and probably independent risk factor for lumbar disc herniation.
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Controversies persist for the best treatment of burst fractures of the thoracolumbar spine. Anterior corpectomy and discectomy followed by reconstruction with intervertebral cage and posterior fixation, for example, are based mainly on the widespread assumption that intervertebral discs involved in burst-type fractures, typically, do not survive the traumatic event and will degenerate irrevocably. ⋯ Intervertebral discs adjacent to traumatic burst fractures treated with pedicle screw instrumentation and direct end-plate restoration do not routinely seem to progress to severe degeneration at 12 to 18 months postinjury.
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Patients often present to spine clinic with evidence of intervertebral disc degeneration (IDD). If conservative management fails, a safe and effective injection directly into the disc might be preferable to the risks and morbidity of surgery. ⋯ Treatment of degenerating rabbit intervertebral discs with hUTC in a hydrogel carrier solution might help restore the MRI, histological, and biomechanical properties toward those of nondegenerated controls. Treatment with cells in saline or a hydrogel carrier devoid of cells also might help restore some imaging, architectural, and physical properties to the degenerating disc. These data support the potential use of therapeutic cells in the treatment of disc degeneration.