The spine journal : official journal of the North American Spine Society
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Achieving fusion across the lumbosacral junction is challenging because of the unfavorable biomechanics associated with ending a fusion at this level. Bicortical placement of S1 pedicle screws can increase the construct stability at the lumbosacral junction; however, construct failure and pseudoarthrosis can still result. Iliac screws have been shown to increase the stiffness of lumbosacral constructs, but disadvantages include difficulty in connecting the iliac screw to adjacent sacral screws, painful screw loosening or prominence requiring removal, and the inability to place the screws in some patients with previous iliac crest autograft harvest. ⋯ Three-dimensional image guidance allows for safe placement of large S2 sacral alar screws that can provide additional biomechanical stability to lumbosacral constructs or serve as an alternate point of sacral fixation when S1 pedicle screws cannot be salvaged or placed in a medial trajectory.
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Review
Causal assessment of occupational carrying and low back pain: results of a systematic review.
Occupational low back pain (LBP) is a common musculoskeletal disorder that results in high healthcare use and a heavy societal burden from morbidity and medical costs. The etiology of LBP is unclear, although numerous physical activities in the workplace have been implicated in its development. Determining the causal relationship between LBP and specific occupational activities requires a rigorous methodological approach. ⋯ This review failed to identify high-quality studies that supported any of the Bradford-Hill criteria to establish causality between occupational carrying and LBP. Based on these results, it is unlikely that occupational carrying is independently causative of LBP in the populations of workers studied.
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Low back pain (LBP) is a common musculoskeletal disorder associated with a considerable social and economic burden within the working-age population. Despite an unclear etiology, numerous physical activities are suspected of leading to LBP. Declaring a causal relationship between occupational activities and LBP remains challenging and requires a methodologically rigorous approach. ⋯ The studies reviewed did not support a causal association between workplace manual handling or assisting patients and LBP in a Bradford-Hill framework. Conflicting evidence in specific subcategories of assisting patients was identified, suggesting that tasks such as assisting patients with ambulation may possibly contribute to LBP. It appears unlikely that workplace manual handling or assisting patients is independently causative of LBP in the populations of workers studied.
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Discectomy is a common procedure for treating sciatica. However, both the operation and preceding herniated disc alter the biomechanical properties of the spinal segment. The disc mechanics are also altered in patients with chronic contained herniation. The biomechanical properties of the disc can potentially be restored with an elastomeric nucleus replacement implanted via minimally invasive surgery. ⋯ This study demonstrates that despite having different material properties, a nucleus replacement implant can restore the axial compressive mechanical properties of a disc after a discectomy. The implant carries compressive load and transfers the load into annular hoop stress.
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Vertebral osteolysis has been reported as a complication of off-label recombinant human bone morphogenetic protein-2 (rhBMP-2) use in transforaminal lumbar interbody fusion (TLIF). It has been postulated that end plate violation during disc space preparation, rhBMP-2 overdosing, or a combination thereof can contribute to the development of vertebral osteolysis when rhBMP-2 is used in the lumbar interspace. ⋯ It has been proposed that rhBMP-2-induced vertebral osteolysis occurring in TLIF procedures may be secondary to end plate violation during disc preparation or overdosing of rhBMP-2. Although overdosing may have also contributed to vertebral osteolysis in our two cases, the end plate violation from subchondral cyst formation that was present on preoperative CT scans seemed to be the origin of the osteolysis suggesting that the presence of preoperative subchondral cysts may be an additional risk factor for development of osteolysis in these patients.