Spine
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Almost 20% of joint replacement implants fail at 15 to 20 years. Reports suggest that systemic effects of metal-on-metal implants and local effects of total joint arthroplasty implants contributing to implant failure are immune system based. Sometimes implant wear debris can cause implant failure resulting from bone fracture, infection, or implant fracture/failure; most often, aseptic osteolysis or loosening leads to wear debris. ⋯ Corrosion-chemical oxidation comprising reduction reactions involving electron transport-produces electrochemical degradation. Metallic implant degradation occurs when electrochemical dissolution and mechanical/physical wear are combined (i.e., tribocorrosion). With metal-on-metal implants, even with relatively low levels of wear and particle release, pathology caused by metal debris such as pseudotumor/fibrous tissue growth can lead to early implant failure.
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When a patient presents with spine problems, the spine surgeon would do well to avoid use of, reliance on, and acceptance of radiographs as the sole or primary source of information. Measurement of pelvic incidence and lumbar lordosis, although crucial, does not take into account the effort the patient must make to move, the level of involvement of other parts of the body, and the history of previous procedures and outcomes. Radiographs may show pathology that is not consistent with the appearance of the patient. How should we assess this situation?
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In treating patients with idiopathic scoliosis and Lenke 1C curves, surgeons must choose between selective fusion of the thoracic spine (STF) and nonselective fusion of the thoracic and lumbar spines. Research shows mixed results. Demura et al reported that 40% of patients who had undergone selective fusion of the thoracic curve were decompensated 2 cm after 2 years, and 89% of those treated with nonselective fusion were balanced in the thoracic and lumbar planes, regardless of preoperative balance.