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5.1 Total Facet Prosthesis Components—The total facet replacement may comprise a variety of shapes and configurations. Its forms may include, but are not limited to, ball and socket articulating joints, joints having a free-floating or semi-constrained third body, metallic load-bearing surfaces, and spring and dampening mechanisms. Additionally, it may be a unilateral or bilateral design.
5.2.1 Test Chambers—In case of a multispecimen machine, each chamber shall be isolated to prevent cross-contamination of the test specimens. The chamber shall be made entirely of corrosion resistant materials, such as acrylic plastic or stainless steel, and shall be removable from the machine for thorough cleaning between tests.
5.2.2 Component Clamping/Fixturing—Since the purpose of the test is to characterize the wear and kinematic function of the total facet prosthesis, the method for mounting components in the test chamber shall not compromise the accuracy of assessment of the weight loss or stiffness variation during the test. For example, prostheses having complicated superior and inferior surfaces for contacting bone (for example, sintered beads, hydroxylapatite (HA) coating, plasma spray) may be specially manufactured to modify that surface in a manner that does not affect the wear simulation.
5.2.3 The device should be securely (rigidly) attached at its bone-implant interface to the mating test fixtures.
5.2.4 The motion of the superior test fixture (more posterior fixture in Figs. 1 and 2) relative to the inferior testing fixture shall be constrained in three-dimensional space except for the components in the direction of specified test motions/loads.
正常脊椎都有一个向前的弯曲度,长期睡在硬床垫上会令这种弯曲消失,肌肉纤维会一直处在紧绷状态,一旦剧烈活动,就会发生急性腰椎间盘突出。建议:床垫的软硬度,以躺在上面腰部没有明显下陷最为适宜,而且床垫要有一定弹力,翻身时可辅助腰部力量,缓解腰椎的磨损度。如果是睡木板床,则可在上面加一个5~10厘米的软垫。▲版权信息:本文为《生命时报》(微信号:LT0385)原创,未经授权禁止转载。...
髋臼及股骨假体安放:人工全髋关节置换术可以有效改善髋关节活动,但由于大部分患者骨盆倾斜、畸形时间较长,关节周围软组织处于异常位置,关节受力改变,若按常规关节置换经验安放髋臼及股骨假体,术后很容易出现关节脱位,所以,怎样调整及安放假体的角度是手术成功的关键。...
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