Kolodziej P, Lee F S, Patel A, Kassab S S, Shen K L, Yang K H, Mast J W
Department of Orthopaedic Surgery, Wayne State University School of Medicine, Detroit, MI, USA.
Clin Orthop Relat Res. 1998 Feb(347):79-85.
The schuhli out is a device designed to lock an AO 4.5-mm cortical screw to a 4.5-mm dynamic compression plate independent of bony contact with the plate. The nut engages the screw below the plate, elevating the plate, and locking the screw at a 90 degrees angle, thus preventing toggling. Photoelastic modeling and biomechanical testing on sheep tibias were done to determine the mechanical properties of constructs using schuhli nuts. Use of schuhli nuts was shown to decrease stress in the bone below the plate. The initial axial stiffness of a construct fixed with schuhli nuts is less than a construct with standard screws, but the rate of loss of stiffness with cyclic loading is similar. When a cortical defect is present at the near cortex and the screw engages the far cortex only, the use of a schuhli nut significantly improves the stability of the construct compared with a standard screw alone, and behaves mechanically the same as a standard construct with intact cortices. This indicates that the schuhli nut acts as a substitute for a deficient cortex. The schuhli nut can be useful in osteoporotic bone because it prevents the screw from stripping the threads in the bone as the screw is advanced. It also serves to lock the screw to help prevent the screw from backing out. The schuhli nut may be a useful tool to improve stability in the treatment of complex fractures, reconstructions, or in pathologic bone.
舒利螺母是一种装置，旨在将AO 4.5毫米皮质骨螺钉锁定到4.5毫米动力加压接骨板上，而无需螺钉与接骨板有骨接触。螺母与接骨板下方的螺钉啮合，抬高接骨板，并将螺钉锁定成90度角，从而防止螺钉摆动。对绵羊胫骨进行了光弹性建模和生物力学测试，以确定使用舒利螺母的结构的力学性能。结果表明，使用舒利螺母可降低接骨板下方骨骼中的应力。用舒利螺母固定的结构的初始轴向刚度低于用标准螺钉固定的结构，但循环加载时的刚度损失率相似。当近端皮质存在皮质缺损且螺钉仅与远端皮质啮合时，与单独使用标准螺钉相比，使用舒利螺母可显著提高结构的稳定性，并且其力学性能与皮质完整的标准结构相同。这表明舒利螺母可替代缺损的皮质。舒利螺母在骨质疏松性骨中可能有用，因为它可防止螺钉推进时在骨中出现螺纹剥离。它还可用于锁定螺钉，有助于防止螺钉退出。舒利螺母可能是一种有用的工具，可提高复杂骨折、重建手术或病理性骨治疗中的稳定性。
