Brantley A G, Mayfield J K, Koeneman J B, Clark K R
Harrington Arthritis Research Center, Phoenix, Arizona.
Spine (Phila Pa 1976). 1994 Aug 1;19(15):1752-8. doi: 10.1097/00007632-199408000-00016.
The effects of pedicle screw size (major diameter and length) on fixation stiffness in osteoporotic and nonosteoporotic vertebrae were evaluated in vitro.
Lumbar vertebrae were obtained from two fresh frozen human spines. Bone mineral densities were determined using dual energy radiograph absorptiometry, followed by nondestructive mechanical testing of the specimens instrumented with pedicle screws. A loading technique was used that more closely mimics loading of pedicle screws in vivo.
Testing revealed that for good quality bone, screw size had a significant effect on fixation stiffness, but the effect of penetration depth depended on pedicle fill, and vice versa. In nonosteoporotic bone, the use of a longer screw increased fixation stiffness if the screw filled up the pedicle by 70% or more. The use of wider screws increased the fixation stiffness if the penetration depth was 80% or more.
Screw size had little or no effect on fixation stiffness in osteoporotic bone.
在体外评估椎弓根螺钉尺寸（大直径和长度）对骨质疏松性和非骨质疏松性椎体固定刚度的影响。
从两个新鲜冷冻的人体脊柱获取腰椎。使用双能X线吸收法测定骨密度，随后对植入椎弓根螺钉的标本进行无损力学测试。采用了一种更接近体内椎弓根螺钉加载情况的加载技术。
测试表明，对于质量良好的骨骼，螺钉尺寸对固定刚度有显著影响，但穿透深度的影响取决于椎弓根填充情况，反之亦然。在非骨质疏松性骨骼中，如果螺钉填充椎弓根达70%或更多，则使用更长的螺钉可增加固定刚度。如果穿透深度为80%或更多，则使用更宽的螺钉可增加固定刚度。
螺钉尺寸对骨质疏松性骨骼的固定刚度影响很小或没有影响。
