Leggon R, Lindsey R W, Doherty B J, Alexander J, Noble P
Department of Orthopaedic Surgery, Baylor College of Medicine, Houston, Texas 77030.
J Orthop Trauma. 1993;7(5):450-7. doi: 10.1097/00005131-199310000-00008.
The comparative holding strength of cannulated screws (CS) versus solid core screws (SCS) has not been reported, although differences exist in the respective diameters of their outer thread and pilot drill holes. Our objectives were to characterize these differences and determine the holding power of CS compared with SCS in cortical and cancellous bone. The dimensions of the Synthes (Paoli, PA) 3.5-mm SCS, 3.5-mm CS, 6.5-mm SCS, and 7.0-mm CS were measured, and the cross-sectional area for thread purchase was calculated. Using adult canine femurs, small-fragment 3.5-mm SCS were inserted in cortical (midshaft) and cancellous (condyle) bone of one limb, and CS were placed in similar locations in the contralateral limb. The same technique was used for large-fragment CS and SCS. Pull-out testing was performed using an MTS machine (MTS Systems, Minneapolis, MN) with axial loads applied at 5 mm/s, and data were analyzed to determine the effects of screw type, location, and size. Differences in CS versus SCS design result in higher cross-sectional areas available for SCS thread purchase. Yet no significant differences exists between screw types (SCS vs. CS) in either cortical or cancellous bone. In cancellous bone, large-fragment screws required more force to pull out than did small screws (p = 0.000). The mean force required to pull out small-fragment screws was higher in cortical bone than in cancellous bone (p = 0.000). These data suggest that the clinical decision to use CS versus SCS should not be based on pull-out strength.
尽管空心螺钉（CS）和实心螺钉（SCS）的外螺纹直径和导向钻孔直径存在差异，但尚未有关于二者比较握持强度的报道。我们的目的是描述这些差异，并确定CS与SCS在皮质骨和松质骨中的握持力。测量了Synthes（位于宾夕法尼亚州波利）3.5毫米SCS、3.5毫米CS、6.5毫米SCS和7.0毫米CS的尺寸，并计算了螺纹咬合的横截面积。使用成年犬股骨，将小碎片3.5毫米SCS插入一侧肢体的皮质骨（骨干中部）和松质骨（髁部），将CS置于对侧肢体的相似位置。对大碎片CS和SCS采用相同技术。使用MTS机器（MTS系统公司，明尼阿波利斯，明尼苏达州）进行拔出试验，轴向加载速度为5毫米/秒，并对数据进行分析以确定螺钉类型、位置和尺寸的影响。CS与SCS设计的差异导致SCS螺纹咬合的可用横截面积更大。然而，在皮质骨或松质骨中，螺钉类型（SCS与CS）之间不存在显著差异。在松质骨中，大碎片螺钉比小螺钉需要更大的力才能拔出（p = 0.000）。拔出小碎片螺钉所需的平均力在皮质骨中高于松质骨（p = 0.000）。这些数据表明，使用CS还是SCS的临床决策不应基于拔出强度。
