George C J, Lindsey R W, Noble P C, Alexander J W, Kamaric E
Joseph Barnhart Department of Orthopedic Surgery, Baylor College of Medicine, Houston, Texas 77030, USA.
J Orthop Trauma. 1998 May;12(4):267-72. doi: 10.1097/00005131-199805000-00009.
This biomechanical study was done to determine the effect of the level of a single distal screw in a static intramedullary (IM) femoral nail on the stability of fixation of a fracture in the distal third of the femur.
Fifteen composite fiberglass femora were osteotomized transversely in the distal third of the femur. A Grosse-Kempf nail was implanted into the femurs, which were divided into three groups of five specimens. Single screw distal nail locking was varied distal to the osteotomy site for each group at 2.5, 5.0, and 7.5 centimeters, respectively.
All instrumented femurs were mounted on a servohydraulic testing machine and fitted with transducers to measure axial, rotational, and bending displacements. Specimens were cyclically loaded (one hertz) in simultaneous torsion (moment: +/- 10 newton-meters) and axial compression (amplitude: 2,000 newtons) for 500 cycles with a 250-pound abductor force.
Data from linear and rotational transducers were sampled at 100 hertz for five cycles before cycling, every 100 cycles of loading, and immediately after cycling. Custom computer software was developed to convert transducer signals into static and dynamic measurements of axial motion (in millimeters), rotation (in degrees), and angulation (in degrees).
Osteotomy site dynamic rotation increased significantly in specimens locked at 7.5 centimeters when compared with the 2.5-centimeter group. There was minimal difference between the stability of the 5.0-centimeter and 7.5-centimeter groups. There was no significant change in position at the fracture site before or after cyclic loading with respect to axial shortening, rotation, or bending. Both dynamic axial and angular displacements were also unaffected by screw position.
The location of a single distal interlocking screw in static IM nail fixation of distal third femur fractures can significantly affect rotational stability but not axial or angular fixation.
进行这项生物力学研究，以确定静态股骨髓内钉中单个远端螺钉的位置对股骨远端三分之一处骨折固定稳定性的影响。
15根复合玻璃纤维股骨在股骨远端三分之一处进行横向截骨。将一根Grosse-Kempf钉植入股骨，这些股骨被分为三组，每组五个标本。每组在截骨部位远端分别于2.5厘米、5.0厘米和7.5厘米处进行单枚螺钉远端锁定。
所有植入器械的股骨均安装在伺服液压试验机上，并配备传感器以测量轴向、旋转和弯曲位移。标本在同时进行扭转（力矩：±10牛顿米）和轴向压缩（振幅：2000牛顿）的情况下以1赫兹的频率循环加载500次，同时施加250磅的外展力。
线性和旋转传感器的数据在循环加载前的五个周期、每100个加载周期以及循环加载后立即以100赫兹的频率进行采样。开发了定制的计算机软件，将传感器信号转换为轴向运动（以毫米为单位）、旋转（以度为单位）和成角（以度为单位）的静态和动态测量值。
与2.5厘米组相比，在7.5厘米处锁定的标本中截骨部位的动态旋转显著增加。5.0厘米组和7.5厘米组的稳定性之间差异最小。在循环加载前后，骨折部位在轴向缩短、旋转或弯曲方面的位置没有显著变化。动态轴向和成角位移也不受螺钉位置的影响。
在股骨远端三分之一骨折的静态髓内钉固定中，单个远端锁定螺钉的位置可显著影响旋转稳定性，但不影响轴向或成角固定。
