Antoci Valentin, Raney Ellen M, Antoci Valentin, Voor Michael J, Roberts Craig S
Shriners Hospitals for Children, Honolulu, HI 96826, USA.
J Pediatr Orthop. 2006 Jul-Aug;26(4):466-70. doi: 10.1097/01.bpo.0000226279.16449.8d.
The greatest angle that can be formed by the crossing wires at the proximal tibia level without altering safe corridors approaches only 60 degrees. Consequently, the wires are positioned more in the coronal than the sagittal plane. Looking for an increase in sagittal bending stiffness, we evaluated different wire positioning within the proximal tibia and their effect on the stiffness of external fixation of proximal tibia.
A fiberglass composite tibia fixed into an idealized ring external frame was tested with a servohydraulic test frame. Load-deformation behavior was compared among the different wire positioning within the proximal tibia under identical conditions of central axial compression, medial compression-bending, posterior compression-bending, posteromedial compression-bending, and torsion. Stiffness values were calculated from the load-deformation and the torque-angle curves.
The sample with 3 wires positioned within the bone-2 wires crossed 1 cm posteriorly from the center of the tibia and the third wire placed in coronal plane 1 cm anteriorly from the center of the tibia-was significantly (P < 0.05) stiffer in posterior, posteromedial, and torsional loading configurations compared with all other wire positions within the bone.
This new wire positioning within the proximal tibia-2 wires crossed 1 cm posteriorly from the center of the tibia and the third wire placed in coronal plane 1 cm anteriorly from the center of the tibia-increased overall stiffness of external fixation, predominantly in sagittal plane.
This work provides a rationale to control proximal tibia external fixation stiffness in sagittal plane.
在不改变安全通道的情况下，胫骨近端交叉钢丝所能形成的最大角度仅为60度。因此，钢丝更多地位于冠状面而非矢状面。为了增加矢状面弯曲刚度，我们评估了胫骨近端内不同的钢丝定位及其对胫骨近端外固定刚度的影响。
将一个玻璃纤维复合材料胫骨固定在一个理想化的环形外固定架中，使用伺服液压测试架进行测试。在相同的中心轴向压缩、内侧压缩弯曲、后侧压缩弯曲、后内侧压缩弯曲和扭转条件下，比较胫骨近端内不同钢丝定位的载荷-变形行为。根据载荷-变形曲线和扭矩-角度曲线计算刚度值。
与骨内所有其他钢丝位置相比，在骨内放置3根钢丝的样本——2根钢丝在胫骨中心后方1 cm处交叉，第三根钢丝在胫骨中心前方1 cm处位于冠状面——在后方、后内侧和扭转加载配置下明显更硬（P < 0.05）。
这种在胫骨近端内的新钢丝定位——2根钢丝在胫骨中心后方1 cm处交叉，第三根钢丝在胫骨中心前方1 cm处位于冠状面——增加了外固定的整体刚度，主要是在矢状面。
这项工作为控制胫骨近端矢状面外固定刚度提供了理论依据。
