Johner R, Joerger K, Cordey J, Perren S M
Clin Orthop Relat Res. 1983 Sep(178):74-9.
The rigidity of lag-screw fixation of experimental tibial fractures was tested in 27 anatomic specimens. Spiral osteotomies with a 60 degree angle of ascent were produced using a Gigli saw. Three screws with an axial force of 100 kp were inserted at 90 degree, 80 degree, or 70 degree of longitudinal inclination. The 70 degree group was stable in axial compression up to 88 kp and the 80 degree group up to 151 kp. Rigidity in bending was 50% in the 70 degree and 80 degree groups and 27% in the 90 degree group, while rigidity in torsion was 20% as compared with the intact bone. Screws tightened with 50 kp and 150 kp showed increased rigidity as axial screw force increased. There were only small gains in torsion and bending, whereas there was a 200% gain in compression. This confirms the view that in long spiral fractures of the tibia three lag screws alone can maintain sufficient stability to permit early limb mobility. If the screws are inserted perpendicular to the bone, the high resistance to axial compression may permit early partial weight-bearing.
在27个解剖标本上测试了实验性胫骨骨折拉力螺钉固定的刚度。使用线锯制作60度上升角的螺旋形截骨。以90度、80度或70度的纵向倾斜度插入三根轴向力为100kp的螺钉。70度组在轴向压缩力达到88kp时保持稳定，80度组在轴向压缩力达到151kp时保持稳定。70度组和80度组的弯曲刚度为50%，90度组为27%，而扭转刚度与完整骨相比为20%。以50kp和150kp拧紧的螺钉随着轴向螺钉力的增加刚度增加。扭转和弯曲方面仅有小幅度增加，而压缩方面有200%的增加。这证实了以下观点：在胫骨长螺旋骨折中，仅三根拉力螺钉就能维持足够的稳定性以允许早期肢体活动。如果螺钉垂直于骨插入，对轴向压缩的高抵抗力可能允许早期部分负重。
