Optimal orientation of the bone tunnels in the anterior cruciate ligament reconstruction

虽然有报道称韧带移植物在骨隧道处会产生较大的内压，但对前交叉韧带（ACL）重建的最佳骨隧道知之甚少。本研究的目的是确定ACL重建中骨隧道的最佳方向。最佳方向定义为在整个活动范围内施加在移植物上的弯曲和应变最小。首先，在数值分析中，利用计算机重构的三维膝关节模型研究了钻孔的最优方位。其次，在新鲜尸体膝关节实验中，通过对专用装置拍摄的二维X线片进行分析，测量移植物钻孔方向和弯曲角度。股骨钻孔的最佳方位在冠状面向外倾斜20 °，在矢状面向前倾斜23 °。在胫骨中，钻孔应从等距点向内24_O和向前50_O。数值分析的弯曲角与实验结果吻合较好，股骨最大弯曲角为58 °，胫骨最大弯曲角为18 °。股骨侧移植物的畸形大于胫骨侧。由于目前的重建手术对股骨中骨隧道的可能方向存在限制，因此不同的钻孔系统（如由内向外钻孔）似乎有利于防止ACL重建后移植物的早期失效。

Although large internal pressure are reported to occur in ligament grafts at bone tunnels, little is known about the optimal bone tunnels in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to determine the optimal orientation of the bone tunnels in the ACL reconstruction. Optimal orientation is defined to be such that the bending and strain imposed on the graft throughout the range of motion is minimal. First, in the numerical analysis, optimal orientataion of the drill holes was investigated by computer reconstituted three dimensional knee model. Secondly, in the experiment using fresh cadeveric knees, the orientation of drill holes and bending angle of in the grafts were measured by analysing the two dimensional radiografs taken with the specially desined apparatus. The optomal orientation of the drill hole of the femur tilted 20_O laterally in coronal plane and 23_O anteriorly in sagital plane. In the tibia, drill hole should be directed 24_O medially and 50_O anteriorly from the isometric point. Numerically analyzed bening angle corresponded well to the experimental study and the maximal bending angle were 58_O for the femur and 18_O for the tibia respectively. The deformity of the graft in the femoral side is larger than that in the tibial side. Since there is restriction as to the possible orientation of the bone tunnels in femur with current reconstructive procedure, a different drilling system such as inside-out drilling appears to be advantageous to prevent early failure of the graft after ACL reconstruction.