在前交叉韧带重建中，足够的股骨骨道长度对于移植物的固定强度和韧带化过程非常重要。对6名青年健康志愿者的膝关节进行高分辨率核磁扫描，通过测量核磁三维重建的模型发现，在股骨骨道位置为I.D.E.A.L.点的情况下，骨道外口越高，或股骨骨道角度越大，其骨道长度越长；某一骨道长度的骨道外口在股骨外髁的外侧皮质上呈现连续的曲线分布，30、35和40 mm骨道的平均最大股骨骨道角度分别为17.2°±8.6°、31.6°±9.1°和41.4°±8.8°。因此，除股骨和髁间窝大小等解剖因素外，前内入路位置和股骨骨道位置的相对关系决定了股骨骨道的长度。对于固定的股骨骨道位置，要获得更长的股骨骨道，需相对位置更低的前内入路，使用下方辅助入路或增大屈膝角度可以明确的延长股骨骨道。
It is important to have a sufficient femoral tunnel length for the graft fix strength and the maturation in the anterior cruciate ligament reconstruction. The high resolution MRI is used on the knees of 6 young healthy volunteers. Based on the reconstructed MRI 3D models. two main observations are made:for the I.D.E.A.L. point as the fixed femoral tunnel location, the higher the tunnel outlet point, or the larger the femoral runnel angle, the longer tunnel would be achieved; and the outlet curves with the tunnel length of 30mm, 35mm, 40mm arranged from lower to upper in an ascending order on the lateral cortex of the lateral femoral condyle, with the mean maximum femoral runnel angle of 17.2°±8.6°, 31.6°±9.1° and 41.4°±8.8°. Therefore, beside the anatomy characteristics such as the sizes of the femur and the intercondylar notch, the length of the femoral tunnel in the trans-portal reconstruction is related with the anterior-medial portal position. For a fixed tunnel location, to get a longer tunnel length, the relative position of the skin portal to the tunnel location should be even lower, and using the accessory for the anterior-medial portal or increasing knee flexing angle, a longer femoral tunnel would be obtained.
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