四象限分区法用于前交叉韧带多纤维束动态受力分析

Dynamic mechanical study of anterior cruciate ligament by a four quadrant zoning method

目的介绍四象限分区法在测量国人前交叉韧带(anterior cruciate ligament,ACL)多纤维束动态受力分析中的应用;并探讨了膝关节活动中ACL多纤维束动态力学特性。方法采集8侧正常国人膝关节标本,评估标本完整性后向ACL胫骨止点中心做斜行骨隧道,游离ACL胫骨侧止点,以四象限法平均分为4个区:1区,后内区;2区,后外区;3区,前外区;4区,前内区。将4个区的附着纤维束分别连接至自制"膝关节交叉韧带测力计"传感器上,连接系统后分别在膝关节屈曲90o位和伸直0o位将ACL各纤维束张力调零后测量膝关节4自由度(屈伸、内外翻、内外旋、前抽屉试验)内各纤维束的动态受力变化。结果2区和3区纤维束在由屈至伸的过程中所受张力逐渐增大,2区纤维束最大为22.52N±8.60N(30o),3区纤维束最大为13.98N±3.47N(0o);3区和4区纤维束在由伸至屈的过程中张力逐渐增大,4区纤维束最大为14.68N±5.29N(90o),3区纤维束最大为9.84N±5.06N(60o)。所有纤维束在外翻、内外旋、前抽屉试验中张力增加。内翻试验中所有纤维束张力增加不明显,1区纤维束在3个膝关节自由度内张力变化不明显。结论膝关节伸直过程中受力承担最大作用的纤维束主要分布在ACL胫骨止点后外分区内,屈曲位的主要承力纤维分布于前内分区,前外分区则有以上两种纤维束的附着,可能为ACL纤维束中动态受力连续变化的中转部分所在位置。四象限分区法测量ACL多纤维束动态受力有助于利用标准分区方法了解ACL多纤维束动态受力连续变化趋势,为进一步深入探讨ACL多纤维束连续动态受力提供了参考依据。

Objective To introduce a 4 quadrant zoning method measuring dynamic force distribution of multi-bundle fibers in anterior cruciate ligament （ACL） to find out the mechanical relationship between tibial footprint and force distribution of ACL multi-bundle fibers. Methods A cadaveric study was performed with 8 normal Chinese human knees. After the integrity evaluation of each specimen d, the tibial insertion site of ACL was detached from plateau through a tibial tunnel. The footprint was averagely separated into 4 zones according to sagittal plane and coronal plane as zone 1 （posteromedial zone）, zone 2 （posterolateral zone）, zone 3 （anterolateral zone） and zone 4 （anteromedial zone）. Fibers were also separated into 4 bundles according to each attached zone and linked to the custom-made force transducers. Zero strain was set to all bundles at 90o and 0o respectively and forces of each bundle were measured during 0-120o of knee cyclic motion in four degree of freedom （DOF） of knee joint during flexion and extension. Results The forces measured from zone 2 and 3 increased during extension. The max force of zone 2 reached 22.52±8.60N （30o） and thatof zone 3 reached 13.98±3.47N （0o）. Forces of zone 3 and 4 increased during flexion. The max force of zone 3 was 9.84±5.06N （60o） and that of zone 4 was 14.68±5.29N （90o）. Forces in all fibers increased during the valgus, rotation and anterior drawer tests. Force distribution in zone 1 did not change in most DOF of knee. Conclusion The fibers attached to the posterolateral zone contributes to the largest restraint of anterior tibial translation. While the anteromedial zone plays the most important role during knee flexion. The anterolateral zone contains the fibers functioning as linkage during flexion and extension, so it can be regarded as the transient fiber of ACL during movement. In this study, we found that 4 quadrant zoning method of ACL tibial footprint helps to learn the continuous dynamic force distribution of ACL multi- bundle fibers, and provide the basic parameters for further study.