Biomechanics Study On Effect Of ACL Rupture On LCL In The Knee Joint Of Human

The knee joint is the largest and most complex joints and is one of the most vulnerable joints in human.ACL(anterior cruciate ligament) and LCL(lateral collateral ligament)are the main structures which maintain the stability of the knee joint.The main role of ACL is controlling the antedisplacement of tibial and regulating part of rotation,varus and valgus function in knee flexion.In knee flexion,the LCL plays an important role in controlling the knee function of revolve and varus.Their injury will lead to the instability of knee joint.ACL injury are fairly common and increased as the sports popularity and incidence increased yearly.General ACL injury often with other ligaments and meniscus injury.LCL injury happened was the less separate and the most associated with ACL injury. Why did LCL injury always associate with ACL injury? These are rarely reports by Scholars.This article will firstly clear the anatomical characteristics of ACL and LCL,and then observe the biomechanical impact of LCL while cut off part of ACL and cut off ACL completely.So, it provides a help for ACL reconstruction after ACL injury and non-surgical treatment of ACL injury to prevent secondary injury LCL. Objective To investigate the anatomic characteristics of the ACL and LCL,it will provide a help for the biomechanics study effect of the ACL rupture on the LCL.Method The specimens in this experiment are 6 normal knee joints of adult male.Firstly,observing the shape and form of the ACL and LCL. Then,measuring the length of the anteromedial bundle of ACL,the posterolateral bundle of ACL and LCL when the knee joint located at 0°,30°,60°,90°respectively.Lastly,measuring the transverse diameter and vertical diameter of the attachments of both ACL and LCL.Results 1.Morphological:The fiber of LCL is from the rear apex of the bone side of depression on the femoral condyle to the slight antero-upper part of the bony depression on the fibula head.The fiber of LCL is cylindrical without obvious compartment and bundle,no connectting with lateral joint capsule.The fiber of ACL is from the anterior apart of tibial intercondylar eminence to the inner side of the lateral femoral condyle.The surface tibial of ACL may exist a line from the attachment of tibial to the attachment of femoral.2.Length calculated:①The length of the LCL is gradually decreased at 0°,30°,60°and 90°. There is no significant difference at different angles(P＞0.05),but significant difference in 60°,90°and 0°flexion(P＜0.01).②The length of the anteromedial bundle of ACL is longer than the posterolateral bundle no matter the knee at what location(p＜0.01).The length of the anteromedial bundle of ACL at different locations can be ordered as 90°,0°,30°,60°from maximum to minimum.The difference of length of any two angle is significance(p＜0.01).The maximum length of posterolateral bundle of ACL appears at the location of 0°and the minimum length of poasterolateral bundle occurs at the location of 90°(p＜0.01),the moderate lengths at the location of 30°and 60°and their length have no significant difference(p＞0.05).3.Area calculated:①The area,transverse diameter and vertical diameter of LCL insertion on femur is bigger than that on fibula.There is significant difference between the two insertion(P＜0.05).②The area,transverse diameter and vertical diameter of ACL insertion on tibia is bigger than that on femur.There is significant difference between the two insertion(P＜0.01).Conclusion 1.ACL can be divided into the anteromedial bundle and the posterolateral bundle.2.The posterolateral bundle of ACL and LCL length is the longest when the knee at 0°,but the shortest when the knee at 90°.The anteromedial bundle of ACL length is the longest at the position of 90°,but the shortest when the knee at 60°.3.There is the anatomic foundation about the clinical common appearance of LCL tear on fibular insertion because the area,transverse diameter and vertical diameter of LCL insertion on fibula is smaller than that on femur. Objective To observe the biomechanical impact of LCL while cut off part of ACL and cut off ACL completely,it provides a help for ACL reconstruction after ACL injury and non-surgical treatment of ACL injury to prevent secondary injury LCL.Method The specimens in this experiment are 6 normal fresh knee joints of adult male.At first,all the 6 specimens were classified as the group with intact ACL.To measure the straining of LCL when the knee joints loaded on 400N at straighten 0°,flection 30°,60°and 90°Then,specimens were randomly treated as the group with the anteromedial bundle of ACL ruptured(AMB),and the other knees were treated as the group whose posterolateral bundle of ACL ruptured(PLB),test again.At last,6 specimens was cut off completely,this specimens were treated as ACL complete rupture group and test again.Results:1.Results of the intact ACL group:the train of the LCL are zero at 0°,the compressive train at 30°and 60°,the tensile train at 90°. There is significant difference at all different angle but at 30°and 60°(P＜0.05).2.Results of the AMB ruptured group:the train of the LCL are tensile at 0°,60°and 90°and the tensile train of the LCL are larger at 60°and 90°.the train of the LCL are compressive at 30°.There is significant difference at all different angle but at 60°and 90°(P＜0.05).3. Results of the PLB ruptured group:the train of the LCL are tensile at 0°and 90°and the tensile train of the LCL are larger at 90°.The train of the LCL are compressive at 30°and 60°and the compressive train of the LCL are larger at 30°.There is significant difference at all different angle (P＜0.05).4.Results of the ACL ruptured group:the train of the LCL are tensile at 0°,60°and 90°and the tensile train of the LCL are larger at 60°and 90°.the train of the LCL are compressive at 30°.There is significant difference at all different angle but at 60°and 90°(P＜0.05).5. At 0°,the train of the LCL of all groups were hardly zero.There is no difference about the train of the LCL in all different groups(the intact ACL group,the AMB ruptured group,the PLB ruptured group and the ACL ruptured group),(p＞0.05).6.At 30°,the train of the LCL are all compressive in four groups.The compressive train of the LCL are smaller in the intact ACL group and the AMB ruptured group than in the PLB ruptured group and the ACL ruptured group,the difference are significance(p＜0.05).7.At 60°,the train of the LCL are compressive in the intact ACL group and the PLB ruptured group but tensile in the AMB ruptured group and the ACL ruptured group.There is no difference about the train of the LCL in the intact ACL group and the PLB ruptured group,the same in the AMB ruptured group and the ACL ruptured group (p＞0.05).There is significant difference about the train of the LCL in the compressive strain groups and the tensile strain groups(p＜0.05).8.At 90°, the train of the LCL of all groups were tensile.There is no difference about the train of the LCL in all different groups(the intact ACL group,the AMB ruptured group,the PLB ruptured group and the ACL ruptured group),(p＞0.05).Conclusion:1.When AMB ruptured,PLB ruptured and ACL ruptured the train of the LCL had no effect at 0°and 90°.2.When PLB ruptured and ACL ruptured the train of the LCL becomed smaller,LCL laxity,at 30°.3.When AMB ruptured and ACL ruptured the train of the LCL becomed larger,LCL tension,at 60°.