Abramowitch Steven D, Yagi Masayoshi, Tsuda Eiichi, Woo Savio L-Y
Department of Orthopaedic Surgery, Musculoskeletal Research Center, University of Pittsburgh, Pittsburgh, PA 15213, USA.
J Orthop Res. 2003 Nov;21(6):1124-30. doi: 10.1016/S0736-0266(03)00080-9.
The ideal treatment of a combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) injury to the knee is still debated. In particular, the question of whether reconstruction of the ACL can provide the knee with sufficient multidirectional stability to allow for effective MCL healing needs to be better elucidated. Therefore, the first objective of this study was to quantify the changes in the function of goat knees between time-zero and 6 weeks following a combined ACL/MCL injury treated with ACL reconstruction. Using a robotic/universal force-moment sensor testing system, the kinematics of the knee and in situ forces in the ACL/ACL graft as well as in the sham-operated and healing MCL were evaluated in response to (1) a 67 N anterior-posterior (A-P) tibial load and (2) a 5 Nm varus-valgus (V-V) moment. The second objective was to evaluate the structural properties of the healing femur-MCL-tibia complex (FMTC) and the mechanical properties of the healing MCL at 6 weeks under uniaxial tension. In response to the 67 N A-P tibial load, the A-P translations for the experimental knee increased by as much as 4.5 times from time-zero to 6 weeks (p<0.05). Correspondingly, the in situ forces in the ACL graft decreased by as much as 45% (p<0.05). There was no measurable changes of the in situ force in the healing MCL. In response to a 5 Nm V-V moment, V-V rotations were twice as much as controls, but similar for both time periods. From time-zero to 6 weeks, the in situ forces in the ACL graft dropped by over 71% (p<0.05), while the in situ force in the healing MCL was as much as 35+/-19 N. In terms of the structural properties of the healing FMTC, the stiffness and ultimate load values at 6 weeks reached 53% and 29% of sham-operated contralateral controls, respectively (p<0.05). For the mechanical properties of the healing MCL substance, the values for tangent modulus and tensile strength were only 13% and 10% of sham-operated controls, respectively (p<0.05). These results suggest that the ACL graft stabilized the knee initially, but became loose over time. As a result, the healing MCL may have been required to take on excessive loads and was unable to heal sufficiently as compared to an isolated MCL injury.
膝关节前交叉韧带（ACL）和内侧副韧带（MCL）联合损伤的理想治疗方法仍存在争议。特别是，ACL重建能否为膝关节提供足够的多向稳定性以促进MCL有效愈合这一问题，仍需进一步阐明。因此，本研究的首要目标是量化用ACL重建治疗ACL/MCL联合损伤后0周和6周之间山羊膝关节功能的变化。使用机器人/通用力-力矩传感器测试系统，评估膝关节的运动学以及ACL/ACL移植物、假手术侧和正在愈合的MCL中的原位力，以响应（1）67 N的前后（A-P）胫骨负荷和（2）5 Nm的内翻-外翻（V-V）力矩。第二个目标是评估6周时愈合的股骨-MCL-胫骨复合体（FMTC）的结构特性以及在单轴拉伸下愈合的MCL的力学特性。响应67 N的A-P胫骨负荷，实验膝关节的A-P平移从0周增加到6周时增加了多达4.5倍（p<0.05）。相应地，ACL移植物中的原位力下降了多达45%（p<0.05）。正在愈合的MCL中的原位力没有可测量的变化。响应5 Nm的V-V力矩，V-V旋转是对照组的两倍，但两个时间段相似。从0周到6周，ACL移植物中的原位力下降了超过71%（p<0.05），而正在愈合的MCL中的原位力高达35±19 N。就愈合的FMTC的结构特性而言，6周时的刚度和极限负荷值分别达到假手术对侧对照组的53%和29%（p<0.05）。对于正在愈合的MCL物质的力学特性，切线模量和拉伸强度值分别仅为假手术对照组的13%和10%（p<0.05）。这些结果表明，ACL移植物最初稳定了膝关节，但随着时间的推移变得松弛。因此，与孤立的MCL损伤相比，正在愈合的MCL可能需要承担过多负荷，并且无法充分愈合。
