Fleming B C, Beynnon B D, Tohyama H, Johnson R J, Nichols C E, Renström P, Pope M H
McClure Musculoskeletal Research Center, Department of Orthopaedics, University of Vermont, Burlington 05404.
J Orthop Res. 1994 Nov;12(6):789-95. doi: 10.1002/jor.1100120606.
The objective of this study was to verify a method previously used to determine a reference length for calculations of anterior cruciate ligament strain. In nine knee specimens, an arthroscopic force probe and a Hall effect transducer were placed in the anteromedial band of the ligament. Anteroposterior-directed shear loads then were applied to the knee joint with the knee flexed to 30 degrees. From the sigmoidal curve for shear load versus displacement of the anterior cruciate ligament midsubstance, the length of the transducer at the inflection point was determined graphically by two independent examiners. Previous studies suggested that the inflection point corresponds to the slack-taut transition of the anteromedial band. The force probe was used to determine the actual length of the transducer when the anteromedial band became load bearing. No significant differences were found between the reference lengths determined by the inflection point method and the force probe. The force probe demonstrated that the anterior cruciate ligament became load bearing when an anterior shear load of 8.8 N was applied to the tibia with the knee at 30 degrees of flexion. Furthermore, multiple cycles of anteroposterior shear loading did not influence these values. The force probe verified that the inflection method provides a reasonable estimate of the absolute strain reference (within 0.7% strain).
本研究的目的是验证一种先前用于确定计算前交叉韧带应变的参考长度的方法。在九个膝关节标本中，将关节镜下力探头和霍尔效应传感器置于韧带的前内侧束。然后在膝关节屈曲30度时，对膝关节施加前后方向的剪切负荷。根据前交叉韧带中点剪切负荷与位移的S形曲线，由两名独立检查者通过图形确定传感器在拐点处的长度。先前的研究表明，拐点对应于前内侧束的松弛-拉紧转变。当韧带前内侧束开始承受负荷时，使用力探头确定传感器的实际长度。通过拐点法和力探头确定的参考长度之间未发现显著差异。力探头显示，当膝关节在30度屈曲时，对胫骨施加8.8 N的前向剪切负荷时，前交叉韧带开始承受负荷。此外，多次前后剪切负荷循环并未影响这些值。力探头证实，拐点法能够合理估计绝对应变参考值（应变在0.7%以内）。
