Development of a robotic system for joint mechanical tests : Application to the ligament reconstruction assessment

为了对确定膝关节功能和韧带重建进行有意义的研究，我们一直在开发一种使用机器人技术的关节加载系统，该系统包括机器人机械手和多自由度载荷传感器技术。本研究的目的是开发和改进具有6自由度膝关节位置和力/力矩控制的机器人系统，确定韧带束(如前内侧韧带)对膝关节稳定性的贡献，并评价前交叉韧带和其他韧带多束重建技术的意义。对Sekito和Fujie等人最初开发的6自由度机械手进行了改进。该机械手是专门为关节生物力学测试而设计的，与商业上可用的关节类型机器人相比，能够在更大的运动范围内移动并产生更大的力/力矩。请注意，在旋转执行器的驱动过程中，三个旋转轴在一点相交，这允许运动学计算的简单数学表达式。该机器人系统已成功地用于1)测定前交叉韧带前内侧束、中间束和后外侧束在胫骨前抽屉负荷下的力学功能，以及2)评估犬膝关节胫骨平台平整截骨术的手术技术。后一项研究是为了评估机器人系统的性能。

For a meaningful research to determine the knee function and ligament reconstruction, we have been developing a joint loading system using a robotic technology including a robotic manipulator and multi-DOF load transducer technique. The objectives of the present study are to develop and modify the robotic system capable of 6 degree-of-freedom position and force/moment control of the human knee joint, to determine the contribution of ligament bundles (for example anteromedial bundle of the ACL) to the stability of the knee, and to evaluate the significance of the multi-bundle reconstruction technique of the ACL and other ligaments. A 6-DOF manipulator, originally developed by Sekito and Fujie et al., was modified. The manipulator was designed specially for joint biomechanical tests, capable of moving in larger range of motion and generating larger forces/moments as compared with commercially available articulated-type robots. Note that the three rotational axes cross at a point during the drive of the rotational actuators, which allowed for a simple mathematical expression of kinematic calculation. The robotic system has been successfully used 1)to determine the mechanical function of the anteromedial bundle, intermediate bundle, and posterolateral bundle of the ACL in response to anterior tibial drawer load, and 2)to assess the surgical technique of tibial plateau leveling osteotomy (TPLO) of canine stifle joints. The later study was performed to evaluate the capability of the robotic system.