Assessment of the influence of joint disorder by the measurements of mechanical properties using a robotic arm

到目前为止，许多研究者已经讨论了机械应力的变化对膝关节切除术后的影响。其中，关节软骨切除术后润滑特性的变化，这必须严重关系到关节软骨的表面损伤，尚未得到充分的讨论。另一方面，已经接受的是，关节软骨上的高机械应力影响关节润滑功能，特别是在长时间的静止负荷期间。设计了一种测量关节摩擦力的系统，该系统使用市售的机器人手臂、万能力传感器和用于系统控制的计算机。取健康日本白色家兔5只，体重2.0-2.5 kg，取膝关节10个。通过力传感器同时检测机械臂在20 °屈伸运动过程中的水平力和垂直力，计算水平力与垂直力的比值作为摩擦系数，发现后膝关节的摩擦力在截骨后不久发生了轻微的变化。因此认为，关节软骨切除术在短期内对关节软骨的润滑性能影响不大。股骨颈切除术后力学环境的改变对股胫关节软骨的影响是一个严重的问题。在这项研究中，关节软骨的润滑性能的变化后，椎间盘切除术进行了直接讨论。

So far, many investigators have discussed about the effect of change in mechanical stress on the knee joint after meniscectomy. Amongst that, the change in lubrication properties after the meniscectomy, which must seriously relate surface damages of articular cartilage, has not been sufficiently discussed, yet. On the other hand, it has been accepted that high mechanical stress on articular cartilage affects on the joint lubricating function especially during a prolonged stationary load. A system to measure joint friction was designed using a commercially available robotic arm, a universal force sensor and a computer for the system control. Ten stifles of 5 healthy Japanese white rabbits weighing 2.0-2.5 kg were used for the specimens. Both the horizontal and the vertical forces were simultaneously detected by the force sensor during the flexion-extension motion with the angle of 20 degrees that was composed by the robotic arm. The ratio by the value of horizontal force to vertical one was calculated to be the friction coefficient.It was found that the friction of the stifle joint was slightly changed soon after meniscectomy. It was considered that a meniscectomy has little effects on lubricating properties of articular cartilage during a short period. The effect of the change in the mechanical environment following meniscectomy is a serious problem on the articular cartilage of femorotibial joints. In this study, the change in lubrication property of articular cartilage after a meniscectomy was directly discussed.