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

到目前为止，许多研究者讨论了半月板切除术后机械应力变化对膝关节的影响。其中，与关节软骨表面损伤密切相关的半月板切除术后润滑性能的变化尚未得到充分讨论。另一方面，人们普遍认为关节软骨的高机械应力会影响关节的润滑功能，特别是在长时间的静止载荷下。利用市售机械臂、通用力传感器和计算机进行系统控制，设计了关节摩擦测量系统。选用健康日本大白兔5只10节，体重2.0 ~ 2.5 kg。在由机械臂组成的以20度角进行的屈伸运动中，力传感器同时检测水平力和垂直力。水平力与垂直力的比值即为摩擦系数。我们发现在半月板切除术后，膝关节的摩擦有轻微的改变。我们认为半月板切除术在短时间内对关节软骨的润滑性能影响不大。半月板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。在本研究中，直接讨论了半月板切除术后关节软骨润滑特性的变化。

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.