Robotic tensor device for optimal soft tissue balance in TKA

摘要

Soft tissue balance measurement is necessary for effective total knee arthroplasty (TKA). If optimal ligament balance is not achieved during surgery, it results in laxity of the knee or repeat surgery. In this paper, a newly developed robotic tensor system for measurement of soft tissue balance during TKA is described. The development concepts of the system were to measure collateral ligament balance (joint gap distance and varus angle) after cutting of the tibia and femur and to generate arbitrary lifting force to the knee joint during surgery. The system was created according to the development concepts. The prototype system has an active prismatic joint and a passive rotation joint to assess the joint gap and varus angle. The maximum lifting force is 250 N, the measurement range of the joint gap is 30 mm, and the varus angle is ± 15°. To confirm the force control ability, a basic experiment was performed. The input target force was 100, 150, 200, 250 N, and the output result showed an error within 3N. This experimental result shows that the newly developed system appears to have better accuracy than previous instrumental methods.