Machining and accuracy studies for a tibial knee implant using a force-controlled robot

Area of Science:

• Orthopedic Surgery
• Robotics in Medicine
• Biomedical Engineering

Background:

• Accurate bone preparation is crucial for cementless total knee arthroplasty (TKA) success.
• Robotic systems offer high precision for bone cutting, potentially improving implant fit and joint function.
• Current methods lack precise intraoperative registration and real-time bone quality feedback.

Purpose of the Study:

• To present an alternative intramedullary rod-based registration method for robotic TKA.
• To introduce a hybrid force-velocity control scheme for robotic bone machining.
• To evaluate robotic cut accuracy, surface flatness, and potential for on-line bone quality assessment.

Main Methods:

• Development of novel intraoperative registration and force control strategies for a surgical robot.
• Laboratory-based machining of bone surfaces using the developed robotic system.
• Analysis of cut accuracy, tibial plateau surface flatness (least squares method), and milling forces.

Main Results:

• Robotic machining achieved significantly improved tibial plateau surface flatness (0.1-0.2 mm) compared to conventional methods.
• High angular accuracy of the robot ensured precise bone cut placement.
• An exponential relationship was found between milling forces and local bone density, enabling on-line bone quality assessment.

Conclusions:

• Robotic assistance provides superior accuracy and surface quality in TKA bone preparation.
• The proposed methods enhance intraoperative registration and force control.
• Milling force monitoring offers a promising avenue for real-time intraoperative assessment of bone quality.