An integrated CAD/CAM/robotic milling method for custom cementless femoral prostheses

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Aseptic loosening is the main cause of cementless femoral prosthesis failure.
• Primary stability is critical for osseointegration and long-term success in total hip arthroplasty (THA).
• Custom prostheses offer improved fit and reduced micromotion, enhancing primary stability.

Purpose of the Study:

• To introduce an integrated CAD/CAM/robotic method for milling custom cementless femoral prostheses.
• To improve the primary stability and osseointegration of cementless femoral prostheses.
• To enhance long-term stability in total hip arthroplasty.

Main Methods:

• Utilized femoral CT images and 3D design software for custom prosthesis CAD models.
• Employed a calibrated robotic system with CAM software for precise milling.
• Ensured consistency between CAM software and the robotic system by calibrating transformation matrices.

Main Results:

• Achieved a 90.84% fit rate for custom pig femur stems in femoral cavities.
• Custom prostheses demonstrated maximum gaps of less than 1 mm (diaphysis) and 1.3 mm (metaphysis).
• The method successfully limited errors in robotic milling.

Conclusions:

• The integrated CAD/CAM/robotic approach effectively produces custom cementless femoral prostheses.
• Improved fit and reduced micromotion enhance primary stability, promoting osseointegration.
• This method holds promise for achieving long-term stability in total hip arthroplasty.