Marker-based technique for visualizing radiolucent implant components in radiographic imaging.

Area of Science:

• Orthopaedic Surgery
• Biomedical Imaging
• Materials Science

Background:

• Radiography is the primary method for analyzing orthopaedic implants in vivo.
• Polyethylene components in total knee replacements are radiolucent, hindering direct visualization.
• Current methods for visualizing these components introduce errors due to estimations and simplifications.

Purpose of the Study:

• To develop and validate a method for visualizing radiolucent polyethylene components in total knee replacements using radiography.
• To assess the reproducibility and accuracy of a novel marker-based registration process.

Main Methods:

• Developed an insertion guide for placing tantalum beads into polyethylene tibial liners.
• Micro-computed tomography (micro-CT) was used to obtain 3D surface geometries of bead-inserted liners.
• Evaluated the 3D to 2D registration process using a phantom RSA experiment mimicking in-vivo conditions.

Main Results:

• The insertion guide demonstrated consistent bead positioning within ±0.21 mm.
• The 3D to 2D registration process showed a repeatability of -0.014 ± 0.008 mm.
• The overall visualization method achieved an average error of 0.026 ± 0.047 mm.

Conclusions:

• The novel marker-based visualization method significantly improves registration accuracy and inter-component measurements compared to existing strategies.
• This technique is applicable to other joints and beneficial for long-term analysis of component interactions and implant performance.