Implementation and validation of an implant-based coordinate system for RSA migration calculation.

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Radiology

Background:

• Radiostereometric analysis (RSA) is a key technique for evaluating total knee replacement (TKR) migration.
• Conventional RSA procedures can face challenges with marker visibility and coordinate system alignment.
• Improving the accuracy and reliability of RSA is crucial for clinical decision-making.

Purpose of the Study:

• To evaluate two novel modifications to the conventional RSA procedure for TKR.
• To assess the impact of adding a tibial component landmark and using an implant-based coordinate system.
• To determine if these modifications enhance interpretability, relevance, and standardization without compromising accuracy.

Main Methods:

• An in vitro phantom study using a total knee replacement model.
• Implementation of a new marker strategy including the tibial component stem tip.
• Development of an implant-based coordinate system for migration calculations.
• Translational and rotational phantom studies to assess accuracy and precision.

Main Results:

• The new methods demonstrated no loss of accuracy in translational and rotational phantom studies.
• The enhanced RSA system achieved a precision of <0.05 mm (translations) and <0.03° (rotations).
• Accuracy was determined to be 0.05 mm for translations and 0.15° for rotations.

Conclusions:

• The modified RSA procedures improve implant representation and data standardization.
• These enhancements are suitable for clinical data analysis without compromising measurement precision or accuracy.
• The study validates new methods for more reliable RSA in total knee replacement evaluations.