Precision evaluation of 2 CT-based radiostereometric analysis systems in a cadaver study

Area of Science:

• Medical imaging
• Orthopedic surgery
• Biomechanical analysis

Background:

• Current radiostereometric imaging methods have limitations, including the need for intraoperative marker placement.
• Computed tomography-based radiostereometric analysis (CT-RSA) offers an alternative, eliminating the need for intraoperative markers.
• Novel CT-RSA software systems aim to improve precision and efficiency in analyzing implant migration.

Purpose of the Study:

• To evaluate the precision of a new CT-RSA software system, V3MA.
• To compare the precision of V3MA against an established CT-RSA system, CTMA.
• To assess the impact of different CT scanner models on CT-RSA precision.

Main Methods:

• A porcine cadaver knee with an implant underwent 7 CT scans on two different scanner models (Siemens SOMATOM Force and GE Revolution).
• Paired CT scans were aligned using either voxel gray values (V3MA) or surface points (CTMA) to compute implant translation, rotation, and maximum total point motion (MTPM).
• Linear mixed models analyzed the precision of both software systems and the influence of scanner models.

Main Results:

• Both V3MA and CTMA demonstrated comparable precision, with V3MA showing a slightly lower MTPM (0.09 mm) than CTMA (0.10 mm).
• The difference in MTPM between V3MA and CTMA was -0.002 mm, within the minimal important difference of 0.10 mm.
• CT-RSA precision was higher when using data from the Siemens scanner (MTPM: 0.12 mm) compared to the GE scanner (MTPM: 0.072 mm).

Conclusions:

• The novel V3MA CT-RSA software system achieves precision comparable to the established CTMA system under zero-motion conditions.
• Inter-scanner differences in CT-RSA precision were observed but are considered clinically irrelevant.
• V3MA offers a promising alternative for precise, markerless analysis of implant migration in orthopedic surgery.