An image-free method of elbow external fixation surgery based on computer-assisted navigation: A cadaveric study

Area of Science:

• Orthopedic surgery
• Medical imaging
• Computer-assisted surgery

Background:

• Accurate identification of the elbow flexion-extension (FE) motion axis is critical for precise external fixator placement.
• Traditional fluoroscopy methods for determining the elbow FE axis suffer from high radiation exposure, inaccuracy, and poor repeatability.

Purpose of the Study:

• To evaluate the feasibility and accuracy of a new image-free computer-assisted navigation technique for elbow external fixation.
• To provide a more reliable alternative to traditional imaging methods for elbow surgery.

Main Methods:

• An optical positioning system tracked forearm motion relative to the upper arm using infrared signals.
• 3D principal components analysis (PCA) determined the elbow's rotation axis from trajectory data.
• A custom GUI visualized kinematics and guided axis pin placement for the external fixator.

Main Results:

• The image-free method demonstrated high repeatability for elbow FE movements.
• Key accuracy metrics included RMS-radius within 1 mm, RMS-coplane < 2 mm, Deviation-center ≤ 2 mm, and deviation angle < 1.5°.

Conclusions:

• The developed image-free navigation method significantly improves accuracy and repeatability in elbow external fixation.
• This technique enhances the feasibility and security of elbow external fixation surgery.