An X-ray-free method to accurately identify the elbow flexion-extension axis for the placement of a hinged external fixator.

Abstract

Identifying the elbow flexion-extension (F-E) movement axis is important for placing a hinged elbow external fixator. An X-ray fluoroscopy-based method is widely used in clinical practice, exposing the patient and surgeons to high doses of radiation. Additionally, the accuracy and repeatability of the fluoroscopy-based method are very low and affected by subjective factors. To solve this problem, an X-ray-free method based on kinematics analysis was proposed to identify the elbow F-E movement axis, and a navigation system was built to guide the placement of the elbow external fixator. Our X-ray-free navigation method is more repeatable than the current X-ray fluoroscopy method used clinically. Both our algorithm and the NIST (National Institute of Standards and Technology) algorithm showed high accuracy and repeatability to identify the axis. The method proposed in this study is very promising to avoid a large dose of X-ray radiation and increases the repeatability and performance of identifying the elbow F-E movement axis for the placement of the hinged elbow external fixator.