Error performances of a model-based biplane fluoroscopic system for tracking knee prosthesis during treadmill gait...

Area of Science:

• Biomechanical Engineering
• Medical Imaging Analysis
• Orthopedic Surgery

Background:

• Roentgen stereophotogrammetry (RSP) accurately measures knee prosthesis position and orientation using X-ray images.
• RSP is typically used statically, but biplane fluoroscopy can assess prosthesis kinematics during functional tasks.
• The accuracy of RSP for dynamic tasks like walking remains unclear.

Purpose of the Study:

• To evaluate static and dynamic errors of a model-based biplane fluoroscopic system during treadmill gait.
• To analyze how prosthesis speed and location relative to X-ray sources affect measurement errors.

Main Methods:

• Utilized a model-based biplane fluoroscopic system to track knee joint prosthesis kinematics.
• Performed gait analysis on a treadmill to simulate functional tasks.
• Quantified static and dynamic errors (RMSE) for prosthesis position and orientation.

Main Results:

• Static maximum errors were 0.13° for orientation and 0.06 mm for position.
• Dynamic errors varied by axis and component, with the largest position error at 2.42 mm (vertical axis) and orientation error at 0.95° (medio-lateral axis).
• Errors increased with prosthesis distance from X-ray sources and with higher movement velocities.

Conclusions:

• Biplane fluoroscopy can measure dynamic knee prosthesis kinematics, but errors must be considered.
• Measurement accuracy is influenced by prosthesis location within the X-ray field and movement dynamics.
• Optimal accuracy is achieved near the system's centroid, with reduced precision near detectors.