Mobile Biplane X-Ray Imaging System for Measuring 3D Dynamic Joint Motion During Overground Gait

Area of Science:

• Biomechanics
• Medical Imaging
• Orthopedics

Background:

• Stationary X-ray fluoroscopy systems limit dynamic joint motion analysis, particularly for overground gait.
• Current methods often rely on treadmill-based measurements, which may not fully represent natural walking patterns.

Purpose of the Study:

• To develop and validate a computer-controlled, mobile, biplane X-ray fluoroscopy system for high-speed 3D joint motion imaging.
• To assess the accuracy of this mobile system in measuring 3D knee-joint kinematics during overground walking.

Main Methods:

• A robotic gantry translated two X-ray units to track and image a subject's joint during overground gait.
• In vitro experiments used cadaver knees (intact and total knee arthroplasty) to measure bone and implant kinematics.
• Accuracy was determined by comparing volumetric model measurements with reference data from embedded metal beads.

Main Results:

• The mobile system achieved high accuracy, with maximum root-mean-squared errors of 0.33 mm and 0.65° for TKA knee translations and rotations.
• For intact knees, maximum errors were 0.78 mm and 0.77°, comparable to stationary treadmill systems.
• Concurrent tracking and imaging enhanced measurement accuracy.

Conclusions:

• The developed mobile biplane X-ray fluoroscopy system accurately measures 3D knee kinematics during overground gait.
• This technology overcomes the limitations of stationary systems, offering a more versatile tool for dynamic joint motion analysis.
• The system demonstrates potential for in vivo joint motion studies during natural walking.