Errors in Measuring Glenohumeral Arthrokinematics With 2-Dimensional Fluoroscopy.

Area of Science:

• Orthopedics
• Medical Imaging
• Biomechanics

Background:

• Two-dimensional fluoroscopy is used to measure humeral head translations.
• This technique is susceptible to errors from optical distortion, out-of-plane imaging, and manual landmark identification.

Purpose of the Study:

• To quantify errors and variability in estimating humeral head translated position using fluoroscopy.
• To assess accuracy and reliability in true scapular plane and axillary views.

Main Methods:

• In vivo and in vitro fluoroscopy-based experiments were conducted.
• Errors were measured as bias and accuracy; variability was assessed using intraclass correlation coefficient (ICC) and standard error of measurement.
• Analysis included true scapular plane and axillary views, with variations in imaging plane.

Main Results:

• Optical distortion caused underestimation of linear distances, with accuracies of 0.11 mm (in vitro) and 0.43 mm (in vivo).
• Intrarater reliability was excellent (ICC = .94-.93), and interrater reliability was excellent for true scapular view (ICC = .95) but moderate for axillary views (ICC = .74).
• Standard error of measurement ranged from 0.27 to 0.58 mm; accuracy for 10° out-of-plane images was 0.80-0.87 mm.

Conclusions:

• The study quantifies specific error magnitudes in fluoroscopic measurement of glenohumeral parameters.
• Results suggest implementing measures to minimize errors and improve the reliability of humeral head position measurements.
• Optimizing fluoroscopic techniques can enhance diagnostic accuracy for shoulder joint assessment.