Reliability in 2-Dimensional On-track/Off-track Measurements: Analysis of Key Values for Glenohumeral Bone Loss.

Abstract

Background: The relationship between glenoid bone loss and Hill-Sachs lesions (HSLs), which is known as the glenoid track, has been well described in the literature. Off-track lesions have been found to be associated with recurrent shoulder instability.

Purpose: To assess the intraobserver and interobserver reliability in glenoid track measurement using 2-dimensional (2D) computed tomography (CT).

Study design: Cohort study (diagnosis); Level of evidence, 3.

Methods: Electronic medical records between 2009 and 2019 were reviewed for patients with known shoulder instability and bone loss. Using 2D CT, fellowship-trained orthopaedic surgeons and orthopaedic residents measured glenoid loss and humeral head bone loss to calculate the glenoid track and to assess for on-track and off-track lesions.

Results: A total of 38 patients met the inclusion criteria. For fellowship-trained surgeons, there was moderate intraobserver reliability when assessing the glenoid diameter (intraclass correlation coefficient [ICC], 0.704) and HSI (ICC, 0.720). There was good reliability when evaluating glenoid defects (ICC, 0.761) and glenoid track (ICC, 0.825). Intraobserver assessment of on-track and off-track lesions according to kappa criteria was moderate (κ = 0.531; P < .001). The interobserver reliability among fellowship-trained surgeons for the glenoid track was good (ICC, 0.762); the reliability measurement for the glenoid defect (ICC, 0.672), glenoid diameter (ICC, 0.627), and HSI (ICC, 0.520) were moderate; and the on-track and off-track assessments were moderate (κ = 0.405; P < .001). For the residents, there was moderate intraobserver reliability when assessing the glenoid diameter (ICC, 0.633), glenoid defect (ICC, 0.709), HSI (ICC, 0.536), and glenoid track (ICC, 0.708). Interobserver reliability within the residents was moderate for the glenoid diameter (ICC, 0.542), glenoid defect (ICC, 0.574), and glenoid track (ICC, 0.629) and poor for the HSI (ICC, 0.292). Determination of on- and off-track lesions among residents was fair (κ = 0.234; P < .001).

Conclusion: Among fellowship-trained surgeons, both the interobserver and intraobserver reliability of measuring the glenoid track on 2D CT were good; however, agreement on whether lesions were on-track or off-track was only moderate. The reliability among residents was moderate; however, their agreement on whether lesions were on-track or off-track was poor.