How does dynamic arthroscopic tracking compare with radiologic glenoid track for identification of on- and off-track lesions in anterior shoulder instability?

Abstract

Current treatment paradigms for anterior shoulder instability are based on radiological measurements of glenohumeral bone defects, and mathematical calculation of glenoid track is used to classify lesions into "on-track", and "off-track" morphology. However, radiological measurements have shown high variability, and glenoid track widths under dynamic conditions have been reported to be significantly smaller than those under static radiological conditions. The purpose of this study was to assess the reliability, reproducibility, and diagnostic validity of dynamic arthroscopic standardized tracking (DAST) in comparison with the gold-standard radiological track measurement method for identification of on/off-track bony lesions in patients with anteroinferior shoulder instability METHODS: Between January 2018 and 2022, 114 patients with traumatic anterior shoulder instability were evaluated using 3T MRI or CT scans; glenoid bone loss (GBL), Hill-Sachs interval (HSI), glenoid track (GT), and Hill-Sach's occupancy ratio (HSO) were measured, and defects were classified as on- or off-track, and peripheral-track (HSO%) by two independent researchers. During arthroscopy, a standardized method (DAST) was used to classify defects into on-track (central and peripheral), and off-track by two independent observers. Interobserver reliability for DAST and radiological method was calculated using Kappa statistics and reported as percent agreement. Diagnostic validity (sensitivity, specificity, positive predictive value, and negative predictive value) of DAST was calculated using the radiological (HSO%) track as gold standard. Radiologically measured mean GBL, HSI, GT, and HSO for off-track lesions were lower in arthroscopically classified off-track lesions (DAST) as compared with radiological method. DAST showed near-perfect agreement between 2 observers for on-off track classification (k=0.96, p<0.001) as well as for on-peripheral-off track classification (k=0.88, p<0.001). Radiological method showed greater interobserver variability (0.31, 0.24) with only fair agreement for both classifications. Inter-method agreement varied between 71% and 79% (CI 62-86%) between the 2 observers, and reliability was assessed as slight to fair (K=0.38, 0.16). Overall, for identification of an off-track lesion, DAST showed maximum specificity (81%, 78%) when radiological peripheral-track lesions (HSO% 75-100) were considered as off-track, and maximum sensitivity when arthroscopic peripheral track lesions were classified as off-track. Although the intermethod agreement was low, a standardized arthroscopic tracking method (DAST) showed superior interobserver agreement and reliability for lesion classification in comparison with radiological track method. Incorporating DAST in current algorithms may help reduce variability in surgical decision-making.