Summary

Dynamic arthroscopic tracking performed in a standardized manner (DAST) is highly reliable with near-perfect interobserver agreement for classification of Hill-Sach’s lesions. In contrast, radiological track method was less reliable and showed greater interobserver variability. Incorporating DAST in current algorithms may help reduce variability in surgical decision-making.

Abstract

Purpose

Radiological classification of glenohumeral bone defects into “on-track”, and “off-track” morphology has high inter-observer and intra-observer variability, and this may influence choice of surgical procedure. The purpose of this study was to assess the reliability, reproducibility, and diagnostic validity of dynamic arthroscopic standardized tracking (DAST) in comparison with the current gold-standard radiological track measurement method for identification of on/off-track bony lesions in patients with anteroinferior instability

Methods

Between January 2018 and 2022, 114 patients who presented with traumatic anterior shoulder instability were evaluated clinically and radiologically (MRI and/or CT scan) and Hill-Sach’s lesions (HSL) were classified as on-track or off-track, and peripheral-track (HSO%) by two independent researchers. During arthroscopy, a standardized method of evaluation (DAST) was used to classify defects into on-track, peripheral-track, and off-track lesions by two experienced shoulder surgeons, and the interpretation was documented independently. Interobserver reliability for DAST and radiological (HSO) method classification was calculated using Kappa statistics and reported as percent agreement along with 95% confidence intervals. Diagnostic validity (sensitivity, specificity, positive predictive value, and negative predictive value) of DAST was calculated using the radiological (HSO%) track as a gold standard.

Results

Radiologically measured mean glenoid bone loss (GBL), Hill-Sachs interval (HSI) and Hill-Sach’s occupancy (HSO for off-track lesions were lower in the arthroscopically classified off-track lesions (DAST) as compared with the radiological method. The arthroscopic method showed a near-perfect agreement between the 2 observers for the on-off track classification system (k=0.96, p<0.001) as well as for the on-peripheral-off track classification (k=0.88, p<0.001). The radiological method showed greater interobserver variability (0.31, 0.24) with only fair agreement for both classification systems. Inter-method agreement varied between 71% and 79% (CI 62-86%) between the 2 observers, and reliability was assessed as only slight to fair agreement (K=0.38, 0.16). Overall, DAST showed maximum specificity (81%, 78%) for diagnosis of an off-track lesion by both observers when radiological peripheral-track lesions (HSO% 75-100) were considered as off-track lesions. Similarly, DAST demonstrated maximum sensitivity when arthroscopic peripheral track lesions were classified as off-track lesions.

Conclusion

DAST showed a near-perfect interobserver agreement for lesion classification and the radiological method demonstrated greater variability and less reliability. Clinical relevance: Incorporating DAST in current treatment algorithms may help reduce variability in score-based algorithms for decision-making in anterior shoulder instability.

Level of evidence: Level 1 Diagnostic
Keywords: Instability; Bone defect; glenoid track; Hill-Sachs lesion; Arthroscopy; engaging Hill-Sach’s lesion