Reliability and accuracy of three-dimensional computed tomography in predicting on-track and off-track lesions

Background and Objectives: The bone defects involving both humeral and glenoid following traumatic dislocation of the shoulder are referred to as bipolar bone lesions. It is essential to identify bipolar bone lesions when considering standard stabilization procedures such as Bankart's repair. We aim to correlate the radiological and arthroscopic assessment of bipolar lesions in predicting "on-track" and "off-track" lesions using three-dimensional-computed tomography (3D-CT). Materials and Methods: A prospective observational study was conducted between September 2019 and August 2021. Seventy-four patients with anterior shoulder dislocation were evaluated; of which 45 patients having both radiological imaging and arthroscopic follow-up were included in the study. The radiological and arthroscopic assessment for various parameters such as glenoid diameter (D), defect (d), glenoid track (GT), bone loss (BL), Hill-Sachs (HS) defect, and Hill-Sachs index (HSI) were tabulated and evaluated. Results and Analysis: Inter-observer correlation was calculated using intraclass correlation coefficient (ICC) ranging from 0.61 to 0.80 for most variables (D, d, BL%, GT, and HSI) suggesting a substantial agreement. Almost perfect agreement (0.93) was observed in predicting on- and Off-track lesions and moderate agreement (ICC = 0.56) was observed in calculating HS angle. There was a positive strong correlation between glenoid defect (d) and BL percentage (BL%) among both modalities. Conclusions: 3D-CT proves an essential tool in the preoperative evaluation of the shoulder in patients with recurrent anterior shoulder dislocation; based on the glenoid BL and characterization of the bipolar lesions through the glenoid track concept.