Role of Multi Detector Computed Tomography in the Evaluation of Glenoid Track in Patients with Anterior Instability and Its Correlation with Arthroscopy

Abstract

BACKGROUND Glenoid track is a new classification system developed to biomechanically quantify the effects of a combined glenoid and humeral head bony defects on instability that can be utilized to assess the risk of engagement of a Hill-Sachs lesion in a patient with anterior shoulder instability. The aim of the study is to evaluate the humeral head engagement on the glenoid by utilizing glenoid track method and to compare the results with the arthroscopic findings. METHODS We performed a prospective study of 31 patients with recurrent shoulder dislocation over a period of two years. A 64 slice CT scanner was used. Using post processing technique, the glenoid track was calculated to classify the shoulders as on-track or off-track. RESULTS The glenoid track and concurrent Hill Sachs interval were calculated into 4 entities-"Off-track" lesion with <25% glenoid bone loss [41. 94%], > 25% bone loss [6. 45%], "On-track" lesion with <25% glenoid bone loss [51. 61%] and >25% glenoid bone loss [0]. CONCLUSIONS The glenoid track concept postulated that a Hill-Sachs lesion outside this track was at a high risk for engagement and thus recurrent instability. CT measurement as a predictor of off-track and on-track lesion, using the differences between Hill-Sachs and glenoid track had a p value of 0.0001. The glenoid track concept is important to assess the overall risk for engagement prior to surgery and help in guiding surgical decision making such as bony augmentation procedure.