Objective: The purpose of this study was to determine whether the simultaneous CT or MRI evaluation of Hill-Sachs lesions and glenoid track by use of the on-track off-track method can be used to predict engagement during arthroscopy.

Materials and Methods: A total of 36 CT and MRI examinations were included. We reviewed the CT or MR images of each patient blindly and used the on-track off-track method to predict engagement. These results were compared with the findings related to engagement seen during arthroscopy, which was performed by orthopedic surgeon. Statistical analyses included Fisher exact test.

Results: Using the on-track off-track technique of reading CT and MR images, the reviewers correctly predicted 2 of the 4 engaging (off-track) lesions (50%). Among the 32 shoulders that did not engage (on-track), they correctly predicted 32 (100%). Overall, the accuracy of the on-track off-track method was94.44% with a positive predictive value of 94.142 and the Fisher exact test result showed that the on-track off-track method was significant predictor of engagement (p <0.10).

Conclusion: Our study showed that the on-track off-track method can be used in CT and MRI to accurately assess the bipolar bone loss seen in patients with anterior shoulder instability for predicting the presence of engaging, or off-track, lesions. This information can be used preoperatively to help guide the type of stabilization procedure performed on patients with anterior shoulder instability.

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Dr Saurabh Pandey

Junior Resident, Department of Radio diagnosis, GSVM Medical College, Kanpur