Diagnosis can be suspected by history and physical examination which is usually followed by imaging. Because of the mechanism of injury, apprehension of anterior dislocation is common with provocative maneuvers. Hill–Sachs lesions have been classified as "engaging" or "non-engaging", with engaging lesions defined by the ability of the glenoid to sublux into the humeral head defect during abduction and external rotation. Engaging dislocations have a higher risk of recurrent anterior dislocation, and their presence can help guide surgical management. Imaging diagnosis conventionally begins with plain film radiography. Generally, anteroposterior (AP) radiographs of the shoulder with the arm in internal rotation offer the best yield while axillary views and AP radiographs with external rotation tend to obscure the defect. However, pain and tenderness in the injured joint make appropriate positioning difficult and in a recent study of plain film x-ray for Hill–Sachs lesions, the sensitivity was only about 20%. i.e. the finding was not visible on plain film x-ray about 80% of the time.