should be evaluated for defining a differential diagnosis, such as multiplicity, location, origin (e.g. subcutaneous, intramuscular), size, shape, margins, peritumoral oedema, bone involvement and rate of growth. It is not uncommon for a reporting radiologist to come across vertebral body collapse in day to day practice. A number of imaging options are available to the radiologist to assess the nature of the vertebral body collapse. Vertebral body collapses are broadly divided into benign and malignant depending on the aetiology. Benign collapses are most often due to metabolic diseases such as osteoporosis and trauma. It is vital to be able to differentiate these two categories of vertebral involvement to initiate appropriate therapy. Radiographs have a low sensitivity and specificity in differentiating these categories of vertebral body collapse. MRI on the other hand is excellent at differentiating between benign and malignant lesions on standard imaging sequences. A number of features including retropulsion, T1 signal characteristics, clefts, soft tissue abnormalities, posterior element involvement and contrast enhancement help in this differentiation. Advanced imaging protocols including diffusion and in/out of phase imaging are rarely needed. In some clinical circumstances where the differentiation is not possible despite all these measures, CT scan, follow-up imaging and/or a biopsy may be necessary. Static instabilities are defined by the absence of classic symptoms of instability and are associated with rotator cuff or degenerative joint disease. Dynamic instabilities are subdivided in two main categories. The first category is traumatic unidirectional Bankart surgery (TUBS), which is characterised by a history of trauma resulting in unidirectional anteroinferior instability, commonly associated with a fibrous or osseous Bankart lesion that requires surgical repair. The second category is known as atraumatic multidirectional bilateral rehabilitation inferior capsular shift (AMBRI). This pattern of multidirectional instability is believed to be the result of atraumatic ligamentous and capsular laxity. Treatment is rehabilitation initially, followed by inferior capsular shift if indicated. The anterior instability is characterised by avulsion of the labroligamentous complex from the anteroinferior aspect of the glenoid, which, with complete disruption of the scapular periosteum, is termed a fibrous Bankart lesion. The presence of an associated adjacent glenoid rim fracture is referred to as an osseous Bankart lesion. Osseous Bankart lesions can easily be missed on MR images; therefore, CT arthrography is preferred by some authorities. In posttraumatic posterior dislocation, tears occurring in the posterior labrum are referred to as a reverse Bankart lesion and impaction of the anterosuperior humeral head are called reverse Hill-Sachs defect. Recurrent (atraumatic) posterior shoulder instability has to be distinguished from acute and chronic (locked) posterior dislocation. Recurrent (atraumatic) posterior instability is not related to trauma, but rather to laxity of supporting capsular and muscular structures and/or to the shape of the bony glenoid or the labrum. Learning Objectives: