several factors the anterior posterior a p balloon dimension for a given vertebral body is selected from the ct scan or plain film x ray views of the vertebral body the a p dimension is measured from the internal cortical wall of the anterior cortex to the internal cortical wall of the posterior cortex of the vertebral body in general the appropriate a p balloon dimension is 5 to 7 millimeters less than this measurement the appropriate side to side balloon dimensions for a given vertebral body is selected from the ct scan or from a plain film x ray view of the vertebral body to be treated the side to side distance is measured from the internal cortical walls of the side of the vertebral bone in general the appropriate side to side balloon dimension is 5 to 7 millimeters less than this measurement by the addition of the lumbar vertebral body tends to be much wider than side to side dimension then their a p dimension in thoracic vertebral bodies the side to side dimension and their a p dimensions are almost equal the height dimensions of the appropriate vertebral body balloon for a given vertebral body is chosen by the ct scan or x ray views of the vertebral bodies above and below the vertebral body to be treated the height of the vertebral bodies above and below the vertebral body to be treated are measured and averaged this average is used to determine the appropriate height dimension of the chosen vertebral body balloon long bones which can be treated with the use of balloons.