The pars is a bony part of your spine that could have been broken a long time ago, but is now causing pain due to injury or aggravation.ying face down on the table, in the procedure room, the area of injection will be cleansed with an antiseptic solution and the skin will be numbed. With the assistance of a C-arm fluoroscopic unit (x-ray) the physician directs a needle through the skin and into the pars.