Surgical manipulation of a joint refers to a procedure whereby the surgeon moves the joint slowly and gently through its full range of motion. The patient is anesthetized to allow for full relaxation of the muscles, which would hold and contract otherwise to avoid the pain of movement.
Once you are asleep, the surgeon moves your arm carefully through each motion: flexion, extension, and rotations (internal and external). The arm will also be moved across the body. This movement is called horizontal adduction.
Adhesions and fibrous scar tissue will be torn in the process. The surgeon feels and hears the snapping, popping, grating sound called crepitus that signals release of the adhesions.
Once the adhesions are released, the shoulder will move more smoothly and fully. The manipulation procedure is complete when the affected shoulder has the same range-of-motion as the uninvolved side.