The arm sling immobilizes the joint straight after surgery or after reduction of a dislocated shoulder. The open and light construction of the orthosis makes maintaining personal hygiene easier, particularly around the wound. The OmoLoc, made up of the pelvic/abdominal strap and three individually adjustable arm loops, holds the arm in the 0-degree abduction position and keeps the elbow bent at 90-100 degrees. Limiting movement reduces pain and stabilizes the surgical outcome. The arm loops can be positioned freely along the abdominal strap to suit the patient's individual anatomy.