Adhesion is a common postoperative complication. It results from two injured surfaces growing together and forming a bond between two, or more, structures that were not connected before the operation. An example is adhesive capsulitis, which is caused after shoulder surgery causes bone to grow across the shoulder joint.
Adhesions develop during the recovery phase of an operation as scar tissue grows around the affected area. In places where two damaged structures are close together, inflammation triggers the growth of a protein called fibrin. Fibrin growth is a normal part of healing, but it can cause an adhesion to form where it takes up other proteins, such as collagen, and fails to dissolve.