Arthrocentesis is a type of surgery that restores the function of a joint by relieving the restriction of joint movement caused by a pathologic reaction. When there is infection, inflammation, tumor, or congenital developmental deformity in the joints, it can lead to adhesion, scarring, and contracture of the ligaments, joint capsule, tendons, and soft tissues around the joints even though there is no abnormality of the bones, resulting in dysfunction of the joints. The main purpose of arthrocentesis is to release the adhesion, scarring and contracture of the soft tissues around the joints, thus restoring the normal function of the joints. Arthrocentesis includes release of tendons and muscle tissues, excision of scarred skin contractures and various types of plastic lengthening.