Joint range of motion refers to both the distance a joint can move and the direction in which it can move. There are established ranges that doctors consider normal for various joints in the body. For example, the Merck Manual notes that the knee should ideally be able to flex, or bend, to an angle of 130 degrees. It should also be able to extend so that it’s completely straight.

A reduction in a normal range of motion in any of the joints is known as limited range of motion. Joint range of motion naturally declines as you age, but it can also occur with a number of conditions. Certain exercises may be helpful for improving and maintaining flexibility in the joints.

Causes of Limited Range of Motion
Medical conditions associated with a limited range of motion in the joints include:
-- Ankylosing Spondylitis, which is a type of arthritis that primarily affects the spine
-- Osteoarthritis, which is the most common form of arthritis related to older age and wear and tear of the joints
-- Rheumatoid Arthritis (RA), an autoimmune form of arthritis caused by your immune system attacking your joints
-- juvenile RA, which is an autoimmune form of arthritis that occurs in children under the age of 16 years
-- Cerebral Palsy, which is a group of neurological disorders that causes muscle paralysis and loss of body control.
-- Legg-Calve-Perthes disease, which is a disorder that causes the thighbone to die due to lack of blood flow to the joint.
-- sepsis of the hip and other joints, which is a bacterial infection of the joints
-- Osteomyelitis

Prevention of Limited Range of Motion
Range of motion exercises specifically target joint flexibility. You can do range of motion exercises with a physical therapist. Your doctor or physical therapist can also tell you about exercises that you can easily do at home. These can help you maintain or improve joint flexibility, which helps with overall freedom and ease of movement.

There are three general categories of range of motion exercises are active, active assistive, and passive. You can do active exercises without the assistance of another person. Active assistive exercises rely on your effort and the effort of another person. This other person is often a physical therapist. These exercises are helpful when it’s painful to flex or extend the joint.

Passive exercises rely completely on the effort of the physical therapist or another individual. If you have limited range of motion, you don’t need to do anything. These are typical when the person receiving treatment isn’t physically able to perform the movements that are part of the range of motion exercise.