Joints

Joints are the places where two or more bones meet. They connect the skeleton while allowing the body to move with strength, stability and flexibility. Not all joints move in the same way. Fixed joints, such as those between most bones of the skull, provide protection rather than movement. Slightly movable joints, found for example between the vertebrae, allow limited motion and help absorb forces.

The most mobile are synovial joints, found in the shoulders, hips, knees, elbows and fingers. In these joints, the ends of the bones are covered with smooth cartilage that reduces friction, while a capsule filled with synovial fluid lubricates the joint and helps movements remain smooth. Ligaments hold the bones together, and muscles move the joints by pulling on bones through tendons.

Healthy joints make everyday activities such as walking, climbing stairs, writing and lifting objects possible. They also help maintain balance and absorb the forces created during movement. Regular physical activity strengthens the muscles that support the joints and helps preserve their range of motion. Maintaining a healthy body weight reduces stress on weight-bearing joints such as the hips and knees.

As people age or after injuries, the cartilage or other joint tissues may become damaged, leading to stiffness or pain. Doctors evaluate joint health through physical examinations and imaging techniques such as X-rays, ultrasound or magnetic resonance imaging, depending on the structures that need to be examined.