Pain that is isolated to just one joint is called monoarticular joint pain. A joint may simply be painful (arthralgia) or may also be inflamed (arthritis). Arthritis usually causes warmth, swelling, and rarely redness of the overlying skin. Pain may occur only when the joint is moved or also be present at rest. Fluid may collect within the joint (called an effusion).
Pain that seems to be coming from a joint sometimes originates in a structure outside of the joint, such as a ligament, tendon, or muscle. Examples of such disorders are bursitis, tendinitis, sprains, and strains. Pains caused by these disorders are usually not considered true joint pains.