Acute: Of short and sharp course, not chronic.

Analgesic: A drug or medicine given to reduce pain without resulting in loss of consciousness. Analgesics are sometimes referred to as painkiller medications.

Ankylosis: Stiffness or, more often, fusion of a joint.

Arthrogram: An x-ray of a joint; usually infers the introduction of a contrast agent into the joint capsule.

Arthroscopy: A surgical technique whereby a tube-like instrument is inserted into a joint to inspect, diagnose and repair tissues.

Bursa: A closed fluid-filled sac that functions to provide a gliding surface to reduce friction between tissues of the body. When the bursa becomes inflamed, the condition is known as bursitis.

Cartilage: Firm, rubbery tissue that cushions bones at joints. A more flexible kind of cartilage connects muscles with bones and makes up other parts of the body, such as the larynx and the outside parts of the ears.

Central Nervous System: The central nervous system is that part of the nervous system that consists of the brain and spinal cord. The central nervous system (CNS) is one of the two major divisions of the nervous system. The other is the peripheral nervous system (PNS) which is outside the brain and spinal cord. The peripheral nervous system (PNS) connects the central nervous system (CNS) to sensory organs (such as the eye and ear), other organs of the body, muscles, blood vessels and glands. The peripheral nerves include the 12 cranial nerves, the spinal nerves and roots, and what are called the autonomic nerves that are concerned specifically with the regulation of the heart muscle, the muscles in blood vessel walls, and glands.

Chronic: Of long duration; denoting a disease of slow progress and long continuance.

Collagen: Collagen is the principal protein of the skin, tendons, cartilage, bone and connective tissue.

Connective Tissue: A material made up of fibers forming a framework and support structure for body tissues and organs. Connective tissue surrounds many organs. Cartilage and bone are specialized forms of connective tissue.

Computed Tomography: An x-ray procedure that uses the help of a computer to produce a detailed picture of a cross section of the body. Also called a CT scan or CAT scan.

Corticosteroids: Any of the steroid hormones made by the cortex (outer layer) of the adrenal gland. Cortisol is a corticosteroid.

Etiology: The study of the causes. For example, of a disorder.The word "etiology" is mainly used in medicine, where it is the science that deals with the causes or origin of disease, the factors which produce or predispose toward a certain disease or disorder.

Fibromyalgia: A syndrome characterized by chronic pain, stiffness, and tenderness of muscles, tendons, and joints without detectable inflammation. Fibromyalgia does not cause body damage or deformity. However, undue fatigue plagues the large majority of patients with fibromyalgia and sleep disorders are common in fibromyalgia.

Fluoroscopy: An x-ray procedure that makes it possible to see internal organs in motion. Fluoroscopy uses x-ray to produce real-time video images. After the x-rays pass through the patient, instead of using film, they are captured by a device called an image intensifier and converted into light. The light is then captured by a TV camera and displayed on a video monitor.

Inflammation: A basic way in which the body reacts to infection, irritation or other injury, the key feature being redness, warmth, swelling and pain.

Joint: A joint is the area where two bones are attached for the purpose of motion of body parts. A joint is usually formed of fibrous connective tissue and cartilage. An articulation or an arthrosis is the same as a joint.

Ligaments: A ligament is a tough band of connective tissue that connects various structures such as two bones.

Magnetic Resonance Imaging: An MRI (or magnetic resonance imaging) scan is a radiology technique that uses magnetism, radio waves, and a computer to produce images of body structures. The image and resolution produced by MRI is quite detailed and can detect tiny changes of structures within the body. For some procedures, contrast agents, such as gadolinium, are used to increase the accuracy of the images.

Neuropathic: Chronic pain resulting from injury to the nervous system. The injury can be to the central nervous system (brain and spinal cord) or the peripheral nervous system (nerves outside the brain and spinal cord). Neuropathic pain can occur after trauma and many diseases such as multiple sclerosis and stroke. It is common and affects more than 2 million people in the US alone.

NSAID: Nonsteroidal anti-inflammatory drug. NSAIDs are commonly prescribed for the inflammation of arthritis and other body tissues, such as in tendinitis and bursitis.

Osteoarthritis: A type of arthritis caused by inflammation, breakdown, and eventual loss of cartilage in the joints. Also known as degenerative arthritis.

Polymyalgia Rheumatica: A disorder of the muscles and joints of older persons characterized by pain and stiffness, affecting both sides of the body, and involving the shoulders, arms, neck, and buttock areas.

Polymyositis: A chronic inflammatory disease of muscle that begins when white blood cells, the immune cells of inflammation, spontaneously invade muscles, especially the muscles closest to the trunk or torso, resulting in sometimes severe muscle pain, tenderness and weakness.

Risk Factor: Something that increases a person's chances of developing a disease.

Spondylitis: Inflammation of one or more of the vertebrae of the spine. Diffuse inflammation of the spine is seen in the disease ankylosing spondylitis. Localized spondylitis is seen with infections of a certain area of the spine, such as in Pott's disease.

Tendinitis: Inflammation of a tendon (the tissue by which muscle attaches to bone). Tendinitis most commonly occurs as a result of injury, such as to the tendons around the shoulder or elbow. It can also occur as a result of an underlying inflammatory rheumatic disease, such as reactive arthritis or gout.

Ultrasound: High-frequency sound waves. Ultrasound waves can be bounced off of tissues using special devices. The echoes are then converted into a picture called a sonogram. Ultrasound imaging, referred to as ultrasonography, allows physicians and patients to get an inside view of soft tissues and body cavities, without using invasive techniques.