Ankylosing spondylitis X-ray
Ankylosing spondylitis. Coloured X-ray of the spine of a patient with ankylosing spondylitis, a form of arthritis. This is the lumbar region in the lower back. The condition, which causes inflammation of the joints, has led to severe deformity of the spine; the patient has a fixed kyphosis, an outward curvature of the spine. Ankylosing spondylitis commonly affects the joints between the spinal bones (vertebrae, brown/purple) and the sacroiliac joints (not seen), which link the spine to the pelvis. The joints become painful and stiff. In severe cases, the vertebrae may fuse together completely. The condition is treated with painkillers and regular exercise.
© Cnri/Science Photo Library
Knee replacement, X-ray
Knee replacement. Coloured X-ray of theprosthetic knee (white), seen in profile, of apatient with osteoarthritis. The implant attachesto the leg bones (blue/white), and has a flexiblejoint that can hinge like the old joint. Theimplant is attached to the top of the tibia (shinbone, lower frame) and to the bottom of the femur(thigh bone, upper frame). The other lower legbone (fibula) is also seen (right of tibia), as isthe patella (kneecap, left of implant). Theimplant replaced the old joint that had lost itscartilage due to osteoarthritis. Healthy cartilagereduces friction between the bones, and itsprogressive loss causes joint pain and immobility.
© Zephyr/Science Photo Library
Starfish and abalone, X-ray
Starfish and abalone. Coloured X-ray of a starfish (class Asteroidea) and an abalone (Haliotis sp.). A starfish typically has 5 arms radiating outward from a central disc. Tube feet (not seen) located on the undersides of the arms are used for movement. A starfish does not have a brain. Instead, coordination is controlled by one or more rings of centrally-located nerves. An abalone is a mollusc, related to limpets and snails. Its flat shell contains a row of holes, through which inhaled sea water is expelled after respiration is complete. Several species of abalone are edible and are an important food source.
© D. ROBERTS/SCIENCE PHOTO LIBRARY