I–J

infectious arthritis INFLAMMATIONof a JOINTthat
results from INFECTION. The infectious agent
(PATHOGEN) may be BACTERIAor mycobacteria or a
VIRUS, or fungus and travels to the joint through
the BLOOD circulation. Infectious arthritis, also
called septic arthritis, may also develop as a conse-
quence of contamination during surgery on the
joint. The doctor may withdraw fluid from the
infected joint to examine its cells and determine
the causative pathogen.
Immediate treatment with the appropriate
ANTIBIOTIC MEDICATIONSorANTIFUNGAL MEDICATIONSis
essential to limit damage to the joint. NON-
STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) are
effective for relieving inflammation, PAIN, and
FEVERassociated with infectious arthritis. Some-
times needle aspiration or surgery is necessary to
drain accumulated pus from the joint. With
prompt and appropriate treatment, most people
recover from infectious arthritis with few or no
complications or long-lasting residual effects.
See also OSTEOARTHRITIS; RHEUMATOID ARTHRITIS;
SYNOVITIS; TENDONITIS.

joint An articulating structure that connects two
or more BONEsurfaces to allow movement. The
movement may be slight or the joint fused, such as
the sutures in the cranium (skull). A joint may
function like a hinge, such as the knee and elbow,
or like a ball and socket, such as the hip and shoul-
der. In the carpal (hand) and tarsal (foot) joints, the
bones glide along each other. Synovial capsules
enclose joints that allow extensive movement
between the bone surfaces, such as the knees, hips,
and shoulders. The synovial membrane produces
synovial fluid, which lubricates the bone ends
within the joint to reduce friction between or
among the structures of the joint during move-

ment. Joints are particularly vulnerable to injury

and damage resulting from repetitious motion.

HEALTH CONDITIONS INVOLVING THE JOINTS

ADHESIVE CAPSULITIS ANKLE INJURIES

ANKYLOSING SPONDYLITIS ARTHROGRYPOSIS

CONGENITAL HIP DYSPLASIA CONTRACTURE

DISLOCATIONS EPICONDYLITIS

INFECTIOUS ARTHRITIS KNEE INJURIES

NEUROGENIC ARTHROPATHY OSTEOARTHRITIS

RHEUMATOID ARTHRITIS SYNOVITIS

For further discussion of joints within the con-

text of the structures and functions of the muscu-

loskeletal system, please see the overview section

“The Musculoskeletal System.”

See also BURSA; JOINT REPLACEMENT; LIGAMENT;

MUSCLE; OSTEOARTHRITIS; TENDON.

joint replacement A surgical OPERATION, also

called total JOINT replacement, to remove a

severely diseased or damaged joint and replace it

with a prosthetic joint. OSTEOARTHRITIS and

RHEUMATOID ARTHRITISare often to blame for joint

deterioration severe enough to require joint

replacement. The most commonly replaced joints

are hips, knees, and shoulders. Prosthetic joints

are also available for fingers, elbows, and ankles.

Prosthetic joints are made of a variety of materials,

usually combinations of metals (such as titanium)

and plastic composites (such as polyethylene) that

are durable, strong, and light.

Surgical Procedure

Joint replacement requires a hospital stay of three

to seven days. The surgeon performs the operation

with the person under general ANESTHESIA. For hip

or knee replacement, an option is epidural or

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