C h a p t e r 4 4
Disorders of the Skeletal System: Metabolic and Rheumatic Disorders
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can be excreted easily. Pegloticase is an infusible uricase
agent that works rapidly to reduce serum uric acid and
tophaceous deposits of urate. Prophylactic colchicine
may be used between gout attacks.
Rheumatic Diseases in Children
and the Elderly
Rheumatic diseases differ among children, adults, and
the elderly in terms of diagnosis, impact of activities,
and availability of treatment modalities. These con-
ditions, which affect not only the child but also the
family, can seriously impact a child’s growth and devel-
opment, limit their participation in childhood activities,
and require an extensive plan of drug treatment and
rehabilitation.
Weakness and gait disturbance that often accompany
the rheumatic diseases in the elderly can contribute to
the likelihood of falls and fracture, causing suffering,
increased health care costs, further loss of independence,
and the potential for a decreased life span.
Rheumatic Diseases in Children
Children can be affected by many of the same types of
rheumatic diseases that occur in adults. About 1 child
in every 1000 develops some type of juvenile arthritis.
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It can affect a single joint or multiple joints, and cause
systemic manifestations such as fevers, rash, and eye dis-
orders. Rheumatic disorders of children include juvenile
idiopathic arthritis, juvenile spondyloarthropathies, and
juvenile dermatomyositis.
Juvenile Idiopathic Arthritis
Juvenile idiopathic arthritis (JIA), formerly known as
juvenile rheumatoid arthritis
, is the most common form
of childhood arthritis, and one of the most common
forms of chronic disease in chiddren.
70–74
The disorder
SUMMARY CONCEPTS
■■
Systemic autoimmune rheumatic disorders are
a group of chronic disorders with overlapping
symptoms that are characterized by diffuse
inflammatory lesions and progressive changes in
connective tissue.
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Rheumatoid arthritis (RA) is a chronic systemic
inflammatory disorder affecting multiple joints.
Joint involvement, which is symmetric, begins
with inflammatory changes of the synovium and
formation of a destructive granulation tissue
called pannus that leads to joint instability and
eventual deformity.
■■
Systemic lupus erythematosus is a chronic
autoimmune disorder that affects multiple body
systems, including the musculoskeletal system,
skin, kidneys, cardiovascular system, hematologic
system, and central nervous system.There is an
exaggerated production of autoantibodies, which
interact with antigens to produce an immune
complex.These immune complexes produce an
inflammatory response in affected tissues.
■■
Systemic sclerosis is an autoimmune disorder of
connective tissues. It causes extensive fibrosis
of many body organs and systems including the
sheaths or fascia covering tendons and muscles.
■■
The seronegative spondyloarthropathies,
which include ankylosing spondylitis, reactive
arthropathies, and psoriatic arthritis, affect
the axial skeleton, particularly the spine.
The inflammatory process associated with
the disorders commonly affects areas where
ligaments and tendons attach to bone. Ankylosing
spondylitis, which is characterized by bilateral
sacroiliitis and loss of motion in the spinal
column, is considered a prototype of this
classification category. Although the cause of
the disorders is unknown, there is a striking
association between the HLA-B27 antigen and
development of the spondyloarthropathies.
■■
Osteoarthritis (OA), often referred to as “wear-
and-tear” arthritis, is a slowly destructive
disorder of the articular cartilage. It can occur as
a primary idiopathic disorder or as a secondary
disorder due to congenital or acquired defects in
joint structures. Risk factors for OA progression
include older age, multiple joint involvement,
neuropathy, and, for knees, obesity.The joint
changes associated with OA, which include
progressive loss of articular cartilage and
subchondral bone, result from inflammatory
changes that occur when cartilage tries to repair
itself.
■■
Gout is a crystal-induced arthropathy caused by
the presence of monosodium urate crystals in
the joint cavity. It includes acute gouty arthritis
with recurrent attacks of articular and periarticular
inflammation, and the accumulation of crystalline
deposits, called tophi, in articular surfaces, bones,
and soft tissue surrounding joints.The disorder
is accompanied by hyperuricemia, which results
from overproduction of uric acid or from the
reduced ability of the kidney to rid the body of
excess uric acid.
