Arthropathies/Connective Tissue Diseases

Routine radiographs remain the primary screening technique for evaluating arthropathies.

Radionuclide scans are sensitive for
detecting early changes in articular disease. Technetium-99m methylene
diphosphonate is injected intravenously (15 to 20 mCi), and images of
the involved joints are obtained 2 to 3 hours after injection.
Increased radiotracer is seen in bones and joints because of early
synovitis and osseous inflammation. Findings are not specific.

Ultrasound has demonstrated increased
utility for evaluating ligaments, tendons, and intra-articular
pathology. High-frequency transducers are used for superficial
structures (>7 to 12 MHz). Transverse, longitudinal, and dynamic
images are obtained.

Computed tomography (CT) is used
primarily for surgical treatment planning. Bone stock and extent of
erosions can be evaluated. Thin sections (1 mm at 0.5-mm intervals)
allow coronal and sagittal reformatting and three-dimensional
reconstructions.

Magnetic resonance (MR) techniques are
useful for detection of early bone and soft tissue changes. Specific
techniques have gained popularity for evaluating synovium and articular
cartilage.

Clinical: Rheumatoid arthritis (RA)
affects 1% to 2% of the general population with permanent deformity and
disability in 10% to 20%. Characteristically, RA is a symmetric
polyarthropathy. Diagnostic criteria of the American Rheumatism
Association are as follows:

Laboratory findings: positive rheumatoid factor, elevated erythrocyte sedimentation rate

Radiographic features:

Clinical:

Laboratory findings: negative rheumatoid
factor, elevated erythrocyte sedimentation rate, human leukocyte
antigen (HLA)-B27 antigen often positive.

Imaging features:

Clinical:

Laboratory findings: HLA-B27 antigen positive in 75%

Imaging features:

Clinical:

Laboratory findings: HLA-B27 antigen frequently positive, elevated erythrocyte sedimentation rate

Imaging features:

Clinical:

Laboratory findings: none

Imaging features:

Clinical:

Laboratory findings: HLA-B27 antigen positive in approximately 90%

Imaging features:

Clinical:

Laboratory findings: anemia, leukopenia, positive rheumatoid factor, lupus erythematosus cells, and antinuclear antibodies

Imaging features:

Clinical:

Laboratory findings: elevated erythrocyte
sedimentation rate, positive rheumatoid factor (30% to 40%),
antinuclear antibodies (35% to 96%)

Imaging features:

Clinical:

Classifications:

Imaging features:

Clinical:

Laboratory findings: presence of antibodies to saline extractable nuclear antigen

Imaging features:

Juvenile chronic arthropathy includes a
spectrum of disorders, including juvenile spondyloarthropathies,
seropositive RA, and seronegative (Still disease) arthritis.

Most disorders occur in older children or adolescents and, therefore, have findings similar to the adult disorder.

Still disease occurs in younger children
and accounts for 70% of juvenile chronic arthropathies. Three
categories exist with some overlap:

Distribution: Knee is the most common
site for monoarticular disease. Wrists involved more than hands, feet,
hips, and cervical spine (similar to RA).

Imaging features:

Arthropathy of hemophilia is the result of repetitive hemorrhage.

Hemarthrosis occurs in up to 90% of patients with hemophilia.

Most hemorrhagic episodes occur in childhood.

Distribution: knee, elbow, ankle, hip, shoulder

Imaging features resemble juvenile chronic arthritis:

Gouty arthropathy is the result of deposition of monosodium urate crystals.

Males are affected much more frequently than females.

Radiographic changes take years to manifest.

Distribution: feet most common (85%); ankles, hands, wrists, elbows. May present as olecranon bursitis in the elbow.

Laboratory findings: hyperuricemia

Imaging features:

Hemochromatosis is an inherited disorder
resulting in systemic iron deposition. It also may occur with
cirrhosis, multiple transfusions, or excessive iron intake.

The disorder is most common in men aged more than 40 years.

The arthropathy resembles degenerative joint disease and calcium pyrophosphate deposition disease (CPPD).

Distribution: hands and wrists most common, followed by knees and hips

Imaging features:

CPPD is the most common crystal arthropathy.

The condition affects 5% of the population, generally the middle-aged or elderly.

CPPD crystals are deposited in hyaline and fibrocartilage. Patients may have no symptoms or may present with severe pain.

Distribution: knee, pubic symphysis, and wrist most common, but may involve any joint

Imaging features:

Wilson disease is a rare liver disease resulting in copper deposition in bones, joints, and other tissues.

Copper interferes with normal osteogenesis, resulting in osteomalacia.

Up to 50% of patients develop arthropathy.

Distribution: hands, wrists, feet, shoulders, hips, elbow, knees

Imaging features:

Ochronosis is a metabolic disease caused
by lack of homogentisic acid oxidase. Homogentisic acid (a dark
pigment) is deposited in joints, resulting in cartilage degeneration.

Patients typically present after age 40 years.

Distribution: Spine—may resemble
ankylosing spondylitis. Peripheral joints (knee, hip, shoulder)—similar
to CPPD or osteoarthritis.

Imaging features:

Neurotrophic arthropathy results from repetitive trauma to joint without sensory nerve supply.

Relaxation of supporting structures
results in malalignment of osseous structure fragmentation and, in most
cases, subchondral sclerosis.

Diabetic neuropathy is the most common
cause. Multiple sclerosis, syphilis, syringomyelia, meningomyeloceles,
and congenital insensitivity to pain also may cause neurotrophic
arthropathy.

Distribution: lower extremity, especially foot and ankle

Imaging features:

Primary synovial chondromatosis or
osteochondromatosis is a condition of unknown cause. Synovial
chondromas or osteochondromas form resulting from synovial metaplasia.
There are three phases:

In older patients (>50 years of age)
the condition is twice as common in males as females. However, the
condition is also common in younger females (aged 20–30 years) and most
often involves the hip.

The condition involves the hip in 50% of
cases, but may also involve the knee, elbow, wrist, hand, shoulder, and
temporomandibular joint.

Radiographs may be normal unless the
loose bodies are calcified or ossified. Conventional, CT, and MR
arthrography are more useful to confirm the diagnosis.

Secondary degenerative arthritis follows this condition.

Treatment consists of synovectomy and/or removal of loose bodies.

Pigmented villonodular synovitis (PVNS)
is a relatively uncommon disorder characterized by synovial
proliferation with hemosiderin deposition in synovial tissues.

The condition may involve joints, bursae, or tendon sheaths.

There are diffuse forms (80% involve the knee) and localized forms such as giant cell tumor of the tendon sheath.

The condition is diagnosed most commonly in the second through fifth decades.

PVNS is typically monoarticular involving
the knee followed by the hip, ankle, shoulder, elbow, temporomandibular
joint, and spine.

Radiographic findings are evident in 80%
of cases. Findings include swelling, joint effusion (often denser than
a simple effusion), and cystic or erosive changes in bone.

MR features are characteristic with areas
of low signal intensity on T1- and T2-weighted sequences resulting from
hemosiderin deposition.

Treatment consists of synovectomy.
Recurrence rates are 25% to 50%. Postoperative baseline MR examinations
are recommended for more optimal detection of residual PVNS or
recurrence.

Amyloid arthropathy is attributed to
long-term dialysis using cuprophane dialysis membranes.
B2-microglobulin is deposited in the form of amyloidosis.

Clinically the condition is unusual in
patients on dialysis less than 5 years, but occurs in 80% of patients
on dialysis for more than 10 years. Patients present with pain and
swelling in the involved joints.

Radiographs demonstrate large cystic lesions in bone with lobulated soft tissue swelling. Pathologic fractures may occur.

On MR images the interosseous lesions
demonstrate signal intensity between muscle and fibrous tissue
regardless of the pulse sequence. Distention of the joint and bursa is
common. Rarely large lytic bone lesions (amyloidoma) may be evident
resembling neoplasms.