Imaging In Arthritis
NATIONAL JOURNAL OF HOMOEOPATHY 1999 Mar / Apr VOL VIII NO 2.
Dr S K Gujar
Dr M M Shroff
In clinical practice, joint pain with or without swelling is a common symptom, which may be associated with various forms of arthritic conditions.
Arthritis is inflammation of joints. Arthritis in the appendicular skeleton can be divided into various types- commonest
- Degenerative arthritis - Osteoarthritis.
- Inflammatory arthritis -
- Seropositive and seronegative arthritides,
- Crystal deposition disease
- Infective Arthritis.
Osteoarthritis is a degenerative condition affecting articulations, especially weight bearing joints, which are subjected to maximum "wear and tear". The disease may be "primary" when no underlying cause is found or "secondary" where the joint was abnormal i.e. joints with H/O severe trauma or past infections.
Osteoarthritis anywhere in the body has a number of common:
Radiologically Specific Features
- Joint space narrowing seen due to cartilaged destruction, occurring characteristically in areas of excessive weight bearing.
- Joint space remodeling follows destruction of the cartilage. The joint alignment is altered with formation of new bone and cartilage in the non-stressed areas resulting in peripheral osteophytosis.
- Cyst or geode formation may be seen along with subchondral sclerosis.
- Detached osteophytes or ossification of the cartilagenous debris, forms loose bodies. Only when osteoarthritis ends in pain and immobility, that secondary osteoporosis and soft tissue wasting is seen.
Most commonly affected joint in the body found in clinical practice is the Knee Joint space narrowing with osteophytosis (new bone formation) and loose bodies are seen. The patellofemoral articulation is most commonly affected; medial tibiofemoral compartment being second. In early disease, spiking of the tibial tubercles and marginal osteophytes seen. Standard A-P and lateral views can assess the joint adequately. The presence of varus deformity is best seen on the weight bearing (erect) A-P views. A skyline view is useful to assess the patellofemoral articulation. The assessment for loose bodies may require additional intercondylar (tunnel) views of the knee joint.
Osteoarthritis of the Hip.
The second most affected joint in the body. Secondary osteoarthritis following congenital dysplasia, Perthe's disease, congenital dislocation, slipped epiphysis, aseptic necrosis etc, is more common than primary osteoarthritis.
Joint space reduction and marginal osteophytosis are seen. The femoral head migrates either superiorly or medially. A-P views of the hip usually provide adequate information. In certain cases, a CT scan may show areas of subarticular crescents, as in aseptic necrosis or geode formation in advanced cases.
Osteoarthritis of the Hands:
The carpometacarpal joint of the thumb and the trapezioscaphoid joint are commonly affected, more often in women and classically in milkmen.
In osteoarthritis, the distal interphalangeal joints are affected with joint space narrowing and large peripheral osteophytes resulting in the clinically evident "Heberdens nodes".
Rheumatoid Arthritis Rheumatoid arthritis is a chronic inflammatory joint disorder of unknown cause, common in middle aged females.
The serum is positive for Rheumatoid factor. Polyarticular symmetrical joint involvement and extra articular manifestations are characteristic.
Clinically, patients typically have prolonged joint stiffness and joint pains, which are worse in the mornings. More than 3 joint areas are affected, symmetrical on both sides of the body with at least one joint area in the hand.
The joints typically involved are the small joints especially the metacarpophalangeal, carpal and the metatarsophalangeal joints.
Periarticular osteopenia and marginal erosions are characteristic, resulting from chronic synovial inflammation. Joint space reduction occurs secondary to cartilage destruction by the pannus. Early in the disease, synovial effusion may cause a widening of the joint space and soft tissue swelling around the joint. Joint malalignment is common late in the disease with ulnar deviation of the fingers, swan neck and boutonniere deformities at the interphalangeal joints. In the feet, external deviation of the toes is common.
Radiograph of both hands on a mammographic film (single emulsion film) is a sensitive means to assess the carpal and metacarpophalangeal joints for erosions. Additional views like the Norgaard's ball catcher view may be needed.
In the foot, lateral view of the calcaneum to look for fluffy periosteitis in addition to the standard A-P and oblique views of the foot are useful.
In the hip joint, medial migrations of the femoral head with protrusion of acetabuli are characteristic, with diffuse osteoporosis and bone loss.
Marked erosive disease may also be seen at the elbow joints, shoulder joint and at the acromion. Large subarticular cysts & geodes may be seen in joints such as knee, where tricompartmental joint space reduction is a feature.
In the axial skeleton, symmetrical sacro-ileitis may be seen in the late stages, which rarely results in fusion. Osteoporosis, disc space narrowing and endplate irregularity are seen in the upper cervical spine. Atlanto-axial subluxation may occur due to laxity of ligaments and erosion of the dens.
Dynamic flexion and extension views of the spine demonstrate instability. A MRI of the cervical spine (or a CT scan with reformatting) demonstrates instability, erosions and its effect on the spinal cord.
The Seronegative Spondylo Arthropathies:
These are diseases with peripheral arthropathy, sacrolitis, an increased incidence of the same or similar disease in the family and an absence of the rheumatoid factor.
Ankylosing spondylitis, Psoriatic arthritis, ulcerative colitis and Crohn's disease, Reiter's syndrome is some of these.
Ankylosing Spondylitis
Symmetrical erosive sacroiliitis, which progresses to sclerosis and fusion, is the usual presenting feature. The patient is typically a young adult male with sacroiliac joint pain and stiffness. The disease progresses to involve the spine and the costovertebral junctions leading to severe back stiffness and difficulty in breathing due to immobility of the ribs. 90% of patients (almost all with sacroiliitis and spondylitis) have the HLA B-27 antigen.
Prone postero-anterior views of the sacroiliac joints are used to assess the joint changes. Oblique views of the joint or a CT scan are useful in early cases with subtle erosions.
Erosions of the vertebral margins and ossification of the anterior longitudinal ligaments leads to squaring of the vertebral body. Marginal syndesmophytes, which may extend throughout the spine giving rise to a Bamboo-spine appearance on the lateral lumbar radiographs. Facetal fusion occurs, which is best demonstrated on CT scanning. The rigid spine fractures easily through the disc of the vertebral endplate. Marked reactive sclerosis may lead to an appearance similar to a infective discitis or neuropathic joint.
Bony ankylosis may follow erosion joint space narrowing and osteoporosis at the hip joint.
Enthesopathy may be seen at the iliac, ischial and calcaneal sites of pigamentous and tendinous insertions in the form of a fluffy and exuberated periosteal reaction on routine radiographs of the pelvis and the ankles respectively.
Psoriatic Arthropathy
Erosive arthropathy occurs in about 5% of patients with psoriasis and may actually precede skin lesions. It typically causes small joint disease in the hands and the feet.
Erosions have a predilection for the distal interphalangeal joints. Asymmetric disease and normal bone mineralisation are characteristic. Joint space narrowing may not occur.
Advanced cases show a "cup and pencil" appearance of phalanges due to extreme resorption, resembling a neuropathic joint.
Periosteal reaction along the diaphyses of the phalanges, metacarpals and metatarsals may be seen.
Sacroiliitis and 'floating' syndesmophytes occur in the axial skeleton.
Reiter's Syndrome
A triad of nongonococcal urethritis, uveitis and arthritis typifies this condition.
Arthritic attacks recur with progressive change at joint and enthesis. Feet are affected preferentially with erosions at the metatarsophalangeal and interphalangeal joint of the great toe and periosteitis. Erosions and reactive spur formation at the calcaneum is common. Asymmetric sacroiliitis and non-marginal spinal syndesmophytes are seen uncommonly.
Enteropathic Spondyloarthropathy
Ulcerative colitis, Crohn's disease and Whipple's disease are associated with joint disease. The peripheral fleeting asymmetric arthritis is related to disease bowel activity and usually presents as joint swelling and periosteitis.
Sacroiliitis and spondylitis resemble that in Ankylosing spondylitis and does not relate to gut disease activity.
As for Rheumatoid arthritis, all erosive arthritides involving the hands are well evaluated by high-resolution radiographs of both hands on mammographic film. The sacroiliac joints are assessed with posteroanterior prone views or oblique views and CT scanning were required.
Scleroderma
Progressive systemic sclerosis is characterized by soft tissue atrophy, calcifications, resorption of the terminal phalangeal trifts (acroosteolysis) and an erosive arthritis with joint space narrowing and resorption of bone at the proximal interphalangeal joints, and periarticular calcification.
The feet, ribs and the mandible may be affected with flexion deformities.
Juvenile Chronic Arthritis
This chronic arthritis, affecting children ,may be pauciarticular (few joints) or polyarticular. Subtypes may resemble (and progress to) adult form of Rheumatoid arthritis, ankylosing spondylitis or may be non-specific.
Still's disease is a systemic illness characterised by a poly articular affliction, fever with chills, cutaneous rash, hepatosplenomegaly, lymphadeno-pathy and pleuro-pericarditis (serositis).
Crystal Deposition Arthropathy
Gout:
Gout is a disorder of uric acid handling with deposition of sodium biurate crystals in tissues. It may be primary (enzyme defect in the uric acid cycle) or secondary (overproduction or uric acid due to increased purine catabolism).
Large punched out erosions occur at joint margins. They tend to enlarge towards the cortex of the shaft. Cartilage destruction occurs relatively late. The joint of predilection is Acute gout is the metatarsophalangeal joint of the great toe. In the hand, gout affects the interphalangeal joints.
Gouty tophi are periarticular deposits seen as soft tissue swellings, which later calcify.
In addition to the radiographic findings, the elevated serum uric acid levels and birefringence crystals seen in the aspirated joint fluid is diagnostic.
Infective Arthritis
Large joints are affected more commonly by bacterial (pyogenic) arthritis. The highly virulent pathogens usually staphylococci or streptococci cause rapid destruction of cartilage and bone. Soft tissue swelling and destruction precedes osteoporosis. Bone changes on radiograph appear within 7-10 days of infection.
Subchondral bone destruction and reactive sclerosis follow early joint space narrowing. Articular irregularity and/or bony ankylosis result.
In infants, effusion results in extreme distension of the joint and dislocation of the hip and shoulder are common. TOM Smith arthritis is a severe pyogenic arthritis of the infant hip with gross distortion of the femoral head.
Cross sectional imaging techniques like USG, CT and MR are useful for diagnosis of effusion, bone and soft tissue changes (CT, MR).
Tuberculous infection in the joint starts in the bone or the synovial membrane.
The synovial or juxta articular lesion produces chronic inflammation with soft tissue swelling. This progresses to marginal erosions. The articular cartilage is relatively resistant to tuberculous infection and the joint space is preserved till late in the disease.
The triad of juxta-articular osteoporosis, marginal erosions and mild or no joint space narrowing, is typical for tuberculous arthritis. The hip joint is the commonest site (20%) of affection in the appendicular skeleton followed by the knee joint, then the shoulder joint.
Rarely seen is a cystic destruction of the humeral head without any effusion - caries sicca.
Tuberculous arthritis can also occur in the hands or feet. A classical tubercular osteitis in the small bones of the hands and feet in the "spina ventosa" appearance with medullary expansion and cortical new bone formation with associated soft tissue swelling.
Plain radiography of the affected bones/joints is often adequate for diagnosis. For doubtful early cases, more sensitive modalities such as CT scanning or MRI may be more useful with guided biopsies if required.
