IMAGE OF THE WEEK 2015
IMAGE 01 - 28 January 2015
RHEUMATOID ARTHRITIS OF THE HAND: END STAGE
Figure 1: AP x-ray of the hand in rheumatoid arthritis: extensive sclerosis and volume loss of both rows of carpal bones. Subluxation of the 1st metacarpophalangeal joint and the wrist with ulnar deviation. (Click on image to enlarge)
Rheumatoid arthritis (RA) is debilitating autoimmune disease leading to severe deformities at the joints of the hands, feet and cervical spine (although other joints and organs can be implicated).
It has a lifetime prevalence of 1% in the general population and disproportionately affects women. The incidence of the disease increases with age peaking at 40 – 50 years.
The chance of developing RA is largely a combination of genetic and environmental factors. Genetically, RA has been shown to be linked to specific genes. Mainly, MHC HLA class II genes, HLA-DR4 and HLA-DRB1, in addition to T-cell associated gene PTPN22, commonly mutated in a number of autoimmune disorders.
The basis of the pathophysiology is thought to initially involve the production of Rheumatoid factor; an autoimmune antibody which targets the Fc receptor of macrophages in the synovial membranes. This stimulates the local immune cells causing cytokine release leading to local inflammation and immune invasion. The inflammatory reaction leads to excessive formation of granulation tissue alongside enzymatic tissue damage. This leads to disintegration of joint cartilage and underlying bone which results in deformity of the joint.
The presentation of RA is characterised by swelling, pain and stiffness of the joints of the hand or foot after prolonged periods of inactivity. Morning stiffness is a key feature.
These symptoms are often relieved by movement which distinguishes the disease from osteoarthritis. As the pathology advances the destruction of joint tissues leads to prominent ulnar deviation and subluxation at the metacarpophalangeal joints (see Figure 1). Boutonniere, swan neck and Z shaped thumb deformities can be seen in late stages of the disease.
Figure 2: Lateral x-ray of the wrist in rheumatoid arthritis showing a reduction in joint space and peri-articular osteopenia at the intercarpal and carpometacarpal joints.
(Click on image to enlarge)
X-ray is the current imaging standard for classifying and staging the severity of RA at the hands and feet. While X-ray may not detect pathology in early stages of RA, several identifying radiological features become apparent as the disease progresses. MRI and ultrasound is now having a growing role in the detection of early disease. The most prominent hard tissue changes include a loss of joint space, peri-articular osteopenia and in the late stages of the disease; erosion of bone (see Figures 1 2 & 3).
There is no known cure for RA, management focuses on reducing symptoms and delaying the progression of the disorder. NSAIDs and steroidal medications are given to reduce pain and inflammation in the joints. For long term treatment, non-biologic disease modifying anti-rheumatic drugs (DMARDs) such as methotrexate are used to alter the underlying disease and slow the progression of RA. Relatively newer classes of biologic DMARDs, such as abatacept and rituximab are used in combination with non-biologic DMARDs for stronger clinical effectiveness. These are used at disease outset to limit lasting damage and establish disease control.
Exercise and occupational therapy can help maintain strength and joint flexibility to improve functional ability of patients with RA.
Figure 3: Annotated image of Figure 1 of the hand with severe rheumatoid arthritis. (Click on image to enlarge)
Images and text contributed by
Dr Ian Bickle, Department of Radiology,RIPAS Hospital.
Text contributed by
Matthew Hon and Samuel Jackson, School of Medicine, University of Queensland.
All images are copyrighted and property of RIPAS Hospital.