Frontiers in Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by proliferative synovitis and inflammatory arthritis with erosions. RA targets multiple peripheral joints including the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints. Conventional radiography is still important, but recently, imaging of RA has been dramatically changed by magnetic resonance imaging (MRI) and ultrasonography (US). In this book, we aim to provide comprehensive understanding of RA by ABCDEFGH’s new approach. A: alignment, B: bone, C: capsula articularis, intra-articular, D: distribution, E: extra-articular, F: further information, G: goal, and H: healing.

Category A is alignment. Alignment includes mal-alignment, deformities and fractures, axis, subluxation, luxation, height of carpals, abnormal outline of bones. Mal-alignments and deformities of the joints are common in rheumatoid arthritis (RA). There are various deformities including swan-neck deformities, Button-hole deformities, ulnar deviation of the MCP joints, palamarsubluxation at the MCP joints, Zigzag deformities, splaying laterally of the digits, and so on. In the spine, atlantoaxial subluxation is important in RA.

Category B is the mineralization and shape of the bones. This category includes bone mineralization, erosions, bone cysts, and osteophyte formation. In rheumatoid arthritis (RA), marginal erosion is a hallmark of the disease and occurs in the bare areas of the bone. Especially, juxta-articular osteoporosis is the earliest change in plain radiograph of patients with RA.

Category C is the capsula articularis, intra articular. It includes the changes of joint paces and calcifications. In this category, joint space narrowing (JSN) and ankylosis are important in rheumatoid arthritis (RA). Also, joint effusion and synovitis are detectable by US and MRI.

Category D is the distribution of joint involvement. It includes the four “Distributions” in the body, the region, the joint and the time. These four categories provide important keys for the diagnosis of rheumatoid arthritis (RA) and differential diagnosis of various rheumatic diseases.

Category “E” includes the eaternal bone, extra-articular manifestations. In this category, there are soft tissue swelling, dactylitis, rheumatoid nodules, bursitis, ganglions, tenosynovitis, enthesitis, tendonitis, and calcification in rheumatoid arthritis (RA).