Abstract The mutilans type of rheumatoid arthritis (RA) is refractory to several treatments and involves many types of surgical application. It is difficult to prevent its progress, and it has a poor functional prognosis. However, the definition is not always distinct. In this report, I attempt to clarify the clinical features of the mutilans type of RA and establish an accurate definition of the disease. Previous definitions have been divided into three groups: (1) the mutilans group (Mu-G), which has more than three joints showing severe resorptive bone destruction and joint instability; (2) the suspected mutilans group (sMu-G) which has one to two joints with joint instability or showing no instability but with highly resorptive bone destruction; (3) the Larsen V group (LV-G), which has radiological findings indicating Larsen grade V disease. Patients suffering from rheumatoid arthritis for over 10 years and who do not fall into any of the above groups are referred to as the control group. Among 337 patients who suffered from RA for more than 10 years, 58 were classified as being in the mutilans group, 59 in the suspected Mu-G, 47 in the LV-G, and 173 in the control group. The mutilans group had distinctive features which were different from those of the other groups, which had a radiological finding of Larsen grade V disease or severe resorptive bone destruction without instability. From these data, the definition of the mutilans type of RA should be specified as the Mu-G. Thus, the Mu-G shows a distinctive clinical picture which is unlike that in the other groups. It is important to define the mutilans type of RA clearly because it has a poor prognosis. Early identification will help in the establishment of a treatment plan.
Key words
Key words Arthritis mutilans ・ Larsen grade V ・ Mutilans type ・ Mutilating disease (MUD) ・ Rheumatoid arthritis (RA)
