A case of rheumatoid arthritis who became able to use ready-made prefilled auto-injectors because of the development of self-assistive devices

Abstract

  Various types of biologics with auto-injector for rheumatoid arthritis（RA）have been approved and now we can select them. However, ready-made auto-injectors do not always match the patient's hand function because the hand function of the patient differs individually due to deformation. Here, we report a patient with RA who cannot use ready-made auto-injectors because of very weak grip and thumb deformity. We observed the patient trying a variety of auto-injectors, and found that the presence of safety lock and injection start button made it difficult for her to use them. We focused on an etanercept auto-injector and by developing a self-assistive device which does not require grip power and thumb movements, the patient has become able to use the auto-injector. The skirt-like shape compensates for the loss of grip power, and the weighted lever solved the button problem. At present, there is only one auto-injector in one biological medicine, and it is not possible to select an auto-injector according to the function of fingers. We consider it necessary to develop self-assistive devices adapted to finger function.