Measurement of rehabilitation in thumb MP joint subluxation due to rheumatoid arthritis

As treatment for subluxation due to rheumatoid arthritis (RA), rehabilitation by hand therapy is one option, but the number of therapist is not sufficient. Therefore, a device for rehabilitation of thumb metacarpophalangeal (MP) joint subluxation has been developed. To improve the device, it is necessary to measure in close proximity to the actual rehabilitation. Therefore, the authors tried to measure two kinds of rehabilitation by using motion capture and a contact force sensor. To measure rehabilitation movements, three markers were attached to the metacarpal bone, six markers were attached to each side of the interphalangeal (IP) joint, MP joint and proximal phalanx of the right thumb of the subjects, and a finger model was created by these markers. Further, three markers were placed on the left index of the therapist, and force direction was calculated by these markers. Measurement was conducted on healthy subjects, Rehabilitation was performed by the person who is not a therapist, but received the guidance of the doctor who is coauthor. As a result, the authors could measure rehabilitation by hand therapy, force, point of action and displacement. The results suggest that rehabilitation with traction twice as efficient as that without traction. Furthermore, it was found that rehabilitation is possible with calculated force, and the force is reproducible by the actuator in the device.