The A4 securely supports the forearm, wrist, and thumb while preserving finger movement for the other fingers. This immobilization device is used for treating basal thumb arthritis, De Quervain’s syndrome, and Gamekeeper’s thumb. It’s also suitable for the treatment of acute arthritis flare-up, acute TFCC ligament injuries, arthroplasty, contractures, osseous contusions, complex regional pain syndrome as well as radial nerve paralysis. Furthermore, the A4 can also be used for rheumatoid arthritis, (sub)luxation, and synovitis.

The medial opening makes it easy to slip in and out of the immobilization device.