An MCP ulnar deviation splint holds the knuckles in line when rheumatoid arthritis makes the fingers DRIFT towards the little-finger side.
Worn during daily tasks, it eases knuckle pain, improves how the fingers line up for pinch and grip, and reduces the forces that push the drift further.
It doesn’t reverse a drift that has already set.
It works best early, alongside good control of the arthritis itself.
Why the fingers drift
- Inflamed joint lining stretches the ligaments that hold the knuckles and the tendons in place. See rheumatoid arthritis in the hands
- The extensor tendons slip off the top of the knuckles towards the little-finger side, like a sagittal band injury in slow motion
- Everyday grip pushes the fingers the same way. Opening jars, turning keys and pinching with the thumb all add sideways force
- Once the tendons sit off-center, every grip pulls the fingers further across
The splint can’t undo the drift. It can take away the force that keeps making it worse.
The designs
- Soft splints: neoprene or fabric with dividers between the fingers. Comfortable for day use and easy to wear during tasks
- Thermoplastic splints: a firmer base across the palm with posts or loops that guide each finger back into line
- Resting splints at night: for active flares, a resting hand splint shaped to support the knuckles in line
- Ring splints: for swan neck or unstable finger joints that often come with drift. See figure-of-eight ring splints
Who it helps
- People with early or correctable drift, where the fingers still straighten into line when pushed gently
- People with knuckle pain during daily tasks
- After knuckle joint replacement, once the early dynamic splint phase ends, to protect the new alignment
What goes with it
- Medication and disease control, which does more for the joints than any splint
- Joint protection: jar openers, thicker handles, two-handed lifting, and turning keys with the palm instead of pinching
- Keeping the hand strong in its best alignment
- Night resting during flares, day splints for tasks
Problems to watch for
- Pressure on fragile skin, especially on steroid or other thinning medications
- Swelling during a flare making a splint too tight
- Stiffness if the splint is worn all day with no movement
Get it checked if
- A finger suddenly can’t straighten at the knuckle, which can mean a ruptured tendon
- A hot, swollen joint despite treatment
- Drift getting worse quickly
- Skin breaking down under the splint
This is one of dozens of splints a hand therapist makes. See what a hand therapist does for the full list, and psoriatic arthritis for another inflammatory arthritis that affects the hands.
Line the knuckles up during the day, rest them at night in a flare, and control the arthritis underneath.
Every article on this site is written using the Closing Window Method: name the window your condition runs on, find where you are in it, and act while it’s still open.