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You Try to Open Your Hand. The Ring and Little Fingers Curl Instead.
An anti-claw splint stops the ring and little finger knuckles bending backwards when the ulnar nerve isn’t working. With the knuckles blocked, the long finger tendons can STRAIGHTEN THE FINGERS again, and the hand opens to grip.
You wear it by day, for use, for as long as the nerve takes to recover. After an elbow-level injury that’s often many months, cos the nerve regrows at about 1 mm a day.
It improves how the hand opens. It doesn’t bring back pinch strength or feeling.
Here’s what you’re living with. You reach for a glass and the last two fingers curl into a hook and push it away. Buttons, coins and keys slip. Your thumb pinch feels like it’s made of wet noodles. The little finger catches on your pocket every time you put your hand in.
And here’s what goes wrong if you just wait. The finger joints spend every hour curled. Within weeks to months they shorten into that curl. Then, if the nerve does come back, it wakes up to fingers that physically can’t straighten any more.
The nerve sets its own pace. Keeping the joints ready for it is YOUR job, and the splint is half of that job.
Why do the fingers claw with ulnar nerve palsy?
- The ulnar nerve supplies the small muscles inside the hand that bend the knuckles and straighten the finger joints at the same time. See the hand nerve map.
- When those muscles stop working, the long tendons from the forearm take over unopposed.
- The knuckles pull back and the finger joints curl, most obviously in the ring and little fingers. The index and middle fingers usually escape, because a different nerve (the median) still powers two of their small muscles.
- The hand can’t open around a glass, and objects get pushed away instead of gripped.
Stop the knuckle bending back, and the same tendons that were clawing the finger straighten it.
What else does ulnar nerve palsy look like?
- Numbness in the little finger and the little-finger half of the ring finger.
- A hollow in the web between thumb and index on the back of the hand, where the first muscle has wasted.
- Weak key pinch. The thumb’s end joint bends hard as you try to grip a piece of paper between thumb and index side. Clinicians call it Froment’s sign.
- A little finger that drifts out and won’t tuck back in to the ring finger. That’s Wartenberg’s sign, and it’s why it snags on pockets.
- Clumsiness with fine tasks: buttons, coins, typing, chopsticks.
How is it diagnosed?
- Examination first. Feeling, muscle bulk, pinch, finger spreading. A hand therapist or doctor can usually tell the level of the problem from which muscles are weak.
- Nerve conduction studies and EMG confirm where the nerve is squeezed or injured and how badly. See nerve conduction test results explained.
- Ultrasound or MRI sometimes, to look for what’s pressing on the nerve, such as a cyst at the wrist.
- The splint test. Push the ring and little finger knuckles into a slight bend with your other hand, then try to straighten the fingers. If they straighten, an anti-claw splint will work. If they don’t, the joints are already tight, and they need stretching or casting first.
What causes it?
- Ulnar nerve injury at the elbow or wrist, including cuts and fractures.
- Severe cubital tunnel syndrome with muscle wasting.
- Compression at Guyon’s canal at the wrist, with weakness.
- Combined median and ulnar nerve injuries, where all four fingers claw.
(Odd one, this. An injury at the elbow often claws LESS than one at the wrist, because the elbow injury also weakens the tendons that do the curling. Clinicians call it the ulnar paradox. So if your clawing gets a bit worse as an elbow-level nerve recovers, that can be a sign the nerve is getting somewhere.)
Which anti-claw splint is best?
- Hand-based dorsal splint: a bar over the back of the ring and little finger segments, holding the knuckles slightly bent. Simple and sturdy.
- Figure-of-eight style: slimmer, leaving the palm clear for grip. Usually the one people actually keep wearing.
- Spring or elastic designs: hold the knuckles bent but let them straighten under effort.
- Off-the-shelf versions exist, but the fit at the knuckles matters. Too loose does nothing. Too tight presses on skin you can’t feel.
Whatever the design, it only needs to do one thing: stop the knuckles bending backwards. The finger joints stay free so the hand can work.
How long do you wear an anti-claw splint?
- During the day, for use. This is a functional splint. It’s meant for gripping, writing and daily tasks, not for resting in a drawer.
- For as long as the palsy lasts. Nerves regrow at about 1 mm a day, roughly an inch a month. From the elbow to the hand muscles is a long way, so after an elbow-level injury it’s often 9 to 12 months or more before the hand muscles start to wake.
- At night if the joints are tightening. Your therapist may add a night splint that holds the knuckles bent and the finger joints straight.
- Off for washing, skin checks and exercises.
Exercises to keep the fingers ready
- Finger straightening stretch: hold the ring and little finger knuckles bent with your other hand, then gently push the middle and end joints straight. Hold 10 to 15 seconds, 10 times, 3 times a day.
- Active open hand: with the splint on, open the hand fully and close it. 10 times, several times a day.
- Tabletop position: knuckles bent, fingers straight, like making a duck’s bill. Hold 5 seconds, 10 times. Helped by the other hand until the muscles return.
- Once the muscles start to come back: spreading the fingers against a light rubber band and pinching putty, 10 times, 2 to 3 times a day. Short, frequent sessions. Weak muscles tire fast, and a tired muscle doesn’t learn.
- Skin check: look at the little-finger side of the hand morning and night. You won’t feel a blister, so you have to see it.
Where are you in the window?
Ulnar nerve palsy runs on a CLOSING window, and there are two clocks.
- The joint clock. Fingers held curled for weeks to months shorten into that curl. Splint plus daily stretching keeps this window open almost indefinitely. Skip the stretches and it closes.
- The muscle clock. A muscle left without a nerve supply for too long, roughly 12 to 18 months, often can’t fully recover even when the nerve arrives. That’s why a nerve that’s going nowhere needs a surgeon’s opinion early, not after a year of hoping.
If the window on the muscles has shut, the goal changes. The splint, or a tendon transfer, takes over the job the muscles used to do.
Will the clawing go away?
- After mild compression, such as early cubital tunnel syndrome, the muscles often recover once the pressure is off, over months.
- After surgery to free the nerve, tingling usually improves first. Wasted hand muscles recover slowly and not always fully. See cubital tunnel release recovery.
- After a cut nerve is repaired, the small hand muscles are the hardest thing to get back, especially in adults. See nerve repair recovery.
- When the muscles don’t return, a tendon transfer reroutes a working tendon to stop the knuckles bending back. In effect, it builds the anti-claw splint into the hand.
Can I work and drive with an anti-claw splint?
- Desk work: usually yes. Typing is often easier with the splint than without, because the fingers stop dragging.
- Manual work: depends on grip and pinch. Tools, fasteners and fine assembly are hard while pinch is weak, and numb skin means gloves and extra care with heat and sharp edges.
- Driving: once you can grip the wheel securely and control the car in an emergency. Many people manage. Some need a steering aid.
- Gym and sport: grip-heavy work, like pull-ups and racquets, is limited by the weak small muscles. Protect numb skin from bars and friction.
Problems to watch for
- Pressure marks on numb skin, which you won’t feel.
- Fixed bending of the finger joints if the splint is worn but the stretches are skipped.
- Heavy pinch still weak. The splint doesn’t replace the pinch muscles. Thicker pens and key turners help.
Get it checked today if
- Sudden new weakness or numbness after a cut, fracture or fall.
- A wound, blister or burn on numb skin, especially if it’s red, hot or weeping.
Get it checked if
- Increasing weakness or wasting.
- No sign of any recovery 3 to 4 months after an injury that was expected to recover.
- Finger joints that no longer straighten even with help.
- Numbness spreading beyond the little finger and half the ring finger.
This is one of dozens of splints a hand therapist makes. See what a hand therapist does for the full list.
Block the knuckle, and the hand opens again.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Thousands of hands, wrists and elbows assessed and treated. My credentials are here. This article explains; it doesn’t examine. Fingers that are clawing more each month, not less, deserve a proper assessment soon.
Part of: Hand, wrist and elbow splints: which one, why and how long
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.