A thumb IP splint holds the THUMB TIP JOINT straight while the rest of the thumb and hand stay free.
It’s used for mallet thumb, where the tendon that straightens the tip has been torn or pulled off the bone, and in the weeks after EPL tendon repair or transfer.
Like a mallet finger splint, it only works if the tip is never allowed to bend during the healing period.
The tendon it protects
- The EPL tendon runs from the forearm, around a bony pulley at the wrist, to the tip of the thumb. It’s the tendon that lifts the thumb back and straightens the tip
- At the tip, a jammed or stubbed thumb can tear it or pull off a flake of bone. The tip then droops and can’t straighten on its own
- Higher up, it can be cut, or wear through and rupture weeks after a wrist fracture
One bend of the tip during healing can undo weeks of splinting. Straight means straight, every time the splint comes off.
What it’s used for
- Mallet thumb managed without surgery, the thumb version of mallet finger
- After EPL tendon repair for a cut over the thumb
- After tendon transfer to replace a ruptured EPL, often as part of a larger forearm-based thumb splint in the early weeks. See tendon transfers
- Thumb tip joint sprains and dislocations once put back in place
The designs
- Small tip splint: a thermoplastic shell over the back or front of the tip joint, for mallet thumb
- Hand-based thumb splint with the tip included, when the knuckle also needs support
- Forearm-based thumb extension splint, after higher repairs and transfers, holding the wrist and whole thumb
A typical mallet thumb timeline
- Weeks 0 to 6 or 8: splint on day and night. When changing it for skin care, keep the tip supported straight on a table the whole time
- Next 2 to 4 weeks: splint at night and for risky tasks. Gentle bending begins
- After that: weaned. If the tip starts to droop again, the splint goes back on and you’re reviewed
After a repair or transfer, your surgeon’s protocol sets the timeline, often with early controlled movement.
Problems to watch for
- White, soft skin under the splint
- Pressure over the back of the tip joint, where skin is thin
- Stiffness at the thumb knuckle if it’s held longer than needed
Get it checked if
- The tip droops again after the splint comes off
- You suddenly can’t lift the thumb back at all, especially weeks after a wrist fracture
- Skin breaking down or a nail bed wound under the splint
For the whole thumb, see thumb spica splints and thumb anatomy. This is one of dozens of splints a hand therapist makes. See what a hand therapist does for the full list.
Tip straight, day and night, and never let it bend while it heals.
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.