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Bend It as Much as You Like. Just Don’t Straighten It. Yet.
A PIP extension block splint sits on the back of the finger and stops the middle joint straightening past a set angle, while letting it BEND FREELY. It’s used for volar plate injuries and stable PIP fracture-dislocations. Most people wear it full-time, day and night, for 4 to 6 weeks. It usually starts about 20 to 30 degrees short of straight and is opened roughly 10 degrees a week until the finger reaches straight.
You probably jammed the finger backwards. A ball, a fall, a door. The middle knuckle is fat and sore, and now there’s a splint on the back of it that won’t let you straighten the finger. Feels backwards.
It isn’t. This joint punishes mistakes in both directions. Straighten it too early and an unstable joint can slip back out of place. Stop bending it inside the splint and the middle joint stiffens into a bend that can take months to win back… sometimes it never fully does.
Here’s how the splint works, how long it stays on, and what you do inside it.
What is the volar plate, and why block straightening?
The middle joint of your finger (the PIP joint) has a thick ligament on its palm side called the volar plate. Its job is to stop the joint bending backwards. Jam the finger back hard enough and the plate tears, sometimes pulling a chip of bone off with it.
- When it tears, the joint can slide backwards out of place, especially near full straightening.
- Bent, the joint stays reduced. The block keeps it in that safe range.
- Bending freely keeps the joint moving, which is what prevents the stiffness this joint is notorious for.
Stable when bent, unstable when straight. The splint lets the finger live in the stable half.
For why the middle joint behaves this way, see finger joint anatomy.
Which injuries need an extension block splint?
- Volar plate injuries from a finger bent backwards, the classic ball-sport injury. See jammed finger and ball sports.
- Stable PIP fracture-dislocations that stay in place in the splint.
- After surgery on the middle joint, such as volar plate repair.
- PIP dislocations that were put back and feel unstable near full straightening.
- NOT for a central slip (boutonniere) injury. That one needs the opposite: the middle joint held dead straight. See PIP extension splints. Same joint, opposite splint, so the diagnosis comes first.
How is it diagnosed? The X-ray that matters
- Where it hurts. Tender on the PALM side of the middle joint, often with bruising there, after a finger bent backwards.
- A side-on X-ray. A true side view shows whether a chip has come off and whether the joint surfaces sit evenly.
- Fragment size. Roughly, a chip under about 30% of the joint surface is usually stable. Bigger than that, the joint often won’t stay in place without surgery.
- A second X-ray WITH the splint on, commonly at about one week. The joint surfaces should sit evenly against each other. If a V-shaped gap opens at the back of the joint, the block angle isn’t enough or the injury needs a different plan.
A simple volar plate sprain with no fracture and a stable joint may need less time in a block splint, sometimes buddy strapping alone. That’s decided on a stability test, not on how sore it is.
How long do you wear a PIP extension block splint?
Your surgeon or therapist may give you different dates. Use theirs. This is the conservative version for a fracture-dislocation managed in a splint:
- Week 0 to 1: block set at the angle where the joint stays in place, often around 20 to 30 degrees short of straight. Splint on day and night. Bend the finger fully many times a day.
- Weeks 1 to 4: block opened a little each week, typically by about 10 degrees, with a repeat X-ray if a fracture is involved.
- Weeks 4 to 6: the block reaches straight and the splint comes off. Full straightening encouraged, buddy strapping for activity for a few more weeks.
- Weeks 6 to 12: straightening and strength rebuilt. Bone needs 6 to 12 weeks before the joint is ready for full load.
- Months 2 to 12: the joint can stay thick and slightly stiff for 6 to 12 months while it matures. The swelling is usually the last thing to leave.
This injury runs on a clock. In the first 2 weeks the window is OPEN: a joint that isn’t sitting right can still be fixed simply. From about 2 to 6 weeks it’s CLOSING. Past about 6 weeks it’s SHUT for the simple fixes, and the goal changes to rescuing what the joint can still do. So if the splinted X-ray doesn’t look right, the surgery conversation belongs in the first 2 to 3 weeks, not month 3.
How should an extension block splint fit?
- It sits on the back of the finger, sometimes running onto the back of the hand. The palm side stays open so the finger can curl.
- The finger must bend fully into the palm. If the splint stops the bend, it’s wrong.
- The finger rests against the block when you try to straighten. It shouldn’t be able to pull away from it.
- Straps sit on the segments, above and below the middle joint, not across it.
- Red marks should fade within 20 to 30 minutes of the splint coming off. Watch the back of the middle knuckle, where the skin is thin.
- A refit as swelling drops is normal. A loose strap at night lets the finger straighten past the block while you sleep.
Can I take the splint off to wash?
Only if your therapist has said so and shown you how.
- Keep the finger bent while it’s off. Rest the hand in a loose curl on the table. Never let it lie flat and straight.
- Dry the skin completely, especially between the fingers. Change damp tape or padding.
- Showering: a waterproof cover, or keep the hand out of the water if the splint must stay on.
- Clean the splint with cool water. Heat softens thermoplastic and can change the block angle. (A splint left on the dashboard on a hot day has a new angle. Not the one your therapist chose.)
What exercises do you do in an extension block splint?
These line up with the usual protocol. Your therapist may change them for your joint.
- Fist inside the splint (from week 1). Bend the finger fully into a fist, hold 3 seconds, open back up to the block. 10 slow reps, every 2 hours while awake.
- Tip bends (from week 1). Hold the middle segment still and bend just the fingertip joint. 10 reps, 4 to 6 times a day. This keeps the tendon over the back of the finger from tightening.
- Straighten to the block. Straighten as far as the splint allows, hold 5 seconds. 10 reps, 4 to 6 times a day. No pushing it straight with the other hand in the early weeks.
- The other fingers: full fists, cos they stiffen too when you guard the hand.
- Grip and pinch (from about week 8). Soft putty, 2 to 3 minutes, twice a day, once the joint is confirmed stable.
A finger in one of these splints looks like it’s permanently about to point at something. Think E.T., but not allowed to reach all the way. That’s fine. The point comes later.
How do you wean off the splint?
- The block opens on a schedule, usually weekly, with your therapist adjusting the splint each time.
- Once it reaches straight, the splint comes off and buddy strapping takes over for activity.
- If straightening stalls once the block is gone, your therapist may add an extension splint at night to win the last degrees back.
- Don’t wean on a good day. Wean on the schedule and the X-ray.
When can I drive, work and play again?
- Driving: once you can grip the wheel securely and could control the car in an emergency. Often 1 to 2 weeks for a splinted finger, longer after surgery. Check your insurer.
- Desk work: usually within days. The other fingers type fine.
- Light manual work: around 6 to 8 weeks, buddy strapped.
- Heavy gripping work: around 8 to 12 weeks, sometimes longer.
- Ball sports, climbing, contact: training buddy strapped from around 8 weeks if your surgeon agrees, full unprotected play around 3 months.
What a hand therapist does differently
Makes the splint to the exact angle the X-ray says is safe, opens it on schedule, measures the bend and the straighten at every visit, and changes the plan the week the numbers stall. That’s the whole game with this joint: enough protection to keep it in place, enough movement to keep it from setting.
Problems to watch for
- A finger that stops straightening once the block is gone. A middle joint stuck in a bend is the common long-term problem.
- Pressure on the back of the middle joint.
- Not bending enough inside the splint, which lets the joint stiffen in the protected position.
- Straps loosening, so the finger straightens past the block at night.
Get it checked today if
- There was a cut over the joint at the time of injury. An open dislocation needs the ER, a washout and antibiotics.
- A clunk or visible step at the joint, or the finger slips out of line again.
- The fingertip goes white, blue or cold, or numbness doesn’t settle within minutes of loosening the straps.
- After surgery: spreading redness, heat, discharge or a fever. Call your surgeon.
Get it checked if
- The finger is moving less at week 4 than at week 2.
- Straightening is still limited 2 to 3 weeks after the splint comes off.
- A jammed middle joint is still badly swollen at 2 to 3 weeks and nobody has taken a side-on X-ray.
- A blister or sore over the back of the middle knuckle.
This is one of dozens of splints a hand therapist makes. See what a hand therapist does for the full list.
Block the straightening, keep the bending, and take the block away a step at a time.
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. A middle knuckle that’s moving less each week deserves a review this week.
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.