Is your recovery window still open? Free one-page chart ↓
The Bend Sets a Little More Every Month. The Spring Works Best Before It Does.
Wear a Capener splint for several hours a day, starting with 1 to 2 hours and building up, for somewhere around 6 to 12 weeks. It’s a SPRING-WIRE splint for a middle finger joint (the PIP joint) stuck in a bend. It pushes the joint gently toward straight while you can still bend the finger against it. You stop when the straightening you’ve gained holds between sessions.
It’s used for PIP flexion contractures after sprains, fractures, Dupuytren’s surgery and older boutonniere injuries, once the tissue is ready to be stretched. Worn through the day, often paired with a static splint at night, it gains straightening without stopping you using the hand.
Why bother, if the finger still mostly works?
Because a middle joint that’s held bent doesn’t stay put. The soft tissue on the palm side shortens to fit the bend, and every month it’s left, more of that tissue sets in the shortened position. A bend that’s soft and springy at month 2 can be fixed and woody at month 6…and fixed joints often don’t respond to a splint at all.
The spring works best while the joint still gives a little.
What is a bent middle joint (PIP flexion contracture)?
The PIP joint is the middle knuckle of the finger. On its palm side sits a thick plate of ligament, the volar plate, with ligaments on either side. After a sprain, a fracture, weeks of swelling or weeks in a splint, those tissues tighten in the bent position. The joint loses its last part of straightening, and the finger catches on pockets, gloves and the edge of the table.
One distinction matters before any splint goes on. If you can push the finger fully straight with your other hand but can’t straighten it yourself, that’s a tendon problem (an extensor lag), not a stiff joint. Different cause, different splint. See extensor tendon injuries.
How is a bent finger joint measured?
- Degrees, not feelings. A goniometer, a small protractor for fingers, measures how far short of straight the joint sits. Measured at each visit, it shows whether the splint is working.
- End feel. The therapist pushes gently toward straight. Soft and springy means the tissue can still stretch. Hard and abrupt means it has set.
- Active vs passive. How far you can straighten it yourself versus how far it goes with help. The gap between the two tells tendon from joint.
- The fist. How close the fingertip gets to the palm, so straightening gains never cost you bending.
- X-ray if the bend followed an injury, to check the joint surfaces before stretching anything.
How it works
- A coiled steel wire sits either side of the middle joint.
- Padded supports press gently on the palm side above and below the joint, and on the back of the joint itself.
- The coil pushes the joint toward straight with a low, steady force.
- You can still bend the finger against the spring, so grip and tendon glide continue.
A bent joint straightens under a gentle force held for hours. It resists a hard force held for minutes.
What it’s used for
- Middle joints that won’t straighten after PIP sprains and dislocations.
- Stiffness after finger fractures and long immobilization.
- After Dupuytren’s surgery, where the middle joint drifts back into a bend.
- Older boutonniere injuries, where the joint has stiffened in a bend. A fresh central slip injury usually needs a static PIP extension splint first.
- A finger that won’t straighten after surgery. See can’t straighten a finger after hand surgery.
Who it suits best
- A joint with a soft, springy end feel. If it gives a little when pushed, it’s likely to respond.
- Moderate bends. Very stiff or fixed joints may need serial casting or static progressive splints instead.
- People who need to use the hand during the day while working on the stiffness.
How long to wear a Capener splint
Two numbers matter: hours a day, and weeks overall.
- Hours a day: start with an hour or two, then build up to several hours spread through the day. In my experience the fingers that gain most are the ones that build toward 6 hours or more in total. Total time under gentle stretch moves a joint. A stronger stretch doesn’t.
- Weeks overall: most people wear it for somewhere around 6 to 12 weeks, depending on how stiff the joint was and how consistently it’s worn.
- The stop signal: it’s weaned once the straightening you’ve gained HOLDS between sessions, rather than springing back within an hour of taking it off.
- At night: a static extension splint often holds what the Capener gained during the day.
In Closing Window terms, this is a joint on a clock. While the end feel is still soft, usually in the first 3 months after the injury or surgery, the window is OPEN and a spring can win. As the tissue firms over the following months the window is CLOSING, and the splint needs more hours for less gain. Once the end feel is hard and nothing has changed after 6 to 8 weeks of proper wear, the window for splinting alone is largely SHUT, and the conversation moves to casting or surgery.
How to put it on and use it
- Pads in the right places: the two palm-side pads sit above and below the middle joint, the back pad sits right over the middle knuckle.
- Coils at the joint: the wire coils line up with the side of the middle joint, not the base of the finger.
- Force: a comfortable stretch. Pain, pins and needles or a white fingertip means too much.
- Keep bending the finger. Gaining straightening at the cost of a fist isn’t progress.
- Skin checks over the back of the joint every time it comes off, especially in the first week. Red marks should fade within 30 minutes.
(Off-the-shelf Capener-style splints are sold online in sizes. The coil tension and the pad positions still need setting for your finger…a spring pushing on the wrong spot is how you get a pressure sore instead of a straighter joint.)
Exercises to do alongside the splint
The splint does the slow stretch. These keep the tendons gliding and the gains usable. Warm the hand in warm water for 5 to 10 minutes first if it’s stiff.
- Gentle straightening stretch. Support the finger on a flat surface and press the middle joint gently toward straight with your other hand. Hold 30 seconds, 3 to 5 times, 3 times a day.
- Active straightening. Hold the base of the finger steady with your other hand and straighten the middle joint yourself as far as it goes. Hold 5 seconds, 10 reps, 3 to 4 times a day.
- Full fist. 10 full fists every time the splint comes off. This is your insurance against trading bend for straightening.
- Tendon glides. Straight hand, hook fist, flat fist, full fist. 10 rounds, 3 to 4 times a day.
A typical pattern
- Weeks 1 to 2: short sessions, skin checks, tension adjusted.
- Weeks 2 to 8: longer wear through the day, measurements at each visit.
- After that: weaned once the gain holds between sessions.
Capener vs a static extension splint
- Capener (dynamic): stretches while you keep using and bending the finger. Daytime.
- Static extension splint: holds the joint at its straightest. Usually night, or for fresh injuries that need protecting rather than stretching.
- Many people need both, which isn’t overkill. It’s day and night doing different jobs.
Can you work, type and drive with a Capener splint?
- Typing and desk work: yes. That’s the point of a dynamic splint.
- Driving: usually fine with a single-finger splint, as long as you can grip the wheel and control the car safely.
- Heavy gripping and tools: take it off. The wire can bend or catch, and a hard grip fights the spring. Wear it in the breaks and the evening instead.
- Ball sports and the gym: off for these. Make up the hours elsewhere in the day.
When the spring isn’t enough
- Serial casting: a small cast holds the joint at its straightest and is changed every few days to a week, a few degrees further each time. Better for stiffer joints.
- Static progressive splints: a dial or strap you tighten in small steps, for joints that resist a spring.
- Surgery: a release of the tight tissue (a capsulotomy) is usually considered only after a proper splinting trial, and often not before 3 to 6 months after the injury. After it, you’re back in a splint anyway, so the habits you build now still pay.
For other splints that use force to gain range, see dynamic splints.
What a hand therapist does differently
- Checks joint vs tendon first, so you don’t spend 8 weeks stretching the wrong problem.
- Sets the tension and pad positions for your finger, and adjusts them as the joint changes.
- Measures in degrees at each visit, so progress is a number.
- Switches tools to casting or static progressive splinting when the spring stalls.
This is one of dozens of splints a hand therapist makes. See what a hand therapist does for the full list.
Get it checked today if
- The fingertip goes white, blue, cold or numb and doesn’t recover within a few minutes of taking the splint off.
- A blister or open sore appears over the back of the middle knuckle.
- The finger is hot, red and swollen, or you have a fever.
Get it checked if
- Red pressure marks that last longer than 30 minutes.
- The finger swells more after wear.
- Bending is getting worse as straightening improves.
- No change after around six weeks of consistent wear.
- The end feel is getting harder rather than softer.
Gentle spring, long hours, and keep the fist.
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 joint that’s been bent for more than a few weeks deserves a measurement, not a guess.
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.