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When the Ulna Bone in Your Forearm Is Simply Too Long
Ulnar impaction syndrome is pain on the little-finger side of the wrist caused by the ulna being slightly LONGER than the radius, so it presses into the small wrist bones above it every time you grip or twist. Most cases are treated without surgery first: 3 to 6 months of load changes, a brace for flares, and strengthening. If that fails, the ulna is shortened, and that recovery runs 4 to 6 months.
A few millimeters is enough.
It is a loading problem, not a tearing one. Which is why rest calms it and gripping, twisting or pushing up from a chair brings it straight back.
You probably can’t point to an injury. It just started aching…and then the ache started turning up for every jar lid, every wrung-out cloth, every push-up.
Keep loading it the same way and it doesn’t stay an ache. The cartilage disc on top wears through, the bone underneath bruises, then forms cysts, then loses its cartilage. The early stages reverse. The last one doesn’t.
What is ulnar impaction syndrome?
Your forearm has two bones. The radius is on the thumb side, the ulna on the little-finger side. At the wrist, the radius carries about 80 percent of the load and the ulna about 20.
That split depends on their relative lengths, and it is not a gentle curve. Roughly speaking, 2.5mm of extra ulnar length can push the ulnar share from 20 percent to over 40.
Double the load, through a cartilage disc designed for half of it.
Over years, that disc, the TFCC, wears centrally, then the lunate and triquetrum beneath show bone edema (bruising inside the bone), then cysts, then true cartilage loss.
This is why the MRI report so often says “degenerative central TFCC tear” in someone who never injured their wrist. The tear is the consequence. The length is the cause.
Why does the ulna end up too long?
- Born that way. Some people are simply built ulnar-positive. Usually both wrists.
- After a wrist fracture. A distal radius fracture that healed shortened drops the radius relative to the ulna.
- After a growth plate injury. Premature closure of the radial growth plate, as in gymnast’s wrist.
- Functionally, in pronation and grip. The ulna becomes relatively longer with the forearm turned palm-down and the fist clenched, which is why symptoms are position-dependent. Even a “neutral” wrist can impact under load.
Ulnar impaction symptoms
- Ache on the little-finger side of the wrist, built up gradually, with no injury you can name.
- Worse with the forearm turned palm-down and the wrist tipped toward the little finger: opening jars, wringing a cloth, push-ups, pushing up from a chair, a backhand, a hammer.
- Better with rest, back again within a day of loading it.
- Sometimes clicking, once the disc has worn through.
- Grip that fades on that side under sustained load.
A home check that raises suspicion: turn your palm down, make a tight fist, and tip the wrist toward the little finger. If that reproduces your ache, it fits the pattern. It doesn’t prove it.
How is ulnar impaction diagnosed?
- Examination. The ulnocarpal stress test (wrist tipped toward the little finger, loaded and rotated), tenderness just beyond the end of the ulna, and a check of the forearm joint’s stability.
- The right X-ray. A PA X-ray taken with the forearm pronated and the fist clenched shows ulnar variance properly. A relaxed film underestimates it. Ask whether both wrists were compared.
- MRI. Bone edema or cysts in the lunate and triquetrum is the giveaway. See your hand MRI report, translated.
- Arthroscopy shows the disc, the cartilage and the ligament between the lunate and triquetrum directly, usually when treatment happens at the same time.
If the bone underneath is bruised, the problem is not the disc that sits on top of it.
Nobody is going to spot this on a normal X-ray glanced at in a corridor. It is a millimeter problem, and millimeters need to be measured, not eyeballed.
Ulnar impaction or TFCC tear?
The clinical picture overlaps heavily with a straightforward TFCC tear, and the two often coexist. A long ulna is a common reason a TFCC wears thin.
- TFCC tear: usually a specific injury, a fall or a twist. Sharp, often clicking, sometimes a shifty forearm joint.
- Ulnar impaction: gradual onset, no injury, an ache that builds with load.
- Imaging: a long ulna on the pronated grip X-ray, plus bruising or cysts in the bone on MRI, points to impaction.
- Not this at all: a tendon that snaps over the back of the ulna as you turn the palm up is ECU tendinopathy or subluxation.
Which window are you in?
This one runs on years, not weeks, and it is about cartilage rather than tissue healing.
- OPEN: bone edema only. Fully reversible once load is corrected. This is where non-surgical care does its best work.
- CLOSING: cysts. Still correctable, structure largely preserved. Don’t spend another year waiting to see.
- SHUT for reconstruction: cartilage loss and joint space narrowing. Shortening the ulna no longer resurfaces what’s gone. Salvage surgery replaces reconstructive surgery at this point. The goal changes from fixing the joint to making it comfortable.
Ulnar impaction treatment without surgery
Non-surgical first, and it is worth a real attempt.
- Activity modification. Avoid loaded pronation and ulnar deviation. Lift with the palm facing in or up, keep the wrist straight when you grip, two hands on the kettle.
- Brace. A wrist widget or ulnar-sided support to limit the compressive position. In a flare, a wrist splint that stops the wrist tipping toward the little finger, worn most of the day for 4 to 6 weeks, then for heavier tasks only. Options side by side in TFCC wrist braces.
- Strengthening. The muscles that offload the ulnar side, particularly ECU and pronator quadratus, once pain allows.
- Injection. Corticosteroid into the ulnocarpal joint for a settling window. It quiets the pain. It doesn’t shorten anything.
- Time. Give it 3 to 6 months before calling it failed.
Exercises for ulnar impaction
Pain during each exercise should stay mild (3 out of 10 or less) and settle by the next morning. Do them once a day. These match the TFCC program, cos the muscles doing the protecting are the same ones.
- ECU holds. Forearm resting on a table, palm down. Push the little-finger side of your hand outward against your other hand without letting it move. Hold 10 seconds, 5 to 10 times.
- Forearm rotation holds. Elbow at your side, bent to 90 degrees. Your other hand grips the wrist while you try to turn the palm down, and then up, without moving. Hold 10 seconds, 5 to 10 times each way.
- Grip with a straight wrist. Soft ball or putty, wrist kept level, 3 sets of 10. Never squeeze with the wrist tipped toward the little finger.
- Wrist curls, palm up and palm down. Light dumbbell, 3 sets of 10 to 15, building weekly if the next morning is quiet.
- Weight-bearing ladder. Wall push-ups on fists, then countertop, then knees on the floor, then full. Move up a step only when the current one is pain-free for a week.
Can I go to the gym with ulnar impaction?
- Push-ups: on fists or handles rather than flat palms.
- Pressing and pulling: neutral-grip dumbbells or handles beat a straight bar. Straps take load off the grip.
- Skip for now: dips, front rack, burpees, and anything that tips the wrist toward the little finger under load.
- More position fixes in gym wrist pain.
When do you need surgery for ulnar impaction?
Surgery, when load reduction doesn’t hold. Usually after 3 to 6 months of honest non-surgical care, or sooner if the MRI already shows cysts. The point is the same in all versions: shorten the ulna or decompress it.
- Ulnar shortening osteotomy. A small segment of the ulna removed and the bone plated back together. Reliable, but it is a bone-healing timeline, and the plate is sometimes removed later if it irritates.
- Wafer procedure. A few millimeters of the ulnar head shaved, often arthroscopically. Faster recovery, but limited to smaller amounts of extra length.
- Tidying the TFCC is often done at the same time. On its own, for a long ulna, it doesn’t fix the cause.
Ulnar shortening recovery time
Conservative version. Your surgeon’s protocol wins.
- Weeks 0 to 2: protect. Splint or cast, hand above heart, fingers moving. Stitches out around day 10 to 14.
- Weeks 2 to 6: gentle movement. Removable splint. Wrist and forearm movement as your surgeon allows. No lifting.
- Weeks 6 to 12: bone healing. Bone usually unites in 6 to 12 weeks, sometimes longer, and slower in smokers. Light strengthening once the X-ray shows healing.
- Months 3 to 6: reload. Full loading at about 4 to 6 months. Push-ups and heavy lifting last.
- After a wafer procedure instead: light use in about 2 to 4 weeks, sport and heavier loading around 6 to 12 weeks. See wrist arthroscopy recovery.
Can I work and drive with ulnar impaction?
- Desk work: usually yes. Keep the wrist level on the mouse and don’t rest it tipped toward the little finger.
- Manual work: screwdrivers, wrenches, hammers and heavy palm-down lifting are the worst offenders. Swap grips or tools before you swap jobs.
- After ulnar shortening: desk work often 2 to 4 weeks, light manual work around 3 months, heavy work 4 to 6 months.
- Driving: without surgery, if you can grip and turn the wheel firmly without pain catching you. After shortening, not in a cast or splint, usually not before about 6 weeks. The test is whether you could control the car in an emergency.
What a hand therapist does differently
- Finds the position, not just the spot. Which grip, which rotation, which task loads the ulna, then changes those first.
- Molds the right splint to block the compressive position without freezing the whole wrist.
- Doses the strengthening so the ECU and forearm muscles carry the load the disc can’t.
- Knows when to stop. If 3 to 6 months of genuine effort hasn’t shifted it, the answer is a surgical opinion, not another round of the same.
Get it checked today if
- After a fall, the wrist looks deformed or the end of the ulna is sticking out.
- You can’t turn the forearm at all, or it feels locked.
- Numbness, or a cold or color-changed hand.
- The wrist is hot, red and swollen, especially with a fever.
Call your surgeon today if
- After ulnar shortening: increasing redness, heat, throbbing, discharge or a fever.
- The cast or splint feels too tight, or the fingers are going numb or pale.
- Sudden new pain or a clunk at the plate site, especially after a knock or a fall.
- Pain escalating after the first week, with a shiny, swollen, color-changed, very sensitive hand.
Get it checked if
- Little-finger-side wrist pain has been building for 6 weeks or more without an injury.
- It aches at rest or at night, not just with load.
- Your old wrist fracture healed, and now the other side of the wrist aches with grip.
- 3 to 6 months of genuine load changes haven’t settled it.
The tear is the consequence. The length is the cause. Treat the cause.
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. Little-finger-side wrist pain with no injury behind it deserves the right X-ray, taken the right way.
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.