The Hard Lump That Doesn’t Squash
A carpal boss is a bony lump on the BACK of the hand, right where the index or middle finger’s long bone meets the wrist, caused by a small spur of extra bone at that joint.
It is hard, fixed, and sits in the same place forever.
The single most useful thing to know is that it is bone, not fluid — which is why the wrist ganglion advice you have been reading does not apply to it.
Press a ganglion and it gives slightly. Press a carpal boss and you are pressing bone.
Where exactly
Run a finger from the knuckle of your index or middle finger straight back towards the wrist. The boss sits at the point where that long bone meets the small wrist bones — the second or third carpometacarpal joint.
It is more prominent with the wrist bent forward, and it disappears from view when the wrist is bent back. A ganglion does the opposite.
That one positional trick sorts most of them in clinic before any scan is ordered.
Boss or ganglion
- Consistency: boss is hard and immobile; ganglion is firm but slightly compressible and moves a little
- Position: boss sits at the CMC joints, further towards the fingers; ganglion usually sits more towards the wrist crease, over the scapholunate area
- Behavior: boss never changes size; a ganglion swells and shrinks over weeks
- Transillumination: a torch held against a ganglion glows through it. A boss does not
- Imaging: a lateral X-ray taken with the wrist partly flexed and deviated shows the spur clearly
Confusingly, a ganglion can sit on top of a carpal boss. Both together is common enough to be worth mentioning.
If someone has offered to aspirate it and nothing came out, that was never a cyst.
Does it matter
Mostly, no. Plenty of people have one and never know.
It becomes symptomatic in three ways:
Pressure. It sits exactly where a keyboard wrist rest, a desk edge or a barbell sits. Pain from contact rather than from the joint itself.
Joint irritation. The CMC joints beneath it are nearly rigid, and the spur is a sign of degenerative change there. Loaded wrist extension — press-ups, pushing up from a chair, yoga — provokes it.
Extensor tendon irritation. The tendons that straighten the fingers run directly over the lump. Over years, they can become inflamed or, rarely, rupture.
Treatment
Leave it alone if it does not hurt. There is no benefit to removing a lump that is only doing an impression of a problem.
Offload it. The highest-yield intervention and the one most often skipped.
- Remove the wrist rest rather than adding a softer one
- Press-ups on fists, handles or parallettes instead of flat palms
- A wrist support that limits end-range extension during provoking activity
Corticosteroid injection. Into the joint or the overlying bursa. Useful for a flare, not a structural fix.
Surgical excision. The spur is removed. Reasonable for a boss that keeps flaring after real non-surgical effort.
- Week 0 to 2: splinted, wound healing
- Week 2 to 6: motion restored, scar work begins
- Week 6 to 12: loading returns gradually
- Recurrence is reported in the region of 10 to 20 percent — it is bone, and bone can regrow
Where the underlying CMC joint is clearly arthritic, excision alone often disappoints and fusion of that joint is the more durable answer.
The window
There isn’t a closing one, which makes this a rarity on this site. Nothing is lost by waiting.
The exception: a finger that stops straightening. That is tendon attrition, and tendons that rupture over a bony ridge do not come back with rest.
Otherwise, this is the one lump on the back of your hand you are allowed to simply live with. Rare permission, take it.
Related reading
- Wrist Ganglion Cyst: That Lump on Your Wrist, Explained
- Ganglion Removal Recovery: Recurrence, Scar and Stiffness
- Wrist Arthritis and SLAC Wrist: Where Old Injuries End Up
- Extensor Tendon Repair: Recovery & the Extensor Lag
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.