The Bone Heals on Its Own. It’s the Nail Bed Nobody Looks At.
Fingertip caught in a car door, hit with a hammer, crushed under something heavy. It’s throbbing, the nail is going black, and there might be a crack in the bone on the X-ray.
Here’s the counterintuitive part.
The fracture is usually the least important thing on that X-ray.
The fan-shaped tip of the fingertip bone is surrounded by tough tissue that splints it naturally, and these breaks reliably heal with nothing more than protection.
What decides whether your finger looks and works normally in a year is the nail bed underneath the nail, and whether anyone looked at it.
The blood under the nail
A dark red or black collection under the nail is a subungual hematoma: blood trapped between the nail and the bed, in a space that can’t expand.
That’s where the throbbing comes from, and it’s genuinely one of the more unpleasant kinds of pain in the hand.
Draining it takes literally just seconds.
A small hole is made through the nail, the blood escapes, and the relief is immediate and can be dramatically relieving. If your finger is throbbing under a black nail, this is worth going in for on day one rather than riding it out.
(Please have someone do it properly rather than heating a paperclip at the kitchen table. Sterility matters here, particularly when there’s a fracture underneath, because that turns a closed break into an open one.)
The question that actually matters
Not how much blood is under the nail. Whether the nail itself is still intact and properly seated.
- Nail plate intact, edges still tucked under the skin folds: the nail bed underneath is probably fine. Drain the blood, protect the finger, leave the nail alone.
- Nail split, torn, partly lifted out from its fold, or missing: that means the nail bed under it has very likely been cut, and it should be looked at and repaired.
Repairing it means lifting the nail, stitching the nail bed back together with fine sutures, and replacing the nail or a substitute to hold the fold open while it heals.
A nail bed that heals with a ridge of scar in it grows a ridged, split or lifting nail from then on. Permanently.
That’s the whole argument for taking a squashed fingertip to someone on the day rather than waiting to see how it settles. The bone will be fine either way.
The nail is a one-shot repair.
What the nail does afterwards
Expectations, so nothing surprises you:
- A badly bruised nail usually lifts off over several weeks. That’s normal and not a complication.
- Fingernails grow at roughly 3mm a month, so a completely new nail takes somewhere around 4 to 6 months to reach the end of the finger.
- The new nail often looks strange for a while: thickened, ridged, or slightly discoloured. Judge the final result at about a year, not at three months.
- The nail fold has to be kept open while the nail regrows. That’s why something gets placed back under it, and why you shouldn’t pull it out early.
The fingertip itself
The bone typically needs 3 to 4 weeks of protection in a small splint that covers the tip. Longer if the fracture runs across the base of the bone rather than through the fan-shaped end.
Then the part nobody warns you about: the fingertip unfortunately stays sensitive.
There’s more nerve ending per square centimetre in that pad than almost anywhere on your body, so after a crush injury it can be painfully oversensitive, oddly numb in patches, or both, for months.
Cold intolerance is common and can last a year or more!
This responds well to desensitization: working graded textures against the pad several times a day and using the finger deliberately rather than guarding it. Protecting a sensitive fingertip keeps it sensitive, which is the opposite of what instinct says.
When it’s more than this
- Tissue actually missing from the end of the finger, rather than crushed: that’s a fingertip injury or amputation and needs seeing today.
- The tip won’t straighten on its own afterwards: check for mallet finger, because the tendon can be pulled off in the same accident.
- Increasing redness, throbbing that worsens after day two, or discharge: infection, and an open tuft fracture is a real infection risk.
- A fingertip that stays white, blue or cold: needs seeing immediately.
The short version
Crushed fingertip: get the blood under the nail drained if it’s throbbing, and get the nail bed looked at if the nail is split, lifted or missing.
The fracture will heal. The nail is the part with a deadline.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Tens of thousands of hands, wrists and elbows assessed and treated. My credentials are here. This article explains; it doesn’t examine. A crushed fingertip with a disrupted nail should be seen the same day.