Is your recovery window still open? Free one-page chart ↓
The Finger Still Curls. That Doesn’t Mean the Tendon Is Intact.
A cut flexor tendon does NOT heal on its own. If you cut the palm side of your finger, hand or wrist and afterwards a joint won’t bend by itself, you have a divided flexor tendon until proven otherwise. It needs a hand surgeon, ideally within days. The repair window is roughly the first 2 weeks. After repair, expect about 6 weeks in a protective splint and around 12 weeks before heavy gripping.
This is the important part: the cut ends don’t find each other again.
The muscle up in your forearm pulls the cut end back down the finger like a released elastic, and every day it sits retracted makes the repair harder.
Miss it, and a wound that got four neat stitches can turn into a two-stage reconstruction months later, for a finger that will rarely bend as well as it would have with an early repair.
So here’s how to find it, what the surgeon is weighing up, and what the next 12 weeks look like.
Where are you right now?
- Just cut it. Do the 15-second test below, then go to the red flags at the bottom.
- Stitched in the ER, but something feels off. Do the test anyway. A stitched wound and a working tendon are two different things.
- Already had the repair. Skip to “What happens after flexor tendon repair?”
- Weeks later, and the finger never bent properly. Read the repair window section today, not next week.
How do I know if I cut a flexor tendon?
Each finger is bent by two separate cords running up the palm side. (More on the machinery in hand tendon anatomy.)
- FDP runs all the way to the fingertip and bends the LAST joint.
- FDS stops at the middle bone and bends the MIDDLE joint.
Because they’re separate, you can cut one and keep bending the finger with the other… which is exactly why these get missed in a busy ER at 1am. The finger still curls. Everyone relaxes. The wound gets stitched.
A finger that still bends is not a finger with intact tendons. It’s a finger with at least one intact tendon.
The 15-second test: one tendon at a time
Do this with the uninjured hand doing the holding.
- FDP test. Hold the middle joint of the injured finger dead straight, then try to bend just the fingertip. Can’t? FDP is likely cut.
- FDS test. Hold the OTHER three fingers flat on the table, then try to bend the injured finger at its middle joint. Can’t? FDS is likely cut.
- Sensation. Run a fingertip lightly down each side of the finger. The nerves sit right beside the tendons, so a numb strip along one side means the nerve went too.
- Resting posture. Look at the hand relaxed on a table. Healthy fingers rest in a gentle cascade, each one a little more curled than the one before it, from index to little finger. A finger lying flatter than its neighbors is a finger that has lost its pull.
A partial cut is the sneaky one. The finger still bends, but it hurts badly to bend against resistance, and sometimes there’s a catch or a triggering feeling. Partial tears above about half the tendon can still rupture later, out of nowhere, doing something ordinary.
How is a flexor tendon injury diagnosed?
Mostly with the examination above, done properly. Scans help, but they don’t replace it.
- Clinical exam. The FDP and FDS tests, sensation on both sides of the finger, and circulation: a pink fingertip that refills quickly after you press it.
- X-ray. If glass, metal or a fall was involved, to look for a fragment or a flake of bone pulled off with the tendon.
- Ultrasound or MRI. Useful when a partial tear is suspected or the exam is unclear because of pain and swelling.
- Surgical exploration. The final answer is often in the operating room, where the surgeon can see exactly how much of each tendon and nerve is cut.
What are the flexor tendon zones, and why is Zone 2 the one surgeons swear about?
Surgeons divide the palm side of the hand into five zones, fingertip to forearm. The thumb has its own numbering.
- Zone 1. Past the middle of the finger’s middle bone. Only FDP lives here.
- Zone 2. From the crease in your palm just below the finger, to the middle of the finger’s middle bone. Both tendons, one tight tunnel.
- Zone 3. The palm.
- Zone 4. Inside the carpal tunnel at the wrist.
- Zone 5. The wrist crease and lower forearm.
You only need to care about one distinction.
In Zone 2, both tendons run together inside a tight fibrous tunnel, one sliding inside the other, with almost no spare room. Repair anything in that tunnel and the repair site wants to stick to the walls.
That’s why old textbooks called Zone 2 no man’s land. It isn’t a no-go area anymore, but it is still the zone where the result depends most on the rehab that follows.
Cuts closer to the wrist, in Zones 4 and 5, are technically easier but often involve nerves and arteries at the same time, so the tendon can end up the least of it. See nerve repair recovery for how that half behaves.
And if the fingertip won’t bend after a sudden pull rather than a cut (gripping a rugby jersey, a dog leash, a climbing hold), that’s the tendon tearing off the bone, not a laceration. That one is jersey finger, and it has an even tighter clock.
Does a cut flexor tendon heal on its own? The repair window
No. And this is the clearest closing window in the whole hand.
- Day 0 to 14: OPEN. Primary repair. The tendon ends are still reachable, the sheath hasn’t scarred, the muscle hasn’t shortened. This is where the good outcomes live.
- Weeks 3 to 6: CLOSING. Delayed repair. Harder. The tendon has retracted and the muscle has started to contract. Still often possible.
- Past 6 weeks: SHUT for a simple repair. Usually a two-stage reconstruction with a silicone rod, then a tendon graft, months apart. A much bigger undertaking for a result that is rarely as good. The goal changes; it doesn’t vanish.
Nobody gets this window back. That’s the entire reason I write in this much detail about a finger that “still sort of works”.
A glass-cut palm from washing up looks like nothing. A two-centimeter laceration gets four stitches and a bandage, and the tendon underneath quietly retreats up the finger while everyone congratulates themselves on the neat suturing.
What happens after flexor tendon repair?
The stitched tendon is at its WEAKEST around week three, right when the hand starts feeling normal and the temptation to use it properly becomes almost irresistible.
So the rehab protocol is not caution for caution’s sake. It’s timed against a real dip in strength.
The two ways it goes wrong: the repair RUPTURES, or the repair sticks down and the finger stops gliding. Rehab is a constant negotiation between those two failures.
The splint
A dorsal blocking splint sits on the back of the hand and forearm. It holds the wrist and knuckles bent so the repaired tendon is never stretched hard, while the fingers can still move inside it. Worn day and night, usually for about 6 weeks. It comes off only when your therapist says so, and only for what your therapist says.
Flexor tendon repair recovery, phase by phase
Your surgeon’s protocol takes precedence. This is the typical shape, conservative version.
- Days 3 to 5. First hand therapy visit. Splint made to measure, protected exercises taught, swelling control started.
- Weeks 1 to 6. Splint full-time. Protected exercises only, no gripping, no lifting, no “just testing it”. Weeks 2 to 4 are the riskiest stretch for rupture.
- Weeks 6 to 8. Splint off, or night only. Light active use: eating, washing, typing. Still no lifting or hard grip.
- Weeks 8 to 12. Gentle strengthening starts when your therapist clears it. Light daily tasks become normal.
- Week 12 onwards. Heavier grip, heavier work, sport, built up gradually. The tendon keeps remodeling for months after that.
There’s a second window hiding in here. Glide is mostly won or lost in the first 6 weeks. Adhesions that set in during that time are much harder to shift later. The full week-by-week version is in flexor tendon repair recovery.
What exercises do you do after flexor tendon repair?
Only the ones your hand therapist shows you, in the order they show you. Protocols differ by surgeon, by repair strength and by zone. The wrong exercise at week 3 can pull a repair apart.
That said, a typical early-motion program looks like this, all done INSIDE the splint:
- Passive flexion. Your other hand gently pushes the finger down into a bend. About 10 reps.
- Active extension to the splint. Straighten the fingers on their own until they touch the hood of the splint. About 10 reps.
- Place and hold (if your protocol includes it). The other hand places the finger in a bend, then you let go and hold it there gently for about 5 seconds. About 10 reps.
- How often. Usually every 1 to 2 waking hours. Little and often beats one big session.
Later phases add active fist making and tendon glides (straight hand, hook fist, flat fist, full fist), then blocking exercises that isolate each joint, then putty and grip work from around 8 to 12 weeks.
(This is the bit where the action-film hero cuts the cast off early and climbs a building. Please don’t be the action-film hero.)
When can I work, drive and play sport after flexor tendon repair?
- Desk work, one-handed. Often within 1 to 2 weeks, if the splint and swelling allow and the injured hand does nothing.
- Driving. Not in the splint. Usually around 8 to 10 weeks, once you can grip the wheel firmly and your surgeon agrees. Check your insurer too.
- Light manual work. Around 8 to 10 weeks.
- Heavy manual work. 12 weeks at the earliest, often longer. See returning to work after a hand injury.
- Gym, climbing, contact sport. 12 weeks at the earliest, and climbing or heavy grip sports often later. These load the exact tendon that was cut.
Will my finger be normal again?
Honest answer: most people get a useful, strong finger back. Many don’t get a PERFECT one, especially after Zone 2 repairs.
- The common leftover. A finger that doesn’t quite reach the palm or doesn’t fully straighten. Usually a few degrees, sometimes more.
- What helps. Early repair, a clean cut, one tendon rather than two, no nerve injury, no smoking, and doing the program as written.
- If it sticks down. A second operation to free the tendon (tenolysis) is sometimes offered, usually not before about 3 to 6 months, once the soft tissues have settled and the joints move well passively.
What a hand therapist does differently
We make the splint to fit your hand, then adjust it as the swelling drops. We measure how far each joint bends, actively and passively, every visit. If active bend lags behind passive bend, the tendon is sticking, and the program changes that week.
That’s why flexor tendon rehab is supervised rather than handed out on a photocopied sheet. The sheet can’t see your finger.
Go to the emergency department today if
- The finger is pale, white or cold after a cut. The arteries run right beside the tendons.
- Any joint of the finger won’t bend on its own after a cut.
- Part of the finger is numb after a cut.
- The wound is over the palm side of a finger crease, even if it looks tiny.
Ask specifically to be seen by a hand surgeon. Say the words “I can’t bend this joint”. That sentence changes what happens next.
Call your surgeon today if
- The finger is going red, swollen and very painful to straighten, or you have a fever. That’s a sheath infection, and it runs on hours.
- You felt a pop or a snap, and the finger suddenly can’t bend the way it could yesterday. That can be a rupture, and re-repair is time-critical.
- The splint has broken, come off or no longer fits.
Get it checked if
- The finger bends LESS at week 4 than it did at week 2.
- A cut “healed” weeks ago, but the finger has never bent properly since.
- Gripping hard after an old cut hurts, catches or clicks. That can be a partial tear.
- The finger still won’t fully straighten at 8 to 10 weeks.
Stitching skin is not treating the injury. It’s closing the window.
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 finger that won’t bend after a cut needs a hand surgeon this week, not a wait-and-see.
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.