Tendons are the cords that connect muscle to bone, and the hand has dozens of them: flexor tendons on the palm side that bend the fingers and thumb, extensor tendons on the back that straighten them. A cut from a knife, glass or a tool can divide a tendon, and a sudden wrench can tear one from the bone. A divided tendon does not heal on its own, because the two ends pull apart. Repaired within days by a hand surgeon and followed by hand therapy, most tendon injuries recover well. Left for weeks, the ends retract and scar, and a straightforward repair becomes a reconstruction. If you cannot bend or straighten a joint after a cut, it needs to be seen now.
What is a tendon injury?
Flexor tendons run from muscles in the forearm, through the carpal tunnel, and along the palm side of each finger inside a sheath held close to the bone by pulleys. Extensor tendons run across the back of the wrist and hand and spread into a thin sheet over each finger.
A cut across either surface can divide one or several tendons. Because tendons sit under tension, the ends spring apart, the muscle end retracts up the hand, and nothing bridges the gap. A partial cut can hold and heal with protection, but it can also rupture later. Nerves and arteries run alongside the flexor tendons, and a cut deep enough to divide a tendon often divides a nerve too.
Closed ruptures happen without a wound. The common ones are the flexor tendon to the tip of the ring finger torn from the bone in a tackle (jersey finger), the thumb extensor tendon snapping weeks after a wrist fracture, and mallet finger, which has its own page.
Symptoms
- Inability to bend or straighten one or more joints of a finger or thumb
- Weakness or pain when trying to move the joint
- A wound on the palm or back of the hand, finger or wrist, sometimes small
- Numbness along one or both sides of the finger beyond the cut, meaning a nerve is also divided
- With a closed rupture, a pop or tearing sensation followed by loss of movement
Causes and risk factors
Sharp injuries cause most tendon divisions: kitchen knives, broken glass, box cutters, angle grinders and sheet metal. Closed ruptures come from sport, mostly football, rugby and climbing, where a bent finger is forcibly straightened under load. The thumb extensor can rupture after a wrist fracture or with rheumatoid arthritis, where the tendon frays over a rough bone edge or an inflamed joint.
How it is diagnosed
By examination, and a careful one. Each tendon has its own test, and we check both flexor tendons of each finger separately, every extensor, and the sensation and circulation of each fingertip. A partly divided tendon can still move the joint, so a wound over a tendon with normal movement is not automatically safe.
An X-ray is taken where there may be glass or metal in the wound or where bone may have come away with the tendon. Where a wound lies over a tendon and the examination is uncertain, the most reliable test is to look: the wound is explored in theatre and anything divided is repaired at the same sitting.
Non-surgical treatment
Few tendon injuries can be treated without an operation.
- Partial cuts involving less than half of the tendon's width can be protected in a splint and moved under hand therapy supervision, provided the tendon is not catching.
- Some closed extensor injuries heal with splinting alone: mallet finger, and a central slip injury of the middle joint caught early and splinted straight for six weeks.
Everything else needs the tendon repaired. Hand therapy is not an alternative to surgery for a divided tendon. It is the second half of the treatment after it.
Surgery
Tendon repair should be done within a few days, and at most two weeks of the injury. After that the muscle shortens, the tendon ends fray, the sheath collapses and the gap can no longer be closed directly.
The operation
The wound is extended into a zigzag incision along the finger or palm so the tendon ends can be found, which often means retrieving the retracted end from higher in the hand. The ends are sewn together with a strong core suture of several strands, and the join is smoothed with a fine running suture so it glides through the sheath. Where the tendon has torn off the bone, as in jersey finger, it is reattached with a suture anchor. The pulleys are preserved wherever possible, and a divided nerve is repaired under magnification at the same time.
Where a tendon has been missed for months or is too damaged to repair, the options are a tendon graft, taking a spare tendon from the forearm to bridge the gap, or a tendon transfer, in which a neighbouring tendon that can be spared is redirected to do the lost tendon's job. These are the tendon reconstruction and tendon transfer on our treatment list.
Repairs are day surgery, under a general anaesthetic or a regional block with sedation, and take approximately 45 to 90 minutes for a single finger. A plaster splint protects the repair for the trip home.
Hand therapy after repair
A repaired tendon that is not moved sticks to its sheath; one that is moved too hard ruptures. The path between those two is hand therapy. Within three to five days of surgery our therapists replace the plaster with a custom thermoplastic splint and start a controlled early movement programme, progressing it week by week. Having therapy on site means the programme starts on time.
Recovery, week by week
Indicative, for a flexor tendon repair in one finger. Extensor repairs are usually a little quicker; reconstructions and transfers have their own schedules.
Day of surgery. Hand numb for up to 24 hours from the block. Plaster splint on, hand elevated, fingers free to wiggle within it.
Days 3 to 5. First therapy visit. Plaster replaced by a custom splint holding the wrist and knuckles bent so the repair is slack. Controlled exercises begin.
Two weeks. Sutures removed. Exercises progress. Splint worn at all times except exercises and washing. Office work is possible in the splint.
Six weeks. Splint weaned from six weeks. Light use of the hand for eating, dressing and writing. No gripping, lifting or pulling.
Six to eight weeks. Splint off. Gentle strengthening starts. Driving once you can grip the wheel safely six to eight weeks. Light manual work from about eight weeks.
Twelve weeks. The repair is considered strong. Heavy lifting, contact sport and heavy manual work resume from twelve weeks. Movement and strength keep improving for up to a year.
Risks and complications
Tendon surgery is routine for a hand surgeon, and most repairs heal well. The specific risks are:
- Rupture of the repair, in roughly one in twenty flexor repairs, usually from an unguarded movement in the first six weeks. It needs another operation.
- Adhesions. The healing tendon sticks to its sheath and the finger does not move fully. Therapy prevents most of this. Where it persists after three to six months, an operation to free the tendon, a tenolysis, can help.
- Infection, more likely after dirty wounds, treated with antibiotics.
- Numbness or hypersensitivity where a nerve was divided and repaired. Nerve recovery is slow and often incomplete.
- Cold sensitivity of the finger, and uncommonly complex regional pain syndrome, which is recognised early and treated with therapy.
When to be seen sooner
Contact us, or go to an emergency department, if you have:
- Any cut over a finger, the palm or the wrist with weakness or loss of movement, even if the wound is small
- A cut with numbness beyond it, which means a nerve is likely divided
- A finger that will not bend at the tip after a sporting tackle or grab
- A thumb that has suddenly stopped lifting, particularly weeks after a wrist fracture
If you have had surgery with us and have questions or concerns afterwards, phone the rooms during office hours on (08) 7127 0365.
Frequently asked questions
Will a cut tendon heal by itself?
No. The ends separate as soon as the tendon is divided and there is nothing to bridge the gap. A partial cut can heal with protection. A complete one needs repair.
How soon does it need to be repaired?
Within days, ideally. The result is similar whether the repair happens on day one or day five, but after two weeks the repair becomes harder and after a few weeks it may need a graft instead.
My wound was stitched at the hospital. Does that mean the tendon is fine?
Not necessarily. Skin closure and tendon repair are different things, and a divided tendon under a neatly stitched wound is a pattern we see. If the joint beyond the cut does not move normally, it needs to be assessed.
Why can I not use my hand for twelve weeks?
A tendon repair is only as strong as the sutures for the first few weeks, and it reaches most of its strength at about twelve weeks. Using the hand normally before then risks the repair pulling apart, which means a second operation and a worse result.
What is jersey finger?
A closed rupture of the flexor tendon to the fingertip, usually the ring finger, torn from the bone when a finger catches an opponent's jersey. The tip no longer bends. It needs the tendon reattached within ten days before it retracts too far, and it is often missed as a sprain.
Do I need a referral?
Yes for a consultation with one of our surgeons: a referral from your GP, an emergency department or another specialist. No referral is needed for hand therapy. For an acute injury, phone the rooms on (08) 7127 0365 and we will arrange to see you promptly.
Written and clinically reviewed by Dr Paul van Minnen, MD, PhD, EBOPRAS, FRACS (Plast)
Last reviewed 8 November 2026