Flexor tendon injury
Laceration or rupture of one or more flexor tendons in the hand, fingers or wrist. Most commonly follows a cut from a knife, glass, or sharp tool. Surgical repair is almost always required, followed by a strictly structured hand therapy programme.
📊 Flexor tendon injuries are among the more serious hand injuries seen in Emergency Departments. They are particularly common in young men following accidents with knives, glass, or industrial equipment.
What is a flexor tendon injury?
The flexor tendons are the strong cords that run from muscles in the forearm into the fingers and thumb. They pass through the wrist, into the palm, and along the front of the fingers, attached to the bones of each finger joint. When you bend your fingers, these tendons slide back and forth like cables. A cut across the palm or front of a finger frequently divides one or more of these tendons.
Flexor tendon injuries are described by their "zone" of injury, with Zone 2 (within the finger, where two tendons run together in a tight sheath) being the most demanding to repair, historically called "no man's land" because of how difficult it is to get a good result. Modern techniques and structured hand therapy have transformed outcomes in this zone, but repair still requires meticulous surgery and a highly motivated patient.
Two flexor tendons go to each finger, one bends the middle joint (FDS) and one bends the tip (FDP). The thumb has one (FPL). Even small lacerations can divide tendons completely, because the tendons are tightly packed under the skin. Any cut on the palm side of the hand that affects finger movement should be assumed to involve tendon injury until proven otherwise.
Common causes
- Knife or glass laceration (most common)
- Industrial accidents (saws, sharp tools)
- Crush injuries with skin loss
- Closed avulsion injury (jersey finger, FDP avulsed by sudden grip)
- Spontaneous rupture (rheumatoid arthritis, partial tendon injury)
- Sports injuries (especially rugby for jersey finger)
Who is at risk? Most flexor tendon injuries are accidental and follow contact with knives or glass. Industrial and food preparation workers are at occupational risk. Rugby and grappling sports predispose to jersey finger (avulsion of FDP from the distal phalanx).
Symptoms
Symptoms vary depending on the severity and duration of the condition. Common symptoms include:
- Cut or wound on the palm side of the hand, finger or wrist
- Inability to bend one or more joints of a finger
- Abnormal "resting cascade", the affected finger lies straighter than the others
- Pain on attempted finger movement
- Sometimes minimal external bleeding, but significant deep injury
- Numbness if the digital nerves are also cut
When to seek help: Any cut to the palm side of the hand with loss of finger movement should be treated as a flexor tendon injury until proven otherwise. Attend an Emergency Department urgently for assessment. Early repair (within 1-2 weeks) gives the best outcome.
How is it diagnosed?
Your hand surgeon will take a detailed history and examine the hand and wrist. The following investigations may be arranged to confirm the diagnosis:
- Clinical examination, assessment of each tendon (FDS, FDP) individually
- Testing finger flexion with the other fingers held straight (isolates FDS)
- Testing tip flexion alone (isolates FDP)
- Examination of the "resting cascade" of the fingers
- Assessment of nerve function (sensation, sweating)
- Wound exploration in theatre, the gold standard
Partial tendon lacerations may still allow some movement but are at high risk of late rupture if not repaired. Any wound near a tendon, in a patient who cannot move the finger normally, needs formal exploration in theatre rather than wound closure in the Emergency Department.
Treatment pathway
Treatment is tailored to the severity of the condition, your age, activity level, and overall health. Most conditions are treated in a stepwise fashion, starting with the least invasive options.
Surgical tendon repair
Direct repair of the tendon ends with a strong core suture (typically 4-strand or 6-strand) and a circumferential epitendinous repair. Performed within 1-2 weeks of injury for best results. Any associated nerve injury is repaired at the same time. Day case or short stay surgery.
Structured rehabilitation programme
Hand therapy is not optional, outcomes depend on it. A dorsal blocking splint is worn for 4-6 weeks, with controlled active or passive motion exercises starting within days to prevent the repair from sticking to surrounding tissue. The exact protocol depends on the zone of injury and the strength of repair.
Tendon reconstruction
For tendons injured more than a few weeks previously, or where primary repair has ruptured or scarred down, a staged reconstruction may be needed. A silicone rod is implanted first, allowing a new sheath to form, then a tendon graft is placed at a second operation 2-3 months later.
Recovery
Flexor tendon recovery is one of the most demanding rehabilitations in hand surgery. The repair is at its weakest between weeks 3 and 6 when sutures are bearing the load alone. Rupture in this period is catastrophic for outcome. Patients must follow the splinting and exercise protocol absolutely strictly, this cannot be over-emphasised.
- Dorsal blocking splint: 4-6 weeks
- Active hand therapy: 12 weeks
- Light strengthening: 12-16 weeks
- Heavy gripping and contact sport: 4-6 months
What results can I expect?
Modern outcomes are good in Zone 2 if surgery and hand therapy are excellent, around 70-80% of patients achieve good or excellent function. Other zones generally do better. Some loss of full active flexion is common. Re-rupture rates are 4-10% depending on protocol adherence. Late presentations and failed repairs have less reliable outcomes.
In numbers
Typical activity timelines for this condition. These are approximate and vary considerably between patients. Always follow the specific guidance given by your surgeon and hand therapist.
| Activity | Typical timeline | Notes |
|---|---|---|
| Wear protective splint | 6 weeks | A dorsal blocking splint protects the repair while controlled movement prevents adhesions. Must be worn continuously.[1] |
| Start hand therapy | 3-5 days | Hand therapy with controlled movement usually starts within the first week. The protocol is unique to each patient.[2] |
| Drive | When safe / 6-8 weeks | Driving generally waits until the splint is off and grip is reliable. Earlier if a non-dominant finger and automatic car.[3] |
| Light desk work | In the splint | Office work can resume in the splint when comfortable, ideally with the hand elevated. |
| Manual work | 3-4 months | Heavy gripping, tools, and resisted use return only after the repair has consolidated.[1] |
| Sport | 3-6 months | Contact and impact sport wait until full grip strength has returned and the surgeon confirms safety. |
| Make a full fist | Gradual | Active fist progression follows a strict protocol over weeks. Forcing it early risks rupture.[1] |
Common concerns from patients with this condition or recovering from treatment, and whether they are expected or worth mentioning to your team.
- 1.British Society for Surgery of the Hand: Flexor tendon injury
- 2.British Association of Hand Therapists: Patient information leaflets
- 3.Royal College of Surgeons of England: Driving after surgery guidance
References are to UK clinical guidance and patient information from recognised organisations. This page is for general information and does not replace personalised advice from your own clinical team.
Hand therapy guide
Phased exercise programme, key precautions, and what to expect from rehabilitation for this condition.
How is it diagnosed?
- ✓Clinical examination, assessment of each tendon (FDS, FDP) individually
- ✓Testing finger flexion with the other fingers held straight (isolates FDS)
- ✓Testing tip flexion alone (isolates FDP)
- ✓Examination of the "resting cascade" of the fingers
- ✓Assessment of nerve function (sensation, sweating)
- ✓Wound exploration in theatre, the gold standard
Recovery milestones
- •Dorsal blocking splint: 4-6 weeks
- •Active hand therapy: 12 weeks
- •Light strengthening: 12-16 weeks
- •Heavy gripping and contact sport: 4-6 months