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Flexor and extensor tendon injuries of the fingers
A flexor tendon laceration is identified by testing FDP and FDS separately and is treated by surgical repair within days and rehabilitation with early motion; common closed injuries are mallet finger, treated with a continuous splint, and jersey finger, which needs early repair.
Why it matters in the exam
Questions present a laceration of the palm or finger, or a closed sports injury, and ask which tendon is injured and how to treat it. FDP flexes the distal joint (DIP) and is tested by holding the middle joint and asking the patient to bend the fingertip. FDS flexes the middle joint (PIP) and is tested by holding the other fingers straight and asking the patient to bend the tested finger. The hand is divided into zones: zone II, from the A1 pulley to the FDS insertion, was once called no man's land because both tendons run there in a tight sheath, and results there are poorer because of adhesions. Repair is done in theatre, ideally within days of injury, with a multi-strand core suture, followed by structured rehabilitation with early protected motion to prevent adhesions; the A2 and A4 pulleys are preserved to prevent bowstringing. A cut on the palmar side of the finger can also injure the digital nerve and artery, so sensation is checked on both sides of the finger. Jersey finger is an avulsion of FDP, usually in the ring finger, when a player grabs an opponent's shirt; when the tendon retracts deep into the palm its blood supply is lost and repair is needed within about one week to ten days. Mallet finger is an injury to the extensor at the fingertip: the distal joint droops and cannot straighten; treatment is a splint holding the joint straight continuously for 6–8 weeks, and any flexion during this period restarts the count. Trigger finger results from thickening at the A1 pulley and is treated with a steroid injection and sometimes release.
Key points
- FDP — DIP flexion; FDS — PIP flexion; test each separately.
- Zone II — both tendons in a tight sheath; risk of adhesions.
- Repair within days and rehabilitation with early motion.
- Jersey finger — FDP avulsion, early repair.
- Mallet finger — continuous extension splint for 6–8 weeks.
Summary table
| Injury | How it is recognised | Treatment |
|---|---|---|
| FDP laceration | No DIP flexion when PIP is held | Surgical repair within days and rehabilitation with early motion |
| FDS laceration | No PIP flexion when the other fingers are held straight | Surgical repair; sometimes together with FDP in zone II |
| Jersey finger | Loss of DIP flexion after a pull, usually the ring finger | Early repair, within about one week to ten days when the tendon has retracted |
| Mallet finger | Drooping DIP that cannot straighten | Continuous extension splint for 6–8 weeks; surgery for a large joint fracture with subluxation |
| Trigger finger | Catching and locking on flexion, tender nodule at the finger base | Steroid injection; release of the A1 pulley if it fails |
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Sources
- Green's Operative Hand Surgery, 8th ed. (2022) — Flexor Tendon Acute Injuries
- Campbell's Operative Orthopaedics, 14th ed. (2021) — Tendon Injuries of the Hand
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.