Flexor Tendon Injuries in the ST3 Plastics Interview
How to answer a flexor tendon injury scenario in the ST3 Plastic Surgery interview: FDS/FDP testing, zone 2, BSSH repair timelines, and early active mobilisation.
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The chef with a volar laceration who cannot bend his fingertip is the ST3 hand-trauma station in its purest form: precise examination, zone anatomy, a repair you can describe stitch by stitch, and a rehabilitation plan you genuinely believe in.
How the scenario tends to open
A typical stem: a young right-hand-dominant chef lacerates the volar aspect of a finger at the level of the proximal phalanx and cannot flex the fingertip. Every detail is loaded — occupation and dominance shape the stakes, the level tells you the zone, and the lost fingertip flexion names the tendon.
The approach that scores
History first, asked like a hand surgeon: mechanism and sharpness, time of injury, dominance, occupation and hobbies, tetanus status, contamination, last meal. Then the examination examiners want demonstrated in words: test FDP by holding the PIP joint extended and asking for DIP flexion; test FDS by holding the other fingers extended and asking for PIP flexion; document digital nerve sensation and capillary refill; inspect the wound for visible structures.
Name the zone and its meaning: the proximal phalanx is zone 2 — the fibro-osseous tunnel from the A1 pulley to the FDS insertion, historically "no man’s land" for its unforgiving outcomes. An X-ray excludes fracture or foreign body.
- Timing per BSSH standards: repair within two weeks, ideally within about four days.
- The repair, told as a sequence: regional or general anaesthetic, tourniquet up; Bruner zig-zag extension for exposure; retrieve the retracted proximal end; four-strand core repair with a non-absorbable braided suture; a fine running epitendinous suture to smooth the repair; confirm the tendon glides through the pulleys.
- Pulley principles: preserve A2 and A4; A1, A3, and A5 can be vented to allow gliding.
- Rehabilitation makes or breaks the result: a dorsal blocking splint and early active mobilisation under hand therapy within days — with patient compliance a genuine part of case selection.
Where candidates lose marks
Vague tendon testing — "I would check flexion" — squanders the station’s easiest marks; the FDS/FDP isolation manoeuvres are the expected currency. At ST3 level, stopping at "I would repair the tendon" without technique, suture strategy, or pulley awareness undersells you. And if the examiner offers the late complication — a fingertip that stops bending weeks after repair — think rupture versus adhesions, and know that options range from re-repair to staged tendon grafting.
Rehearse it
Reading about flexor tendon injuries is the easy half. Rehearse this exact scenario out loud, on the clock, with an AI examiner — this scenario is in Reviva’s library, with feedback marked the way the panel marks. Or start with the wider format in the st3 plastics clinical station guide.
Frequently asked questions
- How do you test FDS and FDP?
- FDP: hold the PIP joint extended and ask the patient to bend the fingertip (DIP). FDS: hold the neighbouring fingers fully extended to inactivate their shared FDP, and ask the patient to flex at the PIP joint.
- What is zone 2 and why does it matter?
- The fibro-osseous tunnel from the A1 pulley to the FDS insertion — historically "no man’s land" — where both tendons run in a tight sheath and repairs are most prone to adhesions and stiffness. Outcomes depend as much on rehabilitation as on the repair.
- How soon must a flexor tendon be repaired?
- Within two weeks by BSSH standards, ideally within about four days. Beyond two weeks the tendon retracts and the sheath scars, pushing you towards graft-based reconstruction rather than direct repair.
Sources. Grounded in BSSH standards for flexor tendon injury (repair timelines, zone 2 anatomy, four-strand core plus epitendinous repair, early active mobilisation) as rehearsed in Reviva’s ST3 plastics scenario. Educational only.