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Nerve repair and tendon transfers
A divided nerve is repaired early, without tension, with an epineurial suture; when there is a gap a nerve graft or nerve transfer is used — because axons grow about 1 mm per day and the motor endplates degenerate after about 12 to 18 months; when motor recovery is not possible, a tendon transfer restores movement.
Why it matters in the exam
Seddon and Sunderland classification: neurapraxia (Sunderland 1) — a conduction block without axonal injury, recovering within weeks; axonotmesis (Sunderland 2 to 4) — axonal injury with varying damage to connective tissue; neurotmesis (Sunderland 5) — complete division, which does not recover without surgery. Early primary repair gives the best result; a gap that cannot be closed without tension is bridged with a nerve graft (usually the sural nerve), and in sensory nerves with a gap under 3 cm a conduit can be used. Nerve transfers bring a healthy donor nerve close to the target muscle, such as the Oberlin transfer (an ulnar nerve fascicle to the biceps branch). Follow-up: a Tinel sign advancing along the nerve indicates regrowth.
Principles of tendon transfer: supple joints, good soft tissue, an "expendable" donor whose loss will not harm function, adequate strength — the donor loses one MRC grade, so it must be at least 4 — similar excursion, a straight line of pull, synergy and one function per transfer. Radial nerve palsy: PT to ECRB (wrist extension), FCR or FCU to EDC (finger extension), and PL to EPL (thumb extension). Low median palsy: opponensplasty — EIP, ring finger FDS, PL (Camitz) or ADM (Huber) in children. Ulnar palsy: the "claw" hand is corrected by transfers or capsulodesis (Zancolli), and loss of thumb adduction (Froment sign) — by ECRB or FDS transfer. The MRC scale: 0 — no contraction, 1 — contraction without movement, 2 — movement without gravity, 3 — against gravity, 4 — against some resistance, 5 — full strength.
Key points
- Neurapraxia — Sunderland 1; neurotmesis — Sunderland 5.
- Primary repair without tension; gap — sural graft.
- Growth about 1 mm per day; endplates up to 12 to 18 months.
- Radial: PT to ECRB, FCR to EDC, PL to EPL.
- Donor — at least MRC 4.
Summary table
| Palsy | Missing function | Accepted transfer |
|---|---|---|
| Radial | Wrist extension | PT to ECRB |
| Radial | Finger / thumb extension | FCR or FCU to EDC; PL to EPL |
| Low median | Thumb opposition | EIP, ring finger FDS, PL (Camitz), ADM (Huber) |
| Ulnar | Claw hand, thumb adduction | Zancolli, transfers to the lumbricals; ECRB or FDS for adduction |
| Musculocutaneous (upper trunk) | Elbow flexion | Oberlin transfer (nerve transfer) |
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Sources
- Mackinnon and Dellon, Surgery of the Peripheral Nerve; and Sunderland classification, 1988 and 1951 — Nerve injury grades and repair
- Green's Operative Hand Surgery, 8th edition (2022) — Nerve repair and grafting; Tendon transfers for radial, median and ulnar palsy
- Medical Research Council scale for muscle strength, 1976 revision — Grades 0 to 5
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.