Here is a comprehensive 10-mark answer on Tendon Transfer, fully structured and illustrated.
TENDON TRANSFER
Definition
Tendon transfer is a reconstructive surgical procedure in which a functioning, expendable muscle-tendon unit is detached from its insertion and redirected to restore the lost function of a paralyzed or absent muscle-tendon unit.
"The most common type of reconstructive operation is tendon transfer... Tendon transfer potentially provides earlier improvement in function than nerve repair and may be a better option for some patients' overall rehabilitation."
— Rockwood and Green's Fractures in Adults, 10th ed.
Prerequisites / Principles of Tendon Transfer
These are the fundamental "rules" or criteria that must be satisfied before performing a tendon transfer (remember with the mnemonic "SEEMS SAFE"):
| Principle | Detail |
|---|
| Soft tissue equilibrium | Full passive range of motion in all joints the transfer will act upon must be present. Contractures must be corrected first. |
| Expendable donor | The donor muscle must be expendable — usually possible when two or more muscles perform the same movement. |
| Excursion match | The transferred muscle must have appropriate amplitude (excursion ≈ ⅓ of fiber resting length). Wrist flexors ~33 mm, finger flexors/extensors ~50–70 mm. |
| Motor strength | Donor should ideally have MRC grade 5 power; one grade is routinely lost after transfer. Grade 4 donors may still be used. |
| Synergism | Synergistic transfers are easier to re-educate (e.g., wrist flexors used to power finger extension — they normally co-contract). |
| Single function | One tendon transfer should perform one function only. |
| Alignment / straight pull | The line of action should be as straight as possible; angulation reduces mechanical efficiency. |
| Firm fixation | The tendon is attached end-to-side (preferred) or end-to-end with a Pulvertaft weave — must be strong enough for early mobilization. |
| Expendable function | Transfer must not sacrifice a critical function at the donor site. |
— Miller's Review of Orthopaedics, 9th ed.; Rockwood & Green's Fractures in Adults, 10th ed.
Types of Tendon Transfer
1. Based on Mechanism
| Type | Description |
|---|
| Direct (simple) transfer | The tendon is rerouted in a near-straight path to the recipient tendon |
| Pulley transfer | The tendon passes through a pulley (fibrous loop, bone tunnel) to change direction — e.g., opponensplasty via pisiform pulley |
| Free muscle transfer | An entire muscle (e.g., gracilis) is transplanted with microsurgical neurovascular anastomosis — used when no local donor is available |
2. Based on Functional Goal
| Type | Example |
|---|
| Motor restoration | Restore active movement (paralyzed muscle replacement) |
| Tenodesis | Tendon fixed to bone; passive motion of a proximal joint produces distal joint movement |
| Static stabilization | Prevent deformity rather than restore movement |
Common Clinical Applications
A. Radial Nerve Palsy (High)
Classic "wrist drop" — loss of wrist extension, finger extension, thumb extension.
| Function Lost | Donor Tendon | Recipient |
|---|
| Wrist extension | Pronator teres (PT) | ECRB |
| Finger extension | FCU or FCR | EDC |
| Thumb extension | Palmaris longus (PL) | EPL |
Fig. 1 — Intraoperative view: Tendon transfer for radial nerve palsy
FCR → EDC and PL → EPL transfer at the wrist dorsum. Donor tendons woven into recipient tendons using Pulvertaft technique.
Figure 1. Transfer of flexor carpi radialis → extensor digitorum communis and palmaris longus → extensor pollicis longus for reconstruction of posterior interosseous nerve palsy. Multiple sutures lock the weave (A) to restore finger and thumb extension (B). — Rockwood & Green's Fractures in Adults, 10th ed.
Fig. 2 — Intraoperative: Donor tendons (PT, FCU, PL) exposed in distal forearm prior to transfer
Figure 2. Three donor tendons (PT radially, PL centrally, FCU ulnarly) mobilized for tendon transfer reconstruction of radial nerve palsy.
Fig. 3 — Postoperative outcomes at 45 days: Grip (b) and finger/thumb extension (c) restored
Figure 3. (a) Immediate postoperative view. (b–c) At 45 days: active finger flexion and active extension of digits/thumb confirmed — successful tendon transfer for radial nerve palsy.
B. Median Nerve Palsy — Opponensplasty (Low Palsy)
Loss of thumb opposition (thenar wasting). Restoring opposition is the primary goal.
Donor options for opponensplasty:
- FDS of ring finger (most common) — routed around pisiform pulley
- EIP (extensor indicis proprius)
- Abductor digiti minimi (Huber transfer) — for children
- Palmaris longus with palmaris longus tendon graft
All are inserted into abductor pollicis brevis (APB).
C. Ulnar Nerve Palsy — Anti-Claw Procedure
Loss of intrinsic muscles → claw deformity (hyperextension MCP, flexion IP joints of ring and little fingers).
Goal: Prevent MCP hyperextension = "intrinsic plus" posture.
- FDSP (lumbrical replacement): FDS of middle/ring finger split and rerouted to lateral bands
- Brand procedure: ECRB + tendon graft to A1 pulley of ring/little finger
- EPB rerouting (Bruner): for restoring lateral pinch in thumb adduction weakness
Fig. 4 — EIP to EPL transfer: Intraoperative view (extensor tendon reconstruction)
Figure 4. Extensor indicis proprius (EIP) harvested and rerouted to reconstruct a ruptured extensor pollicis longus (EPL) — a common tendon transfer in rheumatoid arthritis.
D. Other Applications
| Condition | Transfer |
|---|
| Elbow flexion loss (brachial plexus) | Pectoralis major, Steindler flexorplasty (FCR/FCU origin transfer) |
| Foot drop | Tibialis posterior to dorsum (through interosseous membrane) |
| Shoulder abduction loss | Trapezius to greater tuberosity |
| Cerebral palsy | FCU → ECRB (wrist extension), various upper limb transfers |
| Poliomyelitis | Multiple as per neurological deficit |
Structures Involved
Donor Muscle–Tendon Unit Requirements
- Must have intact neurovascular supply
- Adequate muscle fiber length (excursion) and cross-sectional area (force)
- Rule: Excursion = ~⅓ of resting fiber length
- Wrist motors: ~33 mm excursion | Finger motors: ~50–70 mm
Common Donor Tendons in the Upper Limb
| Tendon | Nerve Supply | Normal Action | Used For |
|---|
| Pronator teres | Median | Pronation, weak wrist flex | Wrist extension (→ECRB) |
| FCR | Median | Wrist flexion/radial dev. | Finger extension (→EDC) |
| FCU | Ulnar | Wrist flexion/ulnar dev. | Finger extension (→EDC) |
| Palmaris longus | Median | Wrist flexion (absent 15%) | Thumb extension (→EPL), opponensplasty |
| FDS ring | Median | PIP flexion ring finger | Opponensplasty |
| EIP | Radial | Index extension | EPL reconstruction |
| Brachioradialis | Radial | Elbow flexion | Thumb flexion (→FPL) |
Recipient Structures
- Paralyzed tendon (preferred — end-to-side anastomosis)
- Bone tunnel or pulley (for direction change)
- Lateral band of extensor apparatus
Fixation Methods
- Pulvertaft weave: Multiple transverse passes + locking sutures — strongest fixation
- End-to-side: Allows co-contraction if nerve recovery occurs later
- Bone anchor: For insertional transfers
Disadvantages / Limitations of Tendon Transfer
| Disadvantage | Explanation |
|---|
| Loss of one MRC grade | Transferred muscle routinely loses ~1 grade of strength after transfer |
| Donor site morbidity | Sacrifices a functioning muscle — may weaken original action |
| Single function only | One transfer restores one movement; complex deficits need multiple operations |
| Re-education required | Patient must re-learn to use the transferred muscle for its new function (prolonged physiotherapy) |
| Synergism dependency | Non-synergistic transfers are harder to control and may never be well-coordinated |
| Not curative | Does not restore normal anatomy or sensation |
| Prerequisites strict | Fails if passive ROM is limited, joints are stiff, or skin/soft tissue is scarred |
| Risk of over/under-tension | Incorrect tensioning leads to failure — too tight = restricted motion; too loose = no functional gain |
| Adhesions/scarring | Tendon may become adherent along its path in scarred tissue |
| Delayed rehabilitation | Requires 6–12 weeks immobilization then months of physiotherapy |
| Not applicable if no expendable donor | In extensive multi-nerve injuries, no suitable donor may be available — free muscle transfer needed instead |
Summary Diagram
TENDON TRANSFER — OVERVIEW
══════════════════════════════════════════════════════
Paralyzed Muscle (recipient)
↑
Donor muscle ──────→ Redirected tendon
(expendable, (through subcutaneous
MRC grade 5, tunnel or pulley)
synergistic) ↓
Inserted into recipient
tendon (Pulvertaft weave)
or bone anchor
══════════════════════════════════════════════════════
PRINCIPLES: SEEMS SAFE
S – Soft tissue equilibrium (full passive ROM)
E – Expendable donor
E – Excursion match
M – Motor strength (grade 5 preferred)
S – Synergistic donor preferred
S – Single function per transfer
A – Alignment (straight line of pull)
F – Firm fixation
E – Expendable function not sacrificed
══════════════════════════════════════════════════════
Quick Reference — Marking Scheme Structure for 10 Marks
| Component | Marks |
|---|
| Definition | 1 |
| Principles/prerequisites | 2 |
| Types | 1 |
| Applications (with examples — radial, median, ulnar) | 3 |
| Structures involved (donors, recipients, fixation) | 1.5 |
| Disadvantages | 1.5 |
Total: 10 marks
Sources:
- Rockwood and Green's Fractures in Adults, 10th ed. 2025 — Chapter 20: Nerve Injuries
- Miller's Review of Orthopaedics, 9th ed. — Nerve Injuries and Tendon Transfers
- Current Surgical Therapy, 14th ed. — Muscle and Tendon Transfer ProceduresThis answer covers every component examiners expect for a 10-mark question. Here's a quick orientation:
What's covered:
- Definition — precise surgical definition sourced from Rockwood & Green's
- Principles — 9 key prerequisites using the SEEMS SAFE mnemonic for easy recall
- Types — by mechanism (direct, pulley, free muscle) and by goal (motor, tenodesis, stabilization)
- Applications — with full tables for:
- Radial nerve palsy (wrist drop) — PT→ECRB, FCU→EDC, PL→EPL
- Median nerve palsy — opponensplasty options (FDS, EIP, ADM, PL)
- Ulnar nerve palsy — anti-claw procedures
- Other conditions (foot drop, elbow flexion, CP, polio)
- Structures involved — donor tendons table with nerve supply, normal action, and use; fixation methods (Pulvertaft weave, end-to-side, bone anchor)
- Disadvantages — 11 specific limitations
- 4 intraoperative/postoperative photographs illustrating real surgical scenarios
The mark allocation table at the end maps the answer to the 10-mark rubric so you can allocate writing space in an exam accordingly.