PRINCIPLES OF TENDON TRANSFER

1. PRINCIPLES OF TENDON
TRANSFER

2. Definition
• Re-routing of a functioning muscle tendon
unit (MTU) to a new insertion, in order to
restore a function that has been lost

3. • Established by
– Mayer and Bunnell
• Re-emphasized by
– Littler, Boyes, Curtis, White, and Brand

4. • First successful tendon transfers were
performed in foot to treat deformities caused
during the polio endemic in Vienna in the
1880s by Carl Nicoladoni

5. 1. Supple Joints
2. Soft Tissue Equilibrium
3. Adequate Excursion
4. Appropriate Strength of Donor
5. Expendable Donor
6. Straight Line of Pull
7. Synergy
8. Single Transfer, Single Function

6. Supple Joints
• Maximum passive ROM of all joints
• Casting, stretching, dynamic orthotic use
and/or surgical release
• Joint or contracture release should never be
performed at the same time as tendon
transfer.

7. • Hypermobile joints or excessive joint laxity can
predispose tendon transfers to overcorrection
• Tendon transfers into lateral bands for intrinsic
reconstruction may result in swan neck
deformities in presence of PIPJ hyperlaxity

8. Soft Tissue Equilibrium
• Termed by Steindler
• Free of edema, inflammation, or scar, so that
the tendon transfer can glide freely
• Tendon transfers work best when passed
between the subcutaneous fat and deep
fascial layer
• Scar excised & replaced with a flap
• Skin incisions should be planned so as to place
tendon junctures beneath flaps

9. Adequate Excursion

10. • Donor MTU should have enough excursion, or
linear movement, to achieve the desired
motion at the target joint.
• Equal to or greater than that of the MTU it is
replacing

11. • Excursion:
– Extrinsic finger flexors: 70 mm
– Extrinsic finger extensors & EPL: 50 mm
– Extrinsic wrist motors: 33 mm

12. To augment effective amplitude
• a muscle can be converted from monarticular
to biarticular or multiarticular, & effectively
using the natural tenodesis effect (add 20 to 30 mm)
– FCU or FCR FDC
• Extensive dissection of the muscle from its
surrounding fascial attachments
– BR & FCU

14. Appropriate Strength of Donor
Work capacity by Brand and Thompson

15. • Work capacity proportional to its mass or
volume.
• Relative tension capacities determined by
dividing the work capacity by cross sectional
area of each muscle

16. • Strongest donor (BR and FCU)- relative
strength of 2 units.
• FCR, the wrist extensors, the finger flexors,
and PT- 1 unit.
• Finger extensors- 0.5 units each.
• Weakest donor (PL) and thumb extensors and
abductors- 0.1 units.

17. • Lieber and colleagues
–Architectural features of individual muscles
are highly specialized for function
–An intraoperative laser diffraction method

18. • Muscle used for transfer only when it can be
graded as being at least good (Steindler-
recommended 85% of normal)
• Omer- a muscle usually loses one grade of
strength (on Highet’s clinical scale) after
transfer

20. • When a donor muscle is overtensioned into
passive portion of Blix curve, its potential
contractile force decreases to 28% of its
maximum force
• Power output of a muscle declines with either
redundancy or stretching from its resting point

21. 1. Adjustment of Tension
2. To determine the amount of strength needed
by the recipient muscle
3. Strength of antagonist muscles needs to be
considered to avoid overcorrection

22. Adjustment of Tension:
• tension is set tentatively by a single trial
suture, after which the movement of the parts
resulting from the tenodesis effect from
passive movements is carefully observed

24. Transfers
• Power transfers:
– For restoring grasp, pinch, elbow flexion, and
shoulder abduction/flexion
– Require more powerful donor muscles.
• Positional transfers:
– Restoration of thumb opposition and radial nerve
function

27. Expendable Donor
• There must be sufficient muscle remaining to
substitute for the donor muscle
1. 5 muscles that control supination/pronation
2. 7 muscles that control movement of the hand at
the wrist
3. 18 muscles that flex and extend the digits
4. 20 small muscles of the hand that contribute to
precise motion

28. Straight Line of Pull
• Any direction change or pulley decreases the
force of the transfer
• Exceptions:
– PT to ECRB
– Opponensplasties
• PT to ECRB
– End to end > end to side

29. Synergy
• Wrist extension and finger flexion are
synergistic for grasping
• Wrist flexion and finger extension are
synergistic (FCR to EDC transfer)
• Exception:
– FDS tendons, which have more independent
cortical control

30. Single Transfer, Single Function
• FDS or FCR would be inadequate to restore
both wrist and finger extensions
• Single tendon performs two diametrically
opposing actions simultaneously

32. • If inserted into two tendons having separate
functions, force and amplitude of donor
tendon is dissipated
– FCU to EDC of all 4 fingers
• If a single tendon is transferred into two
separate tendons, at least excursion of the
two be same

33. • In 1974. Burkhalter reported indications of
transfer:
– As a substitute during regrowth of nerve, which
will reduce timing of external splinting & improve
early function
– as a helper adding power to normal reinnervated
muscle functiion
– As a sustitute when recovery after neurorrhaphy
or nerve repair is poor

34. References
• Greens Operative Hand Surgery 6th Edition
• Grabb and Smith's Plastic Surgery, 7th Edition
• Beasleys hand surgery
• Neligan Vol 6 - Hand and Upper Extremity
• Principles of Tendon Transfer. Danielle Wilbur.
Hand Clinic. 32 (2016): 283–289