Tendon transfers, a fundamental aspect of reconstructive surgery, represent a sophisticated intervention in the domain of orthopedics and plastic surgery. This intricate procedure involves the repositioning or redirection of tendons to restore lost function, correct deformities, or alleviate debilitating conditions resulting from tendon injuries, neurological disorders, or musculoskeletal anomalies. By harnessing the body's inherent capacity for adaptation and regeneration, tendon transfers offer a transformative solution to patients grappling with impairments affecting mobility, dexterity, and overall quality of life. Within the realm of medical science, tendon transfers stand as a testament to the innovative intersection of anatomy, biomechanics, and surgical expertise. Guided by meticulous anatomical knowledge and informed by patient-specific considerations, surgeons meticulously navigate the intricate network of tendinous structures to achieve optimal outcomes. This precise manipulation of tendons demands not only technical proficiency but also a profound understanding of functional anatomy, pathological processes, and the dynamic interplay between muscles and joints. The rationale underlying tendon transfers rests upon the principle of functional restoration through strategic tendon re-routing. Whether addressing paralysis resulting from nerve injury or rectifying muscular imbalances precipitated by congenital anomalies, the overarching goal remains consistent: to enhance musculoskeletal function and foster meaningful improvements in patient well-being. By redistributing the forces exerted by muscles across joints, tendon transfers serve as a cornerstone in the rehabilitation arsenal, offering a pathway towards enhanced motor control, stability, and range of motion. In this discourse, we embark on a comprehensive exploration of tendon transfers, delving into the intricacies of surgical technique, patient selection criteria, rehabilitative protocols, and outcomes assessment. Through a synthesis of clinical insights, scientific inquiry, and empirical evidence, we endeavor to illuminate the multifaceted dimensions of this therapeutic modality. By elucidating the underlying principles and practical applications of tendon transfers, we aspire to equip healthcare practitioners with the requisite knowledge and insights to navigate this dynamic landscape and empower patients with newfound avenues for functional restoration and renewed vitality.

1. PRINCIPLES OF TENDON
TRANSFERS
Dr Joe Antony
MBBS, MD(PMR), FCPC, CCEPC, ASTEP(AMERICAN SPINAL INJURY
ASSOCIATION), INSTEP, WEESTEP

2. Contents
• Introduction
• Principles of tendon transfers
• Biomechanical considerations
of Tendon transfer surgeries
Pic- Greens operative hand surgery, 8th edition
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3. Introduction
◦ A tendon transfer is the re-routing of a functioning muscle-tendon unit (MTU)
to a new insertion, in order to restore a function that has been lost.
◦ History
◦ Tendon transfers were first developed in the 19th century to restore ambulation in patients
with poliomyelitis.
◦ During the subsequent World Wars, thousands of soldiers returned home with upper
extremity nerve injuries. This influx of patients caused development of established tendon
transfer procedures
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4. ◦ Indicated in loss of a function due to loss of muscle power that has no potential for
recovery,
◦ which can be due to
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Peripheral nervous system Central nervous system Musculotendinous unit
Nerve root avulsion Traumatic brain injury Loss of muscle or tendon due to
trauma
Failed nerve repair/reconstructions Stroke Tendon rupture ( in
rheumatological conditions like RA)
Delayed presentation of nerve
injuries
Cerebral palsy
Hansen's disease Spinal cord injuries
Other non progressive peripheral
neuropathies and residual nerve
palsies
Other non progressive
myelopathies and focal neurological
deficits

5. Principles
of tendon
transfers
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
• Established by Mayer and
Bunnell
Greens operative hand surgery, 8th edition, Grabb And Smith's Plastic Surgery 8th Edition
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6. Supple Joints
◦ A passive , fluid , adequate range of movement of joint to improve function
should be present before tendon transfer
◦ A transferred tendon can not mobilize a stiff or deformed joint
◦ Stiff joints should be released before tendon transfers either operatively or non-
operatively.
◦ Joint release and tendon transfers should not be done in same sitting
◦ Joint release warrants rehab protocol with immediate and aggressive mobilization
◦ Tendon transfer needs at least 4 weeks for healing
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7. Soft tissue equilibrium
◦ Means,
◦ Tissue induration and inflammation have resolved,
◦ Scars have matured and are as soft as they are likely to become
◦ Tendon should pass through plane between the subcutaneous tissue and deep fascia
◦ Gentle tunneling using a blunt-tipped instrument and probing natural tissue planes to find the path of least resistance.
◦ If scars are obstructing the pathway even after scar maturation, it should be resurfaced with a
fasciocutaenous flap
◦ Surgeons should avoid creating scars on tunneling pathways by planning incisions away.
◦ Non-conventional pathways can be selected to avoid scars
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8. Adequate excursion/ Amplitude of motion
◦ Donor MTU should have enough excursion, or linear movement, to achieve the
desired motion at the target joint.
◦ Excursion of the donor MTU should be equal to or greater than that of the
MTU it is replacing
◦ For Example,
◦ Wrist flexors have an excursion 35mm
◦ Finger extensors have an excursion of 50mm
◦ Finger flexors have an excursion of 70mm
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9. Appropriate strength of donor
◦ The strength of the donor MTU should be matched to that of the MTU whose
function is being restored.
◦ Relative power should be considered rather than absolute power
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Donor MTU is weaker Donor MTU is stronger
Result Transferred tendon not able to move
the joint through functional ROM
Muscle imbalance and abnormal
posture
Particularly in Joint stiffness, Strong antagonist
group present
Weak antagonist group
Example Palmaris longus in replacing wrist
extensor
Brachioradialis replacing EPL
will end up in extention
contracture

10. ◦ If the donor has been injured or denrevated, transfer must be delayed till
complete recovery
◦ In general, a donor MTU will lose up to one grade of motor strength simply by
being transferred
◦ This must also be kept in mind while selecting the donor
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11. Expendable Donor
◦ Donor MTU function should not be lost by trasfering it. There must be another
MTU performing same function
◦ For example,
◦ Wrist has two flexors, Hence either FCU or FCR can be trasfered without losing wrist
flexion
◦ Fingers has two flexors, FDS can be used as a donor MTU , while FDP will preserve the
finger flexion
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12. Straight line of pull
◦ A tendon transfer that has a direct path to its insertion is most effective.
◦ increased force needs to be expended to overcome friction with the surrounding
soft tissues
◦ the transfer will try to migrate so that it does run in a straight line.
◦ However, there are instances in which a direct line of pull is not ideal.
◦ In that case , single robust pulley must be used
◦ Change of direction should be as small as possible
◦ For example,
◦ EIP Opponensplasty
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13. Synergy
◦ Synergy refers to certain movements that are typically combined during routine use.
◦ For example- Wrist extension and finger flexion
◦ The original function of the donor MTU should be synergistic with the function that is being restored.
◦ A tendon transfer that is synergistic, as opposed to antagonistic, is easier for the patient to learn to use.
◦ So, patients find it easier to learn when finger extension is restored with wrist flexors
◦ Rehabilitation is much more difficult if finger extension restored with wrist extension .
◦ This principle doesn’t hold true always,
◦ Its not always possible to find a synergistic group.
◦ Certain donor MTUs, such as the FDS, are able to adapt to a new function readily, whether that function is
synergistic or not
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14. Single transfer, Single function
◦ A single tendon transfer should only perform a single function.
◦ Attempting to restore multiple functions with a single donor MTU will result in loss of
strength and motion.
◦ Exception, a single donor MTU may be used to restore the same movement in multiple
digits.
◦ For example, it is acceptable to use the FDS or FCR to restore MCP extension for all four fingers.
◦ But, FDS or FCR would be inadequate to restore both wrist and finger extensions
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Biomechanical
Considerations
of tendon
transfers
• Selecting the insertion
point
• Tension in donor MTU

16. Selection of insertion point
◦ Generally, The insertion point of a tendon transfer is determined by the normal insertion of the
recipient tendon.
◦ However. there are instances in which the surgeon can choose the insertion point of the tendon
transfer.
◦ A tendon transfer with a large moment arm will generate greater torque, but at the expense of
the arc of motion (greater muscle excursion will be required for a given degree of rotation)
◦ A smaller moment arm will have an increased arc of motion (less muscle excursion is required
for a given degree of rotation), but the transfer will not generate as much torque.
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17. Setting tension in donor MTU
◦ Setting the tension o£ the tendon trans£er is the most aitical and difficult part of the operation.
◦ Ideally, a tendon transfer should be tensioned in such a way as to maximize actin myosin overlap.
◦ Unfortunately, it is impossible to determine this intraoperatively.
◦ Solution is that the tendon transfer should be set at a tension as close as possible to the donor MlUs
preoperative resting tension.
◦ The donor muscle belly is marked at regular intervals before dividing its insertion, and the tendon
transfer is tensioned in such a way as to restore the distance between the intervals.
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18. ◦ A tendon transfer tends to loosen or stretch out during
rehabilitation.
◦ However, a tendon transfer that is set too loosely will not tighten
postoperatively.
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