1qsjsjdjrrjr xdtkekeksk1. Tendons (Deb).ppt

TENDON HEALING &
GRAFTING
DEBORAH DING
PHASE I
MARCH 2019

References
• Peter C. Neligan, Plastic Surgery 3rd Edition, Chapters 9 & 34, Elsevier
Publications, 2012
• Mathes Plastic SurgeryVolume 1, 2nd Edition,Chapter 21
• Essentials of plastic surgery, 2nd edition, Chapter 71
• Kirkendall DT, GarrettWE. Function and biomechanics of tendons.
Scandinavian journal of medicine & science in sports. 1997 Apr 1;7(2):62-6.
• Kelc Robi, Naranda Jakob, Kuhta Matevz andVogrin Matjaz (2013).The
Physiology of Sports Injuries and Repair Processes, Current Issues in
Sports and Exercise Medicine,Associate Prof. Michael Hamlin (Ed.),
InTech, DOI: 10.5772/54234.
• J.W. Strickland, “Flexor tendon injuries: I&II,” Journal of the American
Academy of Orthopaedic Surgeons, vol. 3, no. 1,pp. 44–62, 1995.

References
• Sammer DM, Chung KC.TendonTransfers Part I: Principles ofTransfer and
Transfers for Radial Nerve Palsy. Plastic and reconstructive surgery. 2009
May;123(5):169e.
• W. B. J. Rudge and M. James, “FlexorTendon Injuries in the Hand: A UK Survey
of RepairTechniques and Suture Materials—Are We Following the
Evidence?,” ISRN Plastic Surgery, vol. 2014, Article ID 687128, 4 pages, 2014.
doi:10.1155/2014/687128
• Sebastin, Sandeep J. et al. “History and Evolution of the Kessler Repair.” The
Journal of hand surgery 38.3 (2013): 552–561. PMC. Web. 6 Nov. 2017.
• Wehbé MA, Mawr B, Hunter JM, Schneider LH, Goodwyn BL.Two-stage
flexor-tendon reconstruction.Ten-year experience. JBJS. 1986 Jun
1;68(5):752-63.
• Evans RB. Early active short arc motion for the repaired central slip.The
Journal of hand surgery. 1994 Nov 1;19(6):991-7.

OUTLINE 1. History of tendon transfer
2. Anatomy of tendon and surrounding
structures
3. Biomechanics
4. Tendon healing
5. Principles of tendon transfer
6. Tendon engineering

History
5th century BC
• Hippocrates observed a slender white tubular structure entering
skeletal muscle, and mistook it for a nerve
2nd Century AD
• Galen advised not to repair tendon
• Believed it would cause pain, twitching and convulsion
to the limbs
18th Century AD
• Von Haller challenged Galen’s theory
• Showed that placing a suture in a canine Achilles tendon did not
have any detrimental effects

History
1767
• John Hunter observed the healing of Achilles tendon
• Formation of callus similar to that seen in a healing bone
1882
• Nicoladoni first described transfer of peroneus longus muscle, however procedure failed
1904
• Hunkin reported transplantation of semitendinosus part of biceps to restore a boy’s leg
function
1905 & 1910
• Lange & Kurtz reported tendon graft transplantations
1912
• Lexer reported series of tendon grafts used to repair flexor tendons after rupture, old
lacerations, infection and cases with ischaemic contractures

History
1916
• Mayer published articles that served as the core principles in tendon grafting:
1. Restore normal relationship between tendon and sheath
2. Have the tendon course through tissue that is adapted to gliding of the tendon
3. Imitate normal insertion of the tendon
4. Establish normal tension
5. Create an effective line of traction

History
1936
• Mayer introduced pseudo sheath concept
• Usage of celloidin tube into a scarred tendon gliding bed
• Followed by introduction of tendon graft after 4-6 weeks of implantation
1963
• Basset & Carrol repeated the two-stage tendon grafting technique using
silicon rod
1990s
• Advancement in understanding of tendon healing and tendon engineering

Anatomy of
tendon
• Tendons are glistening white structures interposed between muscles
and bones
• They transmit the force created in muscle to bone, and make joint
movement possible
• Tendons and muscles work synergistically in the direction of the
contraction
• Composed by metabolically active connective tissue, collagen bundle
(arranged in regular spiral pattern)
• Tendons may be surrounded by a bed of loose areolar tissue called
paratenon, or may reside within a tunnel of dense fibrous tissue called
tendon sheath

PARATENON
• Encases tendon in loosely arranged connective tissue in areas not subjected
to mechanical stress
• Loose arrangement allows minimal resistance to movement of the tendon
through tissues and must be preserved if tendon gliding and function are to
persist
• Connective tissue consist essentially of type I and type III collagen fibrils,
elastic fibrils and an inner lining of synovial cells
• Tendon is bathed in a fluid environment similar to synovial fluid

PARATENON
• Within the paratenon, the entire tendon is covered by epitenon
(mesotenon)
o a fine, loose connective tissue sheath containing the vascular lymphatics and
nerve supply
• Epitenon extends deeper into the tendon between the tertiary bundles of
collagen fibrils as endotenon
• Together, paratenon & epitenon are sometimes called the peritendon

TENDON SHEATH
• Consist of 2 layers
1. Parietal (outer) layer: attached to adjacent connective tissue or periosteum
2. Visceral (inner) layer: closely attached to tendon by areolar connective tissue
• Present only in certain tendons as they pass area of increased mechanical
stress
• Inner and outer layers are connected by an elongated mesentery, the
mesotendon.This is important in passage of blood vessels and nerves into
the tendon tissue within a sheath.
• The inner and outer surfaces slide over each other, lubricated by a few
drops of synovia, to reduce friction
• But its most fundamental aspect is to produce a discontinuity between
structures that must move in relation to each other.

COMMON FLEXOR SHEATH
• Synovial sheath in the carpal tunnel of the human hand
• Contains tendons of the flexor digitorum superficialis and the flexor
digitorum profundus, but not the flexor pollicis longus
• On the little finger, it is continued along the whole extent of the flexor
tendons to the terminal phalanx
• The common flexor sheath ends over the remaining three sets of tendons
just distal to the flexor retinaculum.

COMMON FLEXOR
SHEATH
There is a short distance of
bare tendon for index,
middle and ring fingers in
the middle of the palm

TENDON BURSAE
• Located at anatomic sites where a body prominence might compress and wear
the gliding tendon
• Provides a cushion between bones, and tendons and/or muscle around a joint
• Helps to reduce friction and allows free movement

Tendon nutrition and blood supply
• Tendon nutritional supply is bimodal
a) Intrinsic tendon vascularity
b) Synovial diffusion
History
1. Mayer (1916) is credited with the first description in the English literature of
the vascularity of flexor tendons supply from musculotendinous,
osteotendinous, and paratenon.
2. Edwards & Brockis (1946) described a longitudinal intratendinous vascular
network with frequent cross-anastomoses
3. Peacock (1959) demonstrated that the blood supply from the muscular
origin or bony insertion of a tendon supplied only a short segment at either
end, and blood supply to tendon is segmental through mesotenon

• Tendons received their blood supply from three main sources:
Intrinsic system 1. Myotendinous junction
2. Osteotendinous junction
Extrinsic system 3.Vessels from surrounding
connective tissues (paratenon,
mesotenon, vincula)
• Vessel are generally arranged longitudinally within the tendon,
passing around the collagen fibre bundles in endotenon
• In the hand tendons, very few straight vessels are seen and they
tend to be curved to allow them to straighten out during tendon
movement.

• Vessels at the bone insertion do not pass directly through from the bone
into the tendon due to a cartilage layer between the tendon and the bone
• They however anostomose with those of the periosteum, forming an
indirect link with the osseous circulation
• Tendon in an area of low compression are vascularized by small vessels
from surrounding tissue
o Rate of flow is low (10 mL / 100 g / min)
• In contrast, in compressed areas (eg across joint spaces), nutrition comes
from segmental vincula

• Vincula of tendon:
o Slender, tendinous bands that connect Flexor Digitorum Superficialis (FDS)
and Flexor Digitorum Profundus (FDP) to each other and to the phalanges
o Contains vessels that directly supply the tendons

Tendon
nutrition
• Receives nutrition from both vascular and synovial systems
• Synovial fluid diffusion provides rapid delivery of nutrients by imbibition
 fluid is pumped into small conduits in the tendon surface during digital
flexion and extension
• In the absence of vascular inflow, diffusion alone can provide adequate
nutrition for tendon healing

Tendon
nutrition
• The relative contribution of these 2 sources is difficult to determine
clinically.
• However, for rapid tendon healing and functional gliding to be
achieved, it is important to preserve the integrity of these 2 nutritional
sources
• Compromise to either vincula or digital sheath will result in less than
optimal healing

Histology & Biochemistry
• The basic elements of tendon are collagen bundles (70%), cells, and ground
substance or extracellular matrix, a viscous substance rich in proteoglycans.
1. Collagen provides tendon with tensile strength
2. Ground substance provides structural support for the collagen fibres and
regulates the extracellular assembly of procollagen into mature collagen.
3. Proteoglycans regulate tissue strength because they determine the size
and packing of collagen fibrils.
o Strongly hydrophilic, enabling rapid diffusion of water soluble
molecules and migration of cells
o Adhesive glycoproteins (ie fibronectin & thrombospondin) participate
in repair and regeneration processes in tendon

• The collagen fibril diameter in the adult tendon typically ranges from
100 to 200 nm
o Varies with tissue loading
o Increasing tensile loads leads to shift towards higher fibril diameter
• Tenocytes (or fibrocytes), flat tapered cells sparingly distributed among
the collagen fibrils, synthesize both the ground substance and the
procollagen building blocks of protein
• Tenoblasts and tenocytes lie within the extracellular matrix network
and constitute about 90% to 95% of the cellular elements of tendon
• The remaining 5% to 10% consists of chondrocytes at the bone
attachment and insertion sites, synovial cells of the tendon sheath, and
vascular cells, including capillary endothelial cells and smooth muscle
cells of arterioles

• Tenocytes are active in energy generation, and synthesize collagen and
all components of the extracellular matrix.
• All three pathways of energy generation, the aerobic Krebs cycle,
anaerobic glycolysis and the pentose phosphate shunt, are present in
human tenocytes.
• With increasing age, metabolic pathways shift from aerobic to more
anaerobic energy production.

• Collagen is arranged in hierarchical levels of increasing complexity
beginning with tropocollagen, a triple-helix polypeptide chain
• Each tropocollagen is composed of helical arrangement of two α1 and one
α2 collagen chains
• These helical molecules of tropocollagen in turn unite into fibrils, fibers
(primary bundles), fascicles(secondary bundles) that spiral into tertiary
bundles, and finally the tendon itself
• A collagen fiber is the smallest tendon unit which can be mechanically
tested and is visible on light microscopy.
• Although collagen fibers are mainly oriented longitudinally, fibers also run
transversely and horizontally, forming spirals and plaits.

Myotendinous & Osteotendinous junctions
• Myotendinous junction (MTJ) is a highly specialized anatomic region in
the muscle-tendon unit
• At the MTJ, tendinous collagen fibrils are inserted into deep recesses
formed by myocyte processes, allowing tension generated by
intracellular contractile proteins of muscle fibers to be transmitted to
the collagen fibrils.
• This complex architecture reduces the tensile stress exerted on the
tendon during muscle contraction. However, the MTJ still remains the
weakest point of the muscle-tendon unit.

• Osteotendinous junction (OTJ) is a specialized region in the muscle-tendon
unit where the tendon inserts into a bone
• In OTJ, the viscoelastic tendon transmits the force into a rigid bone.
• The OTJ is composed of four zones:
1. A dense tendon zone
2. Fibrocartilage
3. Mineralized fibrocartilage
4. Bone
• The specialized structure of the OTJ prevents collagen fiber bending,
fraying, shearing and failure
Myotendinous & Osteotendinous junctions

Tendon
Biomechanics
• Tendon functions to:
o Transmit force generated by muscle to bone
o Buffer by absorbing external forces to limit muscle damage
• At rest, collagen fibers and fibrils display crimped configuration

Tendon
Biomechanics
• The structure and composition of tendons allow for the unique
mechanical behaviour
• Exhibits non-linear elasticity
• Reflected by a stress-strain curve consisting of three distinct regions
1. Toe region
2. Linear region
3. Yield & failure region

Stress-Strain
Curve
1.Toe region
• Where “stretching out” of crimped
tendon fibrils occurs from
mechanically loading the tendon up to
2% strain

Stress-Strain
Curve
2. Linear region
• Physiological upper limit of tendon
strain
• Collagen fibrils orient themselves in
the direction of tensile mechanical
load and begin to stretch
• Tendon deforms in a linear fashion due
to inter-molecular sliding of collagen
triple helices
• If strain is < 4%, tendon will return to
its original length when unloaded
(elastic and reversible)

Stress-Strain
Curve
3.Yield and failure region
• Where the tendon stretches beyond its
physiological limit and intramolecular
cross-links between collagen fibres fail
• If micro-failure continues to
accumulate, stiffness is reduced and
tendon begins to fail, resulting in
irreversible plastic deformation
• If tendon stretches beyond 8-10% of
its original length, macroscopic failure
soon follows

Tendon healing
• Restoration of normal tendon function after injury
• Aim is to re-establish tendon fibres and gliding mechanism between
tendon and its surrounding structures
• Similar to normal wound healing, tendon healing occurs in three
overlapping phases
1. Inflammatory
2. Proliferative
3. Remodeling

Tendon healing
Inflammatory phase:
• Occurs during the first 24 hours, last up to 2-3 days
• Hematoma is formed. PDGF attracts other growth factors
• IGF-1 stimulates recruitment of fibroblasts and inflammatory cells
• RBC and inflammatory cells (esp neutrophils) enter site
• Macrophages follow suits to initiate phagocytosis of necrotic materials
• Angiogenesis starts (regulated byVEGF & FGF)

Tendon
healing
Proliferative phase:
• Cell proliferation initiated with multilevel growth factors
• Further recruitment and cell migration regulated byTGF-β
o Stimulate tenocyte to migrate and initiateType III collagen synthesis
• ECM components synthesis are paramount during this phase

Tendon
healing
Remodelling stage:
• Begins 6-8 weeks after injury
• Characterized by decrease in cellularity, reduced matrix synthesis, decrease
in type III collagen, and increase in type I collagen synthesis
• Type I collagen fibres are organized longitudinally along the tendon axis and
are responsible for the mechanical strength of the regenerate tissue
• During later phases of remodelling, interactions between the collagen
structural units lead to higher tendon stiffness, and consequently greater
tensile strength
• However, repaired tissue never achieves the characteristics of normal
tendon

Tendon healing
Tendon healing can occur by:
1. Intrinsic mechanism
 Cells coming from within the tendon, ie tenocyte, endotenon, peritendon,
produces new collagen
2. Extrinsic mechanism
 Cells from peritendinous tissue produces new collagen
• Relative contribution of extrinsic and intrinsic cells to tendon healing is
dependent on level of initial injury, quality of surgical repair, and
postoperative regimen
• As a rule, intrinsic cellular healing results in less adhesion formation

Tendon
healing
Intrinsic healing:
• Occurs within the substance of the tendon
• Involves resident tenocytes of the epitenon & endotenon
• Nourished by the intratendinous blood supply and by synovial diffusion
• Synovial diffusion appears more important than vincular blood supply
o In absence of vascularity, whole tendon can be nourished by diffusion

Tendon
healing
Extrinsic healing:
• Originates from cells residing outside the tendon, ie. neutrophils,
macrophages, fibroblasts
• Inflammatory cell activation, neovascularization, fibroblast ingrowth
• Resulting adhesions provide a route for nourishing blood supply
• However, scar tissue results in adhesion formation, which disrupts
tendon gliding

Immobilization and early
remobilization
• Ruptured and immobilized tendons heal with a fibrous gap between the
ruptured ends, whereas sutured ligaments heal without fibrous gap
• Protective immobilization may enhance tendon-to-bone healing compared
with other post repair loading regimens like exercise or complete tendon
unloading
• However, immobilization is not a proper treatment for all repaired tendons,
some require early passive motion

Immobilization and early
remobilization
• Tendons requiring long excursions for function (eg flexor tendons) are
typically encased in synovial sheaths
• To maintain gliding after injury, adhesions between the tendon surface
and its sheath must be prevented.
• Passive mechanical rehabilitation methods have shown to be beneficial
to prevent fibrotic adhesions
• Optimal timing for the initiation of such treatment is about 5 days after
tendon repair
• Controlled loading can enhance healing in most cases
– Fine balance must be reached between loads that are too low (leads to
catabolic state) or too high (leading to micro damage)

Principles
of tendon
transfer
• Tendon transfer is tailored and customized differently in individuals
• There are guidelines and principles to adhere in approaching patient
planned for tendon transfer

Principles
of tendon
transfer
procedures
1. Supple joints prior to transfer
2. Soft tissue equilibrium
3. Donor of adequate excursion
4. Donor of adequate strength
5. Expendable donor
6. Straight line of pull
7. Synergy
8. Single function per transfer

Principles of tendon transfer
procedures
1. Supple joints prior to transfer
• The joint the tendon transfer will move must have maximum passive
range of motion prior to procedure
• If joint is stiff, tendon transfers procedure will fail
• Aggressive therapy is required to achieve and maintain a supple joint
before performing a tendon transfer procedure
• If contracture release is necessary, it should be performed prior to tendon
transfer procedure

procedures
2. Soft tissue equilibrium
• Refers to the idea that a tendon
transfer should pass through a healthy
bed of tissue that is free from
inflammation, oedema and scar
• Necessary to allow the tendon to glide
freely and minimize adhesions
• Following a soft tissue injury, a surgeon
must allow enough time to pass for the
inflammation and oedema to fully
subside
• If the planned tendon transfer must
pass through an area of severely
scarred tissue, the scar should be
excised and replaced with a flap

procedures
3. Donor of adequate excursion
• Excursion: distance a muscle can shorten and is proportional to fibre length
• The excursion or maximum linear movement of the transferred muscle-
tendon-unit (MTU) should be adequate to achieve the desired joint
movement
• The transferred MTU should have an excursion similar to that of the tendon
which it is replacing

procedures
4. Donor of adequate strength
• MTU to be transferred must be strong enough to achieve the desired
movement, but at the same time, should not be too strong
• MTU that is too weak will have inadequate movement and function
• A donor that is too strong will result in imbalanced movement and
inappropriate posture at rest
• When evaluating potential donor MTU, it’s easiest to compare their relative
strength as opposed to absolute strength

procedures
5. Expendable donor
• There must be another remaining muscle that can continue to adequately
perform the transferred MTU’s original function
• It does no good to restore a given movement if another equally important
movement is lost in the process
• When evaluating potential donor MTU’s for transfer, one must be mindful of
the weakness, loss of movement, or imbalance that might occur following the
transfer

procedures
6. Straight line of pull
• Tendon transfer procedures are most effective if there is a straight line of pull
o Direction changes diminish the force that the transferred MTU is able to exert on
its insertion
• A change in direction of just 40˚ will result in a clinically significant loss of force
• However, in some tendon transfer procedures, a direction change is
unavoidable or even necessary
o In these cases, tendon should be passed around a fixed, smooth structure that can
act as a pulley

procedures
7. Synergy
• Principle of synergy refers to the fact that certain muscle groups usually work
together to perform a function or movement
• Wrist flexion and finger extension are synergistic movements that often occur
simultaneously during normal activity
o When wrist is flexed, fingers automatically extend
• Fingers flexion and extension do not normally occur together, and therefore
is not a synergistic movement
• Transferring a wrist flexor to restore finger extension adheres to the principle
of synergy
o Whereas using finger flexor to provide finger extension does not

procedures
7. Single function per transfer
• Single tendon should be used to restore a single function
• Transfer of one MTU to restore multiple functions will result in compromised
strength and movement
• The exception to this rule is that a single MTU can be used to restore the
same movement in more than one digit
• Eg Flexor Carpi Ulnaris cannot be used to power wrist and finger extension
• However, it can be used to power the extension of all four fingers

Indication
for tendon
grafting
Tendon injury
• Not all tendon injuries need to be repaired
• If a severed tendon is not repaired, its function is permanently lost
• This may cause deformity, loss of movement and weakness
• Delay in treatment especially beyond a month can make subsequent
attempts at repair difficult or even impossible depending on the length
of delay and the tendon(s) injured

Indication
for tendon
grafting
Tendon injury
• If unrepaired, the tendon ends retract and get stuck in scar tissue
• The muscle will eventually shortens and withers
• The tunnels through which the tendons run shrink and the joints
affected can stiffen
• Late secondary reconstruction can be performed but the surgery is more
complex, and the results are poorer

Indications
for tendon
grafting
• Tendon grafts are required in patients with a delay in definitive repair
or in whom end-to-end approximation is impossible, eg:
 Crush injuries
 Infected wounds
 Loss of tendon substance
 Loss of tendon sheath and pulley system

Single-
stage VS
Staged
tendon
grafts
Single stage:
• No significant scarring is present
• No associated joint, skin, or pulley reconstruction is needed
• GOAL is to replace tendon only

Single-
stage VS
Staged
tendon
grafts
• Mayer & Ransohoff (1936) described staged tendon reconstruction in
which a rigid rod of celloidin was used to create a pseudosheath, with
grafting carried out 4 to 6 weeks later
• By 1960s, silicone rods were preferred for creating the pseudosheath
o Hunter (1965) published two-staged tendon grafting procedure that is
still widely used until today

Single-
stage VS
staged
tendon
grafts
Two-stage tendon grafts:
• Indicated with condition of joints, soft tissue, pulley system, or flexor tendon
sheath prevents a one-stage procedure
• Excessive scarring of the flexor tendon sheath is the most common
indication
• Patients who have undergone failed single-stage tendon grafting
• No set time for the second stage
• Performed when the soft tissue condition of the finger permits
• At least about 2-3 months after the first stage

• The first stage of a two-stage tendon reconstruction involves
implantation of a silastic rod for induction of a “pseudosheath”
• The pseudosynovial sheath stabilizes by 8 weeks
o Provides lubrication
o Diffusible nutrients
o An organisable vascular system
1st stage

2nd Stage
• The second stage - rod is replaced by an autologous tendon graft

Boyes &
Stark
classificatio
n
• Boyes developed a classification for the assessment of digital
flexor tendon injury
• One-stage grafting is reserved in grade 1 injury
• Two-stage grafting is performed for grade 2-5 injuries

Tendon
sources
• Tendon graft material can be obtained from a number of sources and
for a number of purposes including tendon repair / transfer, ligament
repair, pulley repair and soft tissue interposition
• Common donors:
o Palmaris longus (13cm)
o Plantaris (31 cm)
o Extrinsic third / fourth toe extensor (30 cm)

Tendon sources
Palmaris longus
• Small tendon between the flexor carpi
radialis (FCR) and flexor carpi ulnaris (FCU),
although it is not always present
• The muscle is absent in about 14% of the
population
• Presence is determined by active
opposition of thumb to little finger &
flexion of wrist
Superficial muscles of forearm –
anterior view

Tendon sources
Plantaris
• One of the superficial muscles of the
superficial posterior compartment of leg
• Plantaris tendon is the longest tendon in
the human body
• Absent in 8-12% of the population
• Produces similar quality tendon graft
material to PL with additional length

Tendon sources
Extrinsic toe extensors
• Perfectly reasonable alternatives for those
patients who do not have palmaris or
plantaris
• These tendons are always present
• Provided the intrinsic extensor remain
• Patients should not have any disturbance of
posture in their toes
• Extensor digitorum longus, arises from
anterior crest of fibula, interosseous
membrane and inserts into the dorsal
aponeurosis of 2nd – 4th toe

Tendon sources
Vascularized tendon grafts
• Indicated for cases in which both skin and tendon must be replaced
simultaneously
o Eg traumatic loss of the extensor / flexor tendons
• Donor sites : Free radial forearm with palmaris longus or flexor carpi radialis /
Dorsalis pedis cutaneoutendinous free flap
Active tendon implants
• Hunter (1993), uses porous woven polyester cords within a silicone sheath
• Used as a temporary extended tendon prosthesis
• Fibroblast migrate into the open weave and form collagen
• Proximal fixation by weaving the porous cords through the muscle tendon

Techniques
in tendon
suturing
Good functional outcome of tendon repair relies on:
• Strong low friction repair
• Allow early mobilization post operatively
• Not compromising vascularity of tendon
• Without the formation of adhesions

Techniques
in tendon
suturing
Choice of suture:
• Ideal core suture material should meet these criteria:
– High tensile strength
– Inextensible
– Biologically inert
– Easy to handle and knot
• Prolene: A monofilament polypropylene suture
• Ethibond: Braided polyethylene terephthalate coated with
polybutilate
• Ticron: Braided polyester coated with silicon

• Historically, stainless steel used to be utilized due to its high tensile
strength
• However, became inferior due to the advent of newer sutures
development with easier to handle material
• Increases size of core suture increases the strength of repair
 Using a 2-0 core suture significantly increase maximum tensile strength of the
repair but also increases the resistance to gliding of tendon
 3-0 or 4-0 are generally preferred
Techniques in tendon suturing

Technique
s in
tendon
suturing
J.W Strickland suggested tendon suturing must:
1. Be easy to perform
2. Be reliable
3. Result in homogenous approximation of the cut edges of the
tendon
4. Create a lower gap in the suture zone
5. Provide less interference with tendon vascularity
6. Provide sufficient strength to facilitate early rehabilitation

Technique
s in
tendon
suturing
Core tendon suturing techniques may be
divided into 3 components:
1. Longitudinal component
2. Transverse component
3. Link component

1. Longitudinal component
• Usually placed within the tendon substance
• Allows placement of the transverse and/or link components away
from the divided end of the tendon

2. Transverse component
• Usually placed within the tendon substance
• Converts the longitudinal pull of the suture to a transverse
compressive force
• Prevents the longitudinal component from pulling out

3. Link component
• Represents the junction between a longitudinal and transverse
components
• Or between 2 longitudinal components
• Usually lies outside the tendon

The technique for making a six-strand M-
Tang tendon repair.Two separate looped
sutures are used to make an M-shaped
repair within the tendon.
(A–C) A U-shaped four-strand repair is
completed, which can be used alone for
tendon repair.
(D and E) An additional looped repair is
added at the center, to
complete the six-strand repair.

Recommended surgical tendon repairs
• More than 2 strands as the core repair
– 4 or 6 strands are recommended
• Certain tensions across the repair site
– 10% shortening of tendon segment after repair
• Suture calibers : 3-0 or 4-0 core sutures
• Monofilament, non – absorbable sutures
• Core suture purchase: 7-10 mm
• A simple running or locking peripheral suture
• No peripheral suture if core repair is strong
• Avoid extensive exposure of sutures over tendon surface

Pulvertaft
Weave
technique
• If tendon graft is not of the same dimension as the recipient site,
modification of tendon anchorage and length can be made

Tendon graft healing
• Differs slightly from healing in sutured tendons
• Healing must occur at suture lines and central portion of graft must also
be revascularized to maintain overall tensile strength
• Tendon grafts survive as a combination of living tissue and replacement
of tendon substance by migration and ingrowth of fibroblast
• Suture line: Large proportion of the graft is replaced by ingrowth of new
tissue  regeneration process
• Central portion:Tendon fibroblast are able to maintain the continuity of
the tendon

• Free tendon grafts are viable structures and rely on synovial fluid for
nutrition
• Presence of an intact sheath / pseudosheath is essential for nutrition
• Vessels start to penetrate the ends of the tendons graft by 1 week
• After 2 weeks - vessel ingrowth can be seen from contact with the
surrounding pseudosheath
• By 5-6 weeks – Anostomoses between vessels of tendon graft and
pseudosheath occur

• Vascularity of the tendon graft
surpasses that of the normal tendon at
10 weeks, and normalizes at 15 weeks
• Vascularization is more than 2-3 weeks
slower than for primary tendon repair

Post
operative
rehabilitati
on
• No general consensus on timing of “early rehabilitation”
• Most hand surgeons agreed to start mobilization at day 3 – 5 post op
• Post operative controlled mobilization has been the major reason for
improved results with tendon repair
– Especially in zone II
– Leads to improved tendon healing biology
– Limits restrictive adhesions and leads to increase tendon excursion

Post
operative
rehabilitati
on
• Evans (1994) described a postoperative treatment protocol that
reduces adhesions by limited early active motion (“short arc motion”)
• The regime is based on biomechanical studies that examined the
extensor tendon excursions necessary to prevent adhesion formation
• Duran et al found that 3-5 mm of passive tendon glide is sufficient to
achieve this goal
• Evans reported significant improvement compared to a group of
patients who were immobilized post operatively

Post
operative
rehabilitati
on
• Immobilize children and non compliant
patients
• Casts or splints are applied with the
wrist and MCP joints position in flexion
and interphalangeal joints in extension

Tendon
engineering
• Challenge is met when large quantities of autologous tendon grafts are
needed to repair severe tendon injury and defect
• Substitute to autologous tendon graft
1. Tendon allograft
 Refrigerated tendons showed in several studies that outcomes were rather
disappointing
 Inferior to autograft
2. Artificial tendon
 Usage of non degradable materials
 Challenges met:
– difficulty in healing between host tissue and artificial tendon
– Fibrotic tissue formation
– Fatigue of implant

Tendon
engineering
• Promising strategy to generate autologous tendon graft
• 2 keys in tendon engineering are:
– Scaffold materials
– Seed cells

Scaffold
materials
• Collagen derivatives, acellular tendons, ECM, & polysaccharides
• Ideal tendon scaffolds:
– Biodegrability with adjustable degradation rate
– Biocompatibility before, during and after degradation
– Superior mechanical properties
– Biofunctionality (ability to support cell proliferation and differentiation, ECM
secretion and tissue formation)
– Processability (ability to be processed to form desired constructs of
complicated structures and shapes)

Seed cells • Tenocytes
• Dermal fibroblasts
• Stem cells

Future
direction
• Employment of proper bioreactor
system with dynamic mechanical
loading to generate engineered
autologous tendon graft and therefore
enhance matrix production and
maturation of in vitro engineered
tendon tissues
• Employment of acellular allogenic /
xenogenic tendon tissue to reconstitute
tendon graft

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