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8/3/2019 Muscle & Tendon
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AFFECTIONS of MUSCLE AND
TENDON
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Normal muscle structure
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A layer of dense connective tissue, which is known as
epimysium and is continuous with the tendon, surrounds
each muscle.
A muscle is composed of numerous bundles of muscle
fibers, termedfascicles, which are separated from each
other by a connective tissue layer termedperimysium.
Endomysium is the connective tissue that separatesindividual muscle fibers from each other.
Mature muscle cells are termed muscle fibers or
myofibers.
Each myofiber is a multinucleate syncytium formed byfusion of immature muscle cells termed myoblasts.
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CONTUSION AND STRAINS
A contusion is a bruise of the
muscle with varying degrees of
hemorrhage and fiber disruption.
A strain is a longitudinalstretching or tearing of muscle
fibers or groups of fibers.
Contusions and strains causedisruption of the normal architecture
of the muscle-tendon unit secondary
to interstitial edema, hemorrhage, or
overstretching.
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DIAGNOSIS
History
Contusion and strain injuriesfrequently occur during
strenuous activity.
limp or inability to bear
weight. In mild strains, the animal
became reluctant
Physical examination
Imaging
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Physical Examination With mild contusions the animal may
exhibit minimal lameness
severe contusions, pain and swelling are
present.
The majority of severe contusions occur
in conjunction with fractures
Severe muscle strains are recognized byswelling and pain of the affected muscle
unit.
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Imaging
Radiographs are necessary to
rule out bone injury.
Acute injuries may show soft-
tissue swelling.
Ultrasonography may show
interstitial fluid accumulation.
Diffferential diagnosis
Joint sprain Fracture
Polymyopathies
Polyarthopathies
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MEDICAL MANAGEMENT
- The primary treatment rest.
- With acute injuries, i.e, those in
the initial 24 hours, cold
compresses on the affected
muscle
- If old, topical heat application is
recommended,.
- Nonsteroidal antiinflammatory
drugs and restricted activity.
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Surgical treatment
Surgical treatment is advisedonly when the interstitial fluid
accumulation is very high
resulting in vascular
compromise.
Surgical technique: make the
incision through the skin, cutis
overlying the muscle to be
exposed, when the muscle group
is identified incision through the
fascia is done to decompress.
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MUSCLE-TENDON LACERATION
Lacerations are tears within the
muscle-tendon unit.
Lacerations are usually the result of
penetration of the muscle-tendon unit
by a sharp object.
These injuries most commonly involve
the tendons near the carpometacarpal
and tarsometatarsal joints, but they may
involve muscle units in other parts of
the body.
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DIAGNOSIS
History. The animal usually has an
open wound and a non-weight-bearing
lameness
Radiography- to check for bone
involvment
Physical Examination Findings- non-
weight-bearing lameness.
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SURGICAL TREATMENT
Lacerations require
appositional sutures
If the laceration has occurredthrough tendon, delicate
manipulation and apposition
with small-diameter suture are
recommended.
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Muscle Laceration
debride the wound edges to freshen.
Debride carefully to avoid excess removal of tissue, which will
make apposition of the severed ends difficult.
Place interrupted sutures in the outer muscle sheath around the
circumference of the muscle.
Support the appositional sutures with heavy stent sutures
placed in a cruciate pattern.
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Repair of muscle laceration with appositional sutures sup-
ported by tension stent sutures
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Tendon Laceration
debride the tendon ends.
for small tendons, use small-diameter, nonabsorbable
material placed in a series as interrupted vertical mattress or
cruciate sutures.
For larger tendons, select the largest suture diameter that will
readily pass through the tendon atraumatically.
A locking-loop suture pattern is recommended
Alternatively, use a three-loop pulley, Bunnell-Mayer, or
far-near, near-far suture pattern.
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Far-nearnear-far
Bunnell-Mayertechnique
Three looppulley
Lockingloop
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Healing of muscle and tendon
laceration
Similar to connective
tissue healing
Follows one wound one
scar principle
Strength is regained by
one wound one scar
principle and the
function regained by
active and passive use
of the limb/ muscle
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MUSCLE-TENDON UNIT RUPTURE
Rupture of the muscle-tendon unit
is a complete or partial loss of
integrity of the muscle-tendon unit
caused by extreme overstretching.
Muscle ruptures are the result of a
powerful contraction occurring
during forced hyperextension of the
muscle-tendon unit
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DIAGNOSIS
History: Affected animals usually exhibit a weight-bearing
lameness after strenuous activity.
Physical Examination Findings
Imaging
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Physical Examination Findings
Tarsal hyperflexion is frequently noted in
affected animals.
The animal will be unable to bear weight,
and flaccidity of the Achilles tendon will
be noted upon passive dorsal flexion of thetarsus when the stifle is extended.
Postural changes associated with a
palpable swelling of the Achilles tendon
confirm the diagnosis.
Postural changes and careful palpation of
the muscle-tendon unit confirm the
diagnosis.
Imaging
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Imaging
Ultrasonography is helpful in
determining the extent of tendon fiber
disruption.
Standard craniocaudal and medial-to-
lateral radiographs are indicated to
determine the presence or absence of
bone avulsion from the tuber
calcaneus.
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SURGICAL TREATMENT
Achilles Tendon Rupture
Make an incision over the site of injury on the caudolateral surfaceof the limb.
Identify the three tendons composing the Achilles complex and
suture each tendon separately with an interrupted far-near, near-far
pattern using nonabsorbable, small-diameter (3-0 to 4-0,depending the animal's size) monofilament suture.
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Then, sequentially remove sections of
scar tissue from the center of the mass.
Remove enough tissue so that tension ispresent in the Achilles complex when the
stifle joint is in a normal standing position
and the tarsus is slightly extended.
If excess fibrous tissue is excised,apposition of the cut ends will be difficult.
Suture the cut ends with a three-loop
pulley pattern or maintain apposition with
tendon plating.
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For tendon plating, oppose the cut ends of
the tendon with nonabsorbable
monofilament suture.
Support the anastomosis by placing a small
bone plate adjacent to the tendon
Place interrupted sutures through the plate
holes into the body of the tendon.
Use large-diameter, nonabsorbable
monofilament suture.
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Tendon plating
Small boneplate
Appositional
sutures
MUSCLE CONTRACTURE AND FIBROSIS
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MUSCLE CONTRACTURE AND FIBROSIS
Muscle contracture may occur when
there is replacement of normal muscle-
tendon unit architecture with fibrous
tissue resulting in functional shortening
of the muscle or tendon.
Muscle contracture is most commonly
recognized in the infraspinatus and
quadriceps muscle-tendon units.
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DIAGNOSIS
Any age, breed, or sex of dog may develop quadriceps muscle
contracture; however, it most commonly occurs in immature
patients following distal femoral fracture.
Contracture of the infraspinatus muscle usually occurs in
young, adult, sporting breeds of dogs.
History
Physical Examination Findings
Radiography
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History. Animals with quadriceps muscle contracture usually
are seen for evaluation of lameness 3 to 5 weeks after having
sustained femoral trauma.
Usually there is a history of acute lameness following
strenuous activity in the 3 weeks prior to evaluation for
infraspinatus muscle contracture
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Physical Examination Findings
The stifle joint of animals with quadriceps muscle contracture
has a limited range of motion
Initially the joint can be fully extended but can be flexed only
20 to 30 degrees.
Gradually the amount of flexion decreases to less than 10
degrees.
Contracture may be such that the stifle joint appears hyper
extended.
Cranial thigh muscles are generally atrophied and palpate as a
thickened cord.
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Animals with infraspinatus muscle contracture initially have a
weight bearing forelimb lameness
Soft tissue swelling in the region of the shoulder joint may be
noted.
The characteristic gait abnormality is secondary to progressive
fibrosis and contracture of the infraspinatus muscle.
As the muscle shortens from contracture, external rotation of
the shoulder occurs, causing elbow abduction and outward
rotation of the paw
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Radiography
Standard radiographs do
not show abnormalities of
the muscle-tendon unit but
will help differentiate
fracture or neoplasia as the
cause of lameness.
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SURGICAL TECHNIQUEQuadriceps Contracture
Expose the stifle joint and distal femur through a liberal
craniolateral incision.
Elevate and release adhesions between the quadriceps muscle
group and femur with sharp dissection. Release adhesions between the fibrous joint capsule and femoral
condyles.
Luxate the patella medially and flex the joint to its full extent. If
a functional range of motion (greater than 40 degrees) is notachieved after releasing the adhesions, perform a quadriceps
muscle-tendon unit lengthening procedure.
Z-plasty
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Z-plasty.
Make a longitudinal incision through the center of the muscle-
tendon unit beginning 8 to 10 cm proximal to the patella.
Extend the incision distally to a point 3 cm proximal to the patella.
At the proximal extent of the longitudinal incision, make a
transverse incision laterally through the muscle and fibrous tissue.
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At the distal extent of the longitudinal incision, make a
transverse incision medially through the muscle and fibrous
tissue.
Flex the stifle and allow the cut edges of the longitudinal
incision to slide on each other.
When a functional range of flexion is achieved, place
interrupted sutures across the longitudinal incision to maintain
the desired length of the quadriceps muscle-tendon unit
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Muscle release.
Extend the lateral incision to expose the proximal femur.
At the level of the third trochanter, elevate the quadriceps from
the medial, lateral, and caudal surfaces of the femur.
Incise through the origins of each muscle group to release thequadriceps and allow distal sliding of the muscle group.
Release the vastus intermedius near its point of origin on the
ilium.
Close the surgical wound using standard methods.
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Infraspinatus Muscle
Contracture Perform a craniolateral approach to the
shoulder joint.
Isolate the circumference of the
infraspinatus muscle with sharp
dissection.
Transect the fibrotic muscle and any
fibrous bands restricting movement of
the joint.
Once the fibrous contracture is incised,
the limb will assume a normal position
and a normal range of motion of the
shoulder will be possible.
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