Muscle & Tendon

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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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


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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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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