Muscle & Tendon Injury Flashcards
What are the 4 classification of muscle injuries?
- contusions - blunt
- strains - indirect
- lacerations - sharp
- musculotendinous - overstretching, strain
What is the difference between sprains and strains?
SPRAIN = injures ligaments that connect two bones
STRAIN = injures (stretching, tearing) muscle or the tendon that attaches muscle to bone —> most common at the musculotendinous junction
What muscles are more prone to strains?
those that cross over 2+ joints
What are the 3 stages of muscle strain?
- myositis, bruising
- myositis, tearing of fascial sheath
- tearing of fascial sheath, muscle fiber disruption, hematoma formation
What are the 2 mechanisms of muscle healing?
- direct regeneration of myofibrils
- fibrous scar tissue formation
What 4 things are required for regeneration of myofibrils?
- source of myofibroblasts
- intact extracellular matrix
- adequate vascularization and innervation
- limited wound stress
What is the time frame of strain healing?
- immediate hematoma formation
- 6-12 hr = cellular infiltration and phagocytosis
- 48 hr = healing by capillary invasion, myoblast proliferation, and myofiber formation
- 4-6 days = fibroblast formation and scar formation
- 10 days = new collagen network
- 14 days = tissue strength rapidly increases
(tendons and ligaments take longer due to decreased vasculature)
What muscles are most commonly affected by Stage I and II strains?
power muscles:
- triceps
- biceps femoris
- quadriceps
- tensor fascia lata
- semitendinosus
- semimembranosus
What muscles are most commonly affected by Stage III strains?
secondary muscles
- long head of triceps
- gracillis
- gastrocnemius
- tensor fascia lata
What treatment is recommended for strains? Advanced stages?
early cold compresses, NSAIDs, immobilization
- eliminate gaps
- muscle apposition
- exercise restriction for 12 weeks
What is the most common causes of ruptured long head of triceps and serratus ventralis?
racing greyhounds - depression caudal and distal to scapula
dogs and cats - dorsal displacement of scapula
In what breeds is a ruptured gracillius most common? Where does this most commonly occur? What treatment is required?
- racing greyhounds
- GSDs
- Foxhounds
musculotendinous junction or origin at the medial thigh
surgery
What is the most common muscle strain? What are the 3 most common signs? What treatment is needed?
iliopsoas and pectineus
- pain on muscle palpation
- lameness
- pain on extenion and internal rotation of hip
conservative - rest, NSAIDs, muscle relaxers, rehab
What is muscle contracture? What are 6 causes?
abnormal shortening of muscle, making it resistant to stretch due to fibrous CT replacement
- compartment syndrome
- infection
- trauma
- repetitive strain
- fracture disease
- prolonged immobilization
What muscles are most commonly affected by contracture?
- infraspinatus
- quadriceps
- gracillis
- semitendinosus
- sartorius
- supraspinatus
- teres minor
- iliopsoas
- brachialis
What breeds are most commonly affected by infraspinatus muscle contracture? What signs are seen?
working and athletic dogs —> unilateral
- forelimb lame 4-6 weeks before contracutre seen
- advances limb
- carpal flexation
What is characteristic of infraspinatus muscle contracture? How is it treated?
- shoulder abducted
- elbow adducted
- lower limb externally rotated
tendonectomy at insertion
What is the most common cause of quadricepts muscle contracture? What are the 2 most common signs? Treatment?
common after fractures. inyoung, growing dogs with poor immobilization or post-op use —> not fixed in a way that causes compression
- atrophied muscles
- tight band of muscle fused into callus
early rehabilitation (surgical options limited)
What breed is most commonly affected by gracillis and semitendinous muscle contracture? What are 4 signs? Treatment?
GSDs
- limb jerks
- hyperflexion of tarsus
- internal rotation of metatarsals
- firm muscles
conservative
What signalment is most commonly associated with flexor carpi ulnaris muscle contracture? What sign is seen? Treatment?
puppies 6-24 weeks old
carpus is flexed and unable to be extended
limited activity, support bandages over 2-3 weeks
What is myositis ossificans? What are the 2 most common causes? Treatment?
heterotrophic bone formation in muscle
- trauma
- dogs with VWD - microhemorrhage, chronic inflammation
surgical removal - recurrence common
What is responsible for tendon healing? What are paratendons? Why is it so slow?
fibroblasts to produce new collagen
vascular buds and undifferentiated cells from surrounding tissues (gastrocnemius, triceps)
sheathed and avascular —> especially digital tendons, no gaps!
What is most important for tendon healing? When is limited exercise started?
tensile strength
6 weeks —> typically reaches original strength by 1 year
What kind of suture is used for tendon repair? What 2 patterns are used?
monofilament synthetic long-term absorbable or non-absorbable
- Krachow locking loop - flat tendons, lessens likelihood of pullout
- 3 loop pulley - round tendons, enhances grip and purchase
