ch 70 muscle and tendon disorder Flashcards
(73 cards)
What are the common classifications of muscular injury?
Contusions (blunt injuries), strains (indirect injuries), lacerations (sharp injuries)
Where do muscle strains most commonly occur?
At the musculotendinous junction
When do strains occur?
After powerful active contraction of the muscle occurs simultaneous with passive extension of the muscle unit
What muscles appear to be more prone to injury?
Muscles that cross 2 or more joints
What are the 3 stages of muscular injury?
Stage I: myositis and bruising, architecture intact
Stage II: myositis and some tearing of the facial sheath
Stage III: tearing of the fascial sheath, muscle fiber disruption, hematoma formation
Where are stage I and II injuries more likely?
Power group of muscles (triceps, biceps femoris, quads, tensor fascia lata, semitendinosus, semimembranosus)
Where are stage III injuries more likely?
Long head of triceps, gracilis, gastrocnemius, tensor fascia lata
What are the two processes by which muscle heals?
Direct regeneration of myofibrils, production of fibrous scar tissue
What determines the balance of these two processes (Direct regeneration of myofibrils, production of fibrous scar tissue)?
Source of myoblasts, intact extracellular matrix, adequate vascularization, adequate innervation, limited stress across the healing wound
Increased fibrosis = inadequate ECM, poor vascularization, poor innervation, increased stress across healing wound
Under what conditions will myofibrils lead to quick and complete repair?
Surviving sarcolemal nuclei, intact endomysium
When does hematoma form?
immediately
At what time point does cellular infiltration and phagocytosis occur following injury?
6-12hr
At what time point does healing commence and how does this happen?
48hr after injury
invasion of capillaries and myoblast proliferation followed by myofiber formation
During what time post-injury does fibroblast proliferation and collagen scar formation occur?
4-6d
By what day is the damaged area filled w/ a new collagen network
Day 10
Until what day does tissue strength continue to increase?
Day 14 (entire process slows down after this point)
What is the primary goal of treatment of muscle injury?
Maximize direct myofibril repair while minimizing scar formation by minimizing early disruptive effects of inflammation, edema
By what percentage can the ability of the muscle to produce tension be reduced w/ excessive scar tissue formation instead of myofibril repair?
50%
What are the recommendations within first 48 hours?
Cold compresses and NSAIDs with light compression bandages
Why is early mobilization following muscular injury important?
To ensure proper myofibril orientation
When should surgery be instigated for muscle trauma?
Advanced stage II and stage III strains to eliminate gaps and appose muscle to optimize healing without scar formation;
when initial inflammatory phase has receded (2-3d following injury)
principles of surgery for muscle strain?
Remove hematoma, debride necrotic material, muscle apposition
What type of suture material should be used with surgery for muscle strain? What pattern?
Long-term absorbable monofilament; horizontal mattress tension relieving sutures;
once sufficient tension sutures are placed to hold the bulk of muscle, additional appositional sutures applied through fascial sheaths
What duration of rest is recommended following surgical repair of muscle?
4w
