WEEK 4 - ACUTE MUSCLE INJURIES OF THE LOWER LIMB

Question 1

Muscle injuries - subcategories (2)

Answer 1

Direct
- Contusion
- Laceration

Indirect
- strain / tear
- fatigue induced
- avulsion injury

Question 2

Common MOI for LL muscle injuries

Answer 2

Common MOI in LL

• acceleration injuries
  
  • tears occur at the time of maximum muscle effort within normal working range of muscle
• extensive lengthening (BF)
  
  • tear occur at long muscle lengths
• kicking
  
  • cokcing and ball strike (RF)
  • swing through (BF)
• deceleration (RF)

Question 3

MOI - biceps femoris

Answer 3

early stance
- increased hip and knee torgque
- increase tensile force

late swing
- lengthening contraction
- increase strain and activation

• forceful and extensive hamstring lengthening
• combined hip flex and knee ext
• eccentric internal load

Question 4

MOI - rectus femoris

Answer 4

through toe off and swing
- maximally lengthened
- increase hip flexor activity while knee extensor absorb shock (eccentric)
- increase velocity at hip and knee
- eccentric to slow tibida down

• deceleration
  
  • more upright posture adopted to decelerate, large eccentric force passed through RF to slow speed
• kicking
  
  • the cokcing phase, moving into the acceleration ball strik

Question 5

Gastrocnemius and soleus MOI

Answer 5

through early stance and mid stance
- isometric contraction and elongation of elastic components of muscle tendon unit to store elastic energy, gastroc and soleus contract to propel

Question 6

the role of fatigue in muscle injury

Answer 6

the role of fatigue

• fatigue does not affect
  
  • tensile force to failure
  • elongation (strain) to failure
• fatigue does decrease energy absorption during eccentric contraction
  
  • decrease greatest during early phase of lengthening
  • greater elongation then required to absorb tensile stress in the fatigued state

Question 7

risk factors for re-injury

Answer 7

• high re-injury rates
  
  • hams (20-30%)
  • quads (15-20%)
  • calf (38%)
• factors
  
  • inadequate rehab
  • muscle balance
  • demand greater than capacity
  • fatigue / insufficient recovery

Question 8

Select and apply physical examination assessment skills for common muscle tears.

Answer 8

physical examination

• observation
• functional capacity (WB, compensatory offload)
• loading capacity (contraction through range)
• length capacity
• palpation
• other underlying factors?
  
  • maladaptive movements, retraction of muscle, scars

Hamstring strain = high vs low strain

• hip dominant vs knee dominant loading assessments/exercises
  
  • Hip = SL/DL RDLs
  • Knee = elevated glut bridges

Question 9

Differential diagnoses of muscle injury

Answer 9

• Not to be missed
  
  • avulsion injury to bone / tendon complex
    
    • Ottowa rules
  • subtotal / complete tear of musculotendinous structure
• evaluation to determine
  
  • 2 joint versus 1 joint injury (gastroc vs soleus)
• what could refer to the area
  
  • neural interface problems (e.g from spine, swelling irritates peripheral nerve developing neuropathic symptoms)
  • muscle fatigue / DOMs

clinical interview

• sudden onset of pain ‘pop’ sensation (? audible) vs overuse
• functional level immediately after injury (and progression)
• pain descriptor
• pain area (spread? sensitisation)
• previous injuries (risk factors, poor rehab) or other relevant injuries (compensatory strategies leading to overload)