Week 12 Lecture Flashcards
Describe the key history and clinical examination features that assist in differential diagnosis of hamstring injury from other conditions that present as posterior thigh pain
with specific reference to hamstring muscle-tendon junction injury versus proximal hamstring tendon injury
Diagnosis of muscle injuries (general):
-Clinical diagnosis usually adequate
History, physical examination
-Ultrasound imaging
Defines magnitude and location of injury (esp. MTJ)
May be important in relation to management
-MRI
More accurate, better detail of size of muscle lesion
Better imaging of injuries near MTJ
Can identify lesions at the central tendon
Best at 24-72h days post-injury
Hamstring: TOTAPS Field Assessment: Talk Observe injured area Touch injured area Active movement assessment Passive movement assessment Skills test
Specific Clinical Investigation: Prone palpation Identify ischial tuberosity HS contraction isometric leg straight Palpate distal until highest pain level with some palpatory pressure
High speed injury – Significant dysfunction initially – Tends to settle quicker Slow stretch injury – Less bothersome initially – Slower to return
Describe the Aetiology of hamstrig injury
Frequent injury involving high speed running or extensive lengthening of the hamstrings
Most commonly injured at musculotendinous junction
High re injury rate indicates inadequate rehab or premature return to sport
1.HIGH SPEED INJURY
Terminal swing/early stance phase
Eccentric lengthening. Great length change and negative work performed by biceps femoris
Considerable lengthening under load in second half of swing phase
Injury site proximal head long head biceps musculotendinous junction
– Significant dysfunction initially
– Tends to settle quicker
2.SLOW SPEED STRETCHING INJURY
Semimembranosis prox tendon close to ischial tuberosity
– Less bothersome initially
– Slower to return
Describe the risk factors for hamstring injury commonly reported in the literature
What are the risk factors for the 2 different kinds of hamstring injuries
Extrinsic(environment related) risk factors
-SPEED TRAINING
Particularly susceptible as increased running speed requires a sig increase in cadence
a 3% increase requires a 15% increase in HS eccentric strength
-TRAINING ERRORS
Inadequate warmup
warm up increases amount of force & length a muscle can absorb prior to tearing
Fatigue related to unsuitable structure and content of training
Poor playing surfaces
INTRINSIC FACTORS
-Age(>25 increased risk of injury 4x 20 yo)
-previous injury
-flexibility, more length increased risk of injury
-Strength imbalances
HS:Q ratios
suboptimal vs quads ratio
• Describe some of the common reasons for the high rate of recurrence of hamstring injuries
-Previous hamstring injury is the greatest risk factor - possible that scar tissue may alter local contraction mechanics, therby influencing reinjury risk.
- Inadequate rehab
- Premature return to sport
- Decreased quadriceps flexibility as assessed by the modified Thomas test was an independent risk factor - however hamstring flexibility not been related to higher incidence of strain.
- Muscle imbalance (hamstring to quadriceps)
- Older age
Research found that male college athletes were 62% more likely to sustain a hamstring injury than female athletes and more common in field sports than in court sports.
Pathology of muscle strains
why are they most common at the Musculotendinous junction?
Muscle Strains
• Common in two joint muscles
• Eccentric Contraction (dynamic overload)
– Rapid sarcomere elongation
– Frictional resistance within the muscle framework
– Rate of lengthening (strain) possibly important
• Common at musculotendinous junction (MTJ)
– Due to organisation of CT at MT junction
– Related load orientation & distribution across the MT
junction
• Discuss the evidence for eccentric exercise in hamstring rehabilitation
It’s positive prophylactic effect strongly suggest that it should be a component of a reconditioning program upon return to sport.
• Describe appropriate treatment and management for a patient presenting with an acute hamstring injury
Initial Stage Goals
Protect Healing Tissue
Minimize atrophy and strength loss
Prevent motion loss
• Rest or relative rest – Immobilise vs gentle movement • Ice • Compression • Elevation No HARM
Management of Hamstring injury
Muscle Injury – Acute Response
• Peritrauma (0‐6hrs) – Fibre degeneration
– Myonuclear death & dissolution
– Impaired continuity of sarcolemma
– Myofibrils break up into sarcomere units
• Rupture of small vessels, focal nerve axon damage‐>
Haematoma forms at injury site
• Chemataxic stimuli from damaged cells attract WBC’s
– espec. Neutrophils & Macrophages
• Phagocytosis of damaged muscle fibres & breakdown
metaboles
– eg. Prostaglandin
Early Healing (1‐6 days)
• Satellite cells proliferate
• Satellite cells transformed into myoblasts which fuse
onto myotubes
– Myo‐tube growth factors (interleukins etc.) released
– Enhanced by (gentle) stretching & mechanical loading
• Myotubes extend from torn ends of muscle fibres
• Basal lamina
– Acts as a scaffold for the new muscle fibre (also important for re‐
innervation)
– Maintains a favourable environment for regeneration
• Grow towards intervening scar tissue
Early Healing (1‐6 days)
• Attempt to grow through scar tissue but
not usually possible
• Fibre ends blend into scar tissue
– New ‘mini‐musculotendinous junction’
• Scar tissue contracts to bring regenerated
fibre ends closer together
– Most injuries heal without excessive scar tissue
What is the result of prolonged bed rest on hamstring muscle injuries
Prolonged rest (especially in shortened
position) results in:
– Decrease in muscle resting length
– Decrease in number of sarcomeres in series
– Decreased muscle volume (atrophy)
– Decreased muscle fibre size and number
– Increased intra‐muscular connective tissue
– Increase muscle stiffness
– Decrease muscle activation (50% in 4 weeks)
– Responses less marked and slower in fast twitch muscles
Management of hamstring injury throught the stages of healing
Initial Later inital Intermediate Repair/remodeling Advanced Late advanced
Initial Stage Protect Healing Tissue Minimize atrophy and strength loss Prevent motion loss • Rest or relative rest– Immobilise vs gentle movement • Ice • Compression • Elevation No HARM
Later Initial Stage Therapeutic Exercise • Stationary bike: spin • Isometrics of lumbo‐pelvic region Submax ISOMETRICs at 3 angles (90°60°30°) Early Proprioception • Single leg balance activities • Mini squats variable weight transfer Varied pain‐free angles
Intermediate Stage
Regain pain‐free HS strength, to full ROM
Develop neuro‐muscular lumbo‐pelvic control
Increase movement speed preparing for
functional mvts
Repair/Remodeling Phases Progressive fast walk /running program • twice daily from 1.5‐ 2.5 km/session • 100m run/100m walk Conditioning maintenance • swim, H2O run, bike programs
Advanced Stages
Symptom free all activities
Improve neuro‐muscular lumbo‐pelvic control
Normalize Conc:Ecc Ratio through full ROM
Integrate postural control into Sports
Later advanced stage
Action specific exercise
• Gym: Romanian dead lifts
• Ball: H/S bridge, drop‐catches, glut stability bridge
• Stretch/shortening exercises
– Sport specific exercises
• Kicking program
• Sprint with direction changes, acceleration/deceleration
• Running drills and run with ball pick‐up
– Gym
• Hypertrophy reps
• Progress to strength then power reps over time
What is the result of prolonged bed rest on hamstring muscle injuries
Prolonged rest (especially in shortened
position) results in:
– Decrease in muscle resting length
– Decrease in number of sarcomeres in series
– Decreased muscle volume (atrophy)
– Decreased muscle fibre size and number
– Increased intra‐muscular connective tissue
– Increase muscle stiffness
– Decrease muscle activation (50% in 4 weeks)
– Responses less marked and slower in fast twitch muscles
• Early Mobilisation results in
– Better clearance of haematoma & inflammatory cells
– More rapid regeneration of muscle fibres & connective
tissue
– Earlier restoration of contractile properties
– More rapid restoration of tensile strength
– Facilitates re‐vascularisation of damaged area
• Regenerated muscle & young collagen fibres
better oriented with the original muscle fibres
General management principles of hamstring injuries
Muscle regeneration: Optimal Management
• Aim to balance two competing processes
– Optimise muscle regeneration
– Minimise connective tissue (scar) proliferation
- Fibroblasts appear at injury site within 48
hours
- Early repair favours collagen synthesis over
muscle
- Reduce chances of re‐injury
• Short period of reduced muscle load (3‐5 days)
– Reduces bleeding and accelerated satellite cell activation
– Accelerates appearance of Type‐1collagen in the injured area
- Decreased chance of re‐injury
– Limits the amount of connective tissue at the injury site
– Better remodelling of connective tissue in the endo‐ and perimysium in the later stages of healing
Influence on scarring and regeneration
Early mobilisation
• Regenerated muscle & young collagen fibres
better oriented with the original muscle fibres
Graduated loading process, similar to
many other soft tissue injuries
Factors to consider • Flexibility • Strength Consider 4 keys of muscle specificity 1) Muscle action 2) Muscle group 3) Velocity 4) Energy source (aerobic or anaerobic) • Speed • The sub‐qualities of speed: – Acceleration – Maximum velocity – Speed endurance – Agility (change of direction) – Reaction • Specifics • Proprioception
Role of Fatigue in Muscle Injury
• Appears not to affect:
– Tensile force to failure
– Elongation (strain) to failure
• Fatigue may decrease energy absorption during
eccentric contraction
– Decrease greatest in early phase of lengthening
• Consequently – Greater elongation required to
absorb tensile loads in the fatigued state
• Heavier and slower gait pattern
Askling’s Apprehension Test
What is it
• Passive then active SLR
• Look for:
– Apprehension
– Deficits in speed or active range
• Appears to be an accurate way to judge RTS
Initial study demonstrated much lower reinjury
rates
• Comparison of speed and ROM of active vs.passive SLR
• Based on feelings of apprehension
