Aetiology of Sports Injury

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Aetiology of Sports Injury
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Learning Objectives

• Be able to discuss the multifactorial nature of
  sports injuries
• Have a detailed knowledge of the intrinsic and
  extrinsic risk factors as they apply to common
  overuse lower limb sports injuries

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The Numbers

• One million sports injuries a year in Australia
  that cost 1 billion (Eggers 1990)
• One person in every ten sustains an injury each
  year (Nicholl et al., 1991)

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The Aetiology Of Injury

• Normal structure and function but inadequate
  preparation or excessive demands placed on
  tissues.
• Abnormal structure and function with relatively
  normal demands placed on tissues.

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Intrinsic Causes of Injury

• Structural alignment
• Sex
• Age
• Flexibility
• Physical build

• Previous injury
• Systemic disease
• Physical fitness
• Psychological factors

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Age

• Type and nature of injuries can vary with age
• Younger and older (gt40 years) more injury prone
• Both have reduced muscle mass and strength
• Increased injury in both contact endurance sport

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Older Athlete

• Musculotendonous injuries are the most common.
  Why?
• Reduced flexibility
• Reduced muscle mass and strength
• Reduced blood supply to tendons
• Delayed physiological benefit of exercise

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Young Athletes

• Less protective equipment
• Poorer quality coaching
• Reduced coordination
• Reduced flexibility
• Paediatric only injuries

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KohlersAP view
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Iselinsbase 5th
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Gender

• Injury rates have been 2-4 times higher in female
  military recruits than males (Jones et al. 1988,
  Ross et al. 1994, Yates White 2002)
• Some studies have demonstrated an 8-10 times
  greater risk
• Not seen in civilian studies. Why?
• Types of injury may also vary between sexes

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Female Injuries

• Stress fractures
• ACL
• MCL
• lateral ankle sprains
• Patellofemoral syndrome

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Female Injuries

• Structural differences e.g. genu valgum, wider
  pelvis?, hallux valgus
• Flexibility differences increased ligament
  injuries in females (Griffin, 1994 Almeida et
  al., 1999)

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Unhappy Triad
Osteoporosis
Eating Disorders
Amenorrhea
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Male Injuries

• Reduced flexibility results in more
  musculotendonous injuries
• More acute injuries from contact sports
• Young males 2-3 times more injuries than females
  (Bruns Maffuli 2000)

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Previous Injury

• This can increase the risk of developing a new
  injury by 2-3 fold.
• Injured structures are more prone to further
  injury
• Compensation may cause an injury to a distant
  site from the initial injury

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Structural Alignment

• Abnormal structure and function with relatively
  normal demands placed on tissues
• You must be able to link any biomechanical
  abnormalities to the injury in order to proceed
  with interventions designed to alter biomechanics
  

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Unilateral Overuse Injury

• Biomechanical asymmetries
• Type of activity
• Exercise surface
• Unilateral trauma
• Injury history
• Examination of contralateral asymptomatic
  structure

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Flexibility

• Hypermobility
• Ligamentous laxity
• Muscle flexibility

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Beighton Scale

• 9 point scale for hypermobility
• Thumbs against wrist 2 pts
• gt90 degrees of extension of fingers 2 pts
• gt20 degrees knee hyperextension 2 pts
• gt15 degree extension at elbows 2 pts
• Hands flat on the floor with knees extended 1
  pt
• gt 5 points is sign of hypermobility

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Flexibility Cont.

• Increased flexibility/hypermobility increases
  risk of ligamentous injury
• Reduced flexibility increases the risk of
  musculotendonous injury

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To Stretch or Not to Stretch ?

• Reduced flexibility stretch
• Hypermobile stabalising exercises (increased
  strength without stretch)
• No evidence to support stretching prior to or
  following exercise

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Stretching evidence

• Injury rates the same irrespective of whether the
  athlete stretched prior to exercise (Pope et al
  1998 2000, Yeung Yeung 2001)
• Warming up can reduce the incidence of ankle
  sprains

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Physical Fitness

• Reduced fitness increases injury risk
• Irrespective of experience in the sport
• Pope et al 2000 demonstrated least fit 14 times
  more likely to get injured than most fit

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Physical Build

• Stronger athletes may be more at risk. Why?
• Increased activity levels?
• Increased forces?
• Psychological factors?

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Strength Imbalance
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Strength Imbalance

• Limb dominance only a factor in racquet or ball
  sports
• Strength imbalances between muscle groups gt 10
  may increase injury risk e.g. Cruciate ligament
  injuries
• Limb length differences are a known risk factor

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Body Mass Index

• Only anthropometric factor known to be an injury
  risk factor
• BMI kg/m2
• Normal 18-25
• Above or below doubles the injury risk

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Psychological Factors

• Poor decision making
• Stress
• Anxiety
• Extrovert/Introvert
• Levels of responsibility

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Psychological Response to Injury

• Phase 1 Shock
• Phase 2 Preoccupation
• Phase 3 Reorganisation

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Systemic Disease

• The athlete may have a systemic disease
• The disease may be the reason for undertaking
  exercise e.g. cardiovascular, neurological,
  endocrine or arthritic disease
• An undiagnosed disease may be the underlying
  cause of an injury

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Extrinsic Causes of Injury

• Exercise surface
• Equipment
• Sport/ sports position
• Warm up stretching

• Training errors
• External force
• Climate
• External motivation (peer, parental, coach
  pressure)

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External Force
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External Force

• Underlying intrinsic factors may still be present
  and need to be addressed by the practitioner.
  Examples?

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Exercise Surface

• The harder the surface the greater the intrinsic
  shock absorption required
• Nigg Yeadon (1988) demonstrated increases in
  Achilles tendonopathy and MTSS with exercise on
  hard track surfaces
• No evidence of increased OA with exercise

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Artificial Versus Natural Grass

• Injury profiles are different
• Natural grass more ligamentous injuries
• Natural grass injuries depend upon terrain and
  water content
• Artificial grass Turf toe, abrasions,
  infections, tendon and ligament injuries due to
  increased frictional forces

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Incline and Decline

• Different muscle activity required in each
  situation
• Uphill running requires increased eccentric
  activity of calf and hamstring muscles
• Downhill running requires increased eccentric
  activity of the anterior muscle group and
  quadriceps

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Treadmill Vs Ground

• Reduced contact time at the same velocity
• Reduced stride length so increased strides
• ? Increased pronation
• Increased posterior shear force

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Sporting Activity

• The type of sport and technique used are integral
  to the injury development
• Understand the forces involved in the sport
• Identify the structures at risk of injury
• Determine the biomechanical mechanism of injury
• Use this in the treatment plan

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Sporting Technique

• Athletes skill/level
• Athletes position
• Limb dominance
• Observe their technique where possible

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Training Errors

• Commonest cause of injuries
• 10 rule
• Balance between strength, flexibility and
  endurance training
• Rest days/ different activities
• Variation in training
• Periods of greater activity in the year

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Environmental Factors

• Temperature, humidity and altitude
• Heat injuries syncope, heat cramps, exhaustion
• Cold Injuries chilbains, frostbite, hypothermia,
  raynauds, asthma etc
• Altitude acute mountain sickness, pulmonary and
  cerebral oedema

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Questions ?