Evidence based decision making in endurance Equine Limb Injury - - PowerPoint PPT Presentation

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Evidence based decision making in endurance Equine Limb Injury - - PowerPoint PPT Presentation

Mar 01, 2024 46 likes •486 views

Evidence based decision making in endurance Equine Limb Injury Prevention Program Professor Chris Whitton Summary Evidence based decision making Types of evidence Outcomes Modifiable risk factors Speed Mandatory

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Evidence based decision making in endurance

Equine Limb Injury Prevention Program Professor Chris Whitton

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Equine Limb Injury Prevention Program Equine Limb Injury Prevention Program

Summary

Evidence based decision making

  • Types of evidence
  • Outcomes
  • Modifiable risk factors

− Speed − Mandatory rest periods

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Introduction

Two key processes in catastrophic injuries

  • 1. The accumulation of damage
  • Bone material fatigue
  • 2. The response of bone
  • Bone adaptation
  • Bone repair

Most modifiable with regulation Trainer education

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Evidence

  • 1. Epidemiology
  • Identification of risk factors
  • 2. Bone properties
  • Fatigue properties
  • Bone biology
  • 3. Data from other disciplines
  • TB racing
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Evidence

Epidemiology

  • Excellent screening method
  • Identify risk factors

− Modifiable − Non-modifiable

  • May not be causative
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Evidence

Bone injury and biological data

  • Often simplified
  • May not include full complexity of process
  • Can identify causative factors
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50 60 70 80 90 100 100 10'000 1'000'000

Cycles to failure Load MPa

Bone fatigue

  • Fatigue life

− No. of cycles to failure

Faster Fewer strides

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Racehorse

Bone fatigue

  • High loads

− Failure with relatively few cycles of load − Short fatigue life

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Racehorse

Bone fatigue

  • Damage may be
  • bserved as

microcracks

  • Commonly
  • bserved in highly

loaded areas 2mm

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Racehorse

Bone fatigue

  • Microcracks

accumulate and grow into fractures

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Racehorse

Bone fatigue

  • Microcracks

accumulate and grow into fractures

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Racehorse

Bone fatigue

  • Fractures may progress

to catastrophic failure

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Soft tissue

  • Similar process
  • Cyclic loading causes fibre damage
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Outcomes

Elimination for lameness

  • Common – easier to get good data

Catastrophic injury

  • Rare – adequate data more challenging
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Outcomes Cause Lame

Fatality

Cause Lame

Fatality

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Outcomes

Cyclical loading

Lame

Fatality

Bone injury Soft tissue injury

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Outcomes

Cyclical loading

Lame

Fatality

Bone injury Soft tissue injury

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Outcomes

Cyclical loading

Lame

Fatality

Bone injury Soft tissue injury

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Types of injury

Catastrophic fracture

  • Incomplete fractures propagate to complete

fractures

Non fatal bone injuries

  • Subchondral bone injuries
  • Chip fractures
  • Osteoarthritis

Soft tissue injuries

  • Suspensory ligament
  • Tendon injury

Cyclic loading

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Suspensory ligament injury

  • May be ligament only
  • May be ligament and bone

− MC3 at origin − Sesamoids distally

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Suspensory ligament injury

  • Sustains high loads at midstance

− 660kg at canter (27 km/h) − 1200kg at gallop (48 km/h)

From Harrison et al. 2010 Force N/kg

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Suspensory ligament injury

  • Risk factors

− Older horses, longer careers (Reardon 2012; Perkins

2005; Lam 2007)

− Racing frequency – both too little and too many

(Perkins 2005, Reardon 2010, Hill 2001)

− Distance – increased in last month but lower cumulative distance over time − Pre-existing injury (Cohen 1999, Hill 2001, Lam 2007,

Reardon 2012)

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Suspensory ligament injury

  • Risk factors

− Very similar to those identified for fractures − Biased towards older horses

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Injury prevention

  • Reduce cyclic loading

− Epidemiology and bone biology indicate risk is not linear

Adaptation Damage accumulation

Risk Work load

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Elimination for lameness

Risk factors

  • Interval between rides
  • Speed
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Risk factors

Increasing intervals between rides (MRPs)

  • Reduces number of rides
  • Bone repair

‒ Allow more time ‒ Increases rate

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Intervals between rides

  • Fewer rides – less fatigue

1 2 3 4 5 6 7 8

1 2 3 4 5 6

MRP 19 days MRP 26 days

6 months

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Intervals between rides

  • Fewer rides – less fatigue

1 2 3 4 5

1 2 3 4

MRP 19 days MRP 26 days

6 months

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Intervals between rides

  • Greater time for repair
  • Some increase in repair rates

20 40 60 80 100 120

Km/day

20 40 60 80 100 120

Km/day

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Intervals between rides

Potential risks

  • Loss of bone adaptation

20 40 60 80 100 120

Km/day

20 40 60 80 100 120

Km/day

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Intervals between rides

Potential risks

  • Loss of bone adaptation
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Intervals between rides

Potential risks

  • Loss of bone adaptation
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Risk factors

Speed

  • Direct relationship

between speed and loads in limb

From Witte et al. 2006

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Risk factors

Speed

  • Direct relationship

between speed and loads in limb

Fetlock joint loads

Walk (4 km/h) 0.8 tonnes Trot (13 km/h) 2.3 tonnes Canter (27 km/h) 2.6 tonnes Gallop (48 km/h) 4.0 tonnes

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50 60 70 80 90 100 100 10'000 1'000'000

Cycles to failure Load MPa

Bone fatigue

  • Fatigue life

− No. of cycles to failure

Faster Fewer strides

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Accumulated bone fatigue

Modelling of bone fatigue

  • Stride length v speed (Witte et al. 2006)

y = 0.10x + 1.27

  • Load v speed (Harrison et al. 2014, Harrison et al. unpublished)

y = 1.57x + 18.57

  • Load v fatigue life (Martig et al. 2014)

y = 134.2- log10x

Speed and distance Fatigue life

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Accumulated bone fatigue

Loop speed 120km ride (all regions)

  • Slow – 11.0 km/h
  • Mean – 18.6 km/h
  • Fast – 26.2 km/h

0.5 1 1.5 2 2.5 3 3.5 4 4.5 Loop 1 Loop 2 Loop 3 Loop 4 Slow Mean Fast % fatigue life/loop

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Accumulated bone fatigue

Mean speed

1 2 3 4 5 6 7 80 km 120 km 160 km All Group 7 % fatigue life/ride

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Accumulated bone fatigue

Fastest 2.5% of horses

5 10 15 20 25 30 35 80 km 120 km 160 km All Group 7 % fatigue life/ride

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Accumulated bone fatigue

Reduce speed of fastest horses in 120 km rides

  • (28.2-29.5 km/h)

5 10 15 20 25 30 35 no change minus 1 km/h minus 2 km/h % fatigue life/ride

20% reduction 37% reduction

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Accumulated bone fatigue

  • Function of speed and distance

− 120 km rides accumulate most bone fatigue − Small reductions in speed have large effects for fast rides/horses

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Conclusions

  • Injury prevention

− Endurance specific data for lameness − Most lameness due to cyclic loading − Interventions that reduce cyclic loading likely to reduce majority of injuries − Function of speed and distance accumulation − Pre-existing injury increases risk

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Conclusions

  • Evidence based rule changes

‒ Increasing MRP

  • Effect may not be linear
  • Increase incrementally and monitor effect

− Decrease speeds − Maximise ability to detect pre-existing injury

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Equine Limb Injury Prevention Program

Professor Chris Whitton Head U-Vet Equine Centre 250 Princes Hwy, Werribee 03 97312268

Equine Limb Injury Prevention Program Equine Limb Injury Prevention Program