title: Modelling the effect of race surface and racehorse limb parameters on in silico fetlock motion and propensity for injury.
abstract: BACKGROUND
  The metacarpophalangeal joint (fetlock) is the most commonly affected site of racehorse injury, with multiple observed pathologies consistent with extreme fetlock dorsiflexion. Race surface mechanics affect musculoskeletal structure loading and injury risk because surface forces applied to the hoof affect limb motions. Race surface mechanics are a function of controllable factors. Thus, race surface design has the potential to reduce the incidence of musculoskeletal injury through modulation of limb motions. However, the relationship between race surface mechanics and racehorse limb motions is unknown.
  
  
  OBJECTIVE
  To determine the effect of changing race surface and racehorse limb model parameters on distal limb motions.
  
  
  METHODS
  Sensitivity analysis of in silico fetlock motion to changes in race surface and racehorse limb parameters using a validated, integrated racehorse and race surface computational model.
  
  
  METHODS
  Fetlock motions were determined during gallop stance from simulations on virtual surfaces with differing average vertical stiffness, upper layer (e.g. cushion) depth and linear stiffness, horizontal friction, tendon and ligament mechanics, as well as fetlock position at heel strike.
  
  
  RESULTS
  Upper layer depth produced the greatest change in fetlock motion, with lesser depths yielding greater fetlock dorsiflexion. Lesser fetlock changes were observed for changes in lower layer (e.g. base or pad) mechanics (nonlinear), as well as palmar ligament and tendon stiffness. Horizontal friction and fetlock position contributed less than 1° change in fetlock motion.
  
  
  CONCLUSIONS
  Simulated fetlock motions are specific to one horse's anatomy reflected in the computational model. Anatomical differences among horses may affect the magnitude of limb flexion, but will likely have similar limb motion responses to varied surface mechanics.
  
  
  CONCLUSIONS
  Race surface parameters affected by maintenance produced greater changes in fetlock motion than other parameters studied. Simulations can provide evidence to inform race surface design and management to reduce the incidence of injury.
authors.affiliation: Biomedical Engineering Graduate Group, University of California - Davis, Davis, California, USA.|Department of Anatomy, Physiology and Cell Biology, University of California - Davis School of Veterinary Medicine, Davis, California, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Symons
authors.affiliation: Biomedical Engineering Graduate Group, University of California - Davis, Davis, California, USA.|Department of Neurobiology, Physiology and Behavior, University of California - Davis, Davis, California, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Hawkins
authors.affiliation: Biomedical Engineering Graduate Group, University of California - Davis, Davis, California, USA.|Department of Orthopaedic Surgery, University of California - Davis Medical Center Sacramento, Davis, California, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Fyhrie
authors.affiliation: Department of Biological and Agricultural Engineering, University of California - Davis, Davis, California, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Upadhyaya
authors.affiliation: Biomedical Engineering Graduate Group, University of California - Davis, Davis, California, USA.|Department of Anatomy, Physiology and Cell Biology, University of California - Davis School of Veterinary Medicine, Davis, California, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Stover
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005121:Extremities; D005684:Gait / Q000502:physiology*; D006724:Hoof and Claw / Q000502:physiology; D006736:Horses / Q000502:physiology*; D008662:Metacarpophalangeal Joint / Q000293:injuries / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D016059:Range of Motion, Articular; D012307:Risk Factors; D012420:Running
keywords: dirt; dynamics; horse; modelling; musculoskeletal; synthetic