title: Deducing a mechanism of all musculoskeletal injuries.
abstract: BACKGROUND
  The mechanism of musculoskeletal (MSK) injuries is not well understood. This research applies principles of elastic motion to the anatomy and movement patterns of MSK structures. From this an insight into the application and timing of forces on MSK structures can be established and the mechanism/s of injury derived.
  All MSK structures demonstrate varying degrees of elasticity. Movement occurs primarily as a consequence of Muscle Tendon Unit (MTU) shortening. The application of an applied external force results in MSK structure lengthening.
  
  
  RESULTS
  The MTU acts as a non-idealised Hookean Spring. The resting length of MSK structures is the minimum distance between attachment points. The anatomical constraints results in MSK structures having adequate compressive strength during shortening. Thus MSK injuries only occur during lengthening of the MSK structure. From this with knowledge of MSK movement cycles, we can derive the mechanism of injury.
  
  
  CONCLUSIONS
  MSK injuries result from an inability to counter applied forces whilst lengthening. Muscles, tendons and ligaments can only injure during their lengthening contraction phase. Insertional tendons and bone near attachment points injure during the MTU shortening phase. Injuries to other MSK structures can occur independent of the lengthening and shortening phases such as direct contact injuries.
authors.affiliation: Department of Sports Medicine, South Australian Institute, Adelaide, Australia.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Verrall
authors.affiliation: ATRAD Pty Ltd, Thebarton, Australia; Department of Physical Sciences, University of Adelaide, Australia.
authors.forename: Bronwyn
authors.initials: B
authors.lastname: Dolman
keywords: insertional tendon; muscles; stress fracture; tendons; tensile force