title: Reliability and validity of a novel muscle contusion device.
abstract: BACKGROUND
  Many models have been employed to replicate skeletal muscle injury associated with trauma; however, most are restricted to 1 level of severity.
  
  
  OBJECTIVE
  To create and validate an injury-producing device that could generate multiple levels of injury severity.
  
  
  METHODS
  Validation study.
  
  
  METHODS
  Twenty-six male Wistar rats, 3 to 4 months old.
  
  
  METHODS
  A contusion device was developed and its ability to deliver consistent impacts was validated alone and in the presence of an experimental animal. A free-falling mass (267 g) was adjusted to the desired height (40, 50, 60, or 70 cm) and then dropped.
  
  
  METHODS
  Peak load, peak displacement, impulse, energy, and velocity peak were measured. Injury severity was determined using magnetic resonance imaging.
  
  
  RESULTS
  Outcome measures observed from the device alone were different by height (F(18,136) = 21.807, P < .001, 1-beta = 1.0). Outcomes using the experimental animals were also dependent on height (F(14,102) = 68.679, P < .001, 1-beta = 1.0). Linear regression analyses indicated that height accounted for 17% to 89% of the variance.
  
  
  CONCLUSIONS
  Mild to moderate and moderate to severe injuries can be replicated with this device, which will be useful in evaluating clinical treatments on acute muscle injury.
authors.affiliation: The Pennsylvania State University, University Park, PA 16802, USA. nmm13@psu.edu
authors.forename: Nicole M
authors.initials: NM
authors.lastname: McBrier
authors.forename: Thomas
authors.initials: T
authors.lastname: Neuberger
authors.forename: Nori
authors.initials: N
authors.lastname: Okita
authors.forename: Andrew
authors.initials: A
authors.lastname: Webb
authors.forename: Neil
authors.initials: N
authors.lastname: Sharkey