Reliability and validity of a novel muscle contusion device

Context: 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. Design: Validation study. Patients or Other Participants: Twenty-six male Wistar rats, 3 to 4 months old. Intervention(s): 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. Main Outcome Measure(s): 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-β = 1.0). Outcomes using the experimental animals were also dependent on height (F_14,102 = 68.679, P < .001, 1-β 5 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.