A low cost electromechanical device injury model for hind limb murine muscles

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In daily life, muscle injuries due to accidents, sports, traumatic events or pathological conditions are constantly occurring. Not knowing the forces involved or the torque or the angle at which the injury was caused represent a challenging clinical problem limiting appropriate treatment protocols. In here, we design, developed, built and validated a reproducible well‐characterized injury device for small species at low cost using Arduino platform. The device can perform two types of injuries while varying speed, angle and frequencies; the first one generated by eccentric contractions and the second one by doing torsions. Briefly, under anesthesia the animal is placed in a pre‐warmed bed, then one leg is secured to a foot plate attached to an electric steeper motor providing a torque of 48 N‐m controlled by Arduino. Two electrodes are placed in the rat’s gastrocnemius to generate the injury. For eccentric contraction type of injury, the foot plate moves backward and forward causing dorsi and plantarflexion intermittently at a certain angle and speed. As the bed can rotate 180° fibrillar and tendon ruptures can be determined. The torsion type of injury mimics an ankle sprain at controlled force and speed. This is intended to study joint and tendon damage by mechanical analysis. The instantaneous speed of the movement is measured with an electronic gyroscope attached to the axis of the bed. Torque, isometric and isotonic stimulation can be measured as well. With this, the mechanisms of hypertrophy and muscular strengthening can be studied by measuring their progress with the aim of generating adequate physiotherapy therapies. We are currently validating the device in small species animals. Results will be shown.Support or Funding InformationSupported partially by UNAM‐PAPIIT IA210320 and CONACyT AI‐S‐17636 to KPGP.