Effects of cryotherapy combined with therapeutic ultrasound on oxidative stress and tissue damage after musculoskeletal contusion in rats.

OBJECTIVE: To investigate the combined effects of cryotherapy and pulsed ultrasound therapy (PUT) on oxidative stress parameters, tissue damage markers and systemic inflammation after musculoskeletal injury.

DESIGN: Experimental animal study.

SETTING: Research laboratory.

PARTICIPANTS: Seventy male Wistar rats were divided into five groups: control, lesion, cryotherapy, PUT, and cryotherapy+PUT.

INTERVENTIONS: The gastrocnemius muscle was injured by mechanical crushing. Cryotherapy was applied immediately after injury (immersion in water at 10°C for 20minutes). PUT was commenced 24hours after injury (1MHz, 0.4W/cm(2SPTA), 20% duty cycle, 5minutes). All animals were treated every 8hours for 3 days.

MAIN OUTCOME MEASURES: Oxidative stress in muscle was evaluated by concentration of reactive oxygen species (ROS), lipid peroxidation (LPO), anti-oxidant capacity against peroxyl radicals (ACAP) and catalase. Plasma levels of creatine kinase (CK), lactate dehydrogenase (LDH) and C-reactive protein (CRP) were assessed.

RESULTS: When applied individually, cryotherapy and PUT reduced CK, LDH, CRP and LPO caused by muscle damage. Cryotherapy+PUT in combination maintained the previous results, caused a reduction in ROS [P=0.005, mean difference -0.9×10(-8) relative area, 95% confidence interval (CI) -0.2 to -1.9], and increased ACAP {P=0.007, mean difference 0.34 1/[relative area with/without 2,2-azobis(2-methylpropionamidine)dihydrochloride], 95% CI 0.07 to 0.61} and catalase (P=0.002, mean difference 0.41units/mg protein, 95% CI 0.09 to 0.73) compared with the lesion group.

CONCLUSIONS: Cryotherapy+PUT in combination reduced oxidative stress in muscle, contributing to a reduction in adjacent damage and tissue repair.