Influence of Therapeutic Ultrasound on Skeletal Muscle Regeneration Following Blunt Contusion

Abstract

Athletic trainers typically use therapeutic ultrasound to treat skeletal muscle contusion injuries. However, the structural outcomes underlying this treatment are not well understood. Our working hypothesis was that following a blunt contusion injury to the gastrocnemius muscle, ultrasound treatment would facilitate recovery, as indicated by changes in several biological markers of skeletal muscle regeneration. Eighty male Wistar rats (three-month) were studied. Following anesthetic administration, each animal received a bilateral contusion injury to the gastrocnemius muscle. Pulsed ultrasound treatment was subsequently initiated six hours post-contusion injury unilaterally on the right gastrocnemius muscle, and ultrasound treatment was continued once daily for seven days. The left (non-ultrasound treated) and right (ultrasound treated) gastrocnemius muscles of 10 animals per group were excised at 1-, 3-, 5-, 7-, 14-, 21-, 28-, and 40-days post-contusion injury. There were no differences in muscle mass, total protein concentration, or fiber cross-sectional area between the right and left gastrocnemius muscles at any post-injury time point examined. Further, when fiber cross-sectional area was normalized to muscle mass, there were no differences. Myonuclear number and cross-sectional area per myonuclei between the right and left gastrocnemius muscles were not different. These results suggest that ultrasound, as administered, does not hasten or improve the regeneration of skeletal muscle following contusion injury.

Muscle Injuries in Athletes

“…7,43,59 Other adjunctive therapies hold promise for improving muscle healing and limiting scar formation, but further research is needed to define their roles. 9,11,44,49,50,57,65 …”

“…In a recent study using a rat contusion model, daily therapeutic ultrasound had no effect on muscle healing or regeneration. 65 Earlier translational work demonstrated that pulsed ultrasound could promote satellite cell proliferation, although this modality did not have a significant effect on the overall morphological manifestations of muscle regeneration. 54 Finally, the combination of ultrasound and exercise showed no benefit to skeletal muscle regeneration after contusion injury.…”

“…NSAID use can limit prostaglandin levels and edema after injury. 65 Recent translational data, however, demonstrate that initial benefits from NSAID use may ultimately result in diminished outcomes. 47,50,55 Piroxicam did not adversely affect strength recovery at 1 week in a rabbit muscle strain injury model but did lead to delays in repair, delayed degradation of damaged tissue, and attenuated muscle regeneration.…”

Morphologic study of different treatments for gastrocnemius muscle contusion in rats

“…Although its biological effects in acute and chronic inflammation are not well understood,2, 6, 7, 8 therapeutic ultrasound (TUS) has been recommended. Piedade et al 7 assessed the effects of pulsed application on lacerated gastrocnemius muscle of rats, and observed a significant increase in the number of myotubes in the regeneration zone 14 days after treatment.…”

“…It is important to emphasize that both TUS and muscle stretching are indicated for the treatment of muscle injury,2, 5, 6, 7, 8, 9 but there is still no consensus on when and how to prescribe them. Moreover, it is unclear whether the association between these therapeutic modalities can benefit the muscle regeneration mechanism.…”