RESUMO
BACKGROUND AND PURPOSE: This study investigated the effects of low- and high-intensity intrasound therapy (LITR and HITR) and low-intensity pulsed ultrasound (LIPUS) on the morphology of the healing tendon. METHODS: Forty-five male Sprague-Dawley albino rats, randomized into five groups, were further subdivided into groups A and B except Group 1. Groups 2-5 underwent an induced crush injury to the Achilles tendon. The groups were allocated to serve as controls (Group 1), received no treatment (Group 2), LIPUS once daily (Group 3), LITR twice daily (Group 4), and HITR twice daily (Group 5). Treatment commenced 24 hr post-injury over the first 14 days. Subgroup A animals were killed on day 15 and those in subgroup B were killed on day 31. The tendons were excised and processed for histological studies. RESULTS: LITR and HITR given twice daily caused a significant (p < 0.05) proliferation of tenoblasts in the proliferative phase and enhanced their terminal differentiation to tenocytes in the remodeling phase compared with the untreated and LIPUS-treated groups. LITR and HITR also resulted in a significant increase in the volume fraction of collagen fibers compared with LIPUS. CONCLUSION: Intrasound therapy has a better morphological effect on the healing tendon than LIPUS and may be an option to consider in the treatment of acute tendon injuries.
