Intrasound therapy in tendon healing: is intensity a factor?

OBJECTIVE: This study investigated the effects of low- and high-intensity intrasound therapy (LITR and HITR, respectively) given once daily and twice daily on the morphology and oxidative stress in healing tendon tissue following an acute injury. METHODS: Eighty-five male rats, randomized into six groups were further subdivided into groups A, B, and C, except for Group 1 which was subdivided into A and B only. Groups 2–6 underwent an induced crush injury. The six groups were allocated to: serve as controls (Group 1), receive no treatment (Group 2), HITR twice daily (Group 3), HITR once daily (Group 4), LITR twice daily (Group 5), and LITR once daily (Group 6). Intrasound therapy (ITR) was commenced 24 hours postinjury and was given once daily or twice daily over the first 14 days postinjury. The animals in subgroups A and B were sacrificed on day 15 postinjury, and those in subgroup C were sacrificed on day 31 postinjury. The tendons were excised, and processed for histology and malondialdehyde (MDA) assay. RESULTS: There was no significant difference in the tenocyte population between the HITR- and LITR-treated groups. However, twice-daily treatment in either the low- or high-intensity mode resulted in significant tenocyte proliferation compared with the once-daily treated groups, and also had the highest percentage of tenoblasts compared with the population of tenocytes in the proliferative phase of healing. All treatment protocols marginally lowered the MDA level. CONCLUSION: The role of IRT in tendon healing is influenced more by the frequency of treatment rather than the intensity of the delivered dosage.