Absorption of Hydrocortisone Acetate in Human Connective Tissue Using Phonophoresis

Abstract

Background: Therapeutic ultrasound to drive medication (phonophoresis) has been a mainstay in physical therapy. The most common drug used in phonophoresis is hydrocortisone acetate (HA). A number of studies have been done examining phonophoresis in the delivery of HA through the skin to underlying tissues; however, a study has never been done examining the absorption of HA using phonophoresis on human connective tissue. Hypothesis: Phonophoresis will facilitate the transmission of HA in human connective tissue. Study Design: Randomized controlled study. Methods: Twenty-one patients undergoing anterior cruciate ligament reconstruction surgery were randomly assigned to either a sham or true phonophoresis treatment group. The latter group received 6 minutes of 10% HA ultrasound at a point consistent with the gastrocnemius slip of the semitendinosis tendon (treatment site). The sham group received 6 minutes of 10% HA ultrasound to the same area, but the ultrasound was not turned on. The slip and a sample of the distal attachment of the tendon (control) were removed. Samples were analyzed for HA levels. Results: Although the mean and median levels of HA found at the treatment site were greater than those of the control site (means, 34.1 vs 22.9 parts per billion; medians, 7 vs 0 parts per billion), the levels of HA found at the treatment site were not significantly greater than those at the control site (P = 0.15). There were no statistically significant differences between the true and sham phonophoresis groups in HA levels (P = 0.80) nor in age, sex, or skin thickness. Conclusion: Phonophoresis does not appear to facilitate the absorption of HA in connective tissue when compared with simple absorption (sham). Clinical Relevance: Phonophoresis does not appear to enhance the transmission of HA in human connective tissue; therefore, use of phonophoresis should be reconsidered in inflammatory conditions.