Incisional wound healing: a controlled study of low and high dose ultrasound

• Published in: The journal of orthopaedic and sports physical therapy 1993-11, Vol.18 (5), p.619-628
• Main Authors: Byl, N N, McKenzie, A, Wong, T, West, J, Hunt, T K
• Format: Article
• Language: English
• Subjects: Animals; Collagen - metabolism; Female; Single-Blind Method; Swine; Time Factors; Ultrasonic Therapy - methods; Wound Healing
• ISSN: 0190-6011; 1938-1344
• DOI: 10.2519/jospt.1993.18.5.619

Ultrasound is commonly used by physical therapists, but there is no consensus regarding the most effective therapeutic dose for accelerating healing of open or closed wounds. A controlled, single-blind, posttest experimental study was carried out to compare differences in wound breaking strength and collagen deposition [hydroxyproline (HoPro)]. Forty-eight incisions were surgically induced in three mini Yucatan pigs. Each incision was randomly assigned to a control or an ultrasound treatment group with the sonated incisions further randomly assigned to 5 or 10 days of ultrasound treatment with either high dose ultrasound (HUS) (1.5 W/cm2, continuous mode, 1 MHz, 5 minutes) or low dose ultrasound (LUS) (0.5 W/cm2, pulsed mode, 20% duty cycle, 1 MHz, 5 minutes). Using the nonparametric two-sample Wilcoxon test, the breaking strength was found to be significantly higher in the sonated incisions compared with the control incisions (p < or = 0.02), but there were no significant differences in HoPro. For all groups, the level of HoPro measured the second week was significantly higher (an average of 60%) than measured the first week (p < or = 0.001). A significant interaction was found between the number of days of treatment and the dose of ultrasound. Hydroxyproline was significantly higher in the LUS group compared with the HUS group after 5 days of ultrasound. Both the wound breaking strength and the HoPro levels were significantly higher in the LUS group compared with the HUS group after 10 days of treatment (p < or = 0.02 and 0.01, respectively). The findings from this study suggest that physical therapists can use either LUS or HUS for approximately 1 week to enhance wound breaking strength in an acute incisional wound. However, if the goal is to continue to facilitate collagen deposition and wound strength, then a low dose of ultrasound should be used when treatment is continued for 2 weeks or more.