d Original Contribution COMPARATIVE STUDY OF THE TOPICAL APPLICATION OFALOE VERA GEL, THERAPEUTIC ULTRASOUND AND PHONOPHORESIS ON THE TISSUE REPAIR IN COLLAGENASE-INDUCED RAT TENDINITIS ANTONIO LUIZ MARTINS MAIA FILHO,* ANTONIO BALBIN VILLAVERDE, y EGBERTO MUNIN, y FLA ´ VIO AIMBIRE, y and REGIANE ALBERTINI y# *Faculdade Integral Diferencial, FACID, Teresina, Piauı ´, Brazil; y Centro de Engenharia Biome ´dica, Universidade Camilo Castelo Branco, UNICASTELO, Sa ˜o Jose ´ dos Campos, SP, Brazil; and # Universidade Nove de Julho, UNINOVE, Sa ˜o Paulo, SP, Brazil (Received 14 October 2009; revised 6 May 2010; in final form 15 June 2010) AbstractdThe aim of our study was to compare topical use of Aloe vera gel, pulsed mode ultrasound (US) and Aloe vera phonophoresis on rat paw with collagenase-induced tendinitis. Edema size, tensile tendon strength, tendon elasticity, number of inflammatory cells and tissue histology were studied at 7 and 14 days after tendinitis induc- tion. Pulse mode US parameters were: 1 MHz frequency, 100 Hz repetition rate, 10% duty cycle, and 0.5 W/cm 2 intensity, applied for 2 min each session. A 0.5 mL of Aloe vera gel at 2% concentration was applied for 2 min per session, topically and by phonophoresis. Topical application of Aloe vera gel did not show any statistically signif- icant improvement in the inflammatory process, whereas phonophoresis enhanced the gel action reducing edema and number of inflammatory cells, promoting the rearrangement of collagen fibers and promoting also the recovery of the tensile strength and elasticity of the inflamed tendon to recover their normal pre-injury status. Results seem to indicate that Aloe vera phonophoresis is a promising technique for tendinitis treatment, without the adverse effect provoked by systemic anti-inflammatory drugs. (E-mail: abvillaverde@gmail.com) Ó 2010 World Federation for Ultrasound in Medicine & Biology. Key Words: Aloe vera gel, Therapeutic ultrasound, Phonophoresis, Animal model, Tendinitis. INTRODUCTION Inflammation is a basic pathologic mechanism. The inflammatory reaction involves complex interactions between inflammatory cells (neutrophils, lymphocytes and monocytes/macrophages) and vascular cells (endo- thelial and smooth muscle cells) (Willoughby et al. 2000; Pinheiro and Calixto 2002). Different therapeutic physical techniques have been used for the treatment of inflammatory processes, such as electric stimulation (Gersh 1990), short waves (Bouwhuijsen 1986), heating by infra-red radiation (Michlovitz 1990) and acupuncture (Ziskin et al. 1990). Furthermore, the use of the ultra- sound as an alternative anti-inflammatory therapy was suggested by Dyson et al. (1968). Over the past decades, ultrasound has become largely used for the treatment of a variety of conditions, including the promotion of wound healing, edema reduction and pain relief, for different etiologies (van der Windt et al. 1999; Busse et al. 2002; Korpan et al. 2006). The action of ultrasound on biologic tissue is based on thermal and nonthermal effects of the US waves (O’Brien 2007). Ultrasound waves interacting with bio- logic tissue promotes a local increase in blood flow, temporary increase in the extensibility of collagen struc- tures, such as tendons, ligaments and articular capsule, reduction of joint stiffness, pain and muscle spasm, and produces a mild inflammatory reaction (Draper et al. 1995). Those effects are more pronounced when a pulsed mode US is used instead of a continuous mode and it depends on the irradiation parameters such as funda- mental frequency, intensity, pulse width and pulse repeti- tion rate (O’Brien 2007). The use of pulsed mode US can also generate nonthermal effects, like the cavitation effect caused by the formation of micro-jets inside the biologic tissue. The parameters of ultrasound are crucial for the occurrence of cavitation. This effect, yet highly controversial, may partially explained the action of the Address correspondence to: Dr. Antonio Balbin Villaverde, Uni- versidade Camilo Castelo Branco, UNICASTELO, Parque Tecnolo ´gico de Sa ˜o Jose ´ dos Campos, Rod. Presidente Dutra, Km138, Distrito de Euge ˆnio de Melo, 12247-004, Sa ˜o Jose ´ dos Campos, SP, Brazil. E-mail: abvillaverde@gmail.com 1682 Ultrasound in Med. & Biol., Vol. 36, No. 10, pp. 1682e1690, 2010 Copyright Ó 2010 World Federation for Ultrasound in Medicine & Biology Printed in the USA. All rights reserved 0301-5629/$ - see front matter doi:10.1016/j.ultrasmedbio.2010.06.012