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A study was designed to attempt to develop an experimental animal model for the transverse rectus abdominis musculocutaneous (TRAM) flap. The rat has a well-formed superior epigastric artery with musculocutaneous perforators that have been shown to support a musculocutaneous flap on a single superior pedicle. Despite the anatomical differences between the dominance of the axial longitudinal cutaneous circulation in loose-skinned animals compared with humans, as well as a dominant superior intramuscular pedicle, the rat TRAM model appears to be reproducible and has predictable zones of viability as well as areas that typically do not survive when based on a single superior pedicle. These areas of nonviability correspond to those zones at high risk of nonviability in the human clinical situation: zone 3 and 4 on the contralateral side and zone 3 on the ipsilateral side (tissue lateral to the superficial inferior epigastric supply). Once the reliability and reproducibility of this model was demonstrated (coefficient of variation 18.9%), a study was undertaken to determine whether pharmacological manipulation of this flap altered survival in those areas that are inadequately perfused. The two agents tested were allopurinol (xanthine oxidase inhibitor, antioxidant) and pentoxifylline (microcirculatory rheological agents that is a xanthine analogue and is also believed to have antioxidant potential). The study involved creating right unipedicled TRAM flaps in 30 male specific pathogen-free Sprague-Dawley rats weighing 375 to 450 gm. The transverse skin paddle was centered over the umbilical dimple and measured 5.5 x 2 cm.(ABSTRACT TRUNCATED AT 250 WORDS)

Topical silicone-gel sheeting has been shown to be beneficial in the treatment of established hypertrophic and keloid scars. Certain individuals and incisions in specific body sites appear to be at increased risk for the development of such scars. A simple, inexpensive, and preventive treatment in these individuals at increased risk could potentially minimize the extended period of pressure therapy and repeated steroid injections that are often required to optimize outcome. However, the effects of applying silicone-gel sheeting in the immediate postoperative period as a preventive measure have not been investigated to date. Because silicone-gel sheeting influences the remodeling and maturation phase of collagen formation, we believed it prudent to determine whether silicone-gel sheeting had any deleterious effect on early wound healing, as demonstrated by in vivo biomechanical testing of wound strength and histological assessment. To investigate the potential effects of silicone-gel sheeting on acute wound healing and its possible application for prevention of hypertrophic scars, a study was designed in the hairless guinea pig. In phase 1 of the study, bilateral dorsolateral incisions were made, allowing each guinea pig to serve as its own control. One wound was dressed with silicone-gel sheeting, and the control site was dressed with Nu-gauze dressing. Wounds were then assessed visually and with in vivo biomechanical analysis of wound strength at days 3, 5, and 7 postoperatively (n = 7 per group). Phase 2 of the study compared identical dressings in a similar animal model using a single dorsal midline incision, in which alternate halves of each wound served as the control.(ABSTRACT TRUNCATED AT 250 WORDS)

There has been ongoing clinical and laboratory research to determine the role of surface morphology on capsular contracture. The purpose of this study was to develop a rat model in which capsular contracture occurred frequently and to determine whether surface texturing had any effect on the incidence or degree of capsular contracture as determined by in vivo biomechanical analysis of tissue modulus and histological examination of the tissue at the capsule-implant interface. A new sublatissimus implantation site in the rat was developed in an attempt to avoid subpannicular placement, which has been associated with inconsistent results because of contracture despite texturing, and a high rate of implant exposure secondary to trauma. Each rat (N = 43) was implanted with two devices--one smooth-surface 6-ml implant and one textured Biocell 6-ml implant--both with remote ports to allow for biomechanical analysis. Evaluation was carried out at 1, 2, and 3 months (n = 10) and 6 months (n = 5). Biomechanical evaluation of the implants was carried out in vivo and anonymously. The animals were then killed, and sectioning of the overlying capsule-implant interface from the dome of the implant was performed. Histological evaluation was carried out anonymously with regards to the implant type. Capsular contracture developed in smooth-surface devices in 95% of sites; this became evident on biomechanical analysis at 2 months and progressed to 3 months, after which it remained relatively stable.(ABSTRACT TRUNCATED AT 250 WORDS)