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Evaluation of the biological interaction between the implantation of castor oil polyurethane and chitosan associated with the calcium phosphate receptor tissue in experimental bone defects of the third metacarpal bone of horses


The regeneration of defects caused by bone loss resulting from trauma or disease remains a therapeutic challenge in orthopedics, because sudden growth of connective tissue prevents or hinders the formation of new bone. In veterinary orthopedics, are often required major repairs due to bone loss, thus surgical or pathological origin, making it necessary to use bone implant for aesthetic and functional correction. Experimental models are used to study the process of fracture healing, however, due to anatomical differences, biological and technical models are not always appropriate parameters for the species of interest. These challenges have prompted researchers to develop and study the compatibility of different types of implants to better promote repair on damaged bone areas. The natural polymers are biodegradable and generally have excellent biocompatibility when compared to synthetic polymers. The castor bean is a biomaterial to replace bone tissue and may be used to fill defects or bone loss. Chitosan, another natural biomaterial, promotes cell growth through strong adherence to acquire the cells with the polymer and proliferate at higher speeds. This study aims to evaluate the tissue repair process and behavior of the polymer implant of castor bean or castor chitosan plus calcium phosphate receptor in tissue from experimental bone defects in metacarpal bone III of horses. Six male horses will be use and, under general anesthesia, in each metacarpal III, will be made a circular bone defect of 15 mm diameter, where the depth of the failure will be determined individually and its limit will be the full implementation of cortical-cis. The site of failure is predetermined by the digital radiography dorsopalmar view on surgery to order the point in each animal (eight centimeters distance from the proximal joint surface (carpal-metacarpal) and a midpoint in the central lateral distance). Subsequently, at each failure and random, will be implant with the polymers of castor bean or chitosan, and in the same animal will be implant with the two polymers (one in each forelimb). The animals will be evaluate according to the degree of lameness (before undergoing the surgical procedure all animals should be evaluated and their gait recorded for comparison and evaluation of lameness), physical assessment (daily evaluation will be conduct on the surgical wound condition sutures, infection and inflammatory reaction), radiological evaluation (all animals have the metacarpal III in pre-surgical radiographs, in the immediate postoperative, weekly until 30 days after surgery and monthly for observation of the progress of implementation of the grafts until 180 days postoperatively), an ultrasound (preoperative dorsal region of the metacarpals will be reviewed weekly until 30 days after surgery and monthly for observing the progress of implementation of the implants up to 180 days postoperatively ), thermographic evaluation (the animals will be reviewed before being submitted to surgery in the immediate postoperative period and daily up to 30 days to evaluate circulatory pattern, blood flow and inflammation), histological evaluation (after 180 days the animals will be re-submitted general anesthesia and the implant area will be accessed, with surgery to collect a fragment of the region receiving the implant. This material will be process at the end of the process and the slides will be assessing histologically). (AU)