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Thanks to recent advances in science and engineering, the field of biomaterials stands poised to increase the effectiveness and longevity of established devices as well as to provide new options to biomedical engineers who work at designing future products. From its beginning, the field of bioengineering has focused on providing the best artificial devices - hearing aids, artificial limbs and other prostheses - to replace body parts that are missing, broken, or dysfunctional. Regeneration of body parts requires a biomaterial with a structure, components and chemical signals that allow the body ’s tissue cells to recognize, respond to, and remodel the material without rejecting it as foreign. Bone, cartilage and the major load bearing joints of the body all suffer degenerative changes with age and trauma. This area of research focus will seek solutions to the problems of osteoporosis, the fixation of implants in bone and the replacement of damaged bone and cartilage. This will be achieved through the development of non-metallic biomaterials and resorbable biomaterials that provide appropriate load bearing characteristics and the potential to interact suitably with the biology. The non-metallic materials for bone substitutes serve as scaffolds and may have modified surfaces to encourage natural tissue growth or the ability to be seeded with the hosts own cells before implantation. This will have applications for both bone and cartilage substitute materials. These bone substitutes biomaterials are the second-most implanted of all materials. Resorbable biomaterials, on the other hand, gradually disappear from the body as a result of hydrolysis, because are made from molecules similar to those in the human body, which resorb while the tissue is healing. This eliminates the need for a second surgery. The goal of this thesis is to explain the usefulness of these biomaterials in medical applications and especially in orthopaedics, focusing on the latest acquisitions. The first chapter makes an introduction in biomaterials, with emphasis on orthopaedic biomaterials. The second chapter contains information about: (1) the bone characteristics (anatomy and mechanics), in order to understand the basis for tissue engineered therapies and how damaged bones heal, (2) the non-metallic biomaterials (polymers, biodegradable polymers, ceramics and composites) for bone substitutes, giving examples of modern biomaterials used today and (3) the principles involved in the Modern Cementing Technique. The third chapter is a review of the chemistry of the polymers used in bioresorbable biomaterials, including synthesis and degradation, describe how properties can be controlled by proper synthetic controls such as copolymer composition, highlight special requirements for processing and handling, and presents in detail some of the commercial resorbable biomaterials. / Αυτή η διατριβή εξηγεί τη χρησιμότητα των μη μεταλλικών βιο-υλικών για τα υποκατάστατα οστών και των βιο-απορροφημένων βιο-υλικών στις ιατρικές εφαρμογές και ειδικά στις ορθοπεδικές, που εστιάζουν στις πιό πρόσφατες αποκτήσεις.

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This is an original study to quantify and grade defect healing in a large animal cranial bone substitute model. The study of various therapies to heal cranial defects requires an appropriate ?critical? animal model. An experimental animal model should be analogous and recognizable as an appropriate challenge to human physiology. In addition, the defect must fail to heal unless treated with the tissue engineering therapy under study. Sheep as a large animal model was chosen because of its ability to tolerate creation of large skull defects analogous to clinical scenario, and its biology of healing as a high order mammal would be closer human beings. There is no agreement on the critical size limits for cranial defects. Various sizes have been termed "critical" in publications utilizing sheep. These ranged from 20-22mm. This study will investigate whether a 20mm defect is adequate. Bilateral circular cranial defects of 10, 20 and 25mm diameters were created in 12 adult sheep. Based on guided tissue engineering principles, defect protection was utilized to prevent in-growth of fibroblasts and other connective tissue cells from the surroundings. As bone tissue regeneration strategies usually involve osteoconduction element, an animal model that considered the defect protection role of osteoconduction would be more appropriate. Repopulation and regeneration of the defect was maximized as an added challenge Bioresorbable polylactic acid co-polymer mesh (MacroPoreTM) and Titanium mesh (TiMeshTM) was used as defect protection. The cranial defects were harvested at 8 and 16 weeks. The end-point analysis included Faxitron X-ray images, DEXA (Dual Energy X-ray Absorptiometry), and histology. The defects were graded to assess their ability to eventually heal. 10mm defects fully healed at 16 weeks. There was new bone formation spanning the entire defect seen on histology. 25mm defects were spanned by thin fibrous tissue only. There was variability in the healing potential of 20mm defect. Based on presence of bone islands within the defect, half of the 20mm defects demonstrated ability to heal while the other half actually had new bone spanning the defects on histology. Critical size cranial defect in sheep for the study of bone graft substitute has to be larger than 25mm diameter. The model is then utilized to study the use of Pro Osteon and AGF compared with the gold standard of autologous bone graft.

Many pathologic lesions and several types of fractures in the equine forelimbs involved the bony elements of the metacarpophalangeal joints (fetlock joints) especially the third metacarpal bones and the proximal sesamoid bones. Although the bones of the fetlock joint have been described in a general manner, the variations between equine breeds are still insufficient and differences within the breeds are not completely covered. Therefore, the aim of the current study was to identify the morphometrical variations of these bones between and within some different equine breeds. / Right and left metacarpal, proximal phalangeal and proximal sesamoid bones were collected from 23 horses (10 Thoroughbreds, 5 Standardbreds and 8 Ponies) euthanized for non-orthopaedic reasons. The bones were boiled between 95°C and 99°C for 30 hours, then cleaned and left for 24 hours at room temperature for air drying. Finally, the bones were dried in the drying cabinet at 49.5°C for 8 hours. A number of dimensional parameters were measured using a custom-built apparatus, calliper and plastic tape. These measurements included proximodistal height, lateromedial width, and dorsopalmar depth. All the statistical data were analysed using the ANOVA test and SPSS statistic software except the repeatability data which were analysed by calculating the repeatability coefficient. / This study showed that there were significant variations between the medial and lateral sides of all bones in all breeds. The length to the lateral condyle of Mc3 was greater than the length to the medial condyle of Mc3 in all breeds. The width and depth of the medial condyle was greater than the lateral condyle in all breeds. The lengths of the lateral sides of the P1 bones were greater than the lengths of the medial sides in the right forelimbs of Thoroughbreds and Standardbreds. The width of the medial articular cavity of P1 was greater than the width of the lateral articular cavity except in the left limb of Ponies. The depth of the medial articular cavity of P1 was greater than the depth of the lateral articular cavity except in the left limb of Standardbreds. The lateral sesamoid bones in both limbs of Thoroughbreds and Ponies were significantly longer or tended to be longer than the medial sesamoid bones. The lateral sesamoid bones were wider than the medial sesamoid bones in both limbs of Ponies. The depths of the lateral sesamoid bones were the significantly greater or tended to be greater than those of the medial sesamoid bones in both limbs of Thoroughbreds and Standardbreds. / There were many morphometrical variations in the bony elements of the equine fetlock joints of Thoroughbreds, Standardbreds and Ponies. Further studies are needed to identify the reasons and mechanical effects of these differences.

Thesis (Ph. D.)--School of Dentistry. University of Missouri--Kansas City, 2006. / "A dissertation in oral biology and cell biology and biophysics." Advisor: Lynda F. Bonewald. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Nov. 12, 2007. Includes bibliographical references (leaves 121-139). Online version of the print edition.