ABSTRACT
CONTENTS 10.1 Introduction 254 10.2 Clinical Challenges with Bone Repair 254 10.3Bone Biology255
10.3.1Cells of Bone255 10.3.1.1Mesenchymal Stem Cells256 10.3.1.2DiŽerentiation of Mesenchymal Stem Cells toward the
Osteoblast Lineage256 10.3.1.3Osteoprogenitor Cell256 10.3.1.4Preosteoblasts 257 10.3.1.5Osteoblasts 257 10.3.1.6Osteocytes 257 10.3.1.7Bone Lining Cells 259 10.3.1.8Osteoclasts 259
10.3.2Bone Types 259 10.4Fracture Healing259
10.4.1Stage I: Inšammation259 10.4.2Stage II: So§ and Hard Callus Formation 260 10.4.3Stage III: Bone Remodeling 260
10.5Current Strategies for Bone Repair 260 10.5.1Autogra§ 261 10.5.2Allogra§262 10.5.3Orthopedic Implant Materials 262
10.5.3.1Metals 263 10.5.3.2Bioinert Ceramics264 10.5.3.3Nondegradable Polymers 266
254
10.1 INTRODUCTION Bone is one of the several types of connective tissue found in the body, along with cartilage, ligament, tendon, and muscle. Bone serves three primary functions in the body: it provides (a) mechanically stable points for muscle attachment, (b) protection to internal organs, and (c) stores of ions necessary for normal bodily function (Sarkar et al. 2001). Mechanically sound bone can fail, however, from excessive physical loading, disease, or bone density decrease as a function of aging. In fact, as the average age of the U.S. population rises the number of bone injuries requiring some sort of orthopedic intervention continues to rise as well. …is need sustains a large commercial industry in which ∼3 million musculoskeletal procedures are performed annually in the United States grossing more than $2.5 billion annually. Worldwide, the orthopedic biomaterials market is considerably higher, approximately $14 billion, with a large percentage of this coming from joint replacements and a smaller percentage from fracture management (Ratner et al. 2004). …e nature of these procedures varies considerably with the nature of the injury.
