Bone Screws: Specialized devices used in ORTHOPEDIC SURGERY to repair bone fractures.Fracture Fixation, Internal: The use of internal devices (metal plates, nails, rods, etc.) to hold the position of a fracture in proper alignment.Osseointegration: The growth action of bone tissue as it assimilates surgically implanted devices or prostheses to be used as either replacement parts (e.g., hip) or as anchors (e.g., endosseous dental implants).Bone and Bones: A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.Fracture Healing: The physiological restoration of bone tissue and function after a fracture. It includes BONY CALLUS formation and normal replacement of bone tissue.X-Ray Microtomography: X-RAY COMPUTERIZED TOMOGRAPHY with resolution in the micrometer range.Bone Remodeling: The continuous turnover of BONE MATRIX and mineral that involves first an increase in BONE RESORPTION (osteoclastic activity) and later, reactive BONE FORMATION (osteoblastic activity). The process of bone remodeling takes place in the adult skeleton at discrete foci. The process ensures the mechanical integrity of the skeleton throughout life and plays an important role in calcium HOMEOSTASIS. An imbalance in the regulation of bone remodeling's two contrasting events, bone resorption and bone formation, results in many of the metabolic bone diseases, such as OSTEOPOROSIS.Bone Density: The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.Spinal Fusion: Operative immobilization or ankylosis of two or more vertebrae by fusion of the vertebral bodies with a short bone graft or often with diskectomy or laminectomy. (From Blauvelt & Nelson, A Manual of Orthopaedic Terminology, 5th ed, p236; Dorland, 28th ed)Internal Fixators: Internal devices used in osteosynthesis to hold the position of the fracture in proper alignment. By applying the principles of biomedical engineering, the surgeon uses metal plates, nails, rods, etc., for the correction of skeletal defects.Bone Resorption: Bone loss due to osteoclastic activity.Bone Marrow: The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells.Bone Plates: Implantable fracture fixation devices attached to bone fragments with screws to bridge the fracture gap and shield the fracture site from stress as bone heals. (UMDNS, 1999)Bone Neoplasms: Tumors or cancer located in bone tissue or specific BONES.Bone Development: The growth and development of bones from fetus to adult. It includes two principal mechanisms of bone growth: growth in length of long bones at the epiphyseal cartilages and growth in thickness by depositing new bone (OSTEOGENESIS) with the actions of OSTEOBLASTS and OSTEOCLASTS.Bone Marrow Cells: Cells contained in the bone marrow including fat cells (see ADIPOCYTES); STROMAL CELLS; MEGAKARYOCYTES; and the immediate precursors of most blood cells.Bone Diseases: Diseases of BONES.Bone Transplantation: The grafting of bone from a donor site to a recipient site.Thoracic Vertebrae: A group of twelve VERTEBRAE connected to the ribs that support the upper trunk region.Fractures, Bone: Breaks in bones.Bone Regeneration: Renewal or repair of lost bone tissue. It excludes BONY CALLUS formed after BONE FRACTURES but not yet replaced by hard bone.Bone Nails: Rods of bone, metal, or other material used for fixation of the fragments or ends of fractured bones.Lumbar Vertebrae: VERTEBRAE in the region of the lower BACK below the THORACIC VERTEBRAE and above the SACRAL VERTEBRAE.AxisScoliosis: An appreciable lateral deviation in the normally straight vertical line of the spine. (Dorland, 27th ed)Cervical Vertebrae: The first seven VERTEBRAE of the SPINAL COLUMN, which correspond to the VERTEBRAE of the NECK.Fluoroscopy: Production of an image when x-rays strike a fluorescent screen.Spinal DiseasesBone Matrix: Extracellular substance of bone tissue consisting of COLLAGEN fibers, ground substance, and inorganic crystalline minerals and salts.Surgery, Computer-Assisted: Surgical procedures conducted with the aid of computers. This is most frequently used in orthopedic and laparoscopic surgery for implant placement and instrument guidance. Image-guided surgery interactively combines prior CT scans or MRI images with real-time video.Bone Marrow Transplantation: The transference of BONE MARROW from one human or animal to another for a variety of purposes including HEMATOPOIETIC STEM CELL TRANSPLANTATION or MESENCHYMAL STEM CELL TRANSPLANTATION.Orthopedic Procedures: Procedures used to treat and correct deformities, diseases, and injuries to the MUSCULOSKELETAL SYSTEM, its articulations, and associated structures.Bone Substitutes: Synthetic or natural materials for the replacement of bones or bone tissue. They include hard tissue replacement polymers, natural coral, hydroxyapatite, beta-tricalcium phosphate, and various other biomaterials. The bone substitutes as inert materials can be incorporated into surrounding tissue or gradually replaced by original tissue.Cadaver: A dead body, usually a human body.Orthopedic Fixation Devices: Devices which are used in the treatment of orthopedic injuries and diseases.Sacrum: Five fused VERTEBRAE forming a triangle-shaped structure at the back of the PELVIS. It articulates superiorly with the LUMBAR VERTEBRAE, inferiorly with the COCCYX, and anteriorly with the ILIUM of the PELVIS. The sacrum strengthens and stabilizes the PELVIS.Cervical Atlas: The first cervical vertebra.Bone Cements: Adhesives used to fix prosthetic devices to bones and to cement bone to bone in difficult fractures. Synthetic resins are commonly used as cements. A mixture of monocalcium phosphate, monohydrate, alpha-tricalcium phosphate, and calcium carbonate with a sodium phosphate solution is also a useful bone paste.Spinal Fractures: Broken bones in the vertebral column.Atlanto-Axial Joint: The joint involving the CERVICAL ATLAS and axis bones.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Neuronavigation: Intraoperative computer-assisted 3D navigation and guidance system generally used in neurosurgery for tracking surgical tools and localize them with respect to the patient's 3D anatomy. The pre-operative diagnostic scan is used as a reference and is transferred onto the operative field during surgery.Fracture Fixation, Intramedullary: The use of nails that are inserted into bone cavities in order to keep fractured bones together.Spine: The spinal or vertebral column.Femur: The longest and largest bone of the skeleton, it is situated between the hip and the knee.Bone Diseases, Metabolic