Bone Fracture PDF

Bone fracture Prepared by Dr. Rasha Arafa Pathology department Important bone lesions include 1. Fracture 2. Inflammations 3. Osteodystrophies: abnormal bone formation and growth. 4. Tumors.  Histology of bone Long bones are divided into 3 zones: 1. Epiphysis: The part of bone distal t...

Bone fracture Prepared by Dr. Rasha Arafa Pathology department Important bone lesions include 1. Fracture 2. Inflammations 3. Osteodystrophies: abnormal bone formation and growth. 4. Tumors.  Histology of bone Long bones are divided into 3 zones: 1. Epiphysis: The part of bone distal to the growth plate. 2. Metaphysis: The part of bone immediately adjacent to the growth plate and is situated between it and the diaphysis. 3. Diaphysis: The region between 2 growth zones. Gross structure of bone: 1. Thick compact bone: Present in the cortex of long and short bones. 2. Cancellous bones: It is formed of trabeculae perforated by the marrow spaces. It is present in the centers of ribs, vertebrae, and flat bones as skull, scapula, and sternum and sacrum epiphysis of long bones and medulla of long bones.  Histological structure of bone: Bone is formed of: 1. Bone matrix: The bone matrix is formed of mineralized type I collagen where Calcium and phosphate salts, as well as carbonates and citrates are deposited. 2. Bone cells: There are 4 types of bone cells: a) Osteogenic bone cells: They are primitive cells, which can differentiate into osteoblasts. They develop from undifferentiated cells called pericytes present around blood capillaries in the periosteum, endosteum, in the bone marrow cavities and in the Haversian canals. b) Osteoblast cells: They are bone-forming cells. They synthesize the organic components of bone matrix: collagen and glycoprotein to form the osteoid. They also secrete the enzymes phosphatase and pyrophosphates concerned with calcification of bone. They are present at the surface of bone tissue i.e. in the periosteum, endosteum and lining the bone marrow cavities in spongy bone and along the bone trabeculae. c) Osteocytes: Mature bone cells. They are present inside the bone lacunae. They are considered as mature osteoblasts surrounded by calcified matrix. Their function is to maintain the bone matrix. d) Osteoclasts: They are responsible for bone resorption. They secrete collagenase and other proteolytic enzymes to dissolve the organic matrix of bone. They are formed because of fusion of multiple blood monocytes. Bone fracture Types of fracture FACTORS AFFECTING BONE HEALING HEALING BY DIRECT UNION Complication