Adult Medical-Surgical Nursing Musculoskeletal Module: Introduction

The Bones of the Skeleton: Classification  206 bones make up the skeleton:  Axial skeleton (skull and vertebral column)  Appendicular skeleton (limbs)  Bone classification:  Long bones (eg. femur)  Short bones (metacarpals, metatarsals)  Flat bones (scapula, ileum, facial)  Irregular bones (vertebrae)

Joints, Ligaments, Tendons  Classification of joints:  Immoveable (skull, sacro-iliac)  Limited motion (symphysis pubis, vertebral)  Synovial/ freely moveable (synovial membrane lining the joint, secreting lubricating synovial fluid for movement)  Ligaments: articulate bone with bone  Tendons: attach bone to adjacent muscles

Bone Tissue  Cancellous (spongy): more open plan  Cortical (compact): more close together  Lacunae (bone matrix units): arranged in irregular network, “trabeculae”  Periosteum: dense fibrous covering of the bones (attaches ligaments, tendons)  Yellow bone marrow: long bone diaphysis  Red marrow: flat bones, vertebrae, ribs, sternum, ileum, epiphyses:haematopoiesis

Long Bones  The shaft of long bones (diaphysis) is cortical tissue for weight-bearing  The ends of long bones (epiphyses) are cancellous tissue  The ends of long bones are covered at joints with cartilage  The epiphyseal plate: area of growth in childhood, puberty. This is calcified in adulthood

Types of Bone Cells (Osteocytes)  Bone is a dynamic tissue constantly reforming and resorbing:  Osteoblasts (bone formation)  Osteoclasts (bone destruction, resorption, remolding)

Ossification (Bone Formation): Osteoblasts  Osteoblasts secrete collagen and glycoproteins to form a bone matrix  Deposit minerals in the matrix (calcium, magnesium, phosphorus, chloride)  Two ways:  Intramembranous (face and skull) from fibrous tissue  Endochondrial (long bones) from cartilage

Bone Maintenance: Osteoblasts and Osteoclasts  Bone formation by osteoblasts and resorption by osteoclasts is influenced by:  Local stress: usage/ weight-bearing aids bone formation  (Immobility leads to increased calcium resorption from bone and osteoporosis)  Vitamin D (intestinal absorption of calcium)  Parathormone  Calcitonin  Blood supply (inadequate → necrosis)

Stages of Bone Healing following Fracture  Initial trauma → haemorrhage and haematoma  Inflammation/ revascularisation  Callus formation and ossification  Remodelling

Bone Healing: Stage 1  Haemorrhage and haematoma from initial trauma →  Interrupted blood supply causing devitalisation of fractured ends

Bone Healing: Stage 2  Inflammatory process and neovascularisation:  Macrophages promote physiological debridement (inflammation, swelling, pain, loss of function for several days)  Fibrin strands form within fracture haematoma as network for revascularisation, fibroblasts, osteoblasts

Bone Healing: Stage 3  Callus formation:  Collagen and fibrous connective tissue (formed by fibroblasts and osteoblasts) grow towards each other from fractured ends (3-4 weeks)  Ossification of callus (3-4 months in long bone)  Encouraged by immobility, disturbed by excessive movement

Bone Healing: Stage 4  Remodelling to former structure (months-years)

Factors Influencing Healing  Type of fracture and contact of segments  Blood supply  General health, age, nutritional status of the patient: (calcium, vitamin D supplement)  Immobilisation until callus formation with ossification on Xray (serial monitoring)  Surgery: firm approximation/ fixation → quicker healing by direct growth of bone from the endosteum (space within bone)