Fractures

Published: 27/01/2021

My summary notes on fracture classification, their clinical features and repair process (for compact and cancellous bone).

Classification

 

Fracture type	Characteristics
Open or compound	Bone end or some other object has pierced the skin
Closed	Skin remains intact
Displaced or undisplaced	Refers to the alignment of the fractured bones
Spiral or torsion	A fracture where the bone has been twisted apart
Transverse	A fracture in which the break is across a bone at a right angle to the long axis of the bone
Oblique	A fracture in which the line of break runs obliquely (= slanting) to the axis of the bone
Compression (or crush)	Occurs when the bone collapses e.g. vertebrae
Comminuted	Break or splinter of the bone into more than two fragments (common in high-impact trauma)
Greenstick	A fracture in which one side of a bone is broken and the other is bent
Avulsion (or sprain)	The detachment of a bone fragment that results from the pulling away of a ligament, tendon, or joint capsule from its point of attachment on a bone

 

·        Open (or compound) fracture can create a cause for concern due to the possibility of the introduction of microorganisms leading to osteomyelitis

Clinical features

·        Pain – marked tenderness around the site of the fracture

·        Deformity

·        Oedema – localised immediately after injury and becomes more extensive with time

·        Muscle spasm

·        Abnormal movement or crepitus – may be grating between the broken ends of the bone

·        Loss of function

·        Hypovolaemic shock = an emergency condition in which severe blood or fluid loss makes the heart unable to pump enough blood to the body. This can cause many organs to stop working

Ø  fractured shaft may haemorrhage as much as three pints

·        Limitation of joint movement – affected by adhesion formation, tight muscles, pain, spasm, fear, mechanical obstruction or swelling

·        Muscle atrophy

Repair process

 

Wolff’s law states that bone responds to the stresses that are imposed upon it by rearranging its internal architecture to best withstand the stresses

Simple summary – bone is laid down where it is needed and reabsorbed where it is not

Repair process of compact bone

Haematoma

·        The haematoma forms due to the tearing of blood vessels

·        Very small proportions of the bone immediately adjacent to the fracture die and are gradually absorbed

Periosteal or endosteal proliferation

·        Proliferation of cells from the deep surface of the periosteum adjacent to the fracture site

·        These cells are precursors to osteoblasts and form around each fragment of bone

·        At the same time cells proliferate from the endosteum in each fragment both types of cells forming tissue

·        This tissue gradually forms a bridge between the bone ends

·        During this stage the haematoma is gradually reabsorbed

Callus formation

·        Proliferating cells mature as osteoblasts or in some instances as chondroblasts

·        Chondroblasts form cartilage

·        Osteoblasts lay down the intercellular matrix of collagen and polysaccharide which becomes impregnated with calcium salts forming immature bone called callus (or woven bone) [visible on X-ray]

Consolidation

·        Osteoblast activity results in the change of primary callus to bone (which has a lamellar structure) at the end of this stage union is complete

·        New bone forms a thickened mass at the fracture site and obliterates the medullary cavity

Remodelling

·        The lamellar structure changes and the bone adapts by strengthening along the lines of stress imposed upon it

·        The surplus bone formed during healing is gradually removed and eventually the bone structure appears very similar to the original

·        In children – healing is usually very good, difficult to see fracture site on radiograph

·        In adults – may be a permanent area of thickening which might be felt or seen in a superficial bone

Repair process of cancellous bone

·        Haematoma forms but these is no medullary cavity

·        Cancellous bone has a greater area of contact between the fragments

·        Penetration of the bone-forming tissue is facilitated by the open arrangement of trabeculae as it grows out from both fragments

·        Osteogenic cells lay down intercellular matrix, which calcifies to form woven bone

·        The process of remodelling then continues to form the cancellous bone