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Fractures _ General

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FRACTURES _ GENERAL.
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   FRACTURES : GENERAL   DEFINITION A fracture is defined as a break in the bone.TYPES OF FRACTURES Green stick fracture: It is the fracture in the young bone of children where thebreak is incomplete, leaving one cortex intact . Closed fracture: A closed fracture is one whre the fracture haematoma does notcommunicate with the outside. Open fracture: (Compound fracture) This is one where the fracture haematomacommunicates with the outside through an open wound. A Compound fracture is aserious injury as infection may gain entrance into the body through the wound andthereby endanger the limb or even life. Pathological fracture: It is a fracture occurring after a trivial violence in a boneweakened by some pathological lesion. This lesion may be a localised one, like asecondary malignant deposit or a generalised disorder like hyperparathyroidism orsenile osteoporosis. Stress fracture : It is a fracture occurring at a site in the bone subject to repeatedminor stresses over a period of time. Birth fracture: It is a fracture in the new born children due to child due to injuryduring delivery.ANATOMICAL TYPES OF FRACTURES Various names are given to the fractures according to the types of the fracture linesas transverse, oblique and spiral fractures. Comminuted fracture : Here the bone is broken into than two fragments. Steallate fracture: This occurs in flat bones of the skull and in patella, where thefracture lines run in various directions from one point. Avulsion fracture: This is one, where a chip of bone is avulsed by the sudden andunexpected contraction of a powerful muscle from its point of insertion, e.g. thesupraspinatus avulsing the greater tuberisuty of the humerus. Impacted fracture: This is one where a vertical force drives the distal fragment of the fracture into the proximal fragment. Depressed fracture: This occurs in the skull where a segment of bone getsdepressed into the cranium.MECHANISM OF FRACTURE A fracture can be caused by either by direct violence or indirect violence. Direct RACTURES : GENERALhttp://www.e-radiography.net/radpath/f/fracture.htm1 of 2017/08/2013 3:54 PM  violence causes a fracture at the site if impact of the force. Indirect violence is one thatis transmitted to a bone away from the site of impact producing fracture there. The nature of violence can be often inferred from the radiological appearances of the fracture. Direct violence often produces a comminuted fracture. Torsion produces an oblique or spiral fracture. It is important to understand themechanism of fracture as it helps in deciding the manoeuvres for reduction and theposition for stable immobilisation of the fracture. When a man falls from a cocount tree or building top and lands on his heels, heoften sustains a fracture calcaneum and a fracture of the spine. The fracturecalcaneum is caused by the direct violence is cased cased by cased by indirect violence.CLINICAL TYPES From the clinical and treatment points of view, the following types must berecognised. Fresh fracture: (1) Closed fracture, (2) Open fracture, (3) Complicated fracturewhen the fracture is associated with injuries to the neighbouring vessels, nerves or joints. Malunited fracture: The patient comes with an old fracture united in a badposition. Un-united fracture: The patient presents with and old fracture where thefragments have failed to unite. Pathological fracture: This must be suspected when an old person presents with afracture following minimal violence.BIOLOGY OF FRACTURE HEALING It is important to understand the biological process of fracture healing and thefactors influencing, as it helps one to understand the principles of treatment. Thisprocess varies in cortical and cancerous bone.Fracture healing in cortical bone The process of healing of a fracture is in many respects similar to the process of healing of an incised wound. In the healing of an incised wound, the gap is first filledwith blood which clots and later the haematoma is invaded and replaced bygranulation tissue. As the epithelium grows over the gap, the granulation tissuebecomes a fibrous scar. In the healing of a fracture a similar staging can be seen in theearlier phases. However, the end result in the healing of a bone is the formation of mineralised mesenchymal tissue (callus) uniting the broken ends of bone. Fracture healing will be considered as a series of phases which occur in sequencebut also overlap to a certain extent. (I) Inflammatory Phase.a. Stage or haematoma formation. RACTURES : GENERALhttp://www.e-radiography.net/radpath/f/fracture.htm of 2017/08/2013 3:54 PM  b. Stage of granulation tissue. (II) Reparative Phase.a. Stage of fibrocartilaginous callus.b. Stage of bony callus. (III) Remodelling Phase. Stage of Haematoma: When a bone breaks, the gap is filled with blood from theruptured periosteal and endosteal vessels. This blood distends the soft tissues and clotsto form a haematoma. This process takes about 1-2 days. Stage of granulation tissue: The soft tissues in the region undergo the usualchanges of acute aseptic inflammation with vasodilatation and exudation of plasma andleucocytes. The clotted blood is invaded by fine capillaries and young connective tissuecells and converted into granulation tissue in about 2 weeks. The cellular element in thismass consists of multipotent mesenchymal cells which are capable of differentiating intofibroblasts, chondroblasts and osteoblasts. Stage of callus: The granulation tissue next matures into a fibrocartilaginous masswhich holds the fragments together. Because of the peculiarities of microcirculation in cortical bone there is somedegree of cellular death in the ends of the fracture bone. The fundamental healingresponse of bone to injury is by the primary callus response.   Anchoring callus  forms a little distance away from fracture site to stabilise thefragments. In order to bridge gaps, the bridging external callus forms to establishcontact between fracture ends and promote union. Medullary callus forms late from themedullary cavity to unite with the callus from the opposite end. Thus, according to thesituation and function of callus distributed around the fracture site the callus isdescribed as follows. a) Anchoring callus, b) Bridging callus, c) Uniting callus and d)Sealing callus(Fig. 14. 5). The fibrocartilaginous mass is converted first into  spongy immature  bone and laterinto  mature lamellar bone,  producing bony union between the fragments in about 8-12weeks. This conversion takes place in some areas by membranous ossification and inother areas by endochondral ossification. By this time clinical union of the fracture iscomplete. Stage of Remodeling: Once the fracture has been satisfactorily bridged, the newlyformed bone adapts to its new function. The site of fracture undergoes remodeling bymuscular and weight bearing stresses and any slight deformity gets corrected bymoulding. This remodeling process takes up to a year and is seen better in children. Primary bone healing: Healing of fractures has also been achieved by artificialmethods of mechanical compression between the fracture fragments. In this, externalbirdging callus is suppressed and healing is dependent one of the activity of medullarycallus and direct osteonal penetration. Hence, there is no radiologically visible callus.This has been called ‘Primary bone healing’ in the technique of compression plating of fractures. FRACTURES : GENERALhttp://www.e-radiography.net/radpath/f/fracture.htm3 of 2017/08/2013 3:54 PM  Fracture healing in Cancellous bone In fractues at the metaphyseal ends of long bones and in solid bones like vertebrae,the healing process is different. There is no terminal bone death as in cortical fractures. When there is direct contact of fragments, healing occurs by the process of   creeping substitution . New trabeculae formed by intramembranous ossification are laiddown on the srcinal trabeculae to produce bone between the two fragments. Nobridging callus is formed. Once union is estabilished remodelling occurs.FACTORS WHICH INFLUENCE FRACTURE HEALING Fracture treatment is not purely a question of effective fracture reduction andfixation built a complex biological process. The natural tendency for a fracture is tounite . When delay or failure of union occurs, the causes are either local factors at thesite of fracture or defects in the methods employed in treatment. Causes interferingwith the healing of fractures are:a) Imperfect immobilisation: (i) Too little extent of immobilisation. and (ii) Tooshort a period of immobilisation.b) Distraction : Too heavy a pull of the distal fragment by skeletal traction.c) Surgical intervention : This empties the frcture haematoma and strips theperiosteum, interfering with the blood supply and slowing the healing process.Local causesa) Infection : This is the commonest cause for delayed union or non-union in openfractures.b) Inadequate blood supply to one fragment: Certain sites are notorious for slowunion or non-union e.g. (i) Fracture neck of femur. The blood supply to the head of thefemur is poor. (ii) Fracture scaphoid. The blood supply to the proximal fragment is poor.c) Interposition of soft tissues between the fragment prevents bony apposition andinterferes with healing.d) Type of fracture: Transverse fractures unite slowly compared to oblique orspiral fractures.e) Type of bone: Fracture at the cancerous ends of bone unite better than those inthe mid shaft of long bones where cancellous bone is minimal.General Causes Fractures in children unite very rapidly whereas delayed union is common in the RACTURES : GENERALhttp://www.e-radiography.net/radpath/f/fracture.htm of 2017/08/2013 3:54 PM
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