Stage Fractures:-dissolution in the continuity of bone with or without displacement of fragments. Etiology



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Dr. Zainab Jawad ______ Fracture and their management ______4th Stage

Fractures:-dissolution in the continuity of bone with or without displacement of fragments.

Etiology:-

  1. Extrinsic causes:

  • Direct violence: trauma is the most common causes of fractures i.e. automobile injury, falling from a height

  • Indirect violence: bending, torsional, compression and shearing forces are transmitted in a specific fashion and produce a weak link within the bone. It may result in a fracture. Fracture of femoral neck occurs due to fall on the extended rear leg



  1. Intrinsic causes:

  • Violent contraction of muscle causes avulsion fracture. Such fracture occurs frequently in immature animals

  • Pathologic fracture: Bony or systemic disease i.e. neoplasia, bone cyst, rickets, osteoporosis, osteomalasia and nutritional hyper- parathyroidism

  • Repeated stress: cause fatigue fracture

Types of fractures:

  1. According to extent of bone damage:

  1. Complete fracture: the bone is entirely broken in to two fragments and is generally associated with displacement of fragments

  2. Incomplete fracture: it is common in young animals and is characterized by partial loss of continuity and displacement is minimal e.g. greenstick fracture and fissure fracture

  1. According to displacement of the fractured fragments:

  1. Impacted fracture: one end of broken bone is driven in to other end or one bone is driven in to the fracture side of another. Union is rapid but the bone is shortened

  2. Distracted fracture: bone fragments are separated due to sufficient muscle pull

  3. Depression fracture: the fragments are displaced and produce a cavity e.g. fracture of skull bone

  1. According to severity of fracture:

  1. Simple or closed: the fracture site does not communicate with the exterior of the body

  2. Compound or open: the fracture site communicate with the exterior of the body

  1. According to the direction of the fracture line:

  1. Transverse: the fracture line is at right angle to the long axis of bone

  2. Oblique: the line of fracture diagonal to the long axis of bone

  3. Spiral fracture: the fracture line is spiral along the long axis of bone

  4. Comminuted: it comprises of at least three fracture lines and all of them meet at a common point

  5. Multiple: the bone is broken in to three or more segments and soft tissue injuries are usually severe. The fracture lines do not communicate.

  6. Avulsion: a fragment of bone at the site of muscle insertion is detached due to it is forceful contraction

  1. According to stability of fractured fragments:

  1. Stable fracture: the fragments more or less interlock after reduction thus maintain the approximate length of the segment

  2. Unstable fracture: the fracture fragments are unstable after reduction e.g. comminuted or oblique types

  1. According to location of fracture:

  1. Diaphyseal fracture: fracture occurs in the midshaft near the axial centre of diaphysis

  2. Metaphyseal fracture: fracture within the anatomical metaphysis of long bone

  3. Epiphyseal fracture: fracture of epiphysis occurs in mature animal after closure of the epiphyseal plate

  4. Condylar fracture: fracture of the condyle either medial or lateral or both

  5. Articular fracture: fracture involving subchondral bone and articular cartilage

Diagnosis of fracture: the fracture can be diagnosed by pain at the site of fracture, dysfunction, local trauma, abnormal posture and crepitus and most of the cases have history of injury and sudden onset of symptoms. A systematic logical approach is essential to diagnose a fracture. The points of consideration for diagnosis of fracture are:

Pain: pain over the site of fracture is common. This may be only clinical indication in incomplete fracture

Dysfunction: it is most commonly exemplified by lameness. The focal point of lameness should be located and the diagnosis pursued

Local trauma: the area of fracture is swollen and usually contusion or laceration is present in open fracture

Abnormal posture: deformity, a deviation from the normal anatomical structure may be caused by displacement of bony framework. The displacement of bone fragments in a fracture may be angular, longitudinal and rotational. It may result in abnormal mobility

Crepitus: bony crepitus is the gritting sensation transmitted to the palpation finger by the contact of the broken ends on each other. Sometimes crepitus maybe absent in case fracture ends are far apart or are interposed by soft tissue or are impacted

Radiographic signs: at least two views including joints above and below the fracture are required for radiographic diagnosis.

The radiographic signs include:-

  1. A break in the continuity of bone

  2. A line of radiolucency when fragments distracted

  3. A line of radio-opacity when fragments are compressed or superimposed

Note:- all the above signs do not always occur in all fractures but combination of this signs are always present

Repair of Fracture: the rapidity of healing of a fracture is influenced by age, type of fracture, individual response and presence of systemic or local disease. In addition poor reduction, inadequate immobilization, excessive trauma or lack of aseptic procedure in surgery also interrupt or slow the healing process

The process of healing of fracture can be divided into four stages:

  1. Stage of heamatoma

  2. Formation of primary callus

  3. Consolidation of callus

  4. Resorption, replacement and remodeling

Stage of haematoma:

  1. There is a break in continuity of bone and periosteum

  2. The fracture is surrounded by a haematoma which may contain fragments of periosteum, bone marrow, muscles and fascia. As the blood coagulates, a mesh work of fibrin is formed

  3. Bone cells (osteocytes, osteogenic cells) near the fracture site die

  4. Bone cells at a distance from the fracture line continue to live

  5. Tissues in the surrounding area undergo all the changes characteristic to inflammation in soft tissue due to trauma

Stage of formation of primary callus:

  1. The fragments of tissues enclosed in the blood clot and dead tissue cells in the surrounding area degenerate and disintegrate and are removed by phagocytic activity

  2. Macrophages, proliferating capillaries and fibroblasts invade the blood clots, where they produce a network of fibers or granulation tissue which form a spindle shaped cuff around the site of fracture

  3. The pleuripotential connective tissue cells, osteogenic cells and osteoblast of the periosteum, endosteum and Haversian canals proliferate to form trabeculae of spongy bone and fibrocartilage. This trabeculae of new tissue are oriented in the pattern of a vascular tree and advance towards each other from both sides of the fracture site and unite to form the callus

  4. The proliferation and differentiation of osteiogenic cells destined to form bone begins in periosteum, endosteum and Haversian canals within 48 hr. the proliferation of these cells resultsin the formation of cellular trabeculae which advances from each fragment into the fracture gap

  5. The proliferating cells appear across the fracture segments

  1. The periosteum undergoes increased thickening and advanced under the osteogenic layers

  2. The endosteum aslo undergoes similar thickening and the trabeculae of bone advances

  3. Pleuripotential cells at a distance from the fracture site from cartilage and fibrocartilage

Stage of consolidation: the formation of bony trabeculae (cancellous bone) directly by the osteoblasts and indirectly by the replacement of cartilage by bone (enchondral bone) results in bone union. At the completion of this stage the fragments are united

  1. Trabeculae of bone form on outside of the shaft between the fragments (external callus)

  2. The marrow cavity is filled and united by trabeculae of bone (internal callus)

  3. The zone of necrotic bone are reabsorbed and replaced by living bone

Stage of resorption, replacement and remodeling:

  1. The dead ends of the bone fragments are gradually resorbed and replaced by trabeculae of cancellous bone growing in from the external and internal calluses

  2. The bony callus between the fragments is absorbed and replaced by compact bone. This remodeling continues until the area of union resembles mature compact bone

  3. The medullary cavity is restored

  4. The process of remodeling takes place over many months and it is rate of progress is influenced by all factors which influence the healing time of fractures

Biochemical and physiological changes at the site of fracture healing:

  1. The tissue surrounding the area becomes hyperaemic shortly after the fracture

  2. Due to hyperaemia, resorption and transfer of bone minerals from the fracture ends to the fracture haematoma fluid take place

  3. An enzyme phosphatase, secreted by proliferating cartilage cells and osteoblasts increased in the fracture haematoma about six to eight times than normal

  4. During first on or two weeks, the fracture haematoma is markedly acidic, then the PH returns back to the normal

Diagnosis of clinical union: clinical union is the stage in healing process when fixation devices can easily by remove. It can be confirmed by a definite evidence of a palpable callus, absence of pain on application of angulation stress and absence of movements of fragments at the fracture site; and presence of bony callus at the site of fracture as evidence by X-ray examination

Factors influencing rate of union of fracture: rate of repair of fracture is influenced by many factors

  1. Age: union is rapid in young as compared to adult and old animals

  2. Type of fracture: simple fracture unites early as compared to compound fractures

  3. Site of fracture: fractures of extremities unite early than the fracture of the shaft

  4. Injury to surrounding tissue: less injury to surrounding tissue causes early healing

  5. Infection: the presence of infection at the site retards the rate of healing process

  6. Distance between the fracture fragments: the two ends of fractured bone being wide apart or interposition of soft tissues between the fracture ends retard the rate of union

  7. Stage of blood supply: a good blood supply to the fractured bone enhances fracture healing

  8. Degree of reduction and immobilization: a good reduction and immobilization causes early union of fractured fragments

  9. Complications of fracture: presence of infection at the fracture site, delayed and non- union, injury to major blood vessels and nerves delay healing of fractures

  10. Hormones: thyroid hormone, calcitonin, vitamin A and D in physiological doses and anabolic steroid have been reported to enhance rate of healing. On the other hand, corticosteroids are inhibitor of fracture healing.

Principle of treatment:

  1. Avoid unnecessary handling of the patient

  2. Treatment of shock and hemorrhage, if present

  3. Removal of all contaminated and devitalized tissue

  4. Treatment of wound, if any aseptically

  5. Reduction of the fractured fragment, if necessary, to bring the displaced fragment in close approximity as near as possible

  6. Application of immobilization device to immobilize the reduced part to keep in position till clinical union is achieved

Methods of reduction: reduction of fracture refers to the process of replacing the fractured segments as near to their original position as possible. The chief objectives of reduction are to place fragments in perfect or satisfactory anatomical position, correct all rotational displacement and to restore alignment and proper angulation. It may be carried out in three ways

  1. Close manipulation

  2. Mechanical traction with or without manipulation

  3. Open surgical approach

Complete muscle relaxation facilities reduction. This can be achieved by general anesthesia, regional or local anesthesia or by the use of muscle relaxants.

Manipulation: after determining the position of the fragments by palpation and radiography, the reduction is achieved by direct pressure or by a combination of tension and toggling. This method is used for areas of the body where the bones can be easily palpated. During manipulation care should be taken to avoid the damage to the surrounding tissue

Mechanical traction: this technique is used when muscle exert a strong displacing force. In order to overcome the muscle spasm and to bring the displaced fragments in it is original place, and counter-traction are applied.

A common method of application is to first anchor the upper portion of an appendage to the table. Then another attachment is made between the foot and the body of the surgeon and traction is applied by the surgeon on leaning backwards. Local manipulation can be done by hands to reduce the fragments. A Gordon’s extender can also be used to apply traction and counter-traction in small animals



Open approach: the fracture site is surgically exposed under strict aseptic conditions. The fragments are manipulated to bring them in apposition.

Immobilization or fixation:

Immobilization or fixation of a fracture refers to holding the fractured bone segments so that they are motionless with respect to each other. It should be rigid and uninterrupted during the healing process until clinical union is obtained. It is indicated to prevent displacement or angulation of the fragments and to prevent movement and pain



Method of immobilization:

  1. Coaptation splints or cast

  2. Modified Thomas split

  3. Internal fixation

Coaptation splint or cast:

  1. Plaster or Paris

  2. Plastics

  3. Impregnated gauze

  4. Air cast

  5. Wooden strips

  6. Aluminum strips

  7. X-ray film etc.

The material selected for coaptation splint or cast should be light, durable and have minimum bulk. Following point should be considered while using this type of immobilization

  1. The hairs should not be usually clipped

  2. Sufficient padding (cotton stockinet etc.) should be used to prevent further damage to soft tissue, nerve and circulatory system

  3. All bony prominences should be well padded. Overpadding, should however, be avoided as it might impair immobilization

  4. The cast or splint should fit reasonably well and should be accurately moulded to the configuration of the limb

  5. In most cases, joints above and below the fracture site should be incorporated in the cast

  6. After applying the cast, the reduction should be checked by radiography in two different planes

Modified Thomas splint: this is one of the widely used and adoptable splints for small animals and to some extent in large animals. This splint combines the use of limited traction and fixation and good exposure of affected part. Iron rods or duraluminum of aluminum rods in diameters of 3/16, ¼ and 3/8 of an inch are preferred. It is not ordinary used as the sole method of fixation.

It is indicated for fixation of stable fracture after reduction and to support fixation in combination with other types of fixation in joint, tendon or nerve surgery.



Internal fixation: should be used in the following cases:-

  1. Where it is any easy, economical and assumed means for obtaining reduction, healing and good functional recovery

  2. External fixation is not tolerated by the animal

  3. Early ambulation of patient is required

Following methods are generally used for internal fixation:

  1. Intramedullary pin

    1. Steinmann pin

    2. Rush pin

    3. Kuntsher pin



  1. Plates

  2. Transfixation screws

  3. Circumferential wires

  4. kirschner's splint

  5. bone grafts

complication of fracture:

  • infection at the fracture site: as a result of open fracture or by introduction of organism at the time of open reduction through the blood, localized osteomyelitis, hyperemia, demineralization of the fragmented ends, fibrosis resulting in to delayed union or non- union may occur

Diagnosis:- it can be done based on history, clinical symptoms and X- ray examination

Treatment:

  1. Antibiotic (locally and systemic)

  2. Removal of dead bone or any foreign material in the fractured area

  3. Rigid and uninterrupted immobilization of the fractures



  • Delayed union and non- union:

Causes:-

  1. Imperfect apposition; interposition of soft tissue, stripping of periosteum

  2. Impairment of blood supply

  3. Lack of blood clots between fragments

  4. Infection of bone

  5. Distraction of bone fragments

  6. Osteoporosis

  7. Heavy dose of steroid

  8. Reaction to plates and screw

  9. Functional disuse

  10. Tool early motion and weight bearing

X-ray feature of delayed union:

  1. Wide fracture line

  2. Absence or very little presence of external and internal callus

  3. Presence of feathery or wooly appearance of the bone and periosteum at the fracture site

X-ray feature of delayed non- union:

  1. Rounding of the bone ends with sclerosis at the fracture site

  2. Wide and as well defined gap between the bone fragments

  3. Gradual bowing at fracture site, if weight bearing has been allowed

  4. Atrophy of bone below and above the fracture site

  5. Closure of medullary canal in each fragment

Clinical feature of non-union and delayed union:

  1. Abnormal movement at the fracture site

  2. False or soft tissue callus or minimal production of callus at the fracture site

  3. Bowing at the fracture site

  4. Varying degree of pain on using the part

Management of delayed and non- union:

  1. Method of fixation should be critically evaluated

  2. Inspite of rigid immobilization for a sufficient period of time, a state of non-union or delayed union still persists. Surgical measures to promote osteogenesis should be undertaken

  3. Every effort should be made to prevent infection

  4. Use of bone grafting should be considered


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