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Details About DISLOCATION

DEFINITION

  • A joint is dislocated when its articular surfaces are completely displaced, one from the other, so that all contact between them is lost.

CLASSIFICATION ON THE BASIS OF AETIOLOGY

  1. CONGENITAL DISLOCATION
  2. Congenital dislocation is a condition where a joint is dislocated at birth e.g., congenital dislocation of the hip (CDH).
  • ACQUIRED DISLOCATION
  • Acquired dislocation may occur at any age.

Types of Acquired Dislocation

  1. TRAUMATIC DISLOCATION
  • Injury is by far the commonest cause of dislocations and sub-luxa tions at almost all joints.
  • The force required  to dislocate a particular joint varies from joint to joint.

DIFFERENT TYPES OF TRAUMATIC DISLOCATIONS

TYPESDEFINITIONEXAMPLE
ACUTE TRAUMATIC DISLOCATIONThis is an episode of dislocation where the force of injury is the main contributing factor .Shoulder dislocation
OLD  UNREDUCED DISLOCATIONA traumatic dislocation, not reduced, may present as an old unreduced dislocation .Old posterior dislocation of the hip
  RECURRENT DISLOCATIONIn some joints, proper healing does not occur after the first dislocation. This results in weakness of the supporting structures of the joint so that the joint dislocates repeatedly, often with trivial trauma.Recurrent dislocation of the shoulder and patella
FRACTURE-DISLOCATIONWhen a dislocation is associated with a fracture of one or both of the articulating bones, it is called fracture  dislocation.A dislocation of the hip is often associated with a fracture of the lip of the acetabulum
  • PATHOLOGICAL DISLOCATION
  • The articulating surfaces forming a joint may be destroyed by an infective or a neoplastic process, or the ligaments may be damaged due to some disease.
  • This results in dislocation or subluxation of the joint without any trauma e.g., dislocation of the hip in septic arthritis.

PATHOLOGY

Dislocation cannot occur without damage to the protective ligaments or joint capsule.

Usually the capsule and one or more of the reinforcing ligaments are torn

 Permitting the articular end of the bone to escape through the rent

 Sometimes, the capsule is not torn in its substance but is stripped from one of its bony attachments

Rarely, a ligament   may withstand the force          of the injury so that instead of ligament rupture, a fragment of bone at one of its attachments may be chipped off (avulsed).

At the time of dislocation, as movement occurs between the two articulating surfaces

 A piece of articular cartilage with or without its underlying bone may be ‘shaved    off’

Producing an osteochondral fragment within the joint.

CLINICAL FEATURES

  1. Pain
  2. Loss of function
  3. Deformity
  4. Restricted mobility

RADIOLOGICAL EXAMINATION

  1. X-ray should always be taken in two planes  at right  angles to each other
  2. CT scan may also be of help.

COMPLICATIONS

EARLYLATE
RecurrenceMyositis OssificansPersistent InstabilityJoint StiffnessRecurrenceOsteoarthritisAvascular Necrosis.

TREATMENT

  1. ACUTE TRAUMATIC DISLOCATION
  • urgent reduction of the dislocation by:
  1. Conservative methods
  2. A dislocation may be reduced by closed manipulative manoeuvres.
  3. Prolonged traction may be required for reducing some dislocations.
  • Operative methods
  • Operative  reduction in case of:
  • Fracture-dislocation
  • Old unreduced dislocations
  • RECURRENT DISLOCATIONS
  • An individual episode is treated like a traumatic dislocation.
  • For prevention of recurrences, reconstructive proce -dures are required.

DISLOCATION OF SHOULDER JOINT

DEFINITION

  • When the head of humerus is displaced and loses contact with the glenoid cavity, the condition is called dislocation of shoulder.

CLASSIFICATION

    ACUTE DISLOCATIONAnterior DislocationIn this injury, the head of the humerus comes out of the glenoid cavity and lies anteriorly.
Posterior DislocationIn this injury, the head of the humerus comes to lie posteriorly, behind the glenoid.
Inferior Dislocation (Luxation Erecta)The head comes to lie in the subglenoid position.
RECURRENT DISLOCATION 
  1. ACUTE DISLOCATION
  2. ANTERIOR DISLOCATION

DEFINITION

  • In this injury, the head of the humerus comes out of the glenoid cavity and lies anteriorly.

CAUSES

  1. Fall on hand with external rotation of shoulder.
  2. Violence of the joint with upper arm in abduction.
  3. Wide range of movement.

CLASSIFICATION

PreglenoidThe head lies in front of the glenoid. 
SubcoracoidThe head lies below the coracoid process. Most common type of dislocation. 
SubclavicularThe head lies below the clavicle.

PATHOLOGICAL CHANGES

Bankart’s lesionAvulsion of a piece of bone from antero-inferior glenoid rim.
Hill-Sachs lesionThis is a depression on the humeral head in its postero-lateral quadrant.
Rounding off of the anterior glenoid rimOccurs in chronic cases as the head dislocates repeatedly over it.
Associated injuriesFracture of greater tuberosityRotator-cuff tearChondral damage

CLINICAL FEATURES

  1. Extreme pain and swelling of affected shoulder joint.
  2. Pt. resents any movement of shoulder.
  3. Arm may not always lie by the side, may be in slight abduction.

DIAGNOSIS

  1. Gap under the edge of acromion due to absence of humeral head.
  2. On palpation just below the coracoid process, head of humerus may be felt there.
  3. Flattened shoulder.
  4. Abnormal prominence of acromion due to absence of humeral head.
  5. Few tests are performed:`
Dugas’ TestInability to touch the opposite shoulder.
Hamilton Ruler TestBecause of the flattening of the shoulder, it is possible to place a ruler on the lateral side of the arm. This touches the acromion and lateral condyle of the humerus simultaneously.
Callway’s TestVertical circumference of axilla is increased in comparison to the other side.
Bryant’s TestAnterior & posterior folds of axilla are at different levels.
  • X-ray – Trans Lateral View.
  • CT scan

TREATMENT

  1. Reduction under sedation or general anaesthesia
  2. Followed by immobilisation of the shoulder in a chest-arm bandage for three weeks.
  3. After the bandage is removed, shoulder exercises are begun.

TECHNIQUES OF REDUCTION OF SHOULDER DISLOCATION

      KOCHER’S MANOEUVREThis is the most commonly used method. The steps are as follows: Traction— with the elbow flexed to a right angle steady traction is applied along the long axis of the humerus; External rotation—the arm is rotated externallyAdduction—the  externally rotated arm is adducted by carrying the elbow across the body towards the midline; Internal rotation – the arm is rotated internally so that the hand falls across to the opposite shoulder.
  HIPPOCRATES MANOEUVREIn this method, the surgeon applies a firm and steady pull on the semiabducted arm. He keeps his foot in the axilla against the chest wall. The head of the humerus is levered back into position using the foot as a fulcrum.
      GRAVITATIONAL TRACTIONManoeuvre is performed without GA. Pethidine 200 mg is administered. Pt. lies prone on the table. Place a sandbag under the clavicle and arm is allowed to hang over the side of table. Maintain the same position Shoulder is reduced within an hour
  • POSTERIOR DISLOCATION

CAUSES

  1. Due to fall on outstretched hand and internally rotated head.
  2. Direct blow on the front of the shoulder.
  3. Forced internal rotation of the abducted shoulder.

CLINICAL FEATURES

  1. Pain
  2. Deformity
  3. Local tenderness

INVESTIGATIONS

  1. X-Ray – Axial lateral or translateral view

TREATMENT

  1. Arm is abducted at 90⁰ and traction is applied

Then externally rotated

On complete reduction, arm is rested in a broad arm sling.

  1. RECURRENT DISLOCATION

DEFINITION

  • When the shoulder dislocates repeatedly with decreasing trauma, the condition is known as recurrent dislocation.
  • It is usually an anterior dislocation.

CLINICAL FEATURES

  1. Dislocation of shoulder with trivial trauma.
  2. Self-reduction of shoulder.
  3. Sudden external rotation of shoulder.

TREATMENT

  1. Putti-Platt operation
  2. Bankart’s operation
  3. Bristow’s operation
  4. Arthroscopic Bankart repair

DISLOCATION OF THE ELBOW JOINT

CRITERIAPOSTERIOR DISLOCATIONANTERIOR DISLOCATION
DEFINITIONForearm is pushed backwards.Forearm is pushed upwards.
CAUSESFall on outstretched handSpasm of triceps muscleFall on the elbowAssociated with fracture of olecranon, humerus shaft, ulna, radius.
C / FDeformity and swelling of elbowPt. supports affected elbow with hand  ———————-
INVESTIGATIONSX-RayX-Ray
TREATMENTReduction under anaesthesia followed by immobilisation in an above-elbow  plaster slab for 3 weeksReduction by traction
COMPLICATIONSJoint stiffnessMyositis ossificansMedian and Ulnar Nerve injuryVascular injury

DISLOCATIONS OF THE HIP JOINT

CLASSIFICATION

CONGENITAL DISLOCATION 
    ACQUIRED DISLOCATIONPathological DislocationMay be seen in TB or RA.
Paralytic DislocationFollowing poliomyelitis
  Traumatic DislocationAnterior Dislocation
Posterior Dislocation
Central Dislocation

DESCRIPTION OF DISLOCATIONS

CRITERIAPOSTERIOR DISLOCATIONANTERIOR DISLOCATIONCENTRAL DISLOCATION
    DEFINIITONThe head of the femur is pushed out of the acetabulum posteriorly.This is a rare injuryIn this common injury, the femoral head is driven through the medial wall of the acetabulum towards the pelvic cavity.
            CAUSESThe injury is sustained by violence directed along the shaft of the femur, with the hip flexed. It requires a moderately severe force to dislocate a hip, as often occurs in motor accidents. The occupant of the car is thrown forwards and his knee strikes against the dashboard. The force is transmitted up the femoral shaft, resulting in posterior dislocation of the hip. It is, therefore, also known as Dashboard Injury.Legs are forcibly abducted and externally rotated. Fall from a tree when the foot gets stuck and the hip abducts excessively, or in a road accident.Fall on side or a blow on greater trochanter which breaks floor of the acetabulum and drives the head of femur through the floor of the acetabulum into the pelvis.
      TYPESREGULAR DISLOCATIONIliofemoral ligament is placed anteriorly and remains intact when the dislocation of hip has taken place.IRREGULAR DISLOCATIONWhen iliofemoral ligament is completely torn.PUBIC TYPEWhen the head of fgemur lies in front of pubis.   OBTURATOR TYPEWhen head lies in front of obturator foramen i.e. almost in the perineum.      ———————————————
      C / FH/O severe trauma followed by pain, swelling and deformity (flexion, adduction and internal rotation).Shortening of the leg. One may be able to feel the head of the femur in the gluteal region.The limb is in an attitude of external rotation, flexion, abduction. There may be true lengthening, with the head palpable in the groin.    Swelling and bruises in the trochanteric region
CRITERIAPOSTERIOR DISLOCATIONANTERIOR DISLOCATIONCENTRAL DISLOCATION
    INVESTIGATIONSX-Ray : Shenton’s Line is distorted.CT scanX-Ray : Shenton’s Line is distorted.X-Ray:shows fracture of floor of acetabulum femoral head is displaced medially into pelvis.
                TREATMENTTechnique of Closed Reduction The patient is anaesthetised and placed supine on the floor    An assistant grasps the pelvis firmly   The surgeon flexes the hip and knee at a right angle and exerts an axial pull   Usually one hears a‘sound’ of reduction, after which it becomes possible to move the hip freely in all directions   The leg is kept in light traction with the hip abducted, for 3 weeks. ImmobilisationFixed skin traction in a Thomas Splint for 4 weeks and then moblisation on bed for further 2 weeks before wieght bearing.Skeletal traction for 3 weeks through tibial tubercleReduction :Same as posterior dislocation .Under GA, hip is flexed, abducted, and external rotation are corrected by medial rotating and adducting the hip.ImmobilisationFixed skin traction in a Thomas Splint for 4 weeks and then moblisation on bed for further 2 weeks before wieght bearing.Skeletal traction for 3 weeks through tibial tubercleReduction :Under GA, pull thigh strongly and femoral head is levered outwards by adducting the thigh.Immobilisation :Traction is applied distally and laterally for 3 weeks with 15 pounds weight.Rehabilition :After traction has been pulled off, patient may be allowed up with crutches.No weight bearing for 8 weeks.
    COMPLICATIONSInjury to the sciatic nerveAvascular necrosis of the femoral headLate OA of hipMyositis ossificansUnreduced dislocationFemoral nerve injuryObturator nerve injuryAvascular necrosis of femoral headSecondary OAOsteoarthrosisHip stiffnessMyositis ossificans  

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Written by DD

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