Ex fix

Ex fix

• 1.
  External Fixator Dr SauravNarayan Nanda, DNB Trainee, Orthopaedics Lilavati Hospital & Research Centre, Mumbai, India
• 2.
  Definition:- It is anarrangement by which bones & bone fragments are held rigidly by metal pins, which are themselves attached securely to a strong external frame.
• 3.
  Development of Ex-Fix System -Transfixing steinmann pin above & below the # site following POP cast -Charnley compression clamps for Arthrodesis -External fixator frames to control the osteotomy site in leg lengthening procedures by Putti, Abbott, hoffman & subsequently modified by Vidal
• 4.
  Indications:-  Closed comminuted#  # associated with excessive soft tissue damage  # with significant loss of bone  Multiple #  Pelvic # with symphysis pubis disruption  Limb lengthening  Plastic surgical procedures  Infected #
• 5.
  Contra-indications:-  Soft osteoporoticbones  Too small boney fragments  Infected lesions at pin insertion site  Impossible situation- irregular supervision  Surgeon not familiar with the equipments and methods.
• 6.
  Types of frames:- Type 1: Unilateral Uniplanar  Type 2: Uniplanar Bilateral  Type 3 Classical: Bilateral Biplanar  Type 3 Delta: Unilateral Biplanar
• 7.
  Choice of frames:- Theframe of choice should fulfil-  Anatomical needs: ‘Safe’ corridor  Clinical needs: Wound access- Secondary procedures  Mechanical needs: stability against bending, torque and axial load
• 8.
  Biomechanics:-  Intrinsic stabilityof frame(S):- S= E I/L (E= Modules of elasticity=const) (I=Moment of Inertia= const) (L=Distance of frame from axis)  Mechanics of Bone Pin interface:- Number, Pitch & Size of pins  Mechanics of Bone Fixator composite:- -stability against Bending Loads - stability against Torsion - stability against Axial Load
• 9.
  Basic Componets:-  Schanzscrews:- 4.5 mm short threaded for diaphysis 5mm long threaded for metaphysis  Clamps :- Universal clamps Open ended clamps Transverse pin adjusting clamps Tube to tube clamps  Tubes:- 11mm (OD)
• 10.
  Instruments:-  Drill:- Handdrill/ low speed , high torque power drill preferred  Drill bits:- long drill bits (200mm) 3.5 and 4.5 mm diameter  Triple guide assembly:- trocar(3.5mm), inner sleeve(3.4/5) & outer sleeve(5/6)  T handle
• 11.
  Steps of application:-  Pre-operative planning  Procedures & techniques  Post operative care
• 12.
  Pre- operative planning:- Consider the merits of the case  Assessment of the extent of # with good quality radiographs  Choosing Suitable types of pins and frames  Choosing best site of pin insertion  Trial run with the apparatus
• 13.
  Procedures & Techniques:- Aseptic precaution  Wound cleaning if needed  # reduction & stabilization with clamps  Adequate stab wounds creation before inserting the pin in its entry & exit point  Pins are drilled into the bone using hand brace  Pins are advanced till engagement of the threaded portion of the pins to both cortices  Pins in one group should be parallel & jig between two groups  Frame is built & adjusted with radiographic view to achieve the boney fragments in desired position  Dressing of pin site & covering of sharp ends with caps
• 14.
  Post operative care:- Daily examination of the limb & the apparatus  Examination of skin condition- inflamed or tensed  Regular radiographic assessment of boney fragments  Encourage to exercise all affected joints on the day after application of the device  Bed rest until skin wound is healed following non weight bearing mobilization with crutches  Partial weight bearing after callus formation  Frame is removed after radiographic evidence of # union  Partial weight bearing for 1st 1-2wks after removal of the device
• 15.
  Complication:-  Infection ofskin wounds  Infection of bone  Development of joint stiffness  Damage to blood vessel, nerve, or tendons by transfixing pins