External skeletal fixation techniques involve the percutaneous placement of transcortical pins or wires externally connected to a rigid frame to stabilize fractures. It provides minimally invasive stabilization while preserving blood supply, with advantages of immediate weight bearing and joint mobility. Disadvantages include the need for regular cleaning and monitoring to prevent infection, and higher costs compared to internal fixation. Various configurations and equipment like pins, rings, connectors are used for different applications like fracture fixation, limb lengthening, and deformity corrections.

1. External skeletal fixation techniques Shahnawaz ahmad bhat 4857

2. Definition A method of fracture treatment ,that involves the percutaneous placement of a series of transcortical pins or wires , which are externally connected to a rigid frame

3. Indications for use Long bone fractures Open fractures Comminuted fractures that cannot be anatomically reconstructed Osteomyelitis High-energy fractures with soft- tissue injuries and vascular compromise

4. Cont’d........ Transarticular ESF in arthrodesis Temporary splintage during healing of soft tissue or osseous structures Nonunion / with bone graft Corrective osteotomy for antebrachial /tibial growth deformities Limb lengthening procedures

5. Cont’d…… Conjunction with internal fixation- in humeral, femoral or tibial fractures Hybrid ESF system- humeral, radial or tibial fractures with very short distal or proximal fragment

6. Cont’d….. Mandibular or maxillary fractures- usually with acrylic fixators Lubosacral fractures & luxations Avian limb fractures Fracture repair in small exotic mammals

7. Advantages of ESF Minimally invasive method, preserving blood supply & soft tissues No implants at the fracture site Possible closed application which limits iatrogenic trauma Provides immediate wt. bearing after surgery Maintains normal joint mobility Provides optimum environment for osteosynthesis & wound healing compatibility with internal fixation devices Technical ease of application and removal wound management in open fractures Reusability of the pin clamps & connecting bars

8. Disadvantages of ESF Device must be cleaned and monitored regularly Care to prevent additional damage to animal/device Aftercare is more labor intensive More rigid type II and III frames cannot be used for fractures of femur & humerus Difficult to apply and more pain in areas of increased muscle mass Extremely high cost

9. ESF FRAMES LINEAR CIRCULAR HYBRID

10. Equipment ESF 3 BASIC UNITS FIXATION PINS EXTERNAL CONNECTORS LINKAGE DEVICES Inserted into bone To hold major Fragments Support fractured Bones Attach fixation Pins & external Connectors

11. FIXATION PINS : classification on basis of implantation method HALF PIN penetrate only one skin surface but both bone cortices FULL PIN Panetrate one skin surface then both cortices ,and then the opposite Skin Surface

12. On basis of structural design Smooth pin : Rely on friction to remain stable in the bone Threaded pins : Positive profile and negative profile Centrally threaded and end threaded

13. Positive & negative profile threaded pins Pins in which core diameter of the threaded section is smaller than the diameter of the smooth section have negative thread profile If the core diameter is consistent b/w smooth & threaded regions ,thread profile is positive

14. Positive profile transfixation pins used in ESF

15. Centrally threaded & End threaded pins Centrally threaded pins are used as full pins with type ÌÌ or ÌÌÌ external fixator frames Central threads engage bone & smooth pin ends extend beyond the skin surface End threaded pins are described a/c to no. of cortices engaged by threads (one cortex & two cortex end threaded pins) End treaded pin Centrally threaded pin

16. External connectors Made up of stainless steel, titanium alloy , carbon fiber,aluminium or acrylic External fixator & linkage devices may be fashioned from acrylic for ACRYLIC -PIN EXTERNAL FIXATOR (APEF) APEF system contains +ve profile threaded fixation pins ,packaged acrylic & sterilized acrylic column molding tubes

17. SK double clamp Secur-U clamp S K single clamp Kirschner double clamp Kirschner single clamp Kirschner type linkage devices for joining fixation Pins to external connecting bars & external connecting bars to each other.Note the larger holes for the external connecting bars & smaller holes in the bolts for Fixation pins Linkage devices

18. Linear ESF Configurations Type Ì ,ÌÌ or ÌÌÌ configuration TYPE Ì Configuration Utilize half pin splintage fixation pins Connecting frame placed on only one side of the limb Unilateral constructs Classified as * type Іa (unilateral and uniplanar) * type Іb (unilateral and biplanar)

19. Type Ǐ a (unilateral –uniplanar ) fixators All the fixation pins & connecting frame occupy a single plane (uniplanar) Usually applied to cranial medial surface of radius/ tibia and lateral surface of femur/ humerus Fixation pins are half pins

20. Type Ǐb (unilateral -biplanar ) fixators Applied most often to radius & tibia For radius & tibia–one ext. bar is placed on craniomedial surface & 2 nd bar on craniolateral surface

21. Type ǏǏ (bilateral-uniplanar ) fixators Utilize full pin splintage fixation pins Cannot be placed on femur/ humerus because of adjacent body wall Applied only to radius/tibia in mediolateral plane Maximal type ІІa & minimal type ІІb Maximal type ІІa Minimal type ІІb

22. Type ǏǏǏ(Bilateral-biplanar)fixator Combination of type І and type ІІ Type І and type ІІ systems placed approx. 90 ° to each other Can’t be applied to femur or humerus Indicated in very large dogs

23. TIE-IN CONFIGURATION Combination of ESF (type Іa or Іb) with intramedullary pin Increases rigidity of fracture fixation in humerus & femur as type ІІ &Type ІІІ frames cannot be applied No. of fixation pins is limited to 2 or 3 pins above & below the fracture

24. Tie –in configuration

25. Biomechanics Fixator rigidity depends on: Type of configuration- Type ІІІ > type ІІ > type І biplanar type Іb more resistant to cranial/caudal shear forces compared with type ІІ. Number of used pins: at least 2 & up to 4 pins/bone segment Diameter and design of the pins – the diameter ≤ 25 % of the bone’s diameter The fixator rigidity by widening pin spacing within pin groups & by the distance between pin groups The most central pin should be 1-2 cm away from the fracture line

26. Cont’d….. Moving the connecting bar closer to the bone makes the pins more resistant to bending Using a “tie-in” configuration increase significant in bending strength

27. Fixation pin application Preoperative planning Patient fracture assessment Most important principle -asceptic surgery Injured limb suspended from hook in the ceiling Patient Draping choose a surgical approach Delimitation of safe corridors for insertion of pins

28. Cont’d…….. Most proximal and distal pins inserted after a stab skin incision Predrilling a pilot hole with slightly smaller diameter drill bit Transfixating pins inserted by using low-speed power drill Fracture reduced & connecting bar connected to proximal and distal pins by clamps Clamps placed 1-2 cm away from the skin surface Central pins are inserted above and below the fracture Rest of needed pins inserted & bolts tightened

29. Postoperative management Postoperative analgesia Pin-skin interface cleaned with antiseptic solution Incision around pins released/extended in case of skin tension Sterile gauze sponges placed around & b/w fixation pins Limb wrapped with vetrap (bandage material ) Activity restricted to least walking & physical rehabilitation

30. Circular External Skeletal Fixators(CESF) ( Ilizarov technique) Most recent innovation in ESF technique in dogs and cats & also in large animals. Developed by the Russian physician Gavriil A. Ilizarov CESF consist of a series of complete and/or incomplete external rings that are interconnected by a series of threaded rods

31. Cont’d….. These are modular systems which can be assembled in numerous configurations to stabilize fractures and arthrodeses, perform bone lengthening and transport correct angular, translational and rotational deformities Each ring is secured in position along the rod by placing a nut on either side of the ring

32. Cont’d…. Elongation of the frame allows for distraction osteogenesis in which regenerate bone is produced within the gap created when an osteotomy is distracted slowly and sequentially “ Discontinuity of a skeletal segment necessarily triggers the repair process which will continue as long as integrity of both osteogenic tissue & its vascular supply is maintained” Traditional CFs use small diameter wires, rather than pins, as fixation elements

33. Standard circular fixator frame for fracture management

34. Bones can be lengthened by streching a corticotomy 1mm a day The regenerate is composed of Microcolumns originating from both bone ends Radiograph of distraction Callus at 3 wks

35. Regenerated bone appears in the trailing pathway of a distracted bone segment in the dog treated with bone resection & distraction osteogenesis

37. Equipment Wires Rings Wire fixation bolts Threaded rods Nuts Wire tensioner & wrenches

38. Wires : 1.0,1.2 or1.5mm diameter used in cats/ dogs Olive wires- wires with a bead positioned midway along the wire Provide interfragmentary compression & increase stability of frame construct more the no. of fixation wires- more stability of fixation Wire angles < 45°should be avoided

39. Olive wires

40. Rings Partial ring & full ring Five–eighth/stretch ring are used when rings would limit joint motion (elbow/stifle) Partial rings -versatile Full rings -more available holes for rods & wire, not versatile ring diameter , axial stiffness, torsional & bending stiffness Smallest ring allowing ≥2 cm distance b/w skin & inner circumference of ring selected

41. Wire fixation bolts Cannulated wire fixation bolts –allow wire passage via a concentrically placed hole at base of bolt head Slotted wire fixation bolts have an eccentric slot located under the bolt head & parallel to its long axis Wire must be fixed without deformation

42. Frame construction Threaded rods used to connect rings & form frame Telescopic rods- hollow rods used as supports & connecting elements of ring Frames are constructed so that one ring & its wires are placed at proximal end and another ring & its wires are placed at distal end of long bone 2 additional rings placed so that their wires panetrate proximal & distal bone segments close to the fracture

43. Wire tensioner

44. Hybrid External Fixator Combination of a ring & a linear fixator Indicated for fractures with juxtaarticular bone segments May be applied to radius,tibia,femur & humerus Can also be used to stabilize corrective osteotomies for angular limb deformities

45. Larger transfixation wires can be combined with the use of rings & wires in a Hybrid frame

46. Clinical Applications of ESF Fracture fixation Radial & tibial Humeral & femoral Mandibular & maxillary Stabilization of spinal fractures & luxations Arthrodesis Bone lengthening Bone transport for bone defects Angular limb deformity correction

47. Fixation of spinal fractures & luxations Spinal arch external fixator components developed for spinal stabilization Fluoroscopically guided percutaneous pin placement can be performed when applying external skeletal spinal fixation

48. Bone transport (limb salvage) Method by which one or two segments of normal bone adjacent to a defect are slowly transported into the defect while new bone forms in the distraction pathway Used in dogs with radial/tibial neoplasia or severe osteomyelitis with bone loss A segment of bone is created with a corticotomy made 2-3 cm from one end of one of the main fragment

50. Acrylic external fixation Acrylics are commonly used for the repair of fractures The acrylic column acts as both the connecting rod and transfixation pin-gripping device Dental acrylic or hoof repair acrylic are suitable It can be moulded over pins after curing to a dough stage Acrylic ESF offers the advantage of reduced cost , improved versatility & simplified application technique when compared with kirschner ESF

51. Advantages of acrylic system Ability to contour the connecting bar to match any fracture configuration Fixation pins of any diameter may be used Fixation pins do not have to be in the same longitudinal plane Light in weight encouraging earlier return to function

52. cont’d…… Placing the positive profile threaded pin without the difficulties of passing them through clamps Inexpensive system

54. Uses of acrylic fixators Fixation of mandibular & maxillary fractures Fixation of long bone fractures Primary fixation device or intra-oral splint for mandibular & maxillary frcatures

55. Complications of ESF Pin tract infection Focal osteomyelitis Ring sequestrum Premature pin loosening Instability at the fracture site Pin breaking Pin tract osteolysis Pressure necrosis of skin Iatrogenic bone fracture soft tissue impalement

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