External fixation

External fixation

1. EXTERNAL FIXATION

2. DEFINITION External fixation is a method of fixing the fractures with a cluster of pins connected to external bars. Lambotte first used it in 1900

3. INDICATIONS Open fractures with severe soft tissue injury To stabilise long bone, periarticular ,pelvic injuries and multiple trauma patient. For fixation of pelvic fractures. For definitive treatment of some fractures of the long bones and pelvis.

4. COMPONENTS OF EXTERNAL FIXATORS It consists of three basic components namely the pin, clamps and the external rod.

5. PINS The pins are passed through the bones at various levels and fixed to an external frame by the clamps.

6. TYPES OF PINS Half pins: These are very commonly used. Full pins: These are centrally threaded and transfix the entire bone. Diameter – 4 to 5 mm. Thin wires(1.5 – 2mm): These are usually used with circular external fixators and it gains its rigidity by tensioning. Olive wires: This is a thin wire with a bull protrusion at one end.

7. OTHER VARIETIES: Cortical pins: Here the thread diameter increases from the tip to the shaft. Self-drilling pins: Causes frequent fractures due to osteonecrosis. Hydroxyapatite coated pins: These helps to prevent pin loosening and migration in porotic bones.

8. CLAMPS These connect the pins to the rods.

9. TYPES OF CLAMPS: Simple clamps: This connects single pin or wires to the rod or ring. Modules clamp: These connects several pins as clusters.

10. RINGS They are extensively used in Ilizarov’s and hybrid fixators. They are made up of stainless steel, aluminium and carbon. Types of rings are Half rings Full rings 5/8 rings.

11. EXTERNAL RODS These connect the cluster of pins through various clamps. They are made up of one of three materials mentioned above and the cross-section varies from circular, square, oval or multiple faced.

12. TYPES OF EXTERNAL FIXATORS Unilateral frame:This is the simplest external fixator frame. Four pins two above and two below the fracture site are passed through the bone and fixed to the frame. Bilateral frame: This improves the frame stiffness and helps in better control of bending and torsional forces Ring fixators: This has been dealt with separately and is multiplanar Hybrid fixators: This helps to combine the advantage of uniplanar and multiplanar external fixator devices. They are especially useful in fixing periarticular fractures.

13. MODE OF ACTION Compression forces: These force helps to stabilize certain transverse fractures and for compression arthrodesis. Distraction forces: These makes the ligaments, capsules, muscles and other soft tissues taut by ligementotaxis . These forces helps in reduction and retention of fracture fragments.

14. Neutralization forces: This provides neutralizing forces across the fracture site. These are frequently used in conjugation with some internal fixation. The common application is seen in distal radial comminuted fractures. Here distraction forces are provided to reduce the fractures and retained by percutaneous fixation and later the distraction forces are released to provide only the neutralising force across the fractures.

15. Angular forces: They are used to bend, rotate and convert the angulations. Used extensively in Ilizarov’s technique.

16. BIOTECHNICAL PRINCIPLES Pin size: Greater is the pin size, greater is the stability of fixation. Pin number: More number of pins ensure better stability. Pin placement: The ideal placement of the pins include very near on either side of the fracture site or farthest away from the fractures. This is known as “Near far construct”. Rod placement: Rods placed closer to the bone gives better stability. Double stacking the rods also increases the stability. Clamps: The rigidity of fixator decreases considerably if the clamps do not hold the pins firmly. Hence, periodic tightening of the clamp is a useful and effective practice.

17. COMPLICATIONS Pin loosening Pin migration Pin breakage Pin tract infection(10%) Impalement of nerves, muscles, tendons, ligaments etc. Chronic osteomyelitis(0-4%) Septic arthritis if pin is placed very close to the joint Soft tissue contracture.

18. PIN CARE FACTS Inspect the pins everyday If there is discharge, dry sterile dressing is advised In the event of infections, wash the wound with 50 percent normal saline and 50 percent hydrogen peroxide The patient can wash the frame with soap and water for less than five minutes Topical antibiotics should be applied if there is infection. Loose pins should be replaced.

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