Biomechanics of Illizarov and corticotomy.pptx

Biomechanics of illizarov and corticotomy principles

1. Biomechamics of illizarov ring fixator Presented by : Dr Rakesh Dhukia Associate professor, SMS Medical College, Jaipur.

2. The External Fixator Malgaigne 1843

3. The External Fixator Type 1 : Monolateral Type 2 : Bilateral Type 3 : Sectorial Type 4 : Semicircular Type 5 : Circular Type 6 : Hybrid

4. The External Fixator

5. Computerized Fixators

6. History AZTECS, EGYPTIANS, SUSRUTA, BOHLER, THOMAS - Coaptation and immobilisation. SARMIENTO - Agains much opposition advocated coaptation and movement. SIR JOHN CHARNLEY - Advocated compression AO GROUP - Expanded the concept.

7. The AO Group acknowledged that absolute rigidity is not necessary for union. Micromotion are beneficial and desirable. Callus assists in healing.

8. Found that compression via tensioned wires produced rapid union and trabecular bridging Which brings us to the circular small wire fixator. GAVRIL ABRAMOVICH ILLIZAROV

9. Stability with Micromotion The illizarov fixator sets out to achieve: UNION DEFORMITY CORRECTION DISTRACTION OSTEOGENESIS

10. Which micromotion is beneficial: Angular - Produces a horse hoof Rotatory - Produces hypertrophy Distraction and side to side - Produces atrophy Dynamic compressive micromotion - UNION

11. How much micromotion is beneficial? < 1mm

12. The Bicycle Spoke Illizarov used bicycle spoke wires for fixation. Resists angular and rotatory micromotion. Allows the surgeon to control compression and distraction. The ICING ON THE CAKE is the earstwhile bicycle spoke.

13. Uniaxial fixators allow extreme rigidity in one axis. Stability in the opposite axis is inadequate. A tensioned wire is never completely stiff. This allows telescopy. The CANTILEVER

14. Controlled Dynamisation From day 1 Limb function is resumed immediately Stability and early movement

15. SUPPORT AND RING RIGIDITY 1. Material : CCM > STEEL > CARBON 2. Number of Rods : MORE NUMBER, MORE STIFFER 3. Ring diameter : SMALLER RING DIAMETER, STIFFER CONSRUCT How to make construct stiffer?

16. THE TRANSOSSEOUS ELEMENT Number : MORE, STIFFER Diameter : MORE, STIFFER Wire tension : MORE, STIFFER Transosseous separation : NEAR TO THE FRACTURE, STIFFER How to make construct stiffer?

17. More the distance of drop pin from the ring, stiffer the construct. The constuct rigidity

18. Higher the angle between two wires, stiffer is the construct. The constuct rigidity

19. Stiffness can be increased by increasing drop wire angulation. The constuct rigidity

20. Bone placed at the centre of the ring is less stiffer construct. Bone placed slightly at periphery is stiffer construct. The constuct rigidity

21. Pins coated with hydroxyapetite provide less chances of loosening and hence a stiffer construct. The constuct rigidity

22. Olive wires provide stiffer construct. The constuct rigidity

23. The constuct rigidity Internal Stability: if oblique fracture, less stability W osteotomy, more stable

24. CONTRADICTIONS Increased transosseous element diameter : OPERATIVE DAMAGE. Increased number of wires : POLYMYOFASCIODESIS AND TETHERING. Increased support distance : BULKINESS. Increases angle : NEUROVASCULAR RISK.

25. Principles of Corticotomy Presented by : Dr Rakesh Dhukia Associate Proffessor, SMS Medical College

26. Corticotomy/Compactotomy ILLIZAROV,1860 Cutting through only compact bone with preservation of periosteum and bone marrow. A well preserved vascular net Minimal surgical trauma to the bone and surrounding soft tissue.

27. Best way to describe it in stages: 1. Length of skin and soft tissue incision only 0.5-1 cm. 2. Location: where bone is closest to skin. Principles of corticotomy technique

28. 3. The cortex transection to be performed with a small osteotome (preferably 0.5cm)/corticotome so it does not cut into periosteum or marrow. 4. A direct transverse cut to priosteum, separation avoided to protect periosteal arterioles. Principles of corticotomy technique

29. 5. Cortex transection should begun with hammering in fanshaped manner directing the tip to both side without extracting it. 6. There should be minimal blood loss, appearence of dark blood with fatty inclusions is a sign of marrow penetration(stop sign). Stop tapping and transect laterally. Principles of corticotomy technique

30. 7. Sound changes to low pitch or loss of resistance meant cortex is transected, now stop tapping and change the direction without extracting the tip. 8. When the transection of the bone walls is complete there will be signs of penetration outside of the cortex in two side points located opposite the initial cut. A triangular transection is developed. Principles of corticotomy technique

31. 9. Osteotome handle turned with pliers at the farthest point. Cracking sound is sign of complete corticotomy. 10. Careful rotation of distal ring to confirm complete corticotomy (avoid stretching of nerves). Principles of corticotomy technique

32. 11. Always two views (AP and lateral) must be taken to confirm complete transection. 5mm distraction is produced to see the gap better. 12. Minimal distraction(about 2mm) is maintained till distraction is started. Principles of corticotomy technique

33. Avoid the bone transection in center(save nutrient artery). Most suitable segment - where medullary cavity transition into trabecular bone. At leas 6-7 cm away from joint. Area of previous injury, infection, surgery are avoided Most suitable level - metaphysis Level of corticotomy

34. Monofocal Bifocal Types

35. Split off corticotomy - for partial bone defect. S shaped corticotomy - for osteomyelitic cavities. Corticotomy for transverse shifting and bone widening. Special types

36. Typical Mistakes Incision too large. Periosteal separation. Oversized osteotome. Poor choice of level. Destructive hammering and direct cut through medullary canal Induction of bone cut to nearby wire tract. Performance of twisting maneuver before cus are complete. Loss of fragment alignment.

37. Books and youtube help all orthopedic surgeons. But for illizarov you still need an old fashioned teacher.