minimally invasive plate osteosynthesis overview

MINIMALLY INVASIVE PLATE OSTEOSYNTHESIS Overview Introduction - PowerPoint PPT Presentation

Kirsten Deruddere Residents Forum 2014 Advanced Vetcare - Melbourne MINIMALLY INVASIVE PLATE OSTEOSYNTHESIS Overview Introduction Bone healing principles and interfragmentory strain theory ORIF vs biological osteosynthesis

  1. Kirsten Deruddere – Residents Forum 2014 Advanced Vetcare - Melbourne MINIMALLY INVASIVE PLATE OSTEOSYNTHESIS

  2. Overview ⦿ Introduction ⦿ Bone healing principles and interfragmentory strain theory ⦿ ORIF vs biological osteosynthesis ⦿ Changes in plate design ⦿ MIPO principles ⦿ Important articles for exams

  3. Plating History ⦿ Plating has been used since the 1800’s. ⦿ Common complications included infection, malunion or nonunion or poor return to function. ⦿ Steam sterilisation (1886) and xrays (1895) ⦿ 1949 – link between stability and type of bone healing was made

  4. Bone Healing Principles

  5. Direct Bone Healing Summary Absolute stability � Simple fractures and ⦿ osteotomies, articular fractures Accurate anatomic reduction ⦿ Open reduction with direct ⦿ visualisation of fragments Little/no callus forms ⦿ Absolute stability using: ⦿ plates and screws, lag screws, pins, etc Healing takes 2-3 months in ⦿ young animals, up to 12 months in adults

  6. Indirect Bone Healing Summary ⦿ Comminuted fractures, Relative stability non-articular fractures ⦿ No accurate anatomic reduction ⦿ Ideally the fracture is not exposed ⦿ A large callus forms ⦿ Relative stability is achieved using: cast, bridging plates, IM pins, ESF, etc ⦿ Healing takes 4-6 weeks in young animals, or up to 12 weeks in adults

  7. Spectrum of Stability IM Nail Ex Fix Bridge Plating Cast Compression Plating/ Lag screw Absolute Relative (Rigid) (Flexible)

  8. Interfragmentory Strain Theory ⦿ Pluripotent cells are responsive to local deformation within a fracture gap and different tissues can withstand specific levels of deformation beyond which they are unable to survive. ⦿ Granulation tissue (100%)>cartilage (15%)>Bone (2%) ⦿ Bone resorption occurs at the fracture gap under conditions of relative stability to increase the gap, decrease strain and encourage deposition of cartilage and fibrous tissue.

  9. The AO Principles 1962 – AO principles ⦿ (1) restoration of anatomy, ● ● (2) stable fracture fixation, (3) preservation of blood supply, ● (4) early mobilization of the limb and patient. ● � New AO Principles ⦿ Fracture reduction and fixation to restore anatomical relationships; ● ● Fracture fixation providing absolute or relative stability as the “personality” of the fracture, the patient, and the injury requires; ● Preservation of the blood supply to soft tissues and bone by gentle reduction techniques and careful handling; Early and safe mobilization and rehabilitation of the injured part and the ● patient as a whole. � Gradual change to more biological fixation ⦿ ● Plate application Plate design ●

  10. Change from ORIF to Biological Fixation

  11. Change from ORIF to biological osteosynthesis ⦿ Factors contributing to osteomyelitis, non-union and sequestration (Rozbruch 1998): ● Extensive soft tissue dissection ● Disruption of the fracture haematoma ● Multifocal periosteal necrosis secondary to plate compression ● Iatrogenic trauma associated with interfragmentary implants such as lag screws and cerclage wires. � ● Best predictor of success: longer plates and fewer screws ● Time to union during this study went from 20 weeks to 13 weeks as techniques shifted towards biological osteosynthesis. ● Nonunion rates dropped from 10% to 4%. ● Success rates increased despite less use of bone grafts.

  12. ORIF to Biological Osteosynthesis ⦿ Biological osteosynthesis consists of less precise reconstruction and less rigid fixation which reduces iatrogenic trauma to the fracture site and encourages early formation of callus with rapid secondary bone healing. ⦿ Generally this requires the use of locked internal fixators which have minimal implant- to-bone contact, long-span bridging and fewer screws for fixation. ● Ie. Interlocking nails, bridge plating and internal fixator-like devices (locking plates).

  13. Principles of Biological Osteosynthesis ⦿ Indirect reduction ⦿ Flexible fixation ⦿ Avoidance of biological damage ⦿ Less reliance on the use of bone grafts � ⦿ The aim is to produce the best biological conditions for healing rather than absolute stability of fixation. ⦿ � early solid union in both humans and animals ● Biological internal fixation is only applicable to living bone

  14. Changes in Plate Design

  15. Limited Contact Plates ⦿ Early temporary porosity � ● A correlation was seen between porosity and the width of contact of the implant � assumed due to damage to the periosteal blood supply ⦿ Limited contact plate ● Minimise bone contact and impingement on periosteal blood supply � minimises soft tissue necrosis

  16. Locking plates (Internal Fixators) Screw heads lock into the plate � axial and angular ⦿ stability. Stability is not dependent on the frictional forces ⦿ generated by lagging the plate to the bone as for conventional plates. Advantages: Threads are unlikely to strip. ⦿ The plate does not need accurate contouring and sits ⦿ off the bone preserving the extraosseous blood supply. Increased strength against pull-out cf DCP ⦿ Monocortical screws can be used because the locked ⦿ head acts as a second cortex. Some locking screws have a thicker core with increased ⦿ bending stiffness.

  17. Locking Plates ⦿ Anatomic reduction is not necessary ⦿ Iatrogenic trauma to the fracture site is minimised ⦿ Ideal for bridging osteosynthesis, comminuted fractures or fractures with large amounts of bone loss. ⦿ Achieves relative stability and secondary bone healing. � ⦿ Locking plates are ideal for MIPO!

  18. Minimally Invasive Plate Osteosynthesis

  19. What is MIPO? Guiot 2011 VS

  20. Minimally Invasive Plate Osteosynthesis 1. Use of indirect, closed reduction techniques; 2. Epiperiosteal plate insertion through small incisions remote to the unexposed fracture site; and 3. Minimal reliance on secondary implants and bone grafts.

  21. Advantages of MIPO (1) ⦿ Reduced operative time ⦿ Decreased risk of infection ● Shorter surgery time, limited soft tissue trauma, less chance of contamination. ⦿ Increased callus formation ⦿ Preservation of periosteal blood supply ○ Farouk Arch Orthop Trauma Surg 1998, J Orthop Trauma 1999, and Borrelli J Orthop Trauma 2002 showed this in humans. ○ Garfolo VS 2011 – showed this in radii in dog cadavers.

  22. Advantages of MIPO (2) ⦿ Faster healing than ORIF, less care than ESF ● Baumgaertel Injury 1998 – sheep ● Johnson JAVMA 1998 – 35 dogs ⦿ Reduced post-op pain ⦿ More cosmetic closure

  23. Disadvantages of MIPO ⦿ Technically challenging ⦿ Less suitable for simple and intra- articular fractures ⦿ Access to intra-op fluoro is recommended ⦿ Fluoroscopy greatly increases radiation exposure to both patient and surgeon

  24. Case Selection Indications: Comminuted diaphyseal or metaphyseal fractures ⦿ Excellent for radial and tibial fractures (Schmokel JSAP 2007) ⦿ � Less applicable: Simple transverse fractures ⦿ Femoral and humeral fractures are more challenging to achieve alignment ⦿ Metaphyseal and epiphyseal fractures – commonly used in humans with ⦿ special plates � Contraindications: Articular fractures ⦿ If anatomic reduction is required fluoro/arthroscopy should be used ⦿ If major neurovascular bundles overly the approach ⦿ MIPO should not be used if bone is necrotic. ⦿

  25. Indirect Fracture Reduction ⦿ The aim of the reduction is to restore length and alignment so that the joints proximal and distal to the fracture are in the correct orientation. ⦿ Vascularised fragments will be incorporated into the fracture callus. ⦿ Indirect reduction – the fracture is not exposed

  26. Reduction – Hanging limb technique

  27. Reduction Forceps

  28. Circular/unilateral ESF

  29. IM Pin

  30. Pre-contoured plate/push-pull

  31. Fracture Distractor

  32. Traction Tables

  33. Approach Minimise trauma to nerves/vessels ⦿ One distal incision and one proximal, create an ⦿ epiperiosteal tunnel and then stab incisions as needed Optimal number of screws for MIPO in dogs/cats has not ⦿ been determined Human guidelines (Gautier and Sommer) ⦿ ● Span large segments of bone at least 3X the length of the fractured segment ● Screw-to-hole ratio to less than 0.5 ● Leave at least 2-3 screw holes empty over the bone defect. ● Construct stiffness can be increased by increasing plate size, increasing the number of screws or adding an IM pin.

  34. Articles to Read ● Perren J Bone Jt Surg 2002 – Evolution of internal fixation, interesting read and summary of conventional plating, locking internal fixators, reasons for changes in plate designs, ORIF vs MIPO, etc. ● Garfolo VS 2011 – MIPO disrupts less periosteal vasculature of the canine radius than open plating. ● Hudson VCOT 2009 – Great review article on MIPO. ● Rovesti VCOT 2006 – First article using intraoperative skeletal traction in dogs with special tables. ● Pozzi VCOT 2009 – Review of approaches to bones for MIPO – more for practical use than for exams.

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