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Plates-form and function

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AO principles

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Plates-form and function

  1. 1. Pre Basic CoursePlates - form and functionDr Sudarshan Bhandary
  2. 2. Plate : Form and Function• To understand how changes in the design of plates has evolved to meet the needs of the patient• To understand how you can use a plate in several different ways to achieve different types of fixation
  3. 3. Plate : Form and Function• Absolute stability challenged by biological fixation• Osteosynthesis with plates has a firm place in # treatment• Articular #s require stable fixation• Compromise of cortical blood supply a major drawback of conventional plating
  4. 4. Plate : Form• DCP• Reconstruction plate• Semitubular - 1/3rd Tubular Plate• LC-DCP• PC-FIX• LCP• LISS
  5. 5. DCP - 3.5 and 4.5• First introduced in 1969 by Danis• Revolutionary concept of compression plating• Featured a new hole designed for axial compression• Broad 4.5 for Femur & Narrow 4.5 for Humerus & Tibia• DCP 3.5 for Forearm, Fibula, Pelvis & Clavicle
  6. 6. • The screw hole in DCP is like a portion of an inclined & angled cylinder• When the screw is tightened it results in a movement of bone fragment in relation to the plate
  7. 7. • Screw holes allow 1mm compression• Additional compression with 1 more eccentric screw before locking first screw• Oval shape allows 25* inclination in longitudinal & 7* in transverse plane
  8. 8. Technique of application3 drill guidesa) Concentric (Neutral) - Green collar - 0.1 mm offsetb) Eccentric (Load) - Gold collar - 1 mm offsetc) Universal for buttress mode
  9. 9. Problems with DCP• Unstable fixation leads to fatigue & failure• Strict adherence to principles of compression• Compromised blood supply due to intimate contact with underlying cortex• “Refractures” after plate removal
  10. 10. LC-DCP• Represents a design change• Overcome problems with DCP• Plate footprint reduced• Minimized kinking at screw holes• Allows more inclination of screw in longitudinal plane
  11. 11. Technique of application• New spring loaded drill guide• Without pressure - Eccentric hole• With pressure - Neutral
  12. 12. Tubular plates• 3.5 system - 1/3rd Tubular• 4.5 system - Semitubular• Limited stability• Collared hole• Lateral malleolus• Distal ulna / Olecranon• Distal humerus
  13. 13. Reconstruction plates• Deep notches between holes• Accurate contouring in any plane• Pelvis• Acetabulum• Distal humerus• Clavicle• Olecranon
  14. 14. New Systems• Abolish ill effects of plate to bone contact• Concept of “Internal Fixator”• PC - FIX = First implant designed• Self tapping, unicortical, one length screws• Locking head
  15. 15. LCP – Locking Compression Plate
  16. 16. LCP• Latest in the evolution• “ Internal fixator ”• Combination of locking screw with conventional screw• Extraperiosteal location of plate
  17. 17. LCP• Fixed angle stability• Unicortical fixation option• Load & neutral position of screws• Conical screw head• Large diameter
  18. 18. LISS-Less Invasive Stabilization System
  19. 19. LISS
  20. 20. Plate: Function
  21. 21. Principles of rigid internal fixation with plates• Neutralization Plate• Compression plate• Buttress Plate• Bridge Plate• Tension Band Plate
  22. 22. Neutralisation Plate• Used with lag screws , plate is protective• Neutralises the weight bearing forces to protect the lag screws from axial loading• Lag screw generates forces of 3000 N
  23. 23. Compression plating Techniques• With dynamic compression principle (DCP/LC-DCP)• With tension devise• By contouring plate• Additional lag screw thro plate
  24. 24. Compression plating• Compression through plate - DC / LC-DC• Compression with tension devise
  25. 25. Compression with external devise
  26. 26. Contouring Plates• To fit anatomy of bone• Bending pliers• Weakens plate
  27. 27. Buttress Plate• Used when the fracture will only displace in one direction.• Only useful in metaphyseal fractures• Applied so as to resist one deforming force
  28. 28. AO Organisation☻ Philosophies and techniques of treatment will change with time☻ The philosophy that we exist to improve the care given to our patients will last forever
  29. 29. THANK YOU

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