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AO Principles of Fracture treatment & Different Implants.

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AO Principles of Fracture treatment & Different Implants.

  1. 1. AO Principles Of FractureAO Principles Of Fracture Treatment And DifferentTreatment And Different Implant ModalitiesImplant Modalities Dr. Anshu sharmaDr. Anshu sharma
  2. 2. AO System Of ClassificationAO System Of Classification  AO Classification is based on theAO Classification is based on the Type of involved bone (no. 1 to 9),Type of involved bone (no. 1 to 9), Part of involved bone (no. 1 to 3),Part of involved bone (no. 1 to 3), Fracture is extraarticular, partiallyFracture is extraarticular, partially articular or intraarticular ( A,B or C),articular or intraarticular ( A,B or C), Pattern of fracture (1 to 3).Pattern of fracture (1 to 3).
  3. 3. AO PrinciplesAO Principles  The four AO principles of fracture fixation are:-The four AO principles of fracture fixation are:- 1. Fracture reduction to restore anatomical1. Fracture reduction to restore anatomical relationships.relationships. 2. Fracture fixation providing absolute or relative2. Fracture fixation providing absolute or relative stability as the “personality” of fracture, patient andstability as the “personality” of fracture, patient and injury requires.injury requires. 3. Preservation of blood supply to soft tissues and3. Preservation of blood supply to soft tissues and bone.bone. 4. Early and safe mobilization of the injured part and4. Early and safe mobilization of the injured part and the patient as a whole.the patient as a whole.
  4. 4. Fracture ReductionFracture Reduction  Aim of reductionAim of reduction Some fractures are reduced to restoreSome fractures are reduced to restore 1. The bony anatomy and morphology, when perfect1. The bony anatomy and morphology, when perfect anatomical reductionanatomical reduction is required.is required. 2. The relationship between the proximal and distal main2. The relationship between the proximal and distal main fragments. Length, alignment and rotation are restored.fragments. Length, alignment and rotation are restored. This isThis is functional reductionfunctional reduction..  Reduction methodsReduction methods The decision, which reduction method should be used,The decision, which reduction method should be used, depends on the location of the fracture:depends on the location of the fracture: 1. Meta- and diaphyseal fractures usually need1. Meta- and diaphyseal fractures usually need functional reduction.functional reduction. 2. Joint fractures need anatomical reduction.2. Joint fractures need anatomical reduction.
  5. 5. Reduction of diaphyseal fracturesReduction of diaphyseal fractures •• The functional anatomy is restored (length, alignment,The functional anatomy is restored (length, alignment, and rotational axis).and rotational axis). •• The load-bearing axis of the extremity is restoredThe load-bearing axis of the extremity is restored (especially important in the lower limb).(especially important in the lower limb). •• An exception is the forearm which functions as a singleAn exception is the forearm which functions as a single articular unit.articular unit. Reduction of articular fracturesReduction of articular fractures •• The joint surface is restored anatomically.Gaps and stepsThe joint surface is restored anatomically.Gaps and steps in the articular surface must be avoided.in the articular surface must be avoided.  ““Steps” means that there is a difference between theSteps” means that there is a difference between the levels of two main articular fragments.levels of two main articular fragments.  ““Gaps” means that there is some space between twoGaps” means that there is some space between two adjacent main articular fragments.adjacent main articular fragments.  The axial alignment is restored.The axial alignment is restored.
  6. 6. Fracture FixationFracture Fixation  Goal of fracture fixationGoal of fracture fixation 1. To maintain the reduction1. To maintain the reduction 2. To create adequate stability which:2. To create adequate stability which: -Allows early and optimal function of the injured limb,-Allows early and optimal function of the injured limb, -Minimizes pain.-Minimizes pain.  The main goal of internal fixation is to achieve promptThe main goal of internal fixation is to achieve prompt and, if possible, full function of the injured limb. Althoughand, if possible, full function of the injured limb. Although reliable fracture healing is only one element in functionalreliable fracture healing is only one element in functional recovery, its mechanics, biomechanics, and biology arerecovery, its mechanics, biomechanics, and biology are essential for a good outcome.essential for a good outcome.
  7. 7.  Absolute stabilityAbsolute stability •• There is no movement at fracture site.There is no movement at fracture site. •• It is achieved by interfragmentary compression,It is achieved by interfragmentary compression, eg. lag screws, compression plate.eg. lag screws, compression plate. •• There is no callus formation.Direct bone healingThere is no callus formation.Direct bone healing is achieved.is achieved.
  8. 8.  Relative stabilityRelative stability •• Movement at fracture siteMovement at fracture site •• There is no interfragmentaryThere is no interfragmentary compression at fracturecompression at fracture site.It is achieved by splintingsite.It is achieved by splinting or bridging, eg. elastic nailsor bridging, eg. elastic nails •• There is callus formation.There is callus formation. Indirect bone healing isIndirect bone healing is achieved.achieved.
  9. 9. Absolute (Rigid) Relative (Flexible) Spectrum of Stability Cast IM Nail Compression Plating/ Lag screw Ex Fix Bridge Plating
  10. 10. Practically speaking….Practically speaking….  Most fixation probably involvesMost fixation probably involves components of both types of healing.components of both types of healing.  Even in situations of excellent rigid internalEven in situations of excellent rigid internal fixation one often sees a small degree offixation one often sees a small degree of callus formation.callus formation.
  11. 11. Relative (Rigid) Absolute (Flexible) No callus Fixation Stability Callus Reality
  12. 12. Preservation Of Blood SupplyPreservation Of Blood Supply Care for the soft tissuesCare for the soft tissues •• Evaluation of limb swelling.Evaluation of limb swelling. •• Consideration for staged procedure is important:Consideration for staged procedure is important: - Primary stabilization → external fixation.- Primary stabilization → external fixation. - Secondary stabilization → definitive fixation.- Secondary stabilization → definitive fixation. •• Careful reduction procedureCareful reduction procedure -Too intense efforts for perfect reduction are-Too intense efforts for perfect reduction are risky and Increases infection rate.risky and Increases infection rate. •• Minimal invasive surgery.Minimal invasive surgery. •• Good Nursing care of patient with fractures and CareGood Nursing care of patient with fractures and Care during transfer and positioning.during transfer and positioning.
  13. 13. Postoperative carePostoperative care •• Immediately after surgery,the treated extremity isImmediately after surgery,the treated extremity is positioned above the level of the heart to minimizepositioned above the level of the heart to minimize swelling.swelling.  Adequate pain control.Adequate pain control.  Thrombosis prophylaxis.Thrombosis prophylaxis.  Early recognition and treatment of complications.Early recognition and treatment of complications.
  14. 14.  Early joint motion: CPM (continuous passive motion) machines areEarly joint motion: CPM (continuous passive motion) machines are used to provide a continuous but passive (without force of theused to provide a continuous but passive (without force of the patient) motion for limbs where after surgery (knee or elbow)patient) motion for limbs where after surgery (knee or elbow) stiffness of the limb might be expected.stiffness of the limb might be expected.  Partial weight bearing and gradually full weight bearing.Partial weight bearing and gradually full weight bearing.  During follow-up treatment, not only look at the xrays but also at theDuring follow-up treatment, not only look at the xrays but also at the injured limb. Pain, swelling, and tenderness are signs of eitherinjured limb. Pain, swelling, and tenderness are signs of either instability or infection.instability or infection.
  15. 15. Indications for Internal FixationIndications for Internal Fixation  Displaced intra-articular fracture,Displaced intra-articular fracture,  Axial, angular, or rotational instability thatAxial, angular, or rotational instability that cannot be controlled by closed methods,cannot be controlled by closed methods,  Open fracture,Open fracture,  Polytrauma patients,Polytrauma patients,  Associated neurovascular injury.Associated neurovascular injury.
  16. 16. Benefits of Internal FixationBenefits of Internal Fixation  Earlier functional recovery,Earlier functional recovery,  More predictable fracture alignment,More predictable fracture alignment,  Potentially faster time to healing.Potentially faster time to healing.
  17. 17. Screws • Cortical screws: -Greater number of threads -Threads spaced closer together (smaller pitch) -Outer thread diameter to core diameter ratio is less -Better hold in cortical bone. • Cancellous screws: -Larger thread to core diameter ratio -Threads are spaced farther apart (greater pitch) -Lag effect with partially-threaded screws -Theoretically allows better fixation in cancellous bone Figure from: Rockwood and Green’s, 5th ed.
  18. 18. Lag Screw FixationLag Screw Fixation  Screw compresses bothScrew compresses both sides of fx togethersides of fx together  Best form of compressionBest form of compression  Poor shear, bending, andPoor shear, bending, and rotational force resistancerotational force resistance  Partially-threaded screwPartially-threaded screw (lag by design)(lag by design)  Fully-threaded screw (lagFully-threaded screw (lag by technique)by technique)
  19. 19. 1 2 Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987. Lag Screws • “Lag by technique” • Using fully-threaded screw • Step One: Gliding hole = drill outer thread diameter of screw & perpendicular to fx. • Step Two: Pilot hole= Guide sleeve in gliding hole & drill far cortex = to the core diameter of the screw.
  20. 20. Lag ScrewsLag Screws  Step Three: counter sinkStep Three: counter sink near cortex so screw headnear cortex so screw head will sit flushwill sit flush  Step Four: screw insertedStep Four: screw inserted and glides through the nearand glides through the near cortex & engages the farcortex & engages the far cortex which compressescortex which compresses the fx when the screw headthe fx when the screw head engages the near cortexengages the near cortex Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
  21. 21. Lag ScrewsLag Screws  Functional LagFunctional Lag Screw - note theScrew - note the near cortex hasnear cortex has been drilled to thebeen drilled to the outer diameter =outer diameter = compressioncompression  Position Screw -Position Screw - note the near cortexnote the near cortex has not been drilledhas not been drilled to the outerto the outer diameter = lack ofdiameter = lack of compression & fxcompression & fx gap maintainedgap maintained
  22. 22. Figure from: OTA Resident Course - Olsen Lag Screws • Malposition of screw, or neglecting to countersink can lead to a loss of reduction • Ideally lag screw should pass perpendicular to fx
  23. 23. Neutralization PlatesNeutralization Plates  Neutralizes/protectNeutralizes/protect s lag screws froms lag screws from shear, bending,shear, bending, and torsional forcesand torsional forces across fxacross fx  ““Protection Plate"Protection Plate" Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
  24. 24. Buttress / Antiglide PlatesButtress / Antiglide Plates  ““Hold” the bone up.Hold” the bone up.  Resist shear forcesResist shear forces during axial loading.during axial loading.  Used in metaphysealUsed in metaphyseal areas to support intra-areas to support intra- articular fragments.articular fragments.  Plate must matchPlate must match contour of bone to trulycontour of bone to truly provide buttress effect.provide buttress effect.
  25. 25. Bridge PlatesBridge Plates  ““Bridge”/bypassBridge”/bypass comminution.comminution.  Proximal & distalProximal & distal fixation.fixation.  Goal: Maintain length,Goal: Maintain length, rotation, & axialrotation, & axial alignmentalignment  Avoids soft tissueAvoids soft tissue disruption at fx todisruption at fx to maintain fx bloodmaintain fx blood supply.supply.
  26. 26. Tension Band PlatesTension Band Plates  Plate counteracts naturalPlate counteracts natural bending moment seen withbending moment seen with physiologic loading ofphysiologic loading of bonebone  Applied to tension side toApplied to tension side to prevent “gapping”.prevent “gapping”.  Plate converts bending forcePlate converts bending force to compression.to compression.  Examples: Proximal FemurExamples: Proximal Femur & Olecranon.& Olecranon.
  27. 27. Compression PlatingCompression Plating  Reduce & CompressReduce & Compress transverse or obliquetransverse or oblique fx’s.fx’s.  Unable to use lagUnable to use lag screwscrew  Exert compressionExert compression across fractureacross fracture  Pre-bending platePre-bending plate  External compressionExternal compression devices (tensioner)devices (tensioner)  Dynamic compressionDynamic compression w/ oval holes &w/ oval holes & eccentric screweccentric screw placement in plateplacement in plate
  28. 28. Examples- 3.5 mm PlatesExamples- 3.5 mm Plates  LC-DynamicLC-Dynamic Compression PlateCompression Plate::  stronger and stifferstronger and stiffer  more difficult to contour.more difficult to contour.  usually used in theusually used in the treatment radius and ulnatreatment radius and ulna fracturesfractures  Semitubular plates:Semitubular plates:  very pliablevery pliable  limited strengthlimited strength  most often used in themost often used in the treatment of fibulatreatment of fibula fractures.fractures. Figure from: Rockwood and Green’s, 5th ed. Figure from: Rockwood and Green’s, 5th ed.
  29. 29. Dynamic Compression PlatingDynamic Compression Plating  Compression appliedCompression applied via oval holes andvia oval holes and eccentric drillingeccentric drilling  Plate forces bone toPlate forces bone to move as screwmove as screw tightened =tightened = compressioncompression
  30. 30. Dynamic Compression Plates • Note the screw holes in the plate have a slope built into one side. • The drill hole can be purposely placed eccentrically so that when the head of the screw engages the plate, the screw and the bone beneath are driven or compressed towards the fracture site one millimeter. This maneuver can be performed twice before compression is maximized. Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
  31. 31. Locking PlatesLocking Plates  Screw head has threadsScrew head has threads that lock into threadedthat lock into threaded hole in the platehole in the plate  Creates a “fixed angle” atCreates a “fixed angle” at each holeeach hole  Theoretically eliminatesTheoretically eliminates individual screw failureindividual screw failure  Plate-bone contact notPlate-bone contact not criticalcritical Courtesy AO Archives
  32. 32. Locking PlatesLocking Plates  Must have reduction and compressionMust have reduction and compression done prior to using locking screwsdone prior to using locking screws  CANNOT PUT CORTICAL SCREW OR LAGCANNOT PUT CORTICAL SCREW OR LAG SCREW AFTER LOCKING SCREWSCREW AFTER LOCKING SCREW
  33. 33. Locking PlatesLocking Plates  Increased axialIncreased axial stabilitystability  It is much lessIt is much less likely that anlikely that an individual screwindividual screw will failwill fail  But, plates canBut, plates can still breakstill break
  34. 34. Locking PlatesLocking Plates  Indications:Indications:  Osteopenic boneOsteopenic bone  MetaphysealMetaphyseal fractures with shortfractures with short articular blockarticular block  Bridge platingBridge plating
  35. 35. Intramedullary NailsIntramedullary Nails  Relative stabilityRelative stability  Intramedullary splintIntramedullary splint  Less likely to break withLess likely to break with repetitive loading thanrepetitive loading than plateplate  More likely to be loadMore likely to be load sharing (i.e. allow axialsharing (i.e. allow axial loading of fracture withloading of fracture with weight bearing).weight bearing).  Secondary bone healingSecondary bone healing  Diaphyseal and someDiaphyseal and some metaphyseal fracturesmetaphyseal fractures
  36. 36. Intramedullary FixationIntramedullary Fixation  Rotational and axialRotational and axial stability provided bystability provided by interlocking bolts.interlocking bolts.  Reduction can beReduction can be technically difficult intechnically difficult in segmental andsegmental and comminutedcomminuted fractures.fractures.  Maintaining reductionMaintaining reduction of fractures in closeof fractures in close proximity toproximity to metaphyseal flaremetaphyseal flare may be difficult.may be difficult.
  37. 37. • Open segmental tibia fracture treated with a reamed, locked IM Nail.
  38. 38. • Intertrochanteric/ Subtrochanteric fracture treated with closed IM Nail • The goal: • Restore length, alignment, and rotation • NOT anatomic reduction • Without extensive exposure this fracture formed abundant callus by 6 weeks Valgus is restored...
  39. 39. •Classic example of inadequate fixation & stability •Narrow, weak plate that is too short •Insufficient cortices engaged with screws through plate •Gaps left at the fx site Unavoidable result = Nonunion Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987. Failure to Apply Concepts
  40. 40. SummarySummary  Respect soft tissues.Respect soft tissues.  Choose appropriate fixation method.Choose appropriate fixation method.  Achieve length, alignment, andAchieve length, alignment, and rotational control to permit motion asrotational control to permit motion as soon as possible.soon as possible.  Understand the requirements andUnderstand the requirements and limitations of each method of internallimitations of each method of internal fixation.fixation.

Editor's Notes

  •  
  • Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 8, 1987.
  • Use as sole technique of fixation is limited and advocated only in the fibula and femoral neck and unicondylar fractures.
    Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 8, 1987.
  • Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 8, 1987.
  •  
  • Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p.9, 1987.
  • Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, New York, p. 320, 1987.
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