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Locked Plating

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Locked Plating

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    1. Locked Plating

    3. Definition Locked plating, for the purposes of this talk, is a screw and plate construct for the purposes of osteosynthesis, in which the screw engages the plate with a mechanism which secures a fixed angle between the two.

    4. History Locked plating, improvised in various ways for years, and in development for many years, came into widespread commercial availability and clinical use in the United States between 1998 and 2002.

    5. Five stages of new Medical Technology Experimentation Skepticism Fevered enthusiasm / overuse Complications and despair Judicious use

    6. Hopefully, the pendulum is now swinging toward a better understanding of locked plating and judicious useHopefully, the pendulum is now swinging toward a better understanding of locked plating and judicious use

    7. Like much new medical technology, the employment of locked plating was complicated by a lack of a thorough understanding of indications and mechanism of action

    8. The ideal recipe for implant and construct stiffness is still not fully understood. Where maximizing construct stiffness was once the ultimate goal, locked plating has likely created some situations where constructs have, in fact, become TOO stiff.

    9. The correct employment of locked plating techniques necessitates understanding the following: Mechanism of action of locked plating Differences from non-locked plating Indications for locked plating Contra-indications / misuses of locked plating

    10. Recommended Reading Gauthier et al, Injury 2003, Vol 34 Supplement 2, pp. B63-76

    11. Mechanics of locked plating

    12. Traditional (non-locking) plates rely on friction between the plate and the bone achieved by terminally tightening of screws passed through the plate to the bone. Locked plating does not require that the plate be compressed to the bone, as the interface between the plate and screw is secured without this plate-bone compression

    13. With non-locking fixation, failure of fixation may initiate with toggle between the screw and plate, subsequent loss of compression between the plate and bone

    14. Correct and incorrect sequencing in the application of locked plating

    15. Surgical Technique Reduce the joint (if applicable) LAG First (Lag, then Lock) Re-confirm alignment Lock After the second locked screw, no change can be made

    16. The next twelve slides should be viewed as a “slide show”. The screws with green “x”’s represent locking screws, and the screws without “x”’s are non-locking.

    17. (Animation) (In slide show-Bone first shown with no screws showing reduced condyles) First, insert middle conical screw to obtain additional compression Add locking screws to solidify and create fixed angle device (Animation) (In slide show-Bone first shown with no screws showing reduced condyles) First, insert middle conical screw to obtain additional compression Add locking screws to solidify and create fixed angle device

    18. (Animation) Remove middle conical screw and replace with locking screw(Animation) Remove middle conical screw and replace with locking screw

    19. (Animation)(Animation)

    20. (Animation) Now time to coapt plate to shaft 1st screw locked to plate 2nd screw put in load position 3rd screw put in neutral Fragment will not reduce due to the locked screw (Animation) Now time to coapt plate to shaft 1st screw locked to plate 2nd screw put in load position 3rd screw put in neutral Fragment will not reduce due to the locked screw

    21. (Animation) 1st Screw as traditional 4.5 cortical screw Tightened down the bone reduces to the plate 3rd screw as locking screw- eliminates the possibly of toggle and thereby eliminates loosening and shortening Biomechanics especially relevant in osteopenic bone(Animation) 1st Screw as traditional 4.5 cortical screw Tightened down the bone reduces to the plate 3rd screw as locking screw- eliminates the possibly of toggle and thereby eliminates loosening and shortening Biomechanics especially relevant in osteopenic bone

    22. (Animation) Load position to compress fracture(Animation) Load position to compress fracture

    23. (Animation) Axial alignment achieved(Animation) Axial alignment achieved

    24. (Animation) 2nd screw as traditional 4.5 cortical screw reduces bone to plate(Animation) 2nd screw as traditional 4.5 cortical screw reduces bone to plate

    25. (Animation) Axial alignment achieved (Animation) Axial alignment achieved

    26. (Animation) Axial Loading(Animation) Axial Loading

    27. (Animation) Axial loading-Toggle because present construct is relying on friction (Animation) Axial loading-Toggle because present construct is relying on friction

    28. (Animation) 3rd screw as locking screw- eliminates the possibly of toggle and thereby eliminates loosening and shortening(Animation) 3rd screw as locking screw- eliminates the possibly of toggle and thereby eliminates loosening and shortening

    29. Locked Plating Advantages Increased rigidity Decreased toggle Potential use as a reduction tool May permit fixation with less stripping of soft tissues May be helpful in osteoporotic bone

    30. Locked Plating Disadvantages Very expensive Constructs may be too rigid Some percutaneous applications be self-drilling That must be unicortical or strips near cortex No tactile feedback on bone purchase They “allow you to stop thinking” Reduction must still be achieved, it is not magically achieved by locking implant

    31. List of Indications for Locking (Framework)

    32. Indications for Locking Biological Fixation Spanning Comminution (bridging) Percutaneous Techniques in selected indications Implant as reduction tool Metaphyseal / Bicondylar Articular Fractures Short Articular Segment Periprosthetic Fractures Osteoporosis

    33. Biological Fixation Without necessitating compression of the plate to the bone to achieve fixation, locked plating may be applied percutaneously, or with less damage to the vascularized tissue immediately adjacent the bone.

    34. Obese 33 yo female with bilateral open femur fractures

    35. I&D, Spanning external fixation

    36. Locking plate is secured to the peri-articular segment, the metaphyseal is not disturbed or dissected, and then the plate is secured to the diaphysis.

    37. Plate is fixed to the distal fragment in the correct varus / valgus orientation, through a separate incsionPlate is fixed to the distal fragment in the correct varus / valgus orientation, through a separate incsion

    38. Separate incision permits proximal fixation to the boneSeparate incision permits proximal fixation to the bone

    39. Fracture zone is undisturbed, permitting callus formation and secondary healingFracture zone is undisturbed, permitting callus formation and secondary healing

    40. Both the nailed and plated fractures heal with callus Bridging fixation on both sides, with locked bridge plating OR with nail, yields callus formation, secondary bone healing, and good alignment at union.Bridging fixation on both sides, with locked bridge plating OR with nail, yields callus formation, secondary bone healing, and good alignment at union.

    41. Percutaneous Techniques are a form of “biological plating” (in selected indications)

    42. 15 y.o. male

    44. This is a functions like a nail: Secondary healing, Relative stability

    45. Percutaneous / Submuscular Plating

    46. Metaphyseal / Bicondylar Articular Fracture

    47. 36 y.o. male skier

    48. 36 y.o. male skier

    49. With bicondylar involvement, and very small articular segment, locking fixation allows us to secure the joint surface back to the diaphysis in the correct orientation

    50. 4 months out

    51. Long Standing 6 months

    52. Use of Locked Plate as Reduction Tool Lock plate to articular segment in correct alignment Provisionally affix plate to diaphysis Confirm alignment Secure plate to the diaphysis with non-locking or locking screws

    53. Obese 47 y.o. female Open Distal femur fracture

    54. Reduce Joint Reduce jointm then set the correct orientation of the plate on the articular fragment (as with this jg)

    55. Make sure it is not flexed or extended on the lateral view (done in this case with jig)

    56. After joint reduction, make sure that the plate is correctly aligned to the articular segment. Then connect to diaphysis.

    57. Connect reduced joint to Diaphysis

    58. Short Articular Segment

    59. Open Femur Fracture 27 y.o. male Motorcycle vs. flatbed truck, then guard rail Open L femur with segmental loss, Segmental L tibia

    61. Very small remaining articular segment

    62. ORIF and cement spacer in metaphysis

    63. Well healed after subsequent bone grafting

    64. 35 y.o. vs. tractor

    65. Femoral neck fracture plus intertrochanteric fracture equals short articular segment

    68. Periprosthetic Fractures (This is also a form of a short articular segment)

    69. Obese 64 y.o. female

    73. 72 y.o. male TAA Periprosthetic Fracture “Periprosthetic” = Short Articular Segment

    75. Osteoporosis

    76. 74 y.o. diabetic female

    79. Locking Plate Principles Locking plate is an IMPLANT, not a technique There are unique techniques Beware the siren call of M.I.S. (Mal-aligned Implant Surgery)

    80. Locking Implants Still Require Reduction

    81. Unclear Indications / Non-indication

    82. Compression plating in healthy diaphyseal bone does not require locking

    83. 16 y.o. male, healthy bone, non-locking fixation

    84. 18 y.o. female, diaphyseal injury. Locking fixation not necessary

    85. Partial Articular Fractures “B-type fractures” require buttress, not locking.

    86. 24 y.o. male Snowboarder vs. Half-Pipe

    89. Beware “too rigid” construct

    90. 72 y.o. Rheumatoid female on multiple cytotoxic medications. Ground level fall. Repaired with this locking construct

    92. The experience over the last ten years with locking fixation has demonstrated that we now have the ability to make a construct “too strong” or “too stiff”

    93. Particularly in Comminuted metaphyseal fractures, or Very simple transverse or spiral patterns rigid immobilization of the fracture may obliterate all motion, and prevent the formation of callus, leading to non-unions.

    94. In these patterns, the correct answer may be a wider spread of our fixation, allowing more motion around the fragments, and the formation of a more vigorous healing response

    95. Failed varus nonunion revised to this, allowing more motion in the metaphysis and a callus response.

    96. One other potential response to the problem of excess stiffness in locking constructs has been so called “far cortical locking”. This entails over-drilling the near cortex and then placing a screw that engages the far cortex and locks in the plate (see diagram, next slide). This may theoretically allow more motion in the construct, and reduce strain at the screw – plate interface. At the time of this publishing, this technology has not been proven clinically, but may have some promise in the future.

    97. “Far cortical locking”

    98. Locked Plating Mechanics Summary Understand the biomechanical difference from conventional plating Understand the limitations Reduce and lag before locking

    99. Locked Plating Indications Summary Biological Fixation Plate as a reduction tool Metaphyseal / Articular Fractures Short articular segments / periprosthetics Osteoporosis

    100. Thank You

    101. Locked Plating Huge advance in plating Must understand biomechanics and what the various constructs accomplish Need to know and understand the new “rules” of locked plating, as we understand them, and not just apply locked plating blindly

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