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Plate Osteosynthesis

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Principles of Plate Osteosynthesis - Metal Meets Bone

  • Plate Osteosynthesis: Surgical fracture fixation with plates/screws for anatomical restoration.
  • AO Principles:
    • Anatomic reduction: Precise fragment realignment.
    • Stable fixation: Absolute or relative.
    • Blood supply preservation: Minimize soft tissue trauma.
    • Early mobilization: Safe, active movement.
    • 📌 Mnemonic: ASBE (Absolute Stability, Blood supply, Early mobilization).
  • Constructs:
    • Load-sharing: Plate & bone share load.
    • Load-bearing: Plate bears entire load.
  • Healing:
    • Primary: Absolute stability, no callus.
    • Secondary: Relative stability, callus. Load bearing vs load sharing plate osteosynthesis

⭐ Absolute stability (rigid plate) → primary bone healing (minimal callus). Relative stability (bridging plate) → secondary bone healing (callus).

Types & Functions of Plates - The Right Fit

  • Plate Types:

    • DCP (Dynamic Compression Plate): Oval holes → compression.
    • LC-DCP (Limited Contact DCP): Undercut, ↓vascular injury.
    • LCP (Locking Compression Plate): Locking/non-locking screws; angular stability. Internal fixator.
    • Reconstruction: Malleable (pelvis).
    • Tubular (1/3, 1/4): Low-stress (fibula).
    • Specialty: Anatomical (PHILOS, condylar buttress).
  • Plate Functions: 📌 (CNBBT)

    • Compression: Static (prebend)/dynamic (eccentric screw).
    • Neutralization: Protects lag screws.
    • Buttress: Supports articular fragments (tibial plateau).
    • Bridging: Spans comminution; length/alignment.
    • Tension Band: Tension → compression.

Buttress plate function in osteosynthesis

  • DCP vs. LCP:

    FeatureDCPLCP
    MechanismFrictionAngular stability (int. fixator)
    Screw I/FPlate compresses boneScrews lock to plate
    StabilityRelative (axial)Absolute (angular)
    Blood↓ contact↑ preserved (min. contact)
    IndicationSimple #, good boneOsteoporotic, comminuted periart. #

⭐ LCPs: internal fixators, angular stability independent of plate-bone friction. Ideal for osteoporotic bone & comminuted periarticular #.

Indications & Contraindications - Plating Go/No-Go

Indications (Go):

  • Articular Fx (anatomic reduction, abs. stability): e.g., tibial plateau, distal radius.
  • Diaphyseal Fx: Forearm (gold standard), humerus, femur, tibia.
  • Periarticular Fx, osteotomies, nonunion/malunion.

Contraindications (No-Go):

  • Absolute: Active infection, severe soft tissue compromise.
  • Relative: Severe osteoporosis, unfit for surgery, high comminution (IMN better), non-compliance.

Open Fractures (Gustilo-Anderson):

  • Type I & II → primary plating; Type III → staged.

⭐ Plating of both-bone forearm fractures in adults is the gold standard to restore rotational stability (pronation/supination).

Distal radius fracture with volar plate fixation

Surgical Technique - Plating Playbook

  • Pre-op: Templating, implant selection.
  • Approach: Meticulous soft tissue handling (preserve blood supply).
  • Reduction: Direct/Indirect. Provisional K-wires.
  • Plate: Type/length selection. Contour (DCP vital; LCP less if internal fixator).
  • Screws: Lag (interfragmentary compression); DCP (eccentric drilling for compression). Conventional: 3-4 bicortical screws/6-8 cortices per main fragment. LCP: 3 locking screws/fragment. Length: perforate far cortex 1-2mm.
  • Intra-op Imaging: Confirm reduction & hardware.

⭐ To achieve compression with a DCP, the screw is inserted into the eccentric portion of the oval hole, away from the fracture line; tightening the screw then draws the bone fragment towards the fracture.

Eccentric screw placement for compression

Complications - Plate Pitfalls

  • Intraoperative: Neurovascular injury, iatrogenic fracture.
  • Early Postop: Infection (superficial/deep), hematoma, wound dehiscence, compartment syndrome.
  • Late Postop:
    • Implant failure (bending/breakage, screw pull-out/loosening).
    • Biological failure (nonunion, malunion, delayed union).
    • Refracture (post-plate removal), stress shielding & osteopenia, hardware irritation.
  • Prevention: Asepsis, gentle tissue handling, stable fixation.
  • Management (Key):
    • Infection: Debridement, antibiotics, ?implant removal.
    • Nonunion: Bone grafting, revision fixation. Clavicle nonunion with plate breakage and screw pull-out

⭐ Stress shielding under a very rigid plate can lead to cortical osteopenia beneath it, ↑ risk of refracture after implant removal if bone hasn't fully remodeled.

High‑Yield Points - ⚡ Biggest Takeaways

  • Plate osteosynthesis provides absolute stability, crucial for direct (primary) bone healing.
  • Dynamic Compression Plates (DCP) achieve compression via eccentric screw drilling.
  • LC-DCP reduces plate-bone contact, better preserving periosteal blood supply.
  • Locking plates create a fixed-angle construct, acting as an internal fixator, vital for osteoporotic or comminuted fractures.
  • Key indications: articular fractures, forearm fractures, and osteotomies.
  • Stress shielding beneath the plate can cause osteopenia and risk of refracture post-removal.

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Practice Questions: Plate Osteosynthesis

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Nonunion is most common in fracture of the:

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Flashcards: Plate Osteosynthesis

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_____ screws have a smaller thread, low pitch, compression produced by over drilling proximal cortex

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_____ screws have a smaller thread, low pitch, compression produced by over drilling proximal cortex

Cortical

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