Intramedullary Nailing

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IMN: Fundamentals & Principles - Pinpoint Precision

  • Intramedullary Nailing (IMN): Load-sharing implant within medullary canal; acts as internal splint.
  • Principle: Load-sharing, aligns fragments along anatomical axis.
  • Advantages:
    • Central load bearing: ↑ biomechanical stability.
    • Minimally invasive options: ↓ soft tissue stripping.
    • Preserves periosteal blood supply.
    • Early mobilization & weight-bearing.
  • Key Concepts:
    • Reaming: Widens canal for ↑ nail diameter/stability. Risks: ↑ intramedullary pressure, thermal necrosis.
    • Unreamed: Preserves endosteal supply; for open fractures, polytrauma.
    • Locking:
      • Static: Rotational & axial stability (comminuted fractures).
      • Dynamic: Controlled axial compression (transverse/oblique fractures).
    • Working Length: Distance between proximal & distal locks; shorter = stiffer construct. Intramedullary nailing of proximal femur fracture

⭐ IMN promotes relative stability, leading to secondary bone healing with callus formation, unlike absolute stability (primary healing) with compression plating.

IMN: Indications & Contraindications - Go/No-Go Zones

  • Indications (Go Zones):
    • Long bone shaft fractures (femur, tibia, humerus).
    • Segmental & comminuted diaphyseal fractures.
    • Pathological fractures (actual or impending).
    • Polytrauma patients requiring early stabilization.
    • Certain metaphyseal fractures with diaphyseal extension.
    • Corrective osteotomies for malunion/nonunion.
  • Contraindications (No-Go Zones):
    • Active infection (local osteomyelitis or systemic sepsis).
    • Severe soft tissue compromise (e.g., Gustilo Grade IIIC initially).
    • Open physes in skeletally immature (relative; risk to growth plate).
    • Predominantly intra-articular fractures.
    • Medullary canal unsuitable (too narrow, obliterated).
    • Patient medically unfit for anaesthesia/surgery.

⭐ Femoral shaft fractures in adults are most commonly treated with IMN, offering load-sharing benefits and promoting early mobilization.

IMN: Nail Types & Technology - Tools of Trade

  • Nail Materials:
    • Stainless Steel (316L): Strong, cost-effective.
    • Titanium Alloy: ↓ Modulus (↓ stress shielding), MRI compatible, biocompatible. 📌 Titanium Tolerates Body Better.
  • Nail Design:
    • Cannulated: Guidewire passage; easier insertion.
    • Solid: ↑ Strength, ↓ infection spread risk.
    • Slotted: ↑ Flexibility.
    • Unslotted: ↑ Stiffness, ↑ rotational control.
    • Antegrade/Retrograde specific designs.
  • Locking Mechanisms:
    • Static locking: Prevents rotation & shortening.
    • Dynamic locking: Allows compression at fracture site.
  • Essential Tools:
    • Guidewires (ball-tip, J-tip).
    • Reamers: Sequential reaming for canal prep, autograft.
    • Entry Awl.
    • Insertion Jig/Handle.
    • C-arm (Image Intensifier). Types of intramedullary nails

⭐ Titanium nails have a lower modulus of elasticity closer to bone, reducing stress shielding_._

IMN: Surgical Technique & Complications - Steps & Pitfalls

  • Goal: Anatomic reduction & fixation.
  • Indications: Diaphyseal # (long bones).

Surgical Sequence:

Intramedullary Nailing: Reaming and Nail Insertion

Critical Steps & Pitfalls:

  • Entry Point: Crucial for alignment. Error → malreduction.
    • Femur: Piriformis fossa / Trochanteric tip.
    • Tibia: Medial to tibial spine.
  • Reaming: ↑Stability. Risks: thermal injury, embolism. Unreamed for open #.
  • Nail: Correct size (diameter/length) vital.
  • Locking: Static (rotation/axial stability) vs. Dynamic (compression). Pitfall: screw error, N/V injury.

Complications:

  • Intra-op: Iatrogenic #, neurovascular injury.
  • Post-op:
    • Infection, FES.
    • Nonunion, Malunion (rotation >10°, angulation >).
    • Hardware failure, pain (e.g., knee pain with tibial nail).

    ⭐ Femoral nailing: Rotational malunion (internal) most common.

High‑Yield Points - ⚡ Biggest Takeaways

  • Primary indication: Diaphyseal fractures of femur, tibia, humerus.
  • Load-sharing device, allows early weight-bearing, preserves periosteal blood supply.
  • Correct entry point (e.g., piriformis fossa for femur) is crucial for fracture alignment.
  • Reamed nails offer better stability; unreamed nails for open fractures or compromised soft tissue.
  • Static locking prevents rotation and shortening; dynamic locking permits axial compression.
  • Watch for: Malunion, nonunion, infection, fat embolism syndrome, and compartment syndrome.
  • Modern nails are cannulated for guide wire insertion, enhancing placement accuracy.

Practice Questions: Intramedullary Nailing

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