What are the indications and management strategies for using an intramedullary (IM) device in fracture treatment?

Intramedullary Device: Indications and Management

Primary Indications

Intramedullary (IM) nailing is the standard treatment for most long-bone diaphyseal fractures and selected metaphyseal fractures, particularly femoral shaft fractures, where it should be performed within 24 hours to prevent ARDS and fat embolism syndrome. 1

Specific Fracture Indications

Femoral Fractures:

• Femoral shaft fractures: IM nailing is the definitive reference treatment and should be performed within the first 24 hours (versus >24 hours) to reduce risk of fat embolism 1
• Unstable intertrochanteric fractures: Cephalomedullary nail is strongly recommended over sliding hip screw 2
• Subtrochanteric or reverse oblique fractures: Cephalomedullary device is mandatory 2
• Stable intertrochanteric fractures: Either sliding hip screw or cephalomedullary nail is appropriate 2

Other Long Bones:

• Humeral shaft metastases: Locked IM nailing or inflatable nail provides excellent pain relief with regained extremity use within several days 1
• Clavicle shaft fractures: IM locked fixation device (Sonoma CRx) is viable for displaced and shortened fractures 3

Critical Contraindications

IM rods should NOT be used alone in congenital pseudarthrosis of the tibia (CPT) in children - 74% expert consensus disagrees with this approach due to high complication rates (67.7% primary union rate, 17% non-union rate, 48.1% refracture rate) 1

Biomechanical Principles

IM nails function as internal splints that allow secondary fracture healing through:

• Load-sharing with surrounding bone structures for compressive, bending, and torsional loads 4
• Relative stability that promotes callus formation 5
• Strain accommodation: granulation tissue tolerates 100% strain, cartilage 10-15%, bone only 2% 5

The device maintains alignment while permitting controlled motion at the fracture site, acting as a load-sharing device rather than rigid fixation 6

Surgical Timing and Technique

Timing Priorities

Operate within 24-48 hours of admission for optimal outcomes 2, with specific attention to:

• Within first 24 hours for femoral shaft fractures to prevent ARDS and fat embolism 1
• Within first 10 hours shows even lower risk of fat embolism 1
• Delay only for ongoing hemorrhage or cerebral injury with intracranial hypertension, which take precedence 1

Technical Considerations

Key surgical principles:

• Closed nailing is preferred over open procedures to preserve periosteal blood supply 6
• Use the longest possible nail that the bone can accommodate 3
• Insert as far as possible into the medullary canal for maximum stability 3
• Reaming increases extraosseous circulation, which is important for bone healing despite early deleterious effects on endosteal blood flow 4

Device Selection Algorithm

For femoral fractures, follow this decision tree:

1. Stable intertrochanteric pattern?

   • Yes → Sliding hip screw OR cephalomedullary nail 2
   • No → Proceed to step 2

2. Unstable features present (comminution, reverse obliquity, subtrochanteric extension, posteromedial comminution)?

   • Yes → Cephalomedullary nail MANDATORY 2
   • No → Consider patient factors

3. Pathologic fracture anticipated?

   • Yes → Avoid sliding hip screw (lacks healing with planned radiation); use IM nail 2

Combined Fixation Strategies

When IM fixation alone is insufficient:

• CPT in children: 84% expert consensus supports combining external fixation with IM fixation to prevent refractures and axial deformities 1
• Small distal fragments or severe deformity: Consider Ilizarov method as secondary option when other methods fail 1

Perioperative Management

Preoperative Care

• Administer prophylactic antibiotics within one hour of skin incision 2
• Provide IV fluids routinely as patients are often hypovolemic 2
• Do NOT use preoperative traction - no benefit and specifically not recommended 2
• Implement active warming strategies to prevent hypothermia 2

Postoperative Care

• Immediate weight-bearing as tolerated 2
• DVT prophylaxis with fondaparinux or low molecular weight heparin for 4 weeks 2
• Regular paracetamol throughout perioperative period 2
• Cautious opioid use, especially with renal dysfunction; avoid codeine 2
• Early mobilization protocols to reduce complications 2

Critical Pitfalls to Avoid

Common errors that compromise outcomes:

• Using IM rod alone in CPT children - requires combined external fixation 1
• Delaying surgery beyond 24 hours for femoral shaft fractures - increases fat embolism risk 1
• Using sliding hip screw for unstable intertrochanteric patterns - will fail 2
• Applying preoperative traction - wastes resources without benefit 2
• Excessive rigidity in pathologic fractures - complicates revision if infection develops 5

Long-term Considerations

Fracture stability remains the priority throughout healing to prevent both nonunion and infection 5, with the understanding that:

• The metallic implant can be removed after complete osseous healing without loss of function 5
• IM nails are subject to fatigue and can break if bone healing does not occur 4
• Definitive IM nailing may trigger larger systemic inflammation than two-step strategies, but does not increase ARDS incidence in unselected trauma populations 1