Intramedullary Nailing Principles
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Direct answer
Intramedullary nailing fixes a long bone fracture with a rod along the medullary canal, locked by proximal and distal screws. Reamed nails fit more snugly and are favoured in many centres for union, while unreamed nails carry less embolic load and suit patients who cannot tolerate reaming. Static locking prevents shortening and rotation in unstable patterns, whereas dynamic locking allows controlled axial movement that encourages callus in stable fractures.
What you must remember
- Principle: the nail acts as an internal splint along the medullary canal, with interlocking screws controlling length and rotation.
- Reamed nails: larger diameter, better cortical contact and good union rates, but more heat, debris and embolic load.
- Unreamed nails: smaller diameter and less reaming-related embolic load, used when the patient cannot tolerate reaming.
- Static locking: screws at both ends prevent shortening and rotation, which suits unstable or comminuted patterns.
- Dynamic locking: one set of screws is removed or left loose, allowing controlled axial movement that encourages callus in stable fractures.
- Complications: fat embolism, infection, malrotation and malunion, nonunion, iatrogenic fracture and compartment syndrome.
- Rotation check: rotational alignment is compared with the opposite limb before the nail is locked, because malrotation is a common and disabling error.
A nailing sequence from entry point to union
Nailing succeeds or fails early, because entry point, reduction and rotation decide the result before the nail is locked. The steps below follow a femoral nail from setup to follow-up.
- Set up the table: fracture traction on a radiolucent table allows reduction under image intensifier, with the limb positioned to control rotation.
- Choose the entry point: antegrade femoral nails enter through the piriformis fossa or the greater trochanter, while retrograde nails enter through the intercondylar notch.
- Ream to the isthmus: the canal is reamed progressively to a size that engages the isthmus, which gives the nail its stability.
- Insert and check rotation: the nail is passed across the fracture, and rotation is compared with the normal limb before the screws are placed.
- Lock according to the pattern: static locking holds unstable fractures, whereas dynamic locking allows axial loading in stable fractures.
- Follow up for complications: serial radiographs check union, alignment and screw position, and the patient is watched early for fat embolism and infection.
Where the exam tries to catch you
Nailing questions usually test the choice between reamed and unreamed nails and between static and dynamic locking.
- Trap: choosing dynamic locking for an unstable, comminuted femoral shaft fracture Correct: unstable patterns need static locking to prevent shortening and rotation, whereas dynamic locking suits stable transverse fractures.
- Trap: attributing breathlessness after nailing to pneumonia alone Correct: reaming increases embolic load, so fat embolism must be considered in a patient with respiratory distress after surgery.
- Trap: checking only the alignment in the coronal and sagittal planes Correct: malrotation is a classic complication of nailing and is assessed by comparing the limb with the opposite side.
Frequently asked questions
What is the difference between static and dynamic locking in intramedullary nailing?
Static locking places screws at both ends of the nail, preventing shortening and rotation in unstable fractures. Dynamic locking leaves one end free or removes a screw, allowing controlled axial movement that encourages callus in stable fractures.
Why are reamed nails used in intramedullary nailing?
Reamed nails give better contact with the cortex and are associated with good union rates, which is why many centres favour them. Reaming does increase heat, debris and embolic load, so the choice also weighs the patient's physiological status.
What are the complications of intramedullary nailing?
Fat embolism, infection, malrotation and malunion, nonunion, iatrogenic fracture and compartment syndrome are complications of intramedullary nailing. Malrotation is especially important because it is common and hard to correct once the nail is locked.
Which entry points are used for femoral nailing?
Antegrade femoral nails enter through the piriformis fossa or the greater trochanter, while retrograde nails enter through the intercondylar notch of the femur. The choice depends on the fracture pattern, the patient's anatomy and the surgeon's preference.