Principle
An intramedullary nail is a load-sharing implant placed within the medullary canal. It is particularly useful for diaphyseal and selected metaphyseal fractures.
Important design features
- nail diameter
- working length
- cross-sectional geometry
- material stiffness
- locking configuration
- proximal and distal bend or curvature
Reamed versus unreamed nails
Reamed
- permits insertion of a larger diameter nail
- increases construct stiffness
- reaming generates heat and transiently affects endosteal blood supply
Unreamed
- preserves more endosteal circulation initially
- uses a smaller nail
- may be preferred in selected soft-tissue or physiological circumstances
Locking
Interlocking screws control:
- rotation
- length
- axial stability
Static locking provides maximal length stability. Dynamic locking permits controlled axial loading in selected constructs.
Advantages
- load sharing
- relatively small surgical exposure at fracture site
- preservation of periosteal blood supply
- early mobilisation in many fractures
Complications
- malalignment
- infection
- non-union
- hardware failure
- iatrogenic fracture
- joint pain related to entry point or prominent hardware