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Elastic Stable (Flexible) Intramedullary Nailing of Paediatric Femoral Fractures PDF Print E-mail

Unni G. Narayanan, M.D.
Assistant Professor, Division of Orthopaedics,
The Hospital for Sick Children, University of Toronto
Toronto, ON

Introduction
Paediatric femoral fractures are treated by a variety of methods including traction, immediate spica cast, traction followed by spica cast, internal fixation with plate and screws, external fixation and intramedullary fixation. Orthopaedic surgeons remain divided about the optimal method of treatment for children's femoral fractures. The choice of treatment may be influenced by the age of the child, the level and pattern of the fracture and to a great extent, by regional, institutional or surgeons' preferences1. A systematic review of the literature provides little evidence to support one method of treatment over another2. In general, outcomes tend to be uniformly good irrespective of the method of treatment.  


Fig 1. Mid diaphyseal fracture
Elastic Stable Intramedullary Nailing
The technique of elastic stable intramedullary nailing, adapted from existing flexible rod systems, was first described by surgeons from Nancy, France3,4. Ligier et al reported the results of the Nancy experience5. The technique has become one of the most popular methods of fixation of paediatric femoral fractures in North America1. Excellent clinical results have been reported with this technique, which has been variously called "elastic stable intramedullary nailing", "flexible intramedullary nailing" or "Nancy nailing"5-8.

Perceived advantages of this technique include earlier mobilization and more rapid return to function than with nonoperative techniques, and less soft tissue disruption and smaller scars when compared with other surgical methods4.

Fig 2. Proximal Long Spiral fracture
Principle of "Elastic Stability"
The flexible rod is initially bent or curved (plastically deformed). During intramedullary insertion, which is typically retrograde in the femur, the relatively straight medullary canal (compared with the contoured nail) forces the curved rod to straighten within the bone. This elastic deformation creates a bending moment within the long bone which will tend to angulate the fracture in the direction and the plane of the concavity of the curved rod, as the rod wants to return to its initial curved state. This moment is counteracted by a second rod of matched diameter and curve, which balances the first rod with an equal but opposite moment. The two intramedullary nails act complimentarily to stabilize the fracture. This biologic fixation is not rigid but sufficiently stable against angular, translational and torsional deforming forces and is associated with early formation of exuberant callus. Typically , no additional external immobilization is required. However, any significant imbalance in the magnitude or the direction of the moment created by the two nails will result in angulation of the fracture in the direction of the stronger nail.

The titanium nails have been distinguished from other flexible nail systems such as Ender nails, made of stainless steel. The latter are believed to be insufficiently elastic for children's fractures5.

Sometimes three or more flexible rods are inserted in order to better fill the medullary canal to enhance cortical contact, and provide more stable fixation. This constitutes a form of rigid intramedullary fixation, quite different from the Nancy nailing concept.

Fig 3. Do not leave nail tips bent or prominent.
Indications
Elastic stable intramedullary nailing is ideally suited for mid-diaphyseal transverse, short oblique or short spiral fractures of the femur with minimal comminution, in children 5 to 12 years old who are being considered for operative stabilization (Fig. 1). The use of flexible nails can be extended to more proximal, even subtrochanteric fractures and some multifragmentary fractures by modifying the technique to take advantage of the principles outlined above (Fig. 2). The addition of external protection like a knee immobilizer can limit the overall motion of the lower extremity and reduce the deforming forces on the fracture in these situations.

Complications
The most common complications reported are pain and skin irritation at the entry site associated with the prominence of the ends of the nails9. We have shown that nail ends should not be bent, as was originally recommended, but advanced so that they lie against the supracondylar flare of the femur in order to avoid symptoms at the insertion site (Fig. 3). Use of nails of two different diameters is associated with a high rate of loss of reduction in the direction of the stronger rod9. Multifragmentary fractures might be better stabilized by alternative methods of fixation. If used in comminuted fractures, these should be monitored weekly for early loss of reduction, and they might benefit from some additional external immobilization. Although the originators of this technique recommended routine removal of the nails, there is no evidence that this is necessary in the absence of nail-related symptoms.

Summary
Elastic stable intramedullary nailing is an excellent method of managing most, but not all, paediatric femoral fractures that need operative stabilization. It is by no means the only technique nor is there evidence yet that it is superior to other methods. Its advantages make it a valuable choice to consider in managing these fractures. Ultimately, the choice should reflect best evidence and also incorporate patient preferences.

References

  1. Sanders J.O., Browne R.H., Mooney J.F., et al. Treatment of femoral fractures in children by pediatric orthopedists: Results of a 1998 survey. J Pediatr Orthop 2001;21:436-441.

  2. Wright J.G. The treatment of femoral shaft fractures in children: A systematic overview and critical appraisal of the literature. Can J Surg /J Chir Can 2000;43:180-189.

  3. Ligier J.N., Metaizeau J.P., Prévot J. Closed flexible medulary nailing in pediatric traumatology. Chir Pediatr 1983;24(6):383-5.

  4. Metaizeau J.P. L'osteosynthese chez l'enfant par embrochage centro medullaire elastique stable. Sauramps Medical, Montpellier 1988.

  5. Ligier J.N., Metaizeau J.P., Prévot J., Lascombes P. Elastic stable intramedullary nailing of femoral shaft fractures in children. J Bone Joint Surg [Br] 1988;70-B:74-7.

  6. Bar-On E., Sagiv S., Porat S. External fixation or flexible intramedullary nailing for femoral shaft fractures in children. J Bone Joint Surg. [Br] 1997;79-B: 975-8.

  7. Flynn J.M., Hresko T., Reynolds R.A.K., Blasier R.D., et al.. Titanium Elastic nails for Pediatric Femur fractures: A multicenter study of early results with analysis of complications. J Pediatr Orthop 2001;21:4-8.

  8. Carey T.P., Galpin R.D. Flexible intramedullary nail fixation of pediatric femoral fractures. Clin Orthop 1996;332:110-118.

  9. Narayanan U.G., Hyman J.E., Wainwright A.M., Rang M., Alman B.A. The complications of elastic stable intramedullary nail fixation of paediatric femoral fractures, and how to avoid them. 2002. Submitted to J Pediatr Orthop.