ASPECTS OF CURRENT MANAGEMENT Flexible intramedullary nails for fractures in children

©2004 British Editorial Society of Bone and Joint Surgery doi:10.1302/0301-620X.86B7. 15273 $2.00 J Bone Joint Surg [Br] 2004;86-B:947-53. Over the past few years there has been a marked increase in the use of intramedullary fixation in the management of fractures of long bones in children. To some extent this reflects a more interventionist attitude among paediatric orthopaedic surgeons but is also due to technical developments, notably that of the elastic stable intramedullary nail (ESIN). The use of intramedullary devices to stabilise fractures is not new. In the mid-19th century, ivory pins were used for this purpose and were then gradually supplanted by various metal devices.1 These were generally rigid implants, although more flexible ones were introduced in in the 1930s. The school of rigid intramedullary fixation was typified by the Küntscher nail, which achieved great stability in all planes by occupying the entire medullary cross-sectional area of the bone.2 However, its use in growing children was limited by the difficulties encountered in trying to avoid the physes. The Rush nail was introduced at about the same time as the Küntscher nail.3 It was the forerunner of modern elastic intramedullary fixation in that the objective was to achieve three-point fixation on the inner aspect of the cortex. Unlike the stiff Küntscher nail, the Rush nail was slightly flexible and it was intended that it should be pre-bent to the appropriate configuration before insertion.3 Rotational stability was poor, however, and in most situations the flexibility was insufficient to allow insertion points in the metaphysis which were well away from the active physis in children. Others, such as Hackethal4 and Marchetti,5 used bundles of thinner wires which filled the medullary cavity but with stabilisation achieved by splaying the ends of the wires within the bone well beyond the fracture. Ender6 developed this further with his nails, which were the first to feature adaptations to both ends of the nail in order to improve both control of insertion and quality of fixation. These nails could be safely inserted into the metaphysis which made them suitable for consideration in paediatric fractures. In the early 1980s, surgeons in Nancy, France, developed an elastic stable intramedullary nail based on a theoretical concept by Firica.7 Previous experience had suggested that elasticity and stability were not easily combined in one construct. However, working from the concept of three-point fixation used with a single Rush nail, these surgeons were able to improve stability significantly by using two pre-tensioned nails inserted from opposite sides of the bone. Metazieau, Ligier and their colleagues7 were able to show that titanium nails which were accurately contoured and properly inserted could impart excellent axial and lateral stability to diaphyseal fractures in long bones. Rotational stability was also better than had previously been experienced, although this was to remain the weakest point of the technique. The use of titanium nails allowed greater elasticity than was available in the steel nails of the Ender system. Most contemporary work on flexible intramedullary nailing in children’s fractures is based on the Nancy experience, although there remain pockets of Ender and Marchetti enthusiasts. For the purposes of this review, flexible intramedullary nailing is taken to mean elastic stable intramedullary nailing using the concepts espoused by the Nancy group.