IN-VITRO AND IN-VIVO RADIOMORPHOMETRIC ANALYSES OF DISTAL SCREW HOLE POSITION OF THE SOLID TIBIAL NAIL FOLLOWING INSERTION

Objective. The objective of this study was to analyse the position of the distal interlocking holes of an unreamed solid tibial nail relativ e to the adjacent cortices of the tibial bone. Design. In vitro and in vivo radiographic-morphometric analysis. Background. To date, 'radiat ion-independent' intramedullary distal interlocking aiming systems hav e not been successful, primarily because proximally mounted aiming dev ices cannot account for the deformation of the nail during insertion; therefore the distal interlocking holes relative to the adjacent corti ces must be understood. Methods. A two-dimensional radiographic-morpho metric analysis was performed in 40 tibiae after in vitro (n = 20) and in vivo (n = 20) implantation of unslotted stainless steel unreamed 8 - and 9-mm diameter intramedullary nails. Results. The combined in vit ro and in vivo results showed average distances between the upper dist al transverse hole and the anterior aspect of the tibia of 12.3 mm (SD 1.7 mm; variance 2.9 mm(2); range 7.6 mm). Conclusions. The distances between the upper distal transverse hole and the anterior aspect of t he tibia are the most reliable parameters of distal nail hole position . Relevance For a 'radiation-independent' distal interlocking aiming s ystem for unreamed intramedullary tibial nails to be successful, it co uld take advantage of the relatively constant distance between the ant erior cortex and the most proximal distal screw hole. (C) 1997 Elsevie r Science Ltd.