THE DEFORMATION OF SMALL-DIAMETER SOLID TIBIAL NAILS WITH UNREAMED INTRAMEDULLARY INSERTION

'Radiation-independent' aiming systems for the placement of interlocki ng screws in intramedullary tibial nails have Failed because of insert ional related nail deformation. Prior to the development of these dist al aiming systems, the variable position of the nails' interlocking ho les after insertion must be known. In this study, the amount and direc tion of implant deformation of solid stainless-steel tibial nails (dia meters of 8 and 9 mm; n = 20) were analyzed. Measurement of implant de flection (three translations, three angles) in the center of the dista l transverse locking hole was performed with a three-dimensional-magne tic motion tracker system after nail insertion in paired human cadaver tibiae. The results showed combined mean lateral translation of the 8 and 9 mm nails (n = 20) of -4.5 +/- 3.5 mm (range: 14.3 mm) and dorsa l translation -7.8 +/- 5.8 mm (range: 19.2 mm). The combined mean rota tional deformation about the longitudinal axis of the nail was 0.3 +/- 0.7 degrees (range: 2.4 degrees). The authors conclude that a simple aiming arm, mounted on the proximal nail end alone, is not sufficient to provide accurate distal aiming. (C) 1997 Elsevier Science Ltd.