"Biological" internal fixation of long bone fractures: a biomechanical study of a "noncontact" plate system

Based on existing knowledge of noncontact plates, an experimental prototype of a nonperiosteal contact internal fixation implant ("noncontact internal fixator") has been designed. The construct rigidity of osteotomised synthe tic composite femora, fixed with the noncontact fixator and a reamed, stati cally-locked intramedullary nail were compared in axial compression, two-pl ane bending and torsion in four types of diaphyseal fractures. With the exc eption of axial loading in the presence of extensive comminution, the fixat ion stability provided by the noncontact fixator is significantly higher th an that of the tested intramedullary nail. Any degree of cortical contact b etween the two main fragments is important for the stability of this nonper iosteal contact fixation system under axial load. Appropriately-designed "i nternal fixators" could provide not only a number of biological and technic al advantages, but also fixation stability comparable and in certain aspect s superior to that of other fixation methods. (C) 1998 Elsevier Science Ltd . All rights reserved.