This study examined the stability of two different hexapod frames at increasing strut angles and the possible use of an additional strut to aid stability. Hexapod frames have certain advantages over standard circular frames, however disadvantages include a rattle and instability at some strut angles. This could be particularly important when larger diameter rings are used over a shorter distance resulting in lower ring strut angles such as in the femur.A statement of the purposes of the study
Introduction
Fracture healing is governed by biological and mechanical factors. Circular frames are one method to fix fractures. Recently, the number of frame designs that are available has increased and these different designs may have different effects on the mechanical environment created. The senior author has been concerned by the stability of the construction when a short frame is used. This study examined the stability of different frames and the possible use of additional 7th struts to aid stability. The frame configuration was modified with increasing strut angles from 15° − 70°. Each frame was cyclically tested in compression to 200N. The Taylor Spatial Frame was retested with the addition of a seventh strut.Introduction
Method
A modified anodisation technique where a titanium surface releases bactericidal concentrations of silver was developed and called Agluna. Our hypothesis was that silver incorporation was bactericidal and had no effects on the viability of fibroblasts and osteoblasts, would have no negative effect on interfacial shear strength and bone contact in an in vivo trans-cortical implant ovine model. In vitro: Titanium alloy discs were either polished (Ti), anodised (Ano), anodised or Agluna treated (Ag) or anodised and Agluna treated followed by a conditioning step (Ag C). Conditioning was achieved by incubating discs in culture fluid for 48 hrs. The bactericidal effect of these discs was tested by measuring the zone of inhibition of different bacteria grown on agar. Live/dead staining was carried out and silver levels measured using atomic emission spectroscopy. 8 implants were inserted into each sheep (60 in total (n=5)). Grit blasted Titanium alloy (Gb) and Agluna treated grit blasted titanium alloy (Ag) at a silver concentration of 4-6 micrograms/cm2 were compared at 6 weeks. Gb implants, Ag (at 4-6micrograms/cm2), high dose Agluna implants with silver concentrations at 15-20micrograms/cm2 (HdAg) and a grit blasted anodised titanium alloy (Ano) were compared at 12 weeks. Pullout strength and bone-implant contact was quantified.Introduction
Methods
