Modulation of the soft tissue reactions to percutaneous orthopaedic implants

Abstract

To evaluate soft tissue reactions and biofilm formation on percutaneous external fixator screws coated with diamond-like carbon (DLC) and hydroxyapatite (HA) coatings on stainless-steel (SS) pins in an ovine loaded osteotomy model, an Orthofix external fixator was used to stabilize a 3-mm tibial midshaft osteotomy with six tapered pins inserted into the right tibia of 32 skeletally mature Friesland ewes. Animals were divided into four groups; SS, fully coated HA, DLC, and HA-coated threads. At 10 weeks, specimens were harvested and the pins were removed en bloc to examine the interfaces between the surface coatings and the tissues. Fully coated HA pins had a significantly higher percentage of dermal contact with the pin surface than HA-coated threads (p ¼ 0.028). The presence of a biofilm was evident on all pin surfaces except DLC-coated pins. Significantly greater numbers of bacteria were present on fully coated HA and plain stainless-steel pins compared with DLC. The surface of DLC-coated pins had a significantly lower number of bacterial colonies compared to SS (p ¼ 0.028) and fully coated HA pins (p ¼ 0.005). Fully coated HA pins have greater dermal attachment to the pin surface than the other pin coatings investigated. DLC-coated pins have the potential to prevent biofilm formation and bacterial colonization that may reduce infection and consequent pin loosening. An external fixator pin that is partially coated with HA to encourage bone and soft tissue integration and with DLC to reduce biofilm formation is advocated. ß

Development of a soft tissue seal around bone-anchored transcutaneous amputation prostheses

“…DLC has been shown to be as biocompatible as commercially pure titanium [32], and to significantly reduce fibroblast and epithelial cell adherence in vitro, and bacterial colonisation and biofilm formation in vivo [30]. In our study, DLC did not affect downgrowth, % epithelial, or % sub-epithelial layer attachment, and no clinical signs of infection were observed.…”

“…Two straight, grooved implants were tested; small grooved (SG) (groove depth ¼ 0.3 mm, groove width ¼ 0.5 mm), and large grooved (LG) (groove depth ¼ 0.6 mm, groove width ¼ 1.0 mm). SG, LG and RSB implants were also tested with a 2-4 mm coating of diamond-like carbon (DLC) (Diavac ACM LTD , Brunel University, UK) (a low surface energy coating used to inhibit bacterial adhesion [28][29][30]). Porous titanium implants (PTi) were made by plasma-spraying MF pins with a 70-100 mm thick porous titanium layer.…”

Response of a Collagenase-Induced Tendon Injury to Treatment with a Polysulphated Glycosaminoglycan (Adequan)

“…The continuing presence of the original aligned fibrils would then enhance the structural organization of the newly formed small diameter fibrils by providing a template for their growth similar to that seen with the synthetic fiber implants used in tendon repair [37][38][39]. In a similar study, treatment of injured ligaments, using antisense decorin oligodeoxynucleotides, led to an increased development of larger fibrils in early scar and a significant improvement in both scar failure strength and scar creep elongation [40].…”

Materials in Fracture Fixation

“…103,104 Early in vitro data suggest that the attachment of biological tissue to DLC-coated pins may be improved, but the coating has not been investigated in human trials for this purpose. 105 Infection of external fixator pin sites, also termed pin sepsis, presents one of the considerable challenges in using this technique, occurring at a rate of up to 30%. 106 Pin sites are particularly vulnerable to infection because they provide a continuous tract from the skin, which is universally colonized with many different types of bacteria.…”

“…As with pin loosening, the ability of DLC to prevent infection at pin sites has been studied and shown to be effective at reducing the number of bacterial colonies cultured from external fixation pins in an animal model. 105 These results have not yet been replicated in human subjects and so clinical use of this type of coating remains theoretical.…”