title: Development of a soft tissue seal around bone-anchored transcutaneous amputation prostheses.
abstract: Conventional amputation prosthetics are problematic because they rely on the stump-socket interface for attachment. Intraosseous transcutaneous amputation prostheses (ITAP) could solve these problems; however they rely on the integrity of the soft tissue-implant interface as a barrier to exogenous agents, and in the prevention of downgrowth and marsupilisation. We have used an in vivo animal model to study the soft tissue interfaces around bone-anchored transcutaneous implants. We hypothesise that by facilitating and increasing the area of dermal attachment to the implant epithelial down-growth will be reduced. A flange with a series of 24, 0.7 mm holes positioned immediately below the epithelium was used to increase dermal attachment. This significantly reduced downgrowth and optimised the integrity of the collagenous tissue-implant interface at the dermal level. We postulate that the flange reduces relative interfacial movement at the epithelium-implant interface by providing increased surface area for dermal tissue attachment. A tight seal at the dermal tissue level reduces the degree of downgrowth around ITAP, eliminating marsupilisation as a potential failure modality. Surface topography and coatings did not affect the degree of downgrowth or dermal attachment to straight or flanged implants. A significant negative correlation was observed between downgrowth and both epithelial and dermal attachment. This study shows that a soft tissue-implant interface capable of preventing downgrowth and marsupilisation can develop around a bone-anchored transcutaneous implant, given the incorporation of a porous flange positioned in the dermal tissues immediately below the epithelium. This will benefit applications where bone-anchored transcutaneous implants are used.
authors.affiliation: The Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital Trust, Brockley Hill, Stanmore, Middlesex, and The Royal Veterinary College, Hertfordshire, UK. c.pendegrass@ucl.ac.uk
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Pendegrass
authors.forename: Allen E
authors.initials: AE
authors.lastname: Goodship
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Blunn
mesh_terms: D000497:Alloys; D000672:Amputation Stumps; D000818:Animals; D001485:Basement Membrane / Q000254:growth & development*; D001672:Biocompatible Materials; D001842:Bone and Bones / Q000502:physiology*; D005260:Female; D006041:Goats; D019736:Prostheses and Implants; D013977:Tibia / Q000502:physiology; D014025:Titanium
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; C031462:titanium alloy (TiAl6V4); D014025:Titanium