Soft tissue attachment to orthopaedic implant materials
Most orthopaedic endoprostheses are used to replace damaged joint surfaces and rely little on soft tissue attachment for their function. Massive bone tumour implants and solutions to attach external implants to the skeleton for amputees rely on soft tissue attachment for successful function. Massive implants require a tendon-metal attachment to preserve joint movement. Implants for amputees where the skeletally anchored implant penetrates the skin, require soft tissue attachment to produce an effective microbial seal which prevents infection. My thesis aims to investigate the concept that biomimetic soft tissue-implant interfaces can be engineered using surface texturing, coatings and biological augmentation, to enhance the attachment and function of the soft tissues between: 1) Metallic implants and tendons, used for proximal tibial replacement 2) The epithelial and sub-epithelial soft tissues to transcutaneous implants used for amputation prostheses I have shown that soft tissue derived cells' proliferative capacity, morphology and attachment are significantly affected by biomaterials and surface topography of the substrate used to support their growth, whilst biological substrate coatings can be used to optimise these functions to suit the requirements of an implant. My findings have demonstrated that a functionally and morphologically successful tendon soft tissue - implant interface can be engineered using autologous cancellous bone and marrow graft combined with hydroxyapatite coatings in a clamp device, resulting in an interface that has significantly more bone attachment associated with fibrocartilage compared with hydroxyapatite alone. My thesis demonstrates that the soft tissue - implant interface around intraosseous transcutaneous amputation prostheses can be optimised based on natural analogues. Deer antlers produce a microbial seal by engineering a region of thick dermal collagen fibres attached to the bone surface which supports the epithelium. Increasing the surface porosity and area of transcutaneous implants in the dermis results in significantly less epithelial down growth and significantly greater attachment of the epithelial and dermal tissue layers respectively.