Problems associated with soft tissues of the stump and attachment of prosthetic devices for amputees remains a considerable problem. These problems are associated with the transmission of load through the soft tissues of the stump and difficulty in attaching the prosthetic device. Several devices have an osteointegrated transcutaneous prosthesis attached to the residual bone onto which an exo-prostheses is secured thereby transmitting load directly through the skeleton. Infection of these devices is a key issue.

A biomimetic intraosseous transcutaneous device for amputees known as ITAP has been developed which is based on deer antler morphology. We have shown that in deer antlers the dermal and epithelial tissues are tethered by collagen fibres which originate from pores in the bone. In a caprine model where the soft tissue interface of ITAP is porous, dermal and epithelial integration occurs creating a seal and preventing infection. In two clinical veterinary cases an ITAP implant has been successfully used in trans-radial canine amputees. A human trans-humeral amputee who previously could not wear their exo-prosthesis has been treated with ITAP. The surgery was single stage procedure and involved the insertion of an uncemented intramedullary stem into the residual humerus. A porous flange structure positioned adjacent to the dermal tissue which had most of the hypodermis removed was used to promote soft tissue ingrowth.

At two years' post-operation the skin seal has been maintained, there has been no incidence of infection, the patient wears their exo-prostheses for over 8 hours a day and has an almost complete range of shoulder motion. The use of ITAP device in selected cases may revolutionise the way amputees are surgically treated, lead to increased activity levels and more normal life styles in these patients.

Introduction

Total disc replacement (TDR) provides an alternative to fusion that is designed to preserve motion at the treated level and restore disc height. The effects of TDR on spine biomechanics at the treated and adjacent levels are not fully understood. Thus, the present study investigated facet changes in contact pressure, peak contact pressure, force, peak force, and contact area at the facet joints after TDR.