The development of a novel implant: induction of a non-rigid and self-renewing anchorage of artificial implants to bone

Abstract

Artificial implants currently used in orthopaedic surgery and dentistry are anchored to the surrounding bone by rigid mechanical fixation. Long-term studies indicate that the rate of implant failure due to loosening increases steeply after 10 years of function. The loosening is attributed to the micro-movements occurring at the bone implant interface. Non-rigid, self-renewing ligamentous anchorage is nature's solution to the problem of micro-movements. An excellent example of this type of anchorage is the tooth-bone system, where the tooth is anchored to the bone by a fibrous connective tissue. A novel artificial implant, bearing on its surface a unique biological substrate (BS), was designed to induce a ligamentous anchorage of implant to bone. The implant consists of a metallic core to which the BS is bound. The BS is a composite of plastic material and a collagen mesh which is partly incorporated into the plastic material and partly freely extended from its outer surface as artificial Sharpey's fibers. BS fabrication did not affect the capacity of the collagen to withstand non-specific degradation in vitro. Non-weight-bearing implants implanted into the femoral bone of rats induced and maintained a ligament-like tissue up to 4 months. The collagen fibers of the ligament-like tissue were spliced with the artificial BS Sharpey's fibers and were also anchored as Sharpey's fibers into the surrounding bone. Examination of control plastic implants (without the BS) revealed bone formation in close approximation to the implant surface. It is suggested that the novel biological substrate has the capacity to induce and maintain a ligament-like anchorage of implant to bone.