|Titel på arbejdet||The applicability of metallic gold as orthopedic implant surfaces. Experimental animal studies|
|Afdeling / Sted||Department of Orthopaedic Surgery, Aarhus University Hospital|
|Abstract / Summary|
Total hip arthroplasty is a successful form of surgical intervention offered to patients with severe end-stage degenerative joint diseases. Although considered successful with impressive increase in mobility, improved quality of life, and satisfactory pain relief, improvements are still needed, as serious problems regarding long-term implant longevity still exists. Today, aseptic implant loosening is considered to be the main reason for revision surgery. It is regarded as a low-grade inflammatory process, initiated by activated macrophages, which phagocytize wear particles, leading to peri-prosthetic osteolysis and bone-defects. The anti-inflammatory capabilities of gold ions have been established and used in especially inflammatory joint diseases for decades. However, the recent finding that metallic gold implants liberate gold ions in living tissue, now a treatment termed auromedication, creates an opportunity to locally counter-act any inflammatory process that occurs around an implant.
The aim with the experimental studies in this thesis was to investigate, whether metallic gold has a role in orthopaedic context. The possibility to suppress the periimplant inflammation after implant insertion needs to be studied and as a result, short-term studies were conducted to address the initial osseointegration of two differently gold-coated implants and their mechanical fixation. Furthermore, gold particles were administered in an effort to use auromedication as an allograft maintaining treatment to reduce allograft reabsorption, increase total bone stock, and thereby increase initial mechanical fixation.
The results show that metallic implants release gold ions in concurrence with other findings. They also show that complete gold-coated implants had reduced mechanical strength due to reduced implant osseointegration. By reducing the gold coating thickness and also the amount of the gold-coated surface area, equivalent mechanical fixations were achieved compared to control titanium implants. However, no inhibitory effect was found on fibrous tissue formation as otherwise anticipated. Furthermore, no anti-reabsorptive effects could be measured after use of gold particles on bone allograft, although gold ions were released from the particles.
In conclusion, this thesis finds that the mentioned gold ion release also occurs in bone. The effects were not encouraging as no obvious clinical relevant effects were observed in early fibrous tissue formation or allograft resorption. But gold’s inhibitory effect on bone formation resembles other anti-inflammatory drugs previously administered during or after surgery. These results show that metallic gold has no vital role in the early phase of implant surgery. However, the development of a partial gold-coated implant that offers comparable early fixation results is interesting, since the coating combines the osseointegrative properties of a titanium coated implant with the anti-inflammatory capabilities of a local gold surface. This could theoretically suppress the peri-prosthetic inflammation that occurs due to wear particles, and warrants further investigations.