1. Orthopaedic implant components as a source of nanoparticles Ingrid Milošev Jožef Stefan Institute, Ljubljana, and Valdoltra Orthopaedic Hospital, Ankaran, Slovenia Conference on Nano-Safety, Ljubljana, 22-24 April 2009

2. Number of implants and devices for USA (global numbers 2-3 times higher) Type of implantNumber Intraocular implants Intraocular lenses2.500.000 Contact lenses30.000.000 Cardiovascular implants Pace makers400.000 Vascular grafts300.000 Stents1.500.000 Heart valves100.000 Orthopaedic implants Total hip replacements250.000 Total knee replacements250.000 Dental implants910.000 Biomaterial Science, B.D. Ratner, A.S. Hoffman, F.J. Schoen, J.E. Lemons, 2004

4. Indications for total hip replacement: - osteoarthritis - osteoarthritis secondary to dysplasia - aseptic femoral head necrosis - rheumatoid arthritis - post-traumatic arthritis

5. Radigraph image of THR: (A) Post implantation (B) Prior revision surgery – aseptic loosening with osteolytic zones along the stem and changed cup position Animation: http://www.wmt.com/

6. Survivorship curve is a long-term indicator of the successfulness of a particular prosthesis. Data are created based in the Valdoltra Register of hip and knee prostheses. Time in situ / years Cumulative survivorship At 12 years post-op, 90% of prostheses still implanted

7. 71% Aseptic loosening related to the formation of wear debris and consequent osteolysis is reason for revision in >70%.

8. Origin of wear Surface wear damage Wear particles Polyethylene particles Metal particles Cement particles Novel bearing combinations Metal-on-metal Ceramic-on-ceramic Biological consideration of particulate debris Introduction

9. Polyethylene particles origin: acetabular cup, acetabular inlay Wear debris

10. e f Mode 1: two primary bearing surfaces (a,b) Mode 2: primary surface moving against a secondary surface (c, d) Mode 3: primary surfaces including third particles interposed (e, f) d ba c ef

11. Metal particles For SEM analysis – filtrate the bottom layer through 0.2 um polycarbonate filter paper and coat with gold Polyethylene particles For SEM analysis - filtrate the top layer through 0.2 um polycarbonate filter paper and coat with gold Isolation procedure by NaOH digestion