and The National Graduate School for Biomaterials and Tissue Engineering ACADEMIC DISSERTATION To be publicly discussed with the permission of the Medical Faculty of the University of Helsinki, in the large lecture hall (Iso luentosali) Work hard and try your best! If you then fail I am not angry.-my father-This thesis is based on the following original publications. They are referred to in the...

Major advances in total hip replacement have occurred since the prosthesis was first developed by Charnley in the 1960s. Yet substantial concerns currently exist over newer hip implants as a result of rising revision rates and increased risk of cancer. By the 1980s revision rates of total hip replacements were as low as 20% after 15 years of follow-up. Throughout this era, the main focus was re...

The assessment of the primary stability of cementless implants still remains a subjective factor in total hip replacement (THR) and, as a consequence, the excessive press-fitting of a THR component can be the cause of intra-operative fractures. Objective information about the stability of implant-bone structures can be obtained using methods based on vibration analysis. After extensive in vitro...

The occurrence of audible squeaking in some patients with ceramic-on-ceramic (CoC) hip prostheses is a cause for concern. Great effort has been dedicated to understand the mechanics of the hip squeaking to gain a deeper insight into factors contributing to sound emission from CoC hip articulation. Disruption of fluid-film lubrication and friction were reported as the main potential cause, while...

Aseptic loosening is the major failure mode for hip prostheses. Currently, loosened prostheses are revised during open surgery. Because of a high complication rate, this demanding procedure cannot be performed in patients with a poor general health. We are developing an alternative minimally invasive refixation procedure that leaves the prostheses in place, but relies on removing the interface ...

The high density and atomic number of hip prostheses for patients undergoing pelvic radiotherapy challenge our ability to accurately calculate dose. A new clinical dose calculation algorithm, Monte Carlo, will allow accurate calculation of the radiation transport both within and beyond hip prostheses. The aim of this research was to investigate, for both phantom and patient geometries, the capa...