Public Defence: Peder Svenkerud Thoen

MD Peder Svenkerud Thoen at Institute of Clinical Medicine will be defending the thesis “Advancements in Total Hip Arthroplasty - polyethylene, articulation and factors associated with dislocation” for the degree of PhD (Philosophiae Doctor).

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Photo: Amalie Huth Hovland, UiO.

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An electronic copy of the thesis may be ordered from the faculty up to 2 days prior to the public defence. Inquiries regarding the thesis after the public defence must be addressed to the candidate.

Trial Lecture – time and place

See Trial Lecture.

Adjudication committee

  • First opponent: Professor Henrik Malchau, Harvard Medical School, USA and Sahlgrenska University Hospital, Sweden
  • Second opponent: Professor Michael Dunbar, Dalhousie University, Canada
  • Third member and chair of the evaluation committee: Professor II Anne Eskild, University of Oslo

Chair of the Defence

Professor Ivar A. Langmoen, University of Oslo

Principal Supervisor

 Orthopaedic Consultant, Head of Cirro, Stephan M. Röhrl, Oslo University Hospital


Total hip arthroplasty (THA) is one of the most successful treatments offered within the field of orthopedic surgery. There is considerable patient satisfaction, pain reduction and increased activity level for patients with end stage osteoarthritis treated with THA resulting in improved quality of life. Nevertheless, as with all types of surgical interventions, patients with THA are at risk of complications. Complications may be prosthesis component loosening, polyethylene wear and hip prosthesis dislocations. These complications often result in revision surgery, which may be devastating for the individual patient and culminates in a significant socioeconomic burden.

The primary aim of this thesis was to assess whether Vitamin E infused polyethylene in THA improved wear resistance and thereby contributing to overall improved prosthesis longevity. Advancements in polyethylene wear characteristics could also potentially allow for larger femoral head size diameters without increasing wear. Hip prosthesis stability is enhanced by using larger femoral head size, which again reduces the risk of hip prosthesis dislocation. The secondary aim was to explore factors that were associated with revision due to hip prosthesis dislocation in the Norwegian population in recent time.

In two clinical trials we demonstrated that Vitamin E infused polyethylene in THA exhibits low polyethylene wear at mid-term follow-up (5- and 6-years). Also, we showed in a register study that there was an increased risk of revision surgery due to hip prosthesis dislocation in modern THA in Norway when using 28mm femoral head size, posterior approach, and uncemented fixation.

The clinical impact of our work is that Vitamin E infused polyethylene used in THA shows promising wear characteristics, cup stability, and no observable detrimental effects at mid-term follow-up. Results from the register study can guide medical practitioners when evaluating patients for THA.

Additional information

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Published Apr. 20, 2022 10:21 AM - Last modified May 2, 2022 2:21 PM