Digital Public defence: Geir Aasmund Hjorthaug

MD Geir Aasmund Hjorthaug at Institute of Clinical Medicine will be defending the thesis “Effects of inhibition of bone resorption and cyclooxygenase on bone and tendon-to-bone healing - Experimental studies of fracture and tendon-to-bone healing in the rat” for the degree of PhD (Philosophiae Doctor).

The University of Oslo is closed and the trial lecture will be held as a video conference over Zoom.

The trial lecture will follow regular procedure as far as possible, hence it will be open to the public and the audience can ask ex auditorio questions when invited to do so.

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Digital Trial lecture - time and place

See Digital Trial Lecture.

Adjudication committee

  • First opponent: Associate Professor Karl Eriksson, Karolinska Institutet
  • Second opponent: Associate Professor Øystein Bjerkestrand Lian, Kristiansund sykehus
  • Third member and chair of the evaluation committee: Professor Angelika Sorteberg, University of Oslo

Chair of the Defence

Professor Emeritus Lars Engebretsen, University of Oslo

Principal Supervisor

Senior Consultant Sigbjørn Dimmen, Lovisenberg Diakonale Sykehus


Treatment of fractures and ligament injuries often involves orthopedic surgery. In ligament reconstructions, firm tendon-to-bone healing is essential for stability. In fracture treatment, nonunion will significantly impair the outcome. Inhibitors of cyclooxygenase (COX) are effective against pain in orthopedic trauma but might impair bone healing.

The aims of the thesis were to characterize tendon-bone healing and assess the effect of bone resorption inhibition by the bisphosphonate zoledronic acid (ZA). We also aimed to investigate the effect of short-time COX-inhibition by parecoxib on fracture healing. The studies conducted were all experimental animal studies in rats.

The studies confirmed that tendon-to-bone tunnel healing is a slow process. A native layered tendon-bone interface did not recreate. Still, crossing collagen fibers were associated with an increase of biomechanical strength and bone mineral between 4 and 12 weeks of healing. The main effect of ZA was a reduction of tendon graft pull-out strength by 19% at early time points of healing. We found no negative impact of immediate or delayed three-days treatment with parecoxib on shaft fracture healing in rats.

Additional information

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Published May 12, 2020 11:01 AM - Last modified May 29, 2020 10:58 AM