Eirik Aunan

A new method to measure ligament balancing . How balanced are total knee arthroplasties?

Background: Ligament balancing is considered a prerequisite for good function and survival in total knee arthroplasty (TKA). However, there is no consensus on how to measure ligament balance intra-operatively and the degree of stability obtained after different balancing techniques is not clarified.

Purpose: This study presents a new method to measure ligament balancing in TKA and report on the results of a try-out of this method in 70 ligament balanced knees and in 30 knees where ligament balancing was considered unnecessary.

Methods: After implantation of the prosthesis spatulas of different thickness were used to measure medial and lateral condylar lift-off in flexion and extension.

Patellar resurfacing in total knee arthroplasty. A prospective, randomised and double blind study.

Background:The best treatment of the patella during TKA is controversial. The implantation of a patellar component during a TKA adds to the operation time and the costs of the operation. There is a huge variation around the world as to whether the patella is resurfaced or not during TKA.

Purpose:The aim of this study is to determine whether it is a difference in outcome between patella resurfaced knees and not resurfaced knees at 1 and 3 years after TKA.

Method: Prospective, randomised and double blind study. The primary endpoint is the  Knee injury and Osteoarthritis Outcome Score (KOOS).

The secondary endpoints are the Oxford score, Knee Society Score (KSS), stair climbing test with pain scores (VAS) and patient satisfaction (VAS).

Can the combination of information from different alignment axis improve rotational alignment of the femoral component in total knee arthroplasty?

Background: There is a strong relationship between rotational alignment of the femoral component in total knee arthroplasty (TKA) and knee joint kinematics, function and prosthetic survival. Excessive internal rotation may lead to pain, patella-femoral instability, failure of the patellar component  and flexion laxity. Excessive external rotation may cause laxity in flexion  and varus mal-alignment in flexion.

The most widely used secondary reference axes to help navigate the femoral component into rotational alignment corresponding to the CT derived surgical epicondylar axis are the posterior condylar line (PCL), the surgical transepicondylar axis (sTEA) and the antero-posterior axis (APA) (Whiteside's line). More recently the transverse femoral axis (TFA) has been proposed.

Because of the obvious lack of reliability of these secondary alignment axes we started up in 2005 to use a combination of information from three secondary alignment axes in the hope of improving the axial alignment of the femoral component.

Purpose of study: The aim of this study is to estimate the accuracy and precision of the combination technique, and to investigate the degree of patella-femoral joint incongruence as measured by patella-femoral tilt and lateralization that can be expected with this technique for positioning the femoral component in the axial plane. 

Materials and methods: At three years follow up 60 consecutive patients will be examined with a very low-dose three dimensional computed tomography for axial and coronal alignment of the prosthetic components. Standard radiographic evaluation with anterio-posterior, sagital, long leg and patella-axial x-rays will also be performed.

Publikasjoner

• Aunan E. (Outcome after total knee arthroplasty. Presentation of different tools for outcome assessement) Resultater etter kneprotese kirurgi. Forskjellige måleinstrumenter. Symposium October 2011. The Norwegian Hip and Knee Society.
• Aunan E, Næss G. ("High-flex" vs "standard" cruciate retaining total knee arthroplasty. A prospective, non randomized, dobbel blind study) "High-flex" vs "standard" bakre korsbåndsbevarende kneprotese. En kotrollert, ikke randomisert dobbelt blind undersøkelse. Abstract in Høstmøteboken 2011 and oral presentation. Nominated to the best paper award.
• Aunan E. Clinical outcome after arthroscopic rotator cuff surgery. Oral presentation at Artroskopiforeningens vintermøte, feb. 2011.
• Aunan E. Measured resection technique vs. Gap resection technique, advantages and disadvantages. Symposium October 2010. The Norwegian Hip and Knee Society.
• Thoen P S, Aunan E. (Osteosynthesis of fractures in the proximal humerus) Kirurgisk behandling av frakturer i proksimale humerus; komplikasjoner og funksjonelle resultater. Abstract in Høstmøteboken 2010 and oral presentation.
• Alhaug E, Aunan E. (Osteosynthesis of clavicular fractures). (Norwegian). Operativ behandling av claviculafrakturer. Abstract in Høstmøteboken 2009 and oral presentation.
• Aunan E. (How balanced are ligament-balanced total knees?) (Norwegian) I hvilken grad kan man oppnå et stabilt protesekne etter ligamentbalansering? Abstract in Høstmøteboken 2009 and oral presentation.
• Aunan E. (Patellar resurfacing in total knee arthroplasty. A prospective, randomised and double blind study). (Norwegian). Bruk av patellakomponent ved totalprotesekirurgi i knær, en prospektiv, randomisert og dobbelt blind undersøkelse. Lecture at Innlandets helsefaglige forskningskonferanse 2008. 23. sept. 2008.
• Kibsgård T J, Aunan E. Meniscal repair with absorbable arrows, a 3,9 year follow up. Poster at NOF congress in Amsterdam, june 2008.
• Kibsgård T J, Aunan E. ( Meniscal repair with absorbable arrows). (Norwegian). Meniskreparasjon med resorberbare piler. Abstract in Høstmøteboken 2007 and oral presentation. Award winner.
• Aunan E. Sulheim S. (Prospective evaluation of outcome after arthroscopic rotator cuff surgery). (Norwegian). Prospektiv resultatevaluering av artroskopiske rotatorcuffsuturer. Abstract in Høstmøteboken 2007 and oral presentation.
• Aunan E. (Prospective evaluation of outcome after arthroscopic shoulder surgery). (Norwegian) Prospektiv resultatevaluering av artroskopisk skulderkirurgi. Vitenskapelige forhandlinger 2005 and oral presentation.
• Clarke-Jenssen J. Beisland C. Aunan E. Rønning R. Gammanaglen: Bedre enn sitt rykte? - en prospektiv studie av 500 gammanagler SIHF-Lillehammer 1995-2003. Vitenskapelige forhandlinger 2003.
• Aunan E. (Prospective evaluation of outcome after total knee arthroplasty). (Norwegian). Prospektiv kontinuerlig resultatevaluering av kneprotesekirurgi. Abstract in Vitenskapelige forhandlinger 2003 and oral presentation.
• Aunan E. (Measuring outcome after total knee arthroplsty). (Norwegian) Evalueringsverktøy i kneprotesekirurgien. Abstract in Vitenskapelige forhandlinger 2003 and oral presentation.
• Aunan E. [Writing information and consent prior to orthopaedic surgery]. [Norwegian] [Journal Article] Tidsskrift for Den Norske Laegeforening. 123(18):2594-6, 2003 Sep 25.
• Aunan E. [Informed consent prior to surgery]. [Norwegian] [Historical Article. Journal Article] Tidsskrift for Den Norske Laegeforening. 123(18):2597-9, 2003 Sep 25.
• Beisland C. Husby A. Aunan E. Frakturer i proximale femur behandlet med kort 11 millimeters gamma-nagle - et treårsmateriale. Kirurgiske forhandlinger 1998.
• Stromsoe K. Hem ES. Aunan E. Unstable vertebral fractures in the lower third of the spine treated with closed reduction and transpedicular posterior fixation: a retrospective analysis of 82 fractures in 78 patients. [Journal Article] European Spine Journal. 6(4):239-44, 1997.
• Aunan E. Medby PC. Su Chu M. Funikkelblokade ved vasectomier. En prospektiv randomisert dobbelt blind undersøkelse. Kirurgiske forhandlinger 1990. Tildelt Bard urology Award.
• Aunan E. Naess A. Torsion of intra-abdominal lipoma--a rare cause of recurrent or acute abdominal pain. Case report. [Case Reports. Journal Article] Acta Chirurgica Scandinavica. 154(9):539-40, 1988 Sep.