Bearings in hip arthroplasty: Diagnostics and prognosis of adverse reaction to metal debris and long-term risk of revision in young patients

Research output: ThesisPh.D. thesis

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Total hip arthroplasty (THA) has improved the life of millions of patients with debilitating conditionsof the hip such as osteoarthritis (OA). The positive effect on quality of life and function has led THAto become one of the most frequently performed surgical procedures, a frequency that is projectedto rise, especially among young patients. Although the survival of THAs is constantly improved,giving a long enough timeline all THA will eventually wear, break, loosen etc. 25 years aftersurgery 58-74% of all patients still have their primary THA. However, the survival of THAs is thelowest among young patients compared to all other age groups. Although revision surgery ispossible the functional outcome is inferior compared to primary surgery and young patients riskundergoing multiple revisions in their lifetime. This is problematic as young patient likely have thehighest demand for functional outcome compared to older patients. To improve the survival ofTHAs in young patient different bearings have been used. At the turn of the millennium and thefollowing decade, metal-on-metal (MoM) THAs were used, but later showed inferior survival,tendency to metal ion release into the blood and formation of adverse reaction the metal debris(ARMD) in the form of pseudotumors (PTs). The MoM bearings are almost no longer used, andmost countries have implemented lifelong follow-up programs in patients with MoM where metalion levels and radiological findings such as PTs can lead to revision surgery.

Study I
We aimed to investigate the sensitivity and specificity when an orthopedic surgery resident after a short training program performed US scans on patients with THA to detect PTs compared with MARS-MRI as a gold standard. Secondly, we investigated the sensitivity and specificity for US to detect PTs in obese and non-obese patients. We examined 205 patients with 50 pseudotumors on MARS-MRI. We found that the orthopedic resident had a good sensitivity and specificity in both obese and non-obese patients.

Study II
Our aim was to investigate how patient-reported outcome (PRO), metal ion blood levels and ARMD changes over time in hip resurfacing arthroplasties (HRA), MoM and metal-on-polyethylene (MoP) THA at 4 and 13 years. We included 98 hips arthroplasties in 78 patients. The prevalence of PT declined in HRA and MoM THA but increased in MoP THA over time. New PTs were just as common in HRA and MoP THA. Blood levels of cobalt and chromium was higher in HRA and MoM THA compared to MoP THA, but were stable over time. No difference in PROM scores was found between HRA, MoM and MoP THA at first or second examination. Blood levels of cobalt and chromium or PROM scores were not associated with the presence of PTs. In perspective, surgeons should be cautious with using the presence of long-term pseudotumors as revision causes.

Study III
Our aim was to compare the survival and hazard ratio (HR) of revision of primary stemmed cementless THA with MoM, ceramic-on-ceramic (CoC) and ceramic-on-highly crosslinked polyethylene (CoXLP) to that of metal-on- highly crosslinked polyethylene (MoXLP) bearings in patients aged 20-55 years diagnosed with osteoarthritis or childhood hip disorders. We included 21,594 patients from the Nordic Arthroplasty Register Association dataset. MoXLP had higher survival and lower HR for revision than MoM - mainly for revision causes we cannot specify. MoXLP, CoC and CoXLP had similar survival and HR for revision, but longer follow-up is needed to investigate whether CoC and CoXLP have better, equal or worse performance as both CoC and CoXLP tended to have increased HRs. In perspective, we currently believe that either MoXLP, CoC or CoXLP could be the standard bearings in patients aged 20-55 years. 
Translated title of the contributionSlidoverflader på kunstige hofter: Diagnostik, prognose for vævsreaktioner forårsaget af metalslidpartikler og langtidsrisiko for reoperation blandt unge patienter
Original languageEnglish
Awarding Institution
  • University of Southern Denmark
  • Varnum, Claus, Principal supervisor
  • Overgaard, Søren, Supervisor
  • Graumann, Ole, Supervisor
Date of defence9. Jun 2023
Publication statusPublished - 27. Apr 2023


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