Abstracts Posters SICOT-SOF meeting Gothenburg 2010 _2_

Poster
Topic: Arthroplasty - Hip
Abstract number: 25825
DETECTION OF PERIACETABULAR OSTEOLYSIS AROUND UNCEMENTED
CUPS COMPUTED TOMOGRAPHY VS CONVENTIONAL RADIOGRAPHIC
EXAMINATION
Buster SANDGREN, Joakim CRAFOORD, Henrik OLIVECRONA
Karolinska Institute, Stockholm (SWEDEN)
Pelvic osteolysis is a major concern after total hip replacement (THR). This is often
an asymptomatic process leading to severe bone loss and complicated revisions.
Radiographic examination is the standard method to follow these patients. Computed
Tomography (CT) has been shown to be more sensitive in detection of osteolysis.We
compared CT and conventional radiographic examination in asymptomatic patients
operated with uncemented THR. We investigated 207 patients with uncemented cups
with radiographic examination and CT scan and evaluated with a custom made
protocol. The patients were selected from the Swedish Hip Arthroplasty Registry.
They were all asymptomatic, average age 53 years (19-67), time from operation 10
years (7-14).The images were evaluated independently by one orthopaedic specialist
and a radiologist. Kappa statistics was used to measure inters and intra observer
reliability. Osteolytic lesions were found on radiographic examination in 14 of 207
patients compared to 185 on the CT examinations. According to Landis & Koch
evaluation for Kappa coefficients, inter reliability was good (K = 0.64) and intra
reliability was very good (K = 0.81) In those cases where the two observers
disagreed, the images were investigated again and discussed. We found that
radiographs can both under- and over estimated osteolysis. The CT volumes could
be severely distorted by the metal artefacts. We chose not to use any filters as the
scanners have improved the last years and filters can destroy information in the
volumes. In most cases, CT scans reveal much more information concerning
osteolysis than plain radiographs.
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