Abstract
Background: The Duraloc cup is a frequently used metal backed hemispheric porous-coated cementless acetabular cup. Published radiological data on loosening rates remain contradictory. Despite to this contradictory radiological data is the good clinical performance of this cup reported by many authors. The aim of our study was to evaluate radiological outcome (cup migration, acetabular abduction angle, cup anteversion) and possible correlation to clinical data after 12 years.
Methods: Migration analysis of 40 cementless Duraloc 100 cups (38 patients, average age 57 years, range 52 to 68years, 25 male, 13 female) could be retrospectively performed after a 12 year follow up using Einzelbild-Roentgen-Analyse (EBRA) software. An average of 5 standardised anteriorposterior radiographs (range 4 – 8) could be evaluated. Clinical outcome was assessed using HHS score. Cup migration, acetabular abduction angle, cup anteversion, heterotocpic ossification and wear were determined. Statistical evaluation was performed using Mann- Whitney - U test and correlation analysis.
Results: At 12 years follow up the average horizontal migration was 1.51 mm (range 0 to 8.5 mm) and the average vertical migration was 1.44 mm (range 0 to 4.5 mm). The average cup abduction angle was 48° (range 30° to 58°, average cup anteversion was 16° (range 12 to 25°) Average wear of the polyethylene liner at latest follow up was 1.5 mm (range 1.1 to 2.1). Harris hip score improved from average 41 (range 30 – 55) to 90 (range 77 to 95) at latest follow up. We could not find any significance difference between cup migration and gender (p > 0.05). There was no positive correlation between clinical scores and migration data found (r2 = 0.01). The cup diameter however showed positive correlation with cup migration (r2 = 0.8).
Conclusion: Our study shows good radiological and clinical results of the Duraloc cup after 12 years. Radiological migration data did not show any correlation with clinical results. A greater cup diameter however is a risk factor for higher migration.
Correspondence should be addressed to: EFORT Central Office, Technoparkstrasse 1, CH – 8005 Zürich, Switzerland. Email: office@efort.org
