Abstract
Aim: The current trend in fixation of acetabular components is towards press-fit, no-hole components to reduce the wear debris production and its access to the bone prosthesis interface. The purpose of this study is to review the outcome of no holes or holes with or without adjuvant screw fixation in a porous expanded rim modular acetabular component of the same design with a minimum of two year follow up.
Method: This was a retrospective review of the charts and radiographs of 204 consecutive Osteonics PSL acetabular components inserted by the same surgeon. Radiographic analysis included assessments of radiolucencies in the three zones of Charnley & DeLee, as well as assessments of migration and wear using the technique of Livermore. Osteolytic cysts were recorded and any progression noted.
Results: The underlying diagnosis was similar in all groups with osteoarthritis comprising 57%. In the screw group one component has been revised for loosening secondary to impingement. Three had significant osteolysis, all of which have been revised. There was no significant difference for the 28 mm heads between the groups for radiolucencies or migration. The 22 mm heads had a higher rate of linear wear. Complications included seven dislocations, two with grade three heterotopic ossification and one late haematogenous infection.
Conclusion: Comparing acetabular components with and without screws and no-hole components there was no significant difference in radiolucencies, wear and migration. Osteolytic cysts occurred only in cups with holes and screws. Because of these findings the surgeon continues to use the no-hole cup wherever possible in primary and revision arthroplasty. Longer follow up will be required to confirm that this decreased osteolysis persists over time in the no-hole group.
The abstracts were prepared by Professor Alan Thurston. Correspondence should be addressed to him at the New Zealand Orthopaedic Association, PO Box 7451, Wellington, New Zealand.
