Abstract
Introduction and Aims: Wear of ultra-high molecular weight polyethylene (UHMWPE) acetabular cups is a well-known cause of osteolysis and loosening of the components. Improvement of the wear resistance of UHMWPE could extend the clinical life of total hip arthroplasty (THA). Chemical cross-linking in acetylene with gamma radiation is a cheap and effective way of increasing wear resistance of UHMWPE.
Method: This study is a report on 132 patients operated between 1977 and 1984, using the Pretoria monobloc stainless steel hip with 30mm metal head. Acetabular cups were machined from RAM extruded rectangular bars (RCH 1000). Final cups were gamma irradiated in stainless steel containers filled with acetylene gas. Three hundred microns surface cross-linking was achieved at 100kG. At that time, 1059 hip replacements were performed by the two first authors. The retrospective study consisted of measurement of the radiological wear. The criteria was to compare and measure the wear from early post-op radiograph and longest follow-up radiograph. Linear wear was measured according to the Livermore methods. Exclusion criteria included follow-up less than 10 years, sepsis, dislocation and other non wear-related causes of failure. The rarely retrieved cross-linked ace-tabular cups were analysed individually using spectrum electron microsope (SEM).
Conclusion: The South African contribution to the method of cross-linking is important. This is a cheap and effective way to improve the quality of the polyethylene. Results of this long-term group of patients with cross-linked UHMWPE show a significant decrease in the wear rate, significantly increasing the longevity of the THR.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
At least one of the authors is receiving or has received material benefits or support from a commercial source.
