Abstract
Introduction and Aims: Modular acetabular designs are widely used in THA procedures and now accommodate highly cross-linked polyethylene liners. However, polymer processing influences material properties, including a decrease in resistance to crack propagation. This study comparatively evaluated locking mechanism integrity of three modular acetabular designs, which employ conventional and highly cross-linked polyethylene liners.
Method: Locking mechanism integrity was established for both conventional and highly cross-linked polymers through push-out (n=3) and lever-out (n=3) testing of fully seated liners. When possible, liners were reinserted and forcibly disassembled.
Results: The push out and lever out strengths measured for the highly cross-linked polyethylene acetabular liners in this study indicated that short-term disassociation of these components is no more likely than that for the conventional polyethylene liners of each design. Student t-tests confirmed the null hypothesis. In addition, when compared to the strengths of clinically successful modular designs none of the systems evaluated presents any great risk of short-term disassociation. Significant reductions in locking mechanism strength after liner reinsertion were also noted for both polymers.
Conclusion: Short-term static disassociation failure of highly cross-linked polyethylene liners were found to be equivalent to conventional polyethylene liners. Given their touted improvement in wear reduction, they would appear to be a reasonable alternative in the young patient requiring THA. Secondarily, neither conventional nor highly cross-linked polymers should be re-inserted for any reason at the time of surgery.
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.
None of the authors is receiving any financial benefit or support from any source.
