Abstract
While cemented THA has been considered the gold-standard, cementless THA has become a common and even preferred approach for younger individuals and those with acceptable bone stock. Which technology provides superior results and in which patients, however, remains controversial, and has not been systematically studied.
The literature suggests that well-fixed cementless prostheses, and even composite beam cemented prostheses cause stress shielding and progressive osteopenia in the surrounding bone. This compromises and complicates subsequent surgery, particularly in young patients who are at risk for multiple revisions, and may increase the risk of periprosthetic fracture, component failure, and aseptic loosening.
In contrast, polished tapered stems, by behaving according to a taper-slip philosophy, favorably load bone, converting shear stress into radially directed hoop stresses, through the medium of the surrounding visco-elastic cement and its resulting ability to creep.
The C-Stem, (DePuy, Warsaw, Indiana, USA) a cemented triple tapered polished stem is the only stem with published data demonstrating positive remodeling of bone in as many as 20% of patients, and preservation of the critical proximal medial calcar bone. Additional anectdotal reports confirm these results.
The long-term results of cemented stems, which necessarily involve the surviving youngerst cohort in any series, are outstanding. The tapered polished stem technology may improve these historical results, and, by limiting periprosthetic stress shielding and osteopenia, may revolutionize the application of cemented THA in younger patients for whom preservation of bone stock through favorable bone loading is so critical to sustained success of the primary and subsequent revision surgeries.
The abstracts were prepared by Ms Orah Naor. Correspondence should be addressed to Israel Orthopaedic Association at PO Box 7845, Haifa 31074, Israel.
