Roles of Distal Centralizer in Cemented Total Hip Arthroplasty

Abstract

Purpose: This study was performed to find out the influencing factors on cement mantle thickness in cemented total hip arthroplasty. Materials and Methods: Eighty patients were randomly enrolled who received total hip arthroplasty with the third generation cementing technique. Four types of femoral prosthesis (20 patients in each type) were used: Centralign (Zimmer, Warsaw, IN), Precision (Howmedica, Rutherford, NJ), Omnifit (Osteonics, Allendale, NJ), and Elite Plus (Depuy, Warsaw, IN). Size of femoral prosthesis, diameter of stem tip, shape and size of centralizer, and the condition of cement mantle on the radiograph were analyzed. Results: Between the two groups of same or above C1 (C1; A, B, and C1, n=69) and C2 (n=11) by Barrack classification, there was no difference in age, sex, underlying disease, size of applied stem, Dorr ratio, and the distance between stem tip and plug. The difference of distal diameter between centralizer and stem was less than 2 mm in 18 patients, and same or above 2 mm in 62 patients. C2 was more frequently observed in patients with the diameter difference 2 mm (22.2% vs. 11.3%). However, C2 developed in all types of femoral stems, irrespective of their shapes, even the diameter difference was 2 mm. Conclusion: The diameter of distal centralizing device should be at least 2 mm larger than that of stem tip for an optimal cement mantle thickness. In addition, centralizers investigated in this study should be carefully used, and more improved shape of centralizer is required for the successful cement mantle formation.