Description
The RM Pressfit coated with titanium particles is an uncemented elastic monoblock cup made of UHMWPE, representing the advancement of the proven RM Classic Cup system 1. With a mean survival rate of 94.4% for aseptic loosening after 20 years2, the RM Classic is one of the most successful uncemented acetabular cups worldwide.
The RM Pressfit cup achieves its primary stability through an equatorial press-fit. Aided by the flattening of the polar region, compressive forces are guided towards the periphery of the acetabular cup. 3
The coating comprises a thin layer of non-correlating, individually anchored titanium particles that have no structural stiffness between them. 4 This and the elasticity of the UHMWPE material, which is very similar to human cancellous bone 5, ensure that the load transfer and the biomechanical behaviour of the cup remain physiological after the implantation, with the aim of preventing stress shielding. 6
A high polyethylene thickness of the cup, with a low contact stress, resulting in low wear. 7, 8, 9
Benefit
- Based on the proven concept of the elastic RM Classic monoblock cups 1
- Bone-like elasticity of the implant to preserve bone over the long term 6
- Uncemented press-fit primary fixation with additional option for screw fixation 4
- Secondary stability is achieved through the microstructure of the titanium particle coating of the cup 2, 3, 5
- 10 A* ODEP Rating 10
- Bone-like elasticity of the implant to preserve bone over the long term 6
1 Delfosse D, RM Pressfit- innovation based on clinical history in Hip-Joint Surgery. The RM Cup - Long-term experience with an elastic Monobloc acetabular implant. G. Horne, Editor.2008, Einhorn-Presse Verlag. p. 31-39
2 Ihle, M., et al., The results of the titanium-coated RM acetabular component at 20 years: a long-term follow-up of an uncemented primary total hip replacement. J Bone Joint Surg Br, 2008. 90(10): p. 1284-90.
3 Morscher, E.M., Z., Development and first experience with an uncemented press-fit cup. Clin Orthop Relat Res, 1988(232): p. 96-103.
4 Gasser B, Coating of the RM cup in Hip-Joint Surgery. The RM Cup - Long-term experience with an elastic Monobloc acetabular implant. G. Horne, Editor.2008, Einhorn-Presse Verlag. p. 23-30
5 Mathys R, et al. The Coating of hip joint cups on their outer surface. In: Wilbert HG, Eyerer P, editors. Ultra-high molecular weight polyethylene as biomaterial in orthopaedic surgery. Toronto: Hogrefe & Huber Publishers; 1991. p. 243-7.
6 Horne, G.D., P. A.;Dalton, D. J., Does pelvic osteolysis occur with a nonmodular uncemented acetabular component? J Arthroplasty, 2006. 21(2): p. 185-90.
7 Wyss, T.K., P.;Mayrhofer, P.;Notzli, H.;Pfluger, D.;Knahr, K., Five-year results of the uncemented RM pressfit cup clinical evaluation and migration measurements by EBRA. J Arthroplasty, 2013. 28(8): p. 1291-6.
8 Erivan, R., et al., RM Pressfit® cup: good preliminary results at 5 to 8 years follow-up for 189 patients. Hip Int, 2016.
9 Minten, M.J., P.J. Heesterbeek, and M. Spruit, No effect of additional screw fixation of a cementless, all-polyethylene press-fit socket on migration, wear, and clinical outcome. Acta Orthop, 2016: p. 1-5.
10 Latest ODEP ratings can be found at www.odep.org.uk