Early to Mid-Term Results of Revision Hip Replacement Using a Stryker Tritanium Acetabular Shell© Mr J Pegrum MRCS 1, Mr D Kosuge FRCS (Orth) 2, Mr S Muthian MRCS 1, Mr D Johnstone FRCS (Orth)3; 1Specialist Registrar Stoke Mandeville Hospital, 2 Senior Arthroplasty Fellow Stoke Mandeville Hospital, 3Consultant Orthopaedic Surgeon at Stoke Mandeville Hospital, Buckinghamshire Healthcare NHS Trust Introduction: The burden and frequency of revision total hip replacement (THR) surgery is increasing. The key concepts for longevity in uncemented implants is initial implant stability and biological fixation. [1-3] The introduction of biocompatible and osteoconductive highly porous metals, in the last decade, have been used to address osseous ingrowth and implant longevity. Aims & Objectives: The purpose of this study was to assess the Stryker hemispherical modular Tritanium acetabular shell survival against the published literature. Evaluate the radiographic osseous integration of the tritanium implant. (Stryker Tritanium acetabular shell, Stryker Kalamazoo, MI 49002 USA) Methods: The clinical notes and radiographs of patients were retrospectively reviewed. Fifty-four consecutive Stryker hemispherical modular Tritanium acetabular shells were identified. Impaction of allograft bone was used in contained defects. Bone defects were classified according to the method described by Pabrosky et al. [4] Clinical notes and the national joint registry were used to assess implant survival and radiographic osseous integration using the criteria set out by Moore et al. [1] Results: Summary of Key Papers Discussion: The modulus of elasticity of the Tritanium shell is similar to subchondral bone. This allows physiological load transfer which encourages preservation of host bone and avoidance of stress shielding. [2] The Tritanium shell is designed with an average poor size of 546 microns, optimised for bony ingrowth. Osseous integration provides biological fixation which is essential for implant longevity. [1-2] 50% bony contact is required for optimum initial implant stability.[5] We found the versatility of screw configuration with this implant favorable to supplement the initial stability before bony ingrowth occurred. Our consecutive series compares favorably with the reported short to mid-term 80-98.8% survival of other highly porous metal implants in the literature. [3,6-10] These early to mid term results compare promisingly to impaction allografting with cemented cups. Aseptic survival, in a specialist centre, of the acetabular component with impaction allografting is 85.9% at 13 years. [11] Conclusion: Cementless acetabular revision with the Tritanium acetabular shell demonstrated excellent early to mid term clinical results. Further research is required to assess the suitability with pelvic discontinuity. References: 1. Moore MS, et al. Radiographic signs of osseointegration in porous-coated acetabular components. Clin Orthop Relat Res, 2006. 444: p. 176-83. 2. Meneghini RM, et al. Bone remodeling around porous metal cementless acetabular components. J Arthroplasty, 2010. 25(5): p. 741-7. 3. Kim WY, et al. Porous tantalum uncemented acetabular shells in revision total hip replacement: two to four year clinical and radiographic results. Hip Int, 2008. 18(1): p. 17-22. 4. Paprosky WG et al. Acetabular defect classification and surgical reconstruction in revision arthroplasty: a 6-year follow-up evaluation. J Arthroplasty. 1994;9:33–44 5. Sternheim A, et al. Porous metal revision shells for management of contained acetabular bone defects : a comparison between up to 50% bleeding host bone contact and more than 50% contact. J Bone Joint Surg Br, 2012. 94(2): p. 158-62. 6. Kosashvili Y, et al. Salvage of failed acetabular cages by nonbuttressed trabecular metal cups. Clin Orthop Relat Res, 010. 468(2):p.466-71. 7. Van Kleunen JP, et al. Acetabular revisions using trabecular metal cups and augments. J Arthroplasty. 2009 Sep;24(6 Suppl):64-8 8. Skytta ET, et al. Early results of 827 trabecular metal revision shells in acetabular revision. J Arthroplasty, 2011. 26(3): p. 342-5. 9. Unger AS, et al. Evaluation of a porous tantalum uncemented acetabular cup in revision total hip arthroplasty: clinical and radiological results of 60 hips. J Arthroplasty. 2005 Dec;20(8):1002-9. 10. Nakashima Y, et al. Clinical and radiographic evaluation of total hip arthroplasties using porous tantalum modular acetabular components: 5-year follow-up of clinical trial. Mod Rheumatol. 2013 Jan;23(1):112-8 11. Gilbody J, et al. Clinical and radiographic outcomes of acetabular impaction grafting without cage reinforcement for revision hip replacement: a minimum ten-year follow-up study. Bone Joint J, 2014. 96-B(2): p. 188-94. Author Study Type N0 of subjects Conclusions Kim et al 2008 3 Revision surgery Single centre 46 97.8% survival at 40 months Kosashvili et al 6 Revision Surgery 15 80% survival at 48 months in cases of failed acetabular cages or roof rings Van Kleunen et al 2009 7 88 98.8% survival for aseptic loosening at minimum 2 year follow up. Skytta et al 2011 8 Revision Finish National Registry 827 98% survival for aseptic loosening at 3 years (92% for all cause) Unger et al 2005 9 Single surgeon 60 98.3% at 44 months Nakashima et al 2013 10 Primary Surgery Single Surgeon 82 100% 5 years survival We present early to mid-term results of one of these highly porous ingrowth cups used in revision THR in a consecutive single surgeon series. Stryker Tritanium acetabular shell is suitable in revision cases up to Pabrosky 3A. Pabrosky Defect Number of implants 1 19 2A 13 2B 8 2C 4 3A 10 100% survival for aseptic loosening. Survival for all causes 96.8%. One case for recurrent dislocations, in a patient with epilepsy, and one for infection. Both acetabular shells were well fixed during explantation. Radiographic analysis showed 100% survival for osseous integration at a median follow up of 44 (8-70) months.