Abstract

PURPOSE: Total hip arthroplasty (THA) in patients with small or unusual proximal femoral anatomy is challenging due to sizing issues, control of version, and implant fixation. The Wagner Cone is a monoblock, fluted, tapered stem with successful outcomes for these patients; however, there is limited information on subsidence, a common finding with cementless stems.METHODS: We retrospectively reviewed our cases using the modified Wagner Cone (Zimmer, Warsaw, IN) implanted over a 13-year period (2006-2019) in patients with small or abnormal proximal femoral anatomy. We performed 144 primary THAs in 114 patients using this prosthesis. Mean follow-up was 4.5±3.4years (range, 1-13years). Common reasons for implantation were hip dysplasia (52%) and osteoarthritis in patients with small femoral proportions (22%). Analysis of outcomes included assessment of stem subsidence and stability.RESULTS: Survival was 98.6% in aseptic cases; revision-free survival was 97.9%. Femoral subsidence occurred in 84 cases (58%). No subsidence progressed after 3months. Of those that subsided, the mean distance was 2.8±2.0mm. There was less subsidence in stems that stabilized prior to sixweeks (2.2±1.4mm) compared to those that continued until 12weeks (3.9±1.6, p=0.02). Harris Hip, UCLA, and WOMAC scores significantly improved from pre-operative evaluation (p<0.001*, p<0.003*, p«0.001*); there was no difference in outcome between patients with and without subsidence (p=0.430, p=0.228, p=0.147).CONCLUSION: The modified Wagner Cone demonstrates excellent clinical outcomes in patients with challenging proximal femoral anatomy. Subsidence is minor, stops by 3months, and does not compromise clinical outcome.

View details for DOI 10.1007/s00264-022-05608-6

View details for PubMedID 36224431