Long-term follow-up of a low profile, coated, press-fit cup: the trabeculae oriented pattern (T.O.P.) acetabular system

PURPOSE: Total hip arthroplasties (THAs) are rising worldwide, as the functional request of patients who undergo this procedure. The trabeculae oriented pattern (TOP) is a modern cup, which follows the philosophy of the tissue sparing surgery (TSS). Focusing on clinical and radiological results and complications, the authors aim to highlight the outcomes of the TOP at a long-term follow-up (FU). METHODS: A retrospective analysis was completed on THA performed with the TOP cup between 1997 and 2015. Five hundred and eighty-eight patients sustained surgery, for a total of 662 cup implanted. Four hundred and sixty patients (524 hips) were examined. Mean FU was 12 ± 4.9 years (range 5–22). Clinical (HHS, OHS and VAS) and radiological data were obtained. Every complication, reoperation or revision was recorded and analyzed. RESULTS: Clinical evaluation revealed a HHS of 87.1 ± 13.8 an OHS of 41.3 ± 5.4, and a VAS of 1.2 ± 1.1. Acetabular osteolysis was observed in 53 hips. Overall survival rate of the cup was 90.5% (50 revisions), the main causes of cup substitution being aseptic loosening (AL) of the cup combined with the stem (26), of the cup only (13 cases) and periprosthetic joint infection (7 cases). CONCLUSION: TOP cup has demonstrated a good overall survivorship at a long-term FU, even compared with other coated cups, providing excellent clinical result with low rate of complications. Its association with a neck sparing stem permits a physiologic load transmission, reducing the stress shielding effect that could cause early implant mobilization.