Abstract
Background: Cylindrical fully-coated cobalt-chromium stems (CCS) have been widely used in femoral revisions. However, monoblock fluted conical tapered stems (FCTS) are growing in popularity. The present study seeks to determine whether there are any long-term differences between the two designs. Material and methods: A retrospective study of 38 CCS versus 40 FCTS was carried out. Demographic data, clinical variables and radiographic parameters were recorded. Results: Demographic data were comparable. A greater proportion of septic revisions, periprosthetic fractures and previous osteosynthesis failures was observed with FCTS versus CCS (p = 0.012). A greater use of FCTS was recorded in cases with bone defects of type IIIA and higher (p = 0.025). There were no significant differences in terms of in-hospital complications (p = 0.815), postoperative surgical complications or need for reoperation (p = 0.156). The CCS group presented a higher percentage of clinical thigh pain at the end of follow-up (p = 0.006). Additionally, a greater presence of radiolucencies was observed with CCS, especially in proximal zones (1, 7, 10 and 14). More subsidence, tip cortical hypertrophy and stress shielding were recorded in the CCS group. The overall survival at 120 months was 84.2% in the CCS group and 85% in the FCTS group (p = 0.520). When analyzing isolated aseptic loosening as the cause of failure, the survival rate was 94.7% in the CCS group and 95% in the FCTS group (p = 0.506). Conclusions: Both FCTS and CCS with diaphyseal anchorage afford excellent long-term survival rates, with no differences between the two designs. However, a higher incidence of stress shielding, radiolucencies and thigh pain with CCS seems to favor the use of FCTS.