Comparison of single taper and dual taper versions of the same stem design in total hip arthroplasty for primary osteoarthritis

BackgroundIn total hip arthroplasty (THA), the outcomes of single taper (ST) and dual taper (DT) versions of the same stem design have been scarcely studied. A registry study comparing ST and DT versions of the same stem design was designed, aiming to assess: (1) the survival rates and the hazard ratios for failure; (2) the survival rates and the hazard ratios for failure using stem-focused endpoints.Material and methodsA regional arthroplasty registry was interrogated about stem designs with ST and DT versions in cementless THAs performed for primary osteoarthritis. Only the same cup and ceramic-on-ceramic bearings were included: the DT stems had a titanium-on-titanium modularity. Demographic and implant features were recorded. Survival rates and hazard ratios were evaluated and compared. Stem-focused endpoints were also investigated.ResultsA total of 5359 THAs were included, with three stem designs. The two versions of every stem showed different demographics and implant-related features: ST versions were preferentially implanted in heavier young men. For each stem, the two versions had similar survival rates at 5 years (p = 0.076; p = 0.319; p = 0.616) and similar adjusted hazard ratios for failures (p = 0.084; p = 0.308; p = 0.729). When stem-focused endpoints were adopted, the ST and DT versions of the three stems achieved similar survival rates (p = 0.710; p = 0.784; p = 0.983) and similar adjusted hazard ratios (p = 0.647; p = 0.858; p = 0.787). Three neck breakages occurred (0.0007% of all the modular implants).ConclusionsST and DT versions of the same stem design did not show any differences in terms of survival rates and hazard ratios for failures at 5 years.LEVEL OF EVIDENCE: IV.

Automated summary

This study compared the outcomes of single taper (ST) and dual taper (DT) versions of the same stem design in total hip arthroplasty (THA). The results showed no significant differences in survival rates and hazard ratios for failures between the two versions. Similarly, there were no significant differences when stem-focused endpoints were considered. Therefore, the ST and DT versions of the same stem design have similar outcomes in terms of failure rates and survival rates at 5 years.