A Retrospective Cohort Study of the Effects of Canal Filling Ratio and Femoral Bone Density Change on the Outcomes of Anatomical and Double-tapered Wedge Stems.

Objective  This study aims to compare the proximal femoral bone density changes in follow-up X-ray imaging and the proximal filling ratios of stems between anatomical and double-tapered wedge stem designs. Methods  Patients aged between 18 and 80 years who received primary total hip arthroplasty using both types of stems between 2017 and 2019 and had follow-up tests for up to a year were included in the study. Canal filling ratios at 3 levels (lesser trochanter [LT], 2 cm above LT, and 7 cm below LT) using the optimal densitometry method. Femoral bone density changes were measured using the Gruen zoning method. Results  A total of 92 patients (76% female and 24% male) met the inclusion criteria for this study. The mean age was 53.86 ± 13.00 years. The canal filling ratio in the double-tapered wedge group (Accolade II) was significantly higher than that in the anatomical stem group (ABGII) ( p  < 0.001, p  < 0.001, and p  = 0.013) for all levels of measurement. No significant difference was observed between both types of stems in femoral bone density changes in zones 1 and 4. However, there were significant differences in femoral bone change, with bone loss being higher in the anatomical stem group in zone 7 (-25% versus -17%; p  = 0.010). Conclusion  Double-tapered wedge stem had a significantly higher canal filling ratio than the anatomical stem at all levels but had less femoral bone density loss in the follow-up postoperative imaging in zone 7. Furthermore, in zones 1 and 4, there was no significant difference in femoral bone density loss.