[Femoral Stem Subsidence in Total Hip Arthroplasty: Comparison between Fixation Principles].

OBJECTIVE

To compare the magnitude of subsidence between single- (SW) and double-wedge (DW) femoral stems in primary total hip arthroplasties (THAs), and to identify factors associated with clinically relevant subsidence.

METHODS

Retrospective cohort study with 82 patients (164 hips) undergoing bilateral THA between 2012 and 2022, each receiving type-I (Corail) and -II (Summit) stems, both manufactured by DePuy Synthes. Subsidence was measured radiographically up to 6 months postoperatively and was considered clinically relevant when greater than 3 mm. Radiographic variables included cortical enlargement index (CEI) and canal fill rate (CFR). Statistical analyses included paired t-test, logistic regression, and Spearman correlation.

RESULTS

The mean subsidence was 1.93 ± 1.16 mm in type-I stems and 2.23 ± 1.57 mm in type-II ( p  = 0.181). Clinically relevant subsidence occurred in 18.2% of type-I stems and 31.7% of type-II (OR = 2.07; p  = 0.050). Greater subsidence was observed in the first surgery in bilateral arthroplasties ( p  = 0.006). There was no significant correlation between subsidence, age, body mass index (BMI), CEI, or CFR.

CONCLUSION

The DW stems were associated with a higher risk of clinically relevant subsidence. In bilateral THA, subsidence is more pronounced at first surgery, with no detectable influence of demographic or radiographic factors.