Denosumab and bone loss in uncemented total hip arthroplasty: a secondary 5-year follow-up of a randomized controlled...

Denosumab may preserve periprosthetic bone mineral density (pBMD) around uncemented total hip arthroplasty (THA) components. This exploratory analysis of a previously published randomized controlled trial (RCT) aimed to assess the effects of denosumab on BMD 5 years after treatment cessation.

64 non-osteoporotic patients undergoing uncemented THA were enrolled in a randomized, double-blind, placebo-controlled phase-2 trial and received either 2 doses of denosumab or placebo. The primary outcome was pBMD at 12 months, measured by dual-energy X-ray absorptiometry (DEXA). At a mean follow-up of 5.6 years (range 4.3-7.3), 54 patients remained for clinical assessment, DEXA, and plain radiography. The study was registered on ClinicalTrials.gov (NCT01630941).

No differences in pBMD in the acetabular Digas zones or femoral Gruen zones were found between the groups at 5 years. The estimated mean difference in the sum of all zones around the cup was 0.042 g/cm² (95% confidence interval [CI] -0.31 to 0.35; P = 0.8), and for the sum of all Gruen zones -0.06 g/cm² (CI -0.55 to 0.43; P = 0.8). No statistically significant differences were observed in patient-reported outcome measures or the incidence of heterotopic ossification. A gradual decline in pBMD was evident.

At 5 years, the adjusted between-group difference and its 95% confidence interval showed no statistically or clinically relevant effect of denosumab. Whether longer treatment duration or a sequential post-denosumab regimen could influence long-term periprosthetic bone preservation is unknown.