Objective To investigate the effects of denosumab(DEN)and alendronate(AL)on bone mineral density(BMD)around the prosthesis after total hip arthroplasty(THA).Methods A retrospective analysis was conducted on the clinical data of primary osteoporosis(POP)patients who underwent THA at the Affiliated Jinhua Hospital of Zhejiang University School of Medicine from March 2022 to March 2023,the patients were divided into the DEN group and the AL group according to the postoperative protocols.The main observation index was the bone density around the implant(Gruen zone:1st and 7th zones;time points:postoperative day 5(T1),6 months(T2),and 12 months(T3);detection method:dual-energy X-ray absorptiometry).The secondary observation index was the bone metabolism index(bone calcitonin(OC),β-collagen special sequence(β-Crosslaps),and type 1 procollagen N-terminal peptide(P1NP);time points:preoperative(T4),6 months(T2),and 12 months(T3);detection method:enzyme-linked immunosorbent assay).Results A total of 120 patients were included in the study,with 59 in the DEN group and 61 in the AL group.At baseline,there was no statistically significant difference in serum OC,β-Crosslaps and P1NP levels between the two groups(P＞0.05).Periprosthetic BMD showed a decreasing trend in both groups,and periprosthetic BMD was higher in the DEN group than in the AL group in both Gruen zone 1 and Gruen zone 7 at the T2 and T3 time points(P＜0.05).In terms of bone transformation markers,serum OC,β-Crosslaps and P1NP levels showed decreasing trends with prolonged treatment time in both groups(P＜0.05).In addition,serum OC,β-Crosslaps and P1NP levels were significantly lower in the DEN group than in the AL group at T2 and T3 time points(P＜0.05).Conclusion Compared with AL,DEN is more effective in preventing periprosthetic bone loss of the proximal femur and has a better safety profile.