In cementless total hip arthroplasty (THA), femoral stems rely on the initial press‐fit fixation against cortical bone to achieve osseointegration. Decreased bone mineral density (BMD) in postmenopausal women poses natural difficulties in achieving axial and rotational femoral stem stability. The present study examined contributing demographic, surgery-related and postoperative factors in determining the magnitude of early stem migration prior to osseointegration. A prospective cohort of 65 postmenopausal women with hip osteoarthritis (Dorr type A or B femur anatomy) underwent THA with implantation of an uncemented parallel‐sided femoral component. Postoperative femoral stem translation and rotation were measured using model-based radiostereometric analysis. Based on analysis of covariance, which controlled for outliers and randomized antiresorptive treatment with denosumab or placebo, none of the analyzed demographics (including BMI) and surgery-related variables (including the stem-to-canal fil ratio) was associated with stem subsidence. Stem subsidence (mean 1.8 mm, 95% CI 1.2 to 2.4) occurred even in women with normal hip BMD. Total hip BMD and postoperative walking activity (measured three months after surgery) were significantly associated with stem rotation, and height acted as a confounding factor. The effect of walking activity on stem rotation was significant at 5 months (p = 0.0083) and at 11 months (p = 0.0117). This observation confirms the previous results of instrumented hip prostheses on torsional moments affecting stems during daily activities. High-resolution imaging modalities of local bone quality are needed to explore reasons for RSA-measurable stem subsidence even in women with normal hip BMD.

在非骨水泥全髋关节置换术（THA）中，股骨柄依靠最初的压入式固定固定在皮质骨上，以实现骨整合。绝经后妇女的骨矿物质密度（BMD）降低为实现股骨干的轴向和旋转稳定性带来了自然困难。本研究检查了人口统计学，手术相关和术后因素，以确定骨整合前早期茎迁移的程度。65位绝经后髋关节骨关节炎女性（Dorr型或B型股骨解剖）的前瞻性队列接受THA植入无骨水泥的股骨假体。术后股骨柄平移和旋转采用基于模型的放射立体分析法进行测量。根据协方差分析，该药物控制了离群值并使用denosumab或安慰剂进行了随机的抗吸收治疗，因此所分析的人口统计学（包括BMI）和与手术相关的变量（包括茎与管的fil比率）均与茎沉陷无关。甚至在髋部BMD正常的女性中也会发生茎沉陷（平均1.8 mm，95％CI 1.2至2.4）。总髋部BMD和术后行走活动（术后三个月测得）与茎旋转密切相关，而身高则是一个混杂因素。步行活动对茎旋转的影响在5个月（p = 0.0083）和11个月（p = 0.0117）时很显着。该观察结果证实了髋关节假体在日常活动中影响杆的扭转力矩的先前结果。