Sex differences in bone shape and knee osteoarthritis: the Osteoarthritis Initia

放射学或症状性骨关节炎(OA)的发病率和患病率在 女性多于男性；然而，造成这种性别差异的根本原因仍不清楚。几个 对骨性关节炎的性别差异提出了可能的解释，包括雌激素的差异。 水平、体力活动和松弛或调整，但每一个都只有适度的支持证据，没有证据 充分解释了观察到的性别差异。最近，几名调查人员提出， 骨形状与骨关节炎发生的风险和骨关节炎的严重程度相关，基于 人体测量、横断面发现，或在一种情况下对24个人进行统计形状建模 膝盖。我们的小组展示了几种特定的股骨近端形状，通过主动形状进行评估 在老年妇女中，模型(ASM)与髋关节骨关节炎的发生率相关。其他人也有 报道称，以ASM为基础的膝关节形状与膝关节骨关节炎的严重程度有关。这是假定的 骨骼形状的变化发生在关节软骨损伤之前。在拟议的研究中，我们将采取 连续5年收集膝关节X线片和核磁共振成像的优势 骨性关节炎倡议(OAI)。我们将使用ASM方法测量股骨和胫骨的形状 被我们的团队改进了。我们将评估基线骨形是否与发病率或 膝关节骨关节炎的进展、疼痛和功能，以及这些关系是否因性别而不同。我们会 应用基于组的有限建模方法来识别遵循相似轨迹的不同子组 女性和男性的骨骼形状随着时间的推移而变化，并检查两者之间的联系 在基线上评估的各种风险因素(即年龄、性别、体重指数、路线等)和会员资格 使用多项Logistic回归模型对不同性别的骨骼形状轨迹进行了比较。最后，我们会 评估决定骨骼形状随时间变化的特定性别轨迹的风险因素。

Incidence and prevalence of either radiographic or symptomatic osteoarthritis (OA) are much higher in women than men; however, the underlying causes for this sex difference in OA remain unknown. Several potential explanations have been proposed for the sex difference in OA, including differences in estrogen level, physical activity, and laxity or alignment, but each has only moderate supporting evidence, and none fully explains the observed sex differences. Recently, several investigators have proposed that aspects of bone shape are associated with an increased risk of incident OA and with severity of OA, based on anthropometric measures, cross-sectional findings, or in one case statistical shape modeling done on 24 knees. Our group demonstrated that several specific proximal femoral shapes, assessed by Active Shape Modeling (ASM), were associated with incident radiographic hip OA in elderly women. Others have also reported that ASM-based knee shape is associated with severity of radiographic knee OA. It is postulated that changes in bone shape occur prior to cartilage damage in the joint. In the proposed study, we will take the advantage of knee radiographs and magnetic resonance images (MRIs) collected annually for 5 years in the Osteoarthritis Initiative (OAI). We will measure femoral and tibial bone shape using an ASM method improved by our group. We will evaluate whether baseline bone shape is associated with incidence or progression of radiographic knee OA, pain and function and whether these associations differ by sex. We will apply group-based finite modeling methods to identify distinctive sub-groups that follow similar trajectories of bone shape change over time in women and men respectively and examine whether associations between various risk factors assessed at baseline (i.e., age, sex, body mass index, alignment, etc.) and membership of trajectories of bone shape differ by sex using a multinomial logistic regression model. Finally, we will evaluate the risk factors that determine sex-specific trajectories of bone shape change over time.