Cluster analysis successfully identifies clinically meaningful knee valgus moment patterns: frequency of early peaks reflects sex-specific ACL injury incidence

Background: Biomechanical studies of ACL injury risk factors frequently analyze only a fraction of the relevant data, and typically not in accordance with the injury mechanism. Extracting a peak value within a time series of relevance to ACL injuries is challenging due to differences in the relative timing and size of the peak value of interest. Aims/hypotheses: The aim was to cluster analyze the knee valgus moment time series curve shape in the early stance phase. We hypothesized that 1a) There would be few discrete curve shapes, 1b) there would be a shape reflecting an early peak of the knee valgus moment, 2a) youth athletes of both sexes would show similar frequencies of early peaks, 2b) adolescent girls would have greater early peak frequencies. Methods: N = 213 (39% boys) youth soccer and team handball athletes (phase 1) and N = 35 (45% boys) with 5 year follow-up data (phase 2) were recorded performing a change of direction task with 3D motion analysis and a force plate. Th...研究背景：前交叉韧带（ACL）损伤风险因素的生物力学研究通常仅分析部分相关数据，且往往未贴合损伤发生机制开展分析。由于目标峰值的相对出现时机与幅值存在差异，从与ACL损伤相关的时间序列数据中提取目标峰值颇具挑战。 研究目的与假设：本研究旨在对站立早期阶段的膝外翻力矩（knee valgus moment）时间序列曲线形态进行聚类分析。我们提出如下研究假设：1a）离散的曲线形态类别数量较少；1b）存在一类可反映膝外翻力矩早期峰值的曲线形态；2a）两性青年运动员的早期峰值出现频率相近；2b）青春期女性运动员的早期峰值出现频率更高。 研究方法：本研究纳入213名青年足球及手球运动员（阶段1，其中男性占比39%），另有35名拥有5年随访数据的受试者（阶段2，其中男性占比45%）。所有受试者完成变向动作任务时，均采用三维运动分析（3D motion analysis）系统与测力台（force plate）采集运动数据。（原文后续内容截断）