Gender differences in knee abduction during weight-bearing activities: A systematic review and meta-analysis

Background Increased knee abduction during weight-bearing activities is suggested to be a contributing factor for the high knee injury risk reported in women. However, studies investigating gender difference in knee abduction are inconclusive. Objective To systematically review gender-differences in knee abduction during weight-bearing activities in individuals with or without knee injury. Methods A systematic review and meta-analysis were conducted according to the PRISMA guidelines. A search in the databases Medline, CINAHL and EMBASE was performed until September 2015. Inclusion criteria were studies that reported (1) gender differences, (2) healthy individuals and/or those with anterior cruciate ligament (ACL) deficiency or reconstruction or patellofemoral pain PFP, and (3) knee abduction assessed with either motion analysis or visual observation during weight-bearing activity. Results Fifty-eight articles met the inclusion criteria. Women with PFP had greater peak knee abduction compared to men (Std diff in mean; −1.34, 95%CI; −1.83 to −0.84). In healthy individuals, women performed weight-bearing tasks with greater knee abduction throughout the movement (initial contact, peak abduction, excursion) (Std diff in mean; −0.68 to −0.79, 95%CI; −1.04 to −0.37). In subgroup analyses by task, differences in knee abduction between genders were present for most tasks, including running, jump landings and cutting movements. There were too few studies in individuals with ACL injury to perform meta-analysis. Conclusion The gender difference in knee abduction during weight-bearing activities should be considered in training programs aimed at preventing or treating knee injury.