string: …between knee-straining work activities and degenerative knee disorders, retrospective exposure assessment has usually been based on self-reports (Felson et al. 1991; Vingard et al. 1991; Coggon et al. 2000; Sandmark et al. 2000; Seidler et al. 2008; Muraki et al. 2009; Klussmann et al. 2010).