Kneeling and standing up from a chair as performance-based tests to evaluate knee function in the high-flexion range: a randomized controlled trial comparing a conventional and a high-flexion TKA design - van der Ven, P JP; van de Groes, S; Zelle, J; Koëter, S; Hannink, G; Verdonschot, N (BMC Musculoskelet Disord, 2017)