The causal role of smoking on the risk of hip or knee replacement due to primary osteoarthritis. a mendelian randomization analysis of the nord-trØndelag health study. (April 2017) - Johnsen, M.B.; Vie, G.Å.; Winsvold, B.S.; Bjørngaard, J.H.; Åsvold, B.O.; Gabrielsen, M.E.; Pedersen, L.M.; Hellevik, A.I.; Langhammer, A.; Furnes, O.; Flugsrud, G.B.; Skorpen, F.; et al.