Quadrupled Semitendinosus Graft in Anterior Cruciate Ligament Reconstruction

Data checks programmed by a third party after inclusion of participant number 10, 20, 30 and 42. This includes source data verification. Simple size calculations estimating a difference of 50% in strength improvement between both groups at the six months follow-up visit. 80% power and 5% alpha error. Strength measured with dynamometer, laxity with ACL laxity tester and function with 3 scores: IKDC, Tegner-Lysholm and KOOS. Missing data will be minimized by double checking when registering data. It might be necessary to increase sample size to 50 patients of intermediate analysis show it is necessary to find an statistically significant difference. Trial could be stopped early if one intervention shows to be better in the intermediate analysis. These analysis will be conducted after the first 16 and 32 participants have been included.