49 young patients with complete unilateral anterior cruciate ligament (ACL) rupture within the last 10 months, who were unable to compensate for injury (non-coper), were randomized to combined progressive perturbation and progressive quadriceps strength training exercises for 10 preoperative rehabilitation sessions or just progressive quadriceps strength training exercises. The patients undergoing perturbation and strength training did not have significantly different outcomes over those participating in strength only training in the preoperative period.