Multiple-center, multiple-dose, randomized, double-blind, six-arm, active- and placebo-controlled study of repeated intermittent PRN dosing for 24 hours of Intranasal (IN) Morphine Nasal Spray (MNS075) 7.5 mg and 15 mg, 7.5 mg IV morphine infusions and placebo (either IN or IV), in patients with moderate to severe post-surgical pain from elective orthopedic surgery with safety observed for a total of 30 hours post first dose.