Madonna was one "Lucky Star" yesterday, miraculously suffering only minor injuries after taking a nasty spill while horseback riding at a celebrity photographer's Hamptons manse. The 50-year-old pop queen, decked out in full riding gear and helmet, was enjoying the beautiful spring day at famed lensman Steven Klein's horse farm in Bridgehampton. The Material Mom, who suffered broken bones in a similar accident three years ago, was leaping over hurdles on a brown steed on the East End spread when she bit the dust just before 4:30 p.m. In the wake of the titanic tumble, more than 10 people, including her Brazilian boy toy Jesus Luz, 22, rushed to her side. Rescue workers, who arrived minutes later, scooped up the "Like a Virgin" songstress and gingerly carried her on a backboard to a waiting ambulance, which raced to Southampton Hospital. Klein was by her side. She suffered only minor injuries and bruises but will undergo further tests