Mammoth Lakes, California (tca/dpa) — Last month, Mariusz Wirga, a doctor in California, saw a break in his packed schedule, grabbed his skis and dashed off to Mt. Baldy to enjoy the fantastic new snow left by a recent storm. A former ski instructor, he was carving a fine line, lost in the rhythmic pleasure of crisp turns when, out of the corner of his eye, he saw a young snowboarder barreling toward him from above. Wirga swerved to avoid the imminent collision, caught an edge and slammed to the ground so hard he felt his right arm pop out of the shoulder socket. It stretched as far as the mus…