Alphatec Holdings, Inc. (ATEC) shares jumped more than 22% in pre-market trading on Friday after the medical company reported improved third-quarter results and raised its full-year outlook.The company posted a net loss of $28.58 million, or$0.19 per share, narrowing from $39.62 million, or$0.28 per share loss, in the same period last year.Excluding one-time items, Alphatec reported adjusted income of $4.09 million, or$0.03 per share, compared with a loss of $10.64 million, or$0.07 per share, a year ag ...