NEW YORK — Dr. David Altchek, a trailblazing orthopedic surgeon renowned for performing over 2,400 Tommy John surgeries and serving for decades as a cornerstone of sports medicine, passed away Thursday at the age of 68. His death, attributed to a brain tumor he disclosed in 2023, was confirmed by the Hospital for Special Surgery (HSS), where he served as co-chief emeritus. Dr. Altchek’s name became synonymous with innovation in sports injury treatment. As a longtime leader in the field, he was the preferred surgeon for elite athletes suffering ulnar collateral ligament (UCL) injuries — commonly requiring Tommy John surgery.…