Sarah Todd had never been even slightly injured in her basketball career, which she began in the second grade and played rigorously, including training, her entire life. But in February, 2012, the 15-year-old was playing a one-on-one drill in practice when she collided with her opponent. She heard a cracking in her knee and fell immediately to the ground. Beyond a dislocated knee cap, an MRI revealed the damage she had suffered: she had also torn her meniscus and ACL (anterior cruciate ligament).