SplintER Series: Pain in the Palm

A 17 year-old left hand dominant high school baseball player presents with severe, sharp pain in his right hand at the hypothenar eminence with associated numbness and tingling of his 4th and 5th digits. The pain and tingling began after he swung his bat and hit a ground ball. You obtain x-rays and see an abnormality. What is the most likely diagnosis, differential diagnosis, and management plan?