Uncle ruptured anterior bicept tendon on right arm playing tennis. Who treats it? Transplant?

Orthopedic Surgeon. Management will vary depending on the severity of the injury. Your uncle can either begin with his primary care physician or a sports physician, but it may ultimately lead to a consultation with an orthopedic surgeon.
Orthopedist. An orthopedic surgeon would take care of this. If he is in an area with a lot of doctors, then an orthopedist specializing in sports or upper extremity problems might be best. The actual treatment depends on a lot of things, including your uncle's age and which end of the biceps was torn.