Tendon transfer surgery is a type of hand surgery that is performed in order to improve lost hand function. A functioning tendon is shifted from its original attachment to a new one to restore the action that has been lost. Tendon transfer surgery is necessary when a certain muscle function is lost because of a nerve injury. If a nerve is injured and cannot be repaired, then the nerve no longer sends signals to certain muscles. Those muscles are paralyzed and their muscle function is lost. Tendon transfer surgery can be used to attempt to replace that function.