Suggest Alternate Remedy For C3 And C4 Vertebrae Fusion

My father has been diagnosed with a C3 and C4 vetebrae fusion and doctor have suggested to go for an immediate surgery: posterior Occipital Cervical fusion and transoral ondontoid. Currently he has pain in his right leg while walking. He doesnot have any pain in hands and left leg. he also has this from birth. Is operation the only way out or is there any other treatment