 Throughout the duration of this study, patients are required to have follow-up visits at 10 weeks post-surgery and every year after surgery through the 10th year of completion as in the Core CPG study. This follow-up requirement changed from 10 years to 5 years upon device approval. Unlike the Core CPG study, the CPG-CA study does not have a randomized selection of MRI patients as a required component of the study. 