Dr. Courtney Ann O'brien, DO Internal Medicine - Rheumatology Medicare: Accepting Medicare Assignments Practice Location: 2655 1st St Ste 380, Simi Valley, CA 93065 Phone: 805-583-7640 Fax: 805-583-7641
Rheumatology: An internist who treats diseases of joints, muscle, bones and tendons. This specialist diagnoses and treats arthritis, back pain, muscle strains, common athletic injuries and "collagen" diseases.