Tennova Primary Care - Karns. 7210 Oak Ridge Highway. Knoxville, TN 37931. Phone: (865) 647-5500. Directions. Hours: Monday - Friday: 8 a.m. - 5 p.m. The team at Tennova Primary Care - Karns is committed to helping families stay healthy. Our providers specialize in caring for men, women and children ages 2 and older..