Meet Our Team - Physicians

Our highly trained orthopedic surgeons treat patients of all ages for a variety of conditions and injuries. They are focused on keeping athletes of all levels doing the things they love most. Learn more about each of our providers by clicking on the names below.

  • Demers
  • Boyd
  • Krpan
  • McDonald
  • Hwang
  • McDonald

Concussion Management Specialists:

Tim Sullivan, MD​, Pediatrician

Nancy Kerr-Schifrin, Nurse Practitioner


Sierra Orthopedic Institute
Ariana DeMers, DO
James Ivy Boyd III, MD
Thomas McDonald, MD
680 Guzzi Lane, Suite 105, Sonora
(209) 532-0126

Angels Camp Orthopedics
Christopher Krpan, DO
23 N. Main Street, Angels Camp
(209) 736-1147