Surgeons & Staff

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Stephen Nagengast, MD

A Nebraska native, Dr. Stephen Nagengast graduated from Bloomfield High School. He went on to attend Creighton University where he excelled and received his Medical Degree from the Creighton University School of Medicine. He completed his Surgical Internship and Residency at Phoenix Integrated Surgical Residency Program, serving as Chief Resident in General Surgery. Dr. Nagengast is Board Certified by the American Board of Surgery.
Dr. Nagengast began practicing in Lincoln in 1991. He practices all aspects of general and advanced laparoscopic surgery. He has been recognized as an Active Teacher in Family Medicine by the American Academy of Family Physicians. He is a member of the Lancaster County Medical Society, Nebraska Medical Association, and the American Medical Association. Dr. Nagengast received the Outstanding Rural Health Practitioner Award in 2012. This award recognizes providers who exhibit outstanding leadership, dedicated care, and collaboration in improving health services in rural Nebraska. Dr. Nagengast credits his father for his strong work ethic. His father was a small-town family doctor in his hometown of Bloomfield for more than 50 years. His father’s service and love of his profession had a strong influence on the man Dr. Nagengast is today. In the early 1990’s he began serving the rural communities of Auburn, Crete, Nebraska City, Osceola, and Syracuse and his office have been serving these communities ever since. Dr. Nagengast enjoys spending time with his wife and six children. He is an avid outdoorsman who spends time each year fishing and hunting.

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John Fallick, MD

Dr. John Fallick is a native of Columbus, NE where he graduated from Columbus High School. He is a graduate of High Distinction in Biology from Nebraska Wesleyan University. Dr. Fallick received his Medical Degree from the University of Nebraska Medical Center again graduating with Distinction. He completed his Residency in General Surgery at Mayo Graduate School of Medicine. Dr. Fallick is Board Certified by the American Board of Surgery.
Dr. Fallick began practicing in Lincoln when he joined Dr. Stephen Nagengast at General Surgery Associates in 1999. He practices all aspects of general and advanced laparoscopic and robotic-assisted surgery. In addition to his Lincoln clinic, he also serves the community of Seward. He has been recognized as an Active Teacher in Family Medicine by the American Academy of Family Physicians. He has also been very involved in medical staff development at Bryan Health, completing a two-year term as Department of Surgery Chair and four years of medical executive committee. He is a member of the Lancaster County Medical Society, Nebraska Medical Association, and the American Medical Association. Dr. Fallick enjoys spending time with his wife and four daughters. When not at home, they can be found at the lake or at a sporting event. They enjoy all things BIG RED!

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Brad Olberding, MD FACS

Dr. Brad Olberding, better known as Dr. O, is a native of Stuart, NE. He did his undergraduate studies at UNL before attending the University of Nebraska Medical Center where he graduated with Distinction.

He completed his General Surgery Residency at Banner University Medical Center in Phoenix, AZ where he was awarded the Administrative Chief position. Dr. Olberding is Board Certified by the American Board of Surgery and is a Junior Fellow of the American College of Surgeons.
Dr. Olberding is a Veteran of the Army National Guard and served three Tours of Duty, getting his start in medicine as a flight medic and EMT. Dr. Olberding began practicing with General Surgery Associates in 2014. In addition to his Lincoln clinic, he serves the communities of Syracuse, Nebraska City, Fairbury, and Beatrice. He practices all aspects of general and advanced laparoscopic and robotic-assisted surgery. He is a member of the Nebraska Medical Association, Lancaster County Medical Society, and American Medical Association. Brad enjoys spending time with his wife Jackie, their son Arlo, and their daughter Zola. He enjoys everything sports, especially when it comes to the Huskers! GO BIG RED!

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Clint Rathje, DO

Dr. Rathje grew up on a farm just outside of Aurora, Nebraska and received his Bachelor of Science degree from the University of Nebraska-Lincoln. He went on to earn his medical degree from Kansas City University of Medicine and Biosciences where he graduated with honors. He also obtained his Masters of Business Administration in Healthcare Leadership from Rockhurst University in Kansas City while attending medical school. He completed his General Surgery Residency at the University of Kansas in Wichita, Kansas. Dr. Rathje is Board Certified by the American Board of Surgery.
Dr. Rathje enjoys all aspects of general surgery including advanced laparoscopic and robotic-assisted surgery. In addition to his Lincoln clinic, he serves the communities of Central City, Tecumseh, and Wahoo. He is a member of the Nebraska Medical Association, Lancaster County Medical Society, and American Medical Association. In his free time, he enjoys spending time with his wife, Mandi and their four daughters. He enjoys being outdoors, DIY projects, and watching college football, GO HUSKERS!

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Jessica Zaruba, PA-C

Jessica grew up in Norfolk, NE and received her Bachelor of Science degree from College of Saint Mary in Omaha, NE. She graduated from Union College in 2017 with her Master of Physician Assistant Studies. Jessica is board certified by the National Commission on Certification of Physician Assistants.

Jessica is looking forward to an exciting career in general surgery. Throughout her clinical rotations, she was exposed to every facet of medicine and found general surgery to be her passion. She is looking forward to building relationships with patients in the office and helping them to successfully regain their way of life after surgery.

Jessica lives in Lincoln and in her spare time she enjoys physical fitness, outdoor activities, and spending time with her family and friends.

As a Physician Assistant with General Surgery Associates, Jessica assists in direct patient care in the office, hospital, and surgery.

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Kristen Huebsch, PA-C

Kristen was born and raised in Cedar Rapids, Iowa becoming the first Iowa native to join the team.  She received her Bachelor of Arts in Biology from Wartburg College, where she also played volleyball for the Knights.  She then went on to obtain her Masters in Physician Assistant Studies from the University of Nebraska Medical Center.  She is now board certified by the National Commission on Certification of Physician Assistants.

Kristen is excited to help change patient's lives through general surgery.  She enjoys the hands-on nature that this specialty provides and the ability to work with patients of all ages, creating lasting relationships through medicine.

Kristen lives in Lincoln and in her spare time she enjoys staying active, being outdoors, cheering on the Cyclones (and the Huskers), and spending quality time with family and friends.

As a Physician Assistant with General Surgery Associates, Kristen assists in direct patient care in the office, hospital, and surgery.

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Aaron Aldana, PA-C

Aaron was born and raised in Nebraska City, NE and received his Bachelor of Science degree from the University of Nebraska - Lincoln.  While attending UNL, Aaron was a teaching assistant for the Department of Anatomy and Physiology.  He gained experience volunteering at various Lincoln hospitals and working in a rural, critical-access hospital as a patient care technician in the Emergency Department.  He went on to attend the Physician Assistant program at Stephens College in Columbia, Missouri.  Aaron is board certified by the National Commission on Certification of Physician Assistants.

Aaron's life goal is to practice patient-centered care that is evidence-based, safe, and equitable for all patients.  He plans to use the power of collaboration and innovative thinking to address and individualize the needs of each patient.  Aaron is looking forward to building lasting relationships and providing care for patients.

In his free time, Aaron enjoys spending time with his family and friends, watching anything sports related, and traveling every chance he gets.

As a Physician Assistant with General Surgery Associates, Aaron assists in direct patient care in the office, hospital, and surgery.