Our Physicians


Sarah Bibee, PA-C, MHS

Sarah received her undergraduate degree in exercise sports science from East Carolina University followed by a master’s in health science physician assistant studies from South College. She works closely with Dr. Oros in the operating room and following up with patients during their hospital stay and when they return to the in-office clinic. Originally from Knoxville, Sarah enjoys living close to family and spending time outdoors with her dog and exercising.

Jamie Cross, PA-C, MHS

Jamie has always had a passion for anatomy and physiology and while completing x-ray training she determined a career on the front lines of patient care was the right choice. She embraces the responsibility and challenge of both diagnosing and treating patients. With an undergraduate in radiation services from the University of Iowa, Jamie went on to earn her master in health sciences from South College and joined the team at UOS shortly thereafter.

Jamie spends much of her time treating patients in the hospital recovering from surgery following a traumatic event. She enjoys following up with patients when they return for clinic to share in the progress they have made through recovery. In her spare time, Jamie enjoys all things outdoors – running, biking, hiking and being near the water.

David Erpenbach, PA-C

David Erpenbach, PA-C

David was born and raised in Knoxville and received his undergraduate degree from the University of Tennessee in 2009. He earned his Masters in Health Science at South College in 2012 and has been working as an orthopedic Physician Assistant ever since. He now works closely with Dr. Tonne in the hospital, operating room, and clinic settings. In his free time, David enjoys spending time with his wife and son, and being outdoors, whether he's running, hiking, biking, or playing soccer. He is an avid Vols fan and tries to attend home football and basketball games whenever possible.

Ilsa Jones, NP

Ilsa, originally from Northwest Oregon, relocated to Knoxville after deciding to pursue a Bachelors in Exercise Science from the University of Tennessee. After receiving her Masters of Science in Nursing from Marquette University in 2014, she returned to her adopted home of Knoxville.

Her experience with orthopaedic patients started well before nursing as an student athletic trainer with the Lady Vols. From there, she continued to pursue supporting aspects of surgery including personal training, inpatient rehab, and critical care surgery. Alongside Dr. Moss, Ilsa will continue to support patients in the hospital, operating room and clinical setting. Free time is spent predominately with her husband and 2 dogs while continuing to cheer on her Oregon Ducks while living in Big Orange Country.

Erin Kramer, PA-C

Erin graduated from the University of Tennessee where she received her undergraduate degree in Kinesiology.  She then proceeded to attend Lincoln Memorial University-Debusk College of Osteopathic Medicine where she earned her Masters in Physician Assistant Studies.  She works alongside Dr. Holt in the hospital setting, assisting him in the operating room and after patient care, as well as in the clinic setting.  She is from the Knoxville area and is proud to call it home.   In her free time, she enjoys being outdoors with her husband and tailgating for the Vols!

Bradley J. Moore, PA-C

Brad is originally from Austin, Texas but has proudly called East Tennessee home since 1989. After earning his Bachelors degree in Psychology from the University of Tennessee in 2004, he worked with individuals with developmental disabilities before deciding to return to school to become a PA. He received his Masters of Health Science in Physician Assistant studies in 2011 from South College in Knoxville. Brad joined UOS in 2012 as a member of the Joint Replacement team, where he primarily assists in the operating room and manages the care of patients in the hospital after surgery. Brad enjoys photography, hiking, playing guitar, UT sports and especially spending his time off with his wife Christy and their daughter Kaylee.

Dana Pelizza, MPAS, PA-C

Dana, originally from Pittsburgh, PA, joined University Orthopaedic Surgeons in 2009. She received her Masters of Physician Assistant Science from Chatham University in Pittsburgh, PA after attending Pennsylvania State University in State College, PA for her undergraduate degrees. She works alongside Dr. Philip McDowell, assisting him in the operating room, and caring for patients in the hospital and clinic settings. In her free time, Dana enjoys spending time with her husband and step-son, watching and playing sports, and traveling to visit friends and family.

Cassandra Piper, PA-C

Cassy received her undergraduate degree in Biochemistry at Middle Tennessee State University. She attended the University of South Alabama in Mobile where she received a Master in Health Science in Physician Assistant Studies. She works closely with Dr. Kostas Triantafillou in the operating room, hospital setting, and clinic caring for patients following a traumatic event. Originally from East Tennessee, Cassy enjoys spending time with her family, running, and cheering on the VOLS.

Christy Rose, PA-C

Christy was raised in Knoxville, TN and earned her Bachelors in 2006 and Masters in 2008 from the University of Tennessee, Knoxville in Genetics and Biotechnology. She then moved to Nashville and attended Trevecca Nazarene University where she earned an additional Masters in Medicine and Physician Assistant Studies in 2011. She works alongside Dr. Wallace in the hospital, clinical and OR setting managing primary and metastatic bony and soft tissue tumors. She and her husband, Nick, have two beautiful boys and two golden retrievers. They attend Chilhowee Hills Baptist Church and enjoy hanging out with family, photography, traveling, going to movies and cheering on the Vols.

Sydney Sherrell, FNP-BC

Sydney joined University of Orthopaedic Surgeons in 2013. She completed her nursing degree at the University of Tennessee and is a graduate of the Nurse Practitioner program at Carson Newman University. She comes from a family deeply rooted in orthopaedics as her grandfather was one of the pioneers of orthopaedic spine surgery in Knoxville and her husband Chris is a joint replacement surgeon locally. She works closely with hand and upper extremity specialist Dr. Richard Smith at UOS in both the office and operating room setting seeing patients and assisting with surgical procedures. She enjoys travelling and spending time outdoors with her husband, two children, and two step children.


Upon graduating with a nursing degree from the University of Tennessee, Rinnah wanted to advance her skills in providing orthopaedic and trauma care to her patients. She continued her education receiving multiple degrees and most recently earned a Masters Prepared Nurse degree specializing in Adult Gerontological Primary Care. In her role with University Orthopaedic Surgeons, she works closely with patients during their hospital stay providing acute care for orthopaedic and comprehensive health needs. Rinnah is an active member of the National Association of Orthopaedic Nurses and the Tennessee Nurses Association.

Chelsey Weaver, PA-C

Chelsey began her interest in the medical field while volunteering in the emergency department at UT Medical center while obtaining her undergraduate degree in Biology as a student-athlete at Milligan College. She then attended the University of the Cumberlands to receive a Master of Science in Physician Assistant Studies in 2017. It was during this time that Chelsey realized her enthusiasm of being in the operating room and taking care of patients in the hospital. Now, Chelsey works closely with Dr. Christine Seaworth to assist in patient care inside the operating room, hospital, and clinic settings.

Chelsey was born and raised in Maryville and is happy to hold a career so close to home with her husband and adopted dog, Annie. In her free time, Chelsey enjoys exercising and spending time in the mountains.

Benjamin Wendel, PA-C

Benjamin enjoys the hands on patient care he provides in healthcare. He graduated from the University of Tennessee with a bachelor’s degree in biochemistry, cellular and molecular biology and continued on to Lincoln memorial University Debusk College of Osteopathic Medicine to receive his master’s in health sciences. He provides patient care in both the hospital and clinic settings as an extension of the physicians and also assists in operating room as needed.

In his spare time, Benjamin enjoys spending time with his wife and kids outdoors. He is a sports enthusiast and a die-hard UT fan. His family attends Cornerstone Church of Knoxville and professionally he is a member of TAPA, AAPA and PAOS.