Pacific Oaks is proud to have the following in-house specialists help us in providing the highest quality care for our patients.


Mark M Davidson, M.D.
American Board of Gastroenterology and Internal Medicine
Lic # A 67586

Dr. Davidson received his medical degree from David Geffen School of Medicine at UCLA.  He then completed a three year residency program in internal medicine at the UCLA affiliated Veterans Affairs Medical Center in Los Angeles.  Following this training, he completed a three year fellowship program in Gastroenterology with emphasis on liver disorders at the UCLA affiliated Kaiser Permanente Medical Center in Los Angeles.

Dr. Davidson is board certified in both Gastroenterology and Internal Medicine.  He is an attending physician at Cedars Sinai Medical Center and other local hospitals in Los Angeles.  His practice is focused on clinical medicine and he performs a variety of endoscopic procedures.  Thousands of patients have trusted their medical care to Dr. Davidson for a variety of medical disorders especially for screening of colon, esophageal, and gastric cancers.



Robert J. Joseph, DPM
Dr. of Podiatric Medicine
Lic # E4013

Mastering the art and science of surgical podiatry, Dr. Robert Joseph has dedicated the past ten years to refining his skills in the specialty of foot and ankle reconstruction and surgery. A graduate from Ohio College of Podiatric Medicine, Ohio (1995), he completed a two-year surgical residency program and continues to share his knowledge and experience at the Teaching Residency Program at Cedars Sinai Medical Center and Midway Hospital in Los Angeles, California. With multiple locations throughout the county of Los Angeles, Dr. Joseph's goal is to be the premier surgical podiatrist, providing innovative services (specialized care for the immunocompromised patient) and the best patient care possible.



John J. Kowalczyk DO, F.A.C.O.S.
Board Certified Urologist
Lic # ZOA6818

Dr. John Kowalczyk is a widely published urologic surgeon whose association with Lim-Keith Multispecialty Medical Clinic, Inc. began in 1996.  Dr. Kowalczyk provides a full spectrum of urologic care with special expertise in the areas of impotence, incontinence and urodynamics.

A graduate of Loyola University in Chicago, IL, Dr. Kowalczyk received his medical degree and completed his residency at Midwestern University.  He proceeded immediately from his residency into a prestigious fellowship at Indiana University Medical Center, where he studied the latest developments in incontinence and impotence, co-authoring several journal articles with his mentor, John Mulcahy, M.D.

After completing his Fellowship, Dr. Kowalczyk relocated to Southern California and began practicing as a member of the Lim-Keith Multispecialty Medical Center team.  He has also served as Chairman of the American Cancer Society's Man-to-Man Prostate Cancer Program (Central Los Angeles Unit), as Quality Assurance Director for Thompson Memorial Hospital and Director of Urinary Incontinence at Hollywood Community Hospital.

Dr. Kowalczyk continues to contribute to the development of new treatments in urologic surgery.  To date, he has published 12 medical journal papers.  He is board certified by the American Board of Osteopathic Surgeons and in 1999 was named a Fellow of the American Board of Osteopathic Surgeons.

His hospital affiliations include Hollywood Community Hospital, Midway Hospital Medical Center, Glendale Adventist Medical Center and Good Samaritan Hospital.  Dr. Kowalczyk is a member of the American Medical Association, American Osteopathic Association, American College of Osteopathic Surgeons and the American Urologic Association, as well as several California and Los Angeles medical associations.



Dr. Steven J. Waltrip, M.D.
Orthopedic and Rehabilitation Medicine
Lic # A 70446

Dr. Steven Waltrip received his undergraduate degree from Wheaton College near Chicago, Illinois and trained at the Chicago Medical School University of Health Sciences. He completed his residency training at the University of Washington in Seattle.

Board Certified by the American Board of Physical Medicine and Rehabilitation and a member of the North American Spine Society (N.A.S.S.), Dr. Waltrip also serves on the Advisory Board for My Gym Enterprises, a worldwide organization committed to children’s fitness.

Dr. Waltrip is dedicated to returning patients to their highest level of function. He combines a compassionate spirit with an abundance of knowledge and experience to provide the best care possible.

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