Serving the Lansdale Community & surrounding areas since 1973

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826 N. Broad Street Lansdale, PA 19446

"For the last 43 yrs I have been afforded the privilege of attending to the healthcare needs of thousands of people. For each and everyone of them I attempted to provide the best care possible, to the best of my abilities. Throughout these many years I have strived to care for my patients with an academic and empathic approach. I can only  hope that for most, but obviously not all, I have been perceived as successful in that endeavor. I cannot think of any other profession in which the burdens are as great, but the benefit to society and the individual are as significant. I wish good health and longevity to all."  

Barry P. Green, MD

William M. Lee, MD

After more than 30 years of being your physician, on March 20, 2020, I will be retiring from clinical practice of medicine.  Thank you for entrusting me with your medical care.  During my retirement I am planning on spending more quality time with my family.


I have the upmost respect and confidence in my colleagues, and I know that you will be in good hands at Green and Seidner Family Practice.


It has been my pleasure and privilege to care for all of you and your families. I wish you continued good health and all the best in the coming years.



Jack C. Rosenfeld, MD practiced family medicine with his father in Blue Bell, PA for 7 years prior to joining Green & Seidner in 1995. He received his medical degree from Temple University School of Medicine in 1984 and completed his residency at Sacred Heart Hospital in Allentown, PA. Dr. Rosenfeld is certified by the American Board of Family Practice and is a diplomate of the American Board of Medical Examiners.

Jack C. Rosenfeld, MD

In addition, he is a member of the Pennsylvania Medical Society, American Medical Association, American Academy of Family Practice, and the Montgomery County Medical Society, and is an Adjunct Professor for Drexel College of Medicine. He is an Attending Physician at Abramson Center for Jewish Life.

Dr. Rosenfeld serves as our Principal Investigator in numerous phases II, III and IV clinical trials of pharmaceutical products. He was elected chairman of the department of family practice at Abington Health Lansdale Hospital in July 1998, and served until 2002. Dr. Rosenfeld is married and has 2 children.

Susan H. Kennedy, MD, Ph.D. joined Green and Seidner in September 2003. She received her Ph.D. from Jefferson Medical College in 1996 and completed a post-doctoral fellowship position in the Department of Dermatology prior to starting medical school. Dr. Kennedy has received awards for her research and published many articles in the fields of Dermatology and Pathology during her training.

Susan H. Kennedy, MD, Ph.D.

She obtained her medical degree from Jefferson Medical College in June 2000 and completed her residency at Chestnut Hill Family Practice in Philadelphia. She is a member of the American Academy of Family Physicians, the American Medical Association, and the Pennsylvania Medical Society and is certified by the American Board of Family Practice. Dr. Kennedy serves on the Medical Executive Committee as Vice President of the Medical Staff/Board of Lansdale Hospital/Abington Jefferson Health.

Sandra Knudsen, MD joined Green & Seidner in July 2005. She is a 1995 graduate of Elizabethtown College and a 1999 graduate of MCP-Hahnemann University School of Medicine. During medical school, she joined the Air Force Reserves. Upon graduation from medical school, she entered active duty in the United States Air Force.

Sandra Knudsen, MD

She completed her residency at Malcolm Grow Medical Center, Andrews Air Force Base, MD, and then served as a family physician at Dover Air Force Base, DE. Dr. Knudsen is a board certified Family Physician and is a member of the American Academy of Family Physicians, the American Medical Association, and the Pennsylvania Medical Society. Her areas of special interest include pediatrics, nutrition, and lipid disorders. She is married and has 2 children.

Leslie A. Rougeaux, Family Nurse Practitioner, joined Green and Seidner in September 2007. She received her Bachelor of Science degree in Nursing at West Chester University in 1985 and a Masters in Nursing from the University of Pennsylvania in 1993 with an Adult Primary Care Nurse Practitioner specialty.

Leslie A. Rougeaux, CRNP

After graduation, she spent 2 years in the National Health Service Corps providing Primary Care to an underserved community in California. Since 1996, she has been practicing in Montgomery County, PA. In 1998, she completed a Family Nurse Practitioner Post-Masters Certificate program at Allegheny University. She is a member of the American Academy of Nurse Practitioners and board certified by the American Nurses Credentialing Center.

Jennifer joined Green & Seidner Family Practice in March of 2013. She is a Family Nurse Practitioner who earned her Master’s degree in Nursing at La Salle University. Her training has prepared her to provide Primary healthcare to families including pediatrics as well as women’s health.

Jennifer Craig, FNP, CRNP

Before becoming an advanced practice nurse, Jen worked as a staff nurse at Doylestown Hospital’s Intermediate Care and Progressive Care Units specializing in cardiac and pulmonary disease for over 10 years. As a nurse practitioner, Jen has experience in both pediatrics as well as family health.

Prior to becoming an RN, Jen worked for several years as a Medical Office Assistant in Family Practices in Philadelphia, Abington, and Lansdale, including Green and Seidner Family Practice. It was during this time that Jen decided to become a nurse practitioner because she enjoyed watching little babies and their siblings grow and go to school while getting to know the family as a whole. Jen lives in Perkasie with her children, Tyler and Brenna.

Lisa Stringfellow, CRNP, joined Green and Seidner Family Practice in June of 2014. Lisa is a graduate of La Salle University, with a Master’s of Science as a Family Nurse Practitioner, and a Bachelors of Science in Nursing from Bloomsburg University. Lisa is board certified from the American Nursing Credentialing Center. Her training consists of education in adults, pediatrics, and women’s health preparing her to take care of the entire family.

Lisa Stringfellow, CRNP

Prior to graduate school, Lisa worked for 12 years at Abington Memorial Hospital as a staff nurse. During this time, certification as a medical-surgical nurse through the Academy of Medical Surgical Nurses was obtained. Advanced training in the care of trauma, telemetry, orthopedic, and bariatric surgery patients was received as a staff nurse. Lisa served as a preceptor and mentor for nursing students and new hires.

She enjoys teaching First Aid, CPR, and Automated External Defibrillator courses throughout the community as an American Heart Association Basic Life Support Instructor. Lisa is married and has a daughter. She enjoys animals and has a dog and cat that share their home in Hatfield.

Barry P. Green, MD William M. Lee, MD Susan H. Kennedy, MD, PH.D. Sandra Knudsen, MD Leslie A. Rougeaux, CRNP Jennifer Craig, FNP, CRNP Lisa Stringfellow, CRNP

While we are a large sophisticated, efficient, cutting edge medical family practice, we maintain the feeling of a small family practice.  We treat four generations, from newborn to great grandparents.  Consider our family practice part of your family.

Phelps J. Lambert, MD, MS, joined Green and Seidner in August 2016.  Following graduating from Cornell University, he went on to receive his MS in cell biology at East Carolina University and spent several years in medical research.  He went on to receive an MD at St. George’s School of Medicine and completed his residency in family medicine at the Warren Campus of St Luke’s University, in Phillipsburg NJ.  He is board certified in Family Medicine and is a member of the American Academy of Family Physicians.  

Phelps J. Lambert, MD, MS

Dr. Lambert has traveled extensively around the world and is proficient in Spanish, having studied it in Ecuador, Honduras and Guatemala.  He has a wife and young daughter and they love to spend time together traveling and exploring the outdoors.

Phelps J. Lambert, MD, MS jack rosenfeld providers_hero