Linda has over 30 years of Occupational Medicine experience. She started OSN to better the communication & coordination between employers, medical practitioners, and legal counsel. 


Linda is a relationships expert and always available to her clients, partners and staff.  Known as the brain trust with her bi-annual “Journal Clubs”, these events involve a dine and learn atmosphere with presentations on current topics relating to the medical review and workers compensation industry

Linda D. Derringer, BS - President  & Managing Partner
Thomas N. Markham, M.D., M.P.H. - Partner & Medical Director

Dr. Markham has been practicing medicine since the early 1960’s, having completed his residency from the University of Michigan.  


As a retired Naval Medical Officer, Dr. Markham is currently associated with other prominent corporations as acting Medical Director.  Throughout the many years of dedicated service, Dr. Markham has drafted many publications and held teaching and lecturing roles  from 1965 to 1995.

During his career as a Naval Medical Officer, Dr. Markham held positions of Chief Physician, Chief of Occupational Environmental Health Service – Naval Medical Center, Oakland, CA , Commanding Officer in Cincinnati, OH, Norfolk, VA and Pensacola, FL, and Director of Environmental and Occupational Health in Bethesda, MD.

Donato J. Borrillo, M.D., J.D., M.S. 
Associate Medical Director

Dr. Borrillo is a practicing physician, attorney, scientist, pilot and decorated war veteran.  He is a sought after expert in medical and scientific causation. 


Dr. Borrillo has crafted theories in many prominent national legal cases on both defense and plaintiff sides. Having been associated with OSN since 2005,


Dr. Borrillo is also the key member of the on-demand services.

Ronald G. Hawes, M.D. 
Associate Medical Director

In addition to being a Navy veteran, Dr. Hawes is a practicing physician since 1970. 


He has such accolades in Demonstrating Patient Interactions in Characteristics of a Humane Clinician, Physician of the Year, and Noteworthy Achievement. 


Dr. Hawes is a current practitioner with Summa Health System and Akron General Hospitals / Cleveland Clinic, while also being a key member to OSN since 2002.

Associate Medical Directors

Scott Krupkin, M.D., PMR
Associate Medical Director

Dr. Krupkin is a Board Certified practicing Physiatrist and brings a wealth of experience and energy to OSN.


He received his medical degree from St. George's University School of Medicine and has been in practice for more than 20 years.


Dr. Krupkin has a core patient focus in rehabilitation, restoration of function and a return to a high quality of life.

Dr. Krupkin is also a Member of the American Academy of Physical Medicine and Rehabilitation (AAPMR).

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    Tel: (216) 426-2555