Clinical Advisors

Ivan Cheng, M.D., Stanford Medical School

Dr. Ivan Cheng provides consultation and treatment for patients with all spinal disorders, including cervical spine and complex spinal deformities. After obtaining his degree at Harvard Medical School, Dr. Cheng completed his residency in Orthopaedic Surgery at U.C. Davis and his spine surgery fellowship with the world-renowned spine surgery group at Washington University in St. Louis. Board-certified in Orthopaedic Surgery, Dr. Cheng has received numerous awards including the Timothy Bray Trauma Award from U.C. Davis, the Saul Halpern Orthopaedic Teacher of the Year Award from Stanford, the International Society for the Study of the Lumbar Spine Prize in Clinical Research, and Outstanding Paper Awards from the North American Spine Society. In addition to the latest techniques in spinal reconstruction, Dr. Cheng is also trained in minimally-invasive surgery and motion-preserving surgery.


  • Washington University, St. Louis, Fellowship, Spine Surgery (2003-2004)

  • U.C. Davis Medical Center, Residency, Orthopaedic Surgery (1999-2003)

  • U.C. Davis Medical Center, Internship, General Surgery (1998-1999)

  • Harvard Medical School, MD (1998)

  • University of California, Berkeley, BA, Neurology (1993)


  • American Association of Orthopaedic Surgeons

  • North American Spine Society

  • Scoliosis Research Society

  • Cervical Spine Research Society

Recent Publications
  • Carragee EJ, Baker RM, Benzel EC, Bigos SJ, Cheng I, Corbin TP, Deyo RA, Hurwitz EL, Jarvik JG, Kang JD, Lurie JD, Mroz TE, Oner FC, Peul WC, Rainville J, Ratliff JK, Rihn JA, Rothman DJ, Schoene ML, Spengler DM, Weiner BK. (2012) "A biologic without guidelines: the YODA project and the future of bone morphogenetic protein-2 research." Spine J. 2012 Oct;12(10):877-80.

  • Cheng I. (2012) "Spinopelvic parameters: how far have we come?" Spine J May 12(5):447-8.

  • Cheng I, Mayle RE, Cox CA, Park DY, Smith RL, Corcoran-Schwartz I, Ponnusamy KE, Oshtory R, Smuck MW, Mitra R, Kharazi AI, Carragee EJ. (2012) "Functional assessment of the acute local and distal transplantation of human neural stem cells after spinal cord injury." Spine J, Nov;12(11):1040-4.

  • Park DY, Mayle RE, Smith RL, Corcoran-Schwartz I, Kharazi AI, Cheng I. (2013) "Combined transplantation of human neuronal and mesenchymal stem cells following spinal cord injury." Global Spine J 2013; 03(01): 001-006.

Awards and Honors
  • 2012 Western Orthopaedic Association Young Investigator Award: "Functional Assessment of Acute Local versus Distal Transplantation of Human Neural Stem Cells following Spinal Cord Injury"

  • 2010 American Orthopaedic Association-Japanese Orthopaedic Association (AOA-JOA) Traveling Fellow

  • NASS Best Paper Award, North American Spine Society (2008)

  • NASS Outstanding Paper Winner in Medical & Interventional Science, North American Spine Society (2006)

  • Outstanding Paper Award in Surgical Science, North American Spine Society, (2006)

  • The ISSLS Prize in Clinical Research, International Society of the Study of Lumbar Spine, Bergen, Norway (2006)

Chad Prusmack, M.D., Rocky Mountain Spine Clinic, Denver, CO

Undergraduate Degree
  • Harvard University, Cambridge, MA

Medical Degree
  • Columbia University College of Physicians and Surgeons, New York, NY

General Surgery Internship
  • University of Miami, Miami, FL

Neurosurgery Residency
  • University of Miami, Miami, FL

Cerebrovascular / Skull Base Fellowship
  • University of Miami, Miami, FL

Complex Spine Fellowship / Minimally Invasive Spine Fellowship
  • University of Miami, Miami, FL

Professional Affiliations
  • North American Spine Society

  • Miami Project

  • American Association of Neurological Surgeons

  • Minimally Invasive Spine Society

Hospital Affiliations
  • Sky Ridge Medical Center, Lone Tree, CO

  • Medical Center of Aurora, Aurora, CO

Special Interests
  • Minimally Invasive Spine Surgery

  • Complex Cervical/Lumbar Spine Surgery

  • Research and Development of Minimally Invasive Spine Equipment

  • Sports Medicine of the Spine/Brain

  • Neurosurgical Consultant to the Denver Broncos

Jeffrey Geesin, Ph.D.

Dr. Geesin received his Ph.D. from Rutgers University. Upon graduation, Dr. Geesin joined Johnson & Johnson ascending to Director of Research and Development of Wound Healing Technologies. Over the next 15 years, Dr. Geesin held numerous senior positions within Johnson & Johnson and finished his career as the Director of Advanced Technologies and Regenerative Medicine. He currently maintains his own consulting business. Dr. Geesin has authored or coauthored 50 journal articles and has conducted over 75 presentations at scientific conferences. He is currently a member of the Wound Healing Society and the International Cartilage Repair Society.

Gregory Kesteloot, M.D. Brussels, Belgium

Dr Kesteloot maintains a position at AZ Delta, located in Roeselare, Belgium, where he specializes in neurosurgery. He was educated at KatholiekeUniversiteit Leuven and participated in a fellowship at the UZ Leuven for neurosurgical training. Dr. Kesteloot has nearly ten years of experience in his field and maintains professional memberships in the Belgian Society of Neurosurgery and the North American Spine Society.

Educated at Katholieke Universiteit Leuven, Dr. Keteloot completed a neurosurgical training fellowship at UZ Leuven. He maintains professional memberships in the European Association of Neurosurgical Societies, Society of Minimal Invasive Spine Surgery and the North American Spine Society.

Michael Brown, M.D., Colorado Springs Neurological Associates

  • Board Certified Neurosurgeon

  • Member of Practice Since 1988

  • Diplomate, American Board of Neurological Surgery

  • Past President of the Rocky Mountain Neurosurgical Society


  • B.A. – University of Arkansas

  • M.D. – University of Arkansas for Medical Sciences

  • Neurosurgical internship/residency - University Hospital, University of Arkansas for Medical Sciences

Areas of Clinical Interest in Neurosurgery

Spinal Disease including Herniated Lumbar and Cervical Disc, Degenerative Diseases of the Spine, Tic Douloureux (Facial Pain), Cerebrovascular Disorders and Brain Tumor

Kornelis Poelstra, M.D. Florida

Kornelis Poelstra is board certified in orthopaedic spine surgery. He specializes in minimally invasive spine surgeries, arthritis of the spine, spinal deformity, oncologic conditions, spine fractures, disc replacements, spinal cord injuries, and more. He has also done research with wound infections, stem cell implantation, advancements in minimally invasive spinal surgery, and treatment studies after spinal surgery. Dr. Poelstra earned his medical degree from Rijksuniversiteit Groningen, Faculty of Medical Sciences in 1997. He completed his residency in Orthopaedic Surgery at the University of Virginia Medical School and his fellowship at Thomas Jefferson University. Dr. Poelstra is part of the medical staff at Fort Walton Beach Medical Center. He has also received numerous certifications and awards, such as Patient Choice (5 Years) and America’s Top Orthopaedists.

Kevin Walsh, M.D., Cleveland Clinic

Dr. Kevin Walsh is a neurosurgeon with subspecialty fellowship training in both orthopaedic and neurological spine surgery. He did his medical school training at the West Virginia University School of Medicine, and then completed his Neurosurgery residency and Spine Surgery Fellowship training at the Cleveland Clinic Foundation in Cleveland, OH. He has an interest in spinal deformity, and in 2017 will be joining the Department of Neurosurgery in the Allegheny Health Network in Pittsburgh, PA, as the Director of Adult Spinal Deformity for the Network.