Skip to main content

Leadership team

Committed to providing real and lasting improvements in the lives of patients with musculoskeletal issues, today and well into the future.

He received his Doctor of Medicine degree from Boston University School of Medicine and completed a combined residency in pediatrics and physical medicine & rehabilitation at New York University Medical Center. He is certified by the American Board of Physical Medicine and Rehabilitation. He also received a Master of Business Administration degree from Columbia University Graduate School of Business, a Master of Public Health degree from Boston University School of Public Health and a Master of Arts in Medical Science from Boston University Graduate School of Arts and Sciences.

Dr. Wu has worked with the World Health Organization, the United Nations and the Centers for Disease Control and Prevention on issues relating to the rehabilitation of large populations. Dr. Wu's advocacy efforts also include his service as treasurer and member of the President’s Cabinet of the International Society of Physical and Rehabilitation Medicine (ISPRM), as the North and South America continental director of the International Exchange Committee of ISPRM, as president of the board of directors of the Center for the Independence of the Disabled in New York, as president of the board of directors of the Delaware Valley Stroke Council, as president of the New York Society of Physical Medicine and Rehabilitation and as a member of the board of governors of the American Academy of Physical Medicine and Rehabilitation.

Clinical interests
Dr. Wu specializes in improving function in patients of all ages, including those individuals with spine problems. In his healthcare leadership roles, Dr. Wu has consistently advocated for persons with disabilities to have access to cost-effective, high-quality healthcare.

Michael Suk, MD, JD, MPH, MBA, FACS

Michael Suk, MD, JD, MPH, MBA, FACS, is chair of the Geisinger Musculoskeletal Institute and the Department of Orthopaedic Surgery.

He is also the chief physician officer for Geisinger System Services. He holds a law degree and master’s degrees in public health and business administration. In 2016, Dr. Suk was selected as a Baldrige Executive Fellow, and he is a former White House Fellow.

Dr. Suk is on the editorial board of several orthopaedic journals, is the author of numerous scientific articles, and is lead author of a textbook on orthopaedic outcomes measures and instruments. He has received international attention for his work on the link between patient expectations and clinical outcomes in orthopaedic trauma surgery. He has spoken on topics including orthopaedic fracture management, healthcare literacy and access to and delivery of healthcare services.

He received his medical degree from the University of Illinois College of Medicine and a JD/MPH with special certification in healthcare law from Boston University School of Law and School of Public Health. He completed his orthopaedic surgery residency training at Montefiore Medical Center, Albert Einstein College of Medicine in Bronx, N.Y., and a fellowship in orthopaedic trauma at the Hospital for Special Surgery, Weill College of Medicine at Cornell University in New York City. He also holds an MBA from the Kania School of Management at The University of Scranton.

Clinical interests
Dr. Suk’s clinical interests include orthopaedic trauma.

“Under the Geisinger Musculoskeletal Institute model, we are aggressively pursuing a more integrated approach to healthcare. The structure of the institute will make it easier for us to give patients the care they need when they need it, regardless of where they enter Geisinger. It will also promote a team-based approach for all our providers, scientists, researchers, educators and other healthcare professionals. We want the most enthusiastic and energetic people in medicine to start, enhance and shape their careers at Geisinger. Making that happen is one of my personal and professional goals.”

Thomas R. Bowen, MD

Thomas R. Bowen, MD, is chief of Orthopaedic Oncology for the Geisinger Musculoskeletal Institute and an orthopaedic surgeon at Geisinger Medical Center.

Dr. Bowen earned his medical degree from Jefferson Medical College in Philadelphia, Pa. He continued his orthopaedic residency at Geisinger Medical Center and then proceeded to Massachusetts General Hospital and Boston Children's Hospital for fellowship training in orthopaedic oncology.

Dr. Bowen is board certified in orthopaedic surgery by the American Board of Orthopaedic Surgery. He is a fellow of the American Academy of Orthopedic Surgery and the prestigious American Orthopaedic Association.

Clinical interests
Dr. Bowen’s clinical interests include tumors of the musculoskeletal system (bone, cartilage, muscle, tendon, and peripheral nerves). He specializes in limb-preserving surgery for malignant tumors, as well as minimally invasive treatments for benign tumors and bone cysts. He cares for children and adults with tumors of the musculoskeletal system.

“Today, patients are healthier and living longer than ever before. I routinely see patients for follow-up visits who may not have survived only a decade ago. Now, they’re able to attend graduations, take vacations and watch their grandchildren grow up. Helping make those milestones possible is a part of what makes being a surgeon so worthwhile.”

Gerard Cush, MD

Gerard Cush, MD, is the Central Region director for the Geisinger Musculoskeletal Institute. He is also chief of Foot and Ankle Surgery for Geisinger’s Department of Orthopaedic Surgery. Prior to his promotion to regional director, he was director of the Orthopaedic Residency Program from August 2009 to July 2017.

Dr. Cush obtained his medical degree from Temple University in 1998. He then completed his internship at Albert Einstein Medical Center in 1999, and in 2004 he completed his residency at Geisinger Medical Center. Dr. Cush then completed his fellowship in foot and ankle surgery at the Medical College of Wisconsin in 2005.

Dr. Cush is board certified by the American Board of Orthopaedic Surgery.

Dr. Cush is an active member of The American Academy of Orthopaedic Surgeons, American Orthopaedic Foot and Ankle Society, and the Pennsylvania Orthopaedic Society. In 2017, Dr. Cush was inducted into the American Orthopaedic Association, an honor bestowed on only 5 percent of all orthopaedic surgeons.

Clinical interests
Dr. Cush enjoys simple to complex foot and ankle reconstructions that include ankle replacement and ankle fusions. Difficult cases, including Charcot reconstruction and limb salvage, pose challenges for both patient and surgeon, but Dr. Cush feels that this is an area where he can make the most difference. He strives to provide high-quality care that leads to positive and lasting health outcomes. During his consultations, he fully explains patients’ conditions and helps them choose an appropriate treatment plan.

Administratively, Dr. Cush enjoys working across departments and to help improve communication within the Musculoskeletal Institute. Dr. Cush has been working closely with the OR transformation projects that include quality and cost-saving initiatives.

Daniel Feldmann, MD

Daniel Feldmann, MD, is the system chief of Sports Medicine for Geisinger Musculoskeletal Institute. A Geisinger employee since 2002, he has been instrumental in shaping the institute’s thriving Sports Medicine Division. He is also the medical director for Geisinger’s athletic training program.

In addition, he serves as head team physician for Bucknell and Bloomsburg universities, medical director of the Bloomsburg’s graduate program in athletic training and medical consultant for Danville Area School District.

Dr. Feldmann received his BA in 1987 from Gettysburg College, where he played football. He went on to earn an MEd degree in exercise physiology at Temple University, followed by an MD degree at Thomas Jefferson University. He completed an orthopaedic residency at Geisinger Medical Center in 2001. He spent a year as a fellow team physician, studying sports medicine and arthroscopy at the University of Wisconsin before joining Geisinger’s Orthopaedic Department.

He is board certified by the American Board of Orthopaedic Surgery in both orthopaedic sports medicine and orthopaedic surgery and is a member of the American Academy of Orthopaedic Surgeons, the Pennsylvania Orthopaedic Society, the Arthroscopy Association of North America and the American Orthopaedic Society for Sports Medicine.

Clinical interests
Dr. Feldmann’s primary areas of expertise are arthroscopic shoulder surgery for shoulder instability and rotator cuff pathology and knee ligament reconstruction surgery. His clinical interests include shoulder instability, revision shoulder instability surgery and surgery for glenoid bone loss and nontraditional surgical techniques for ACL repair. He lectures on all of these topics and teaches arthroscopic techniques to other surgeons through the Arthroscopy Association of North America.

Dr. Feldmann’s integrated approach to athletic injuries focuses not only on the latest minimally invasive arthroscopic techniques, but also on nonoperative management. He understands that successful outcomes require excellence in both surgical techniques and rehabilitative programs.

William Fred Hess, MD

William Fred Hess, MD, is the chief of Orthopaedic Spine Surgery at Geisinger Musculoskeletal Institute.

Dr. Hess received his medical degree from the University of South Florida in Tampa, Fla., where he also completed his general surgery internship and orthopaedic surgery residency. He completed the Rae R. Jacobs Spine Fellowship at the University of Kansas Medical Center and has been a member of the Department of Orthopaedic Surgery at Geisinger since 1990.

He is a member of the Scoliosis Research Society, as well as a fellow of the American Academy of Orthopaedic Surgeons. He is board certified by the American Board of Orthopaedic Surgery.

Clinical interests
Dr. Hess’s clinical interests are spine trauma and pediatric and adult spine deformity, including scoliosis, kyphosis, tumors and post-traumatic deformities. These interests have led him to provide care in many third-world settings, mainly through his involvement with the Foundation for Orthopaedics and Complex Spine. He has performed reconstructive spine surgery in Ecuador, Ghana, Barbados and Jamaica since 1994.

“I am proud to provide surgical spine care to patients at Geisinger, but also around the world,” he says. “To those who have been given much, much is to be expected. We are all called to return the blessings we have received to others less fortunate.”

Daniel Scott Horwitz, MD

Daniel Scott Horwitz, MD, is an orthopaedic surgeon who specializes in orthopaedic trauma. Dr. Horwitz is the chief of Trauma for the Geisinger Musculoskeletal Institute.

Dr. Horwitz received his medical degree from Washington University, St. Louis. He completed his internship at St. Luke’s-Roosevelt Hospital Center and his residency at Columbia University Medical Center. In addition, he completed a fellowship in trauma at the University of Utah Hospital and Clinics.

He is board certified by the American Board of Orthopaedic Surgery.

Clinical interests
Dr. Horwitz specializes in unstable pelvic and acetabular fractures, complex articular injuries and nonunions/osteomyelitis. He leads one of the largest orthopaedic trauma teams in the country, providing care at three Level II trauma centers and at one Level I center. Dr. Horwitz has published extensively on aspects of orthopaedic trauma, ranging from fracture fixation and early evaluation of geriatric patients to health system issues, including efficiency and medical legal questions.

He currently supervises two international trauma research fellows, actively teaches orthopaedic residents and lectures nationally and internationally on all aspects of orthopaedic trauma.

Joel Klena, MD

Joel Klena, MD, is chief of the Division of Hand and Microvascular Surgery for the Geisinger Musculoskeletal Institute, as well as program director for the Geisinger Orthopaedic Surgery Residency. He assumed this role in 2017 after being the associate residency director for eight years.

Dr. Klena received a BS with honors from the United States Merchant Marine Academy (USMMA) at Kings Point, NY, graduating ninth in his class with dual degrees in marine engineering and marine transportation. His time at the USMMA included service in the Gulf War conflict and captaining the Academy’s NCAA Division I Rugby Team.

After fulfilling his naval and maritime commitments, he attended medical school at the State University of New York’s Upstate Medical College in Syracuse and completed orthopaedic surgery residency training at Geisinger Medical Center. He returned to Syracuse for a fellowship in hand and upper extremity surgery, including time at Texas Scottish Rite Children’s Hospital in Dallas.

He serves on the resident education committee for the American Society for the Surgery of Hand and is a member of the American Orthopaedic Society.

Clinical interests
Dr. Klena has extensive peer-reviewed publications within hand literature. He has provided guidance for resident research efforts, with a particular focus on upper extremity trauma, minimally invasive surgical techniques and resident education.

In 10 years with Geisinger, Dr. Klena has led the hand division from a single surgeon based in Geisinger’s central region to the successful recruitment and geographic expansion of 6 hand surgeons providing care for patients throughout Geisinger.

The motto of his undergraduate alma mater best summarizes his approach to leadership and his dedication to service: “Acta non verba” or “Deeds, not words."

 David J. Kolessar, MD

David Kolessar is an orthopaedic surgeon, a subspecialist in adult reconstruction and joint replacement surgery and chief of the Division of Adult Hip Reconstruction for the Geisinger Musculoskeletal Institute. Dr. Kolessar has an in-depth understanding of the details and complexities involved in primary and revision hip and knee replacements. He has an academic appointment as a clinical associate professor of orthopaedic surgery at Temple University School of Medicine.

Dr. Kolessar obtained his medical degree from Temple University. He completed his internship and residency at Albert Einstein Medical Center and a fellowship in adult reconstruction and total joint replacement at Mayo Clinic in Rochester, Minn.

Dr. Kolessar is board certified by the American Board of Orthopaedic Surgery. He is a member of the American Academy of Orthopaedic Surgeons, the American Association of Hip and Knee Surgeons, the International Congress for Joint Reconstruction, the International Geriatric Fracture Society and the Pennsylvania Orthopaedic Society.

Clinical interests
Dr. Kolessar focuses on contemporary surgical techniques and multimodal pain management protocols in combination with an accelerated recovery program for today’s active patients with a goal of short-stay hip and knee replacement surgeries.

William Mirenda, MD

William Mirenda, MD, is chief of pediatric orthopaedics for the Geisinger Musculoskeletal Institute, a position he has held since 2006. He has more than 35 years of experience treating children with orthopaedic issues.

Dr. Mirenda attended Penn State University as an undergraduate and received his medical degree from Jefferson Medical College in Philadelphia. He completed two years of general surgery training in Roanoke, Va., followed by an orthopaedic surgery residency at Jefferson University Hospital in Philadelphia and the A.I. duPont Institute in Wilmington, Del. Dr. Mirenda also completed two fellowships, one in pediatric reconstructive surgery at Orthopaedische Klinik des Wickernhauses in Rummelsburg, West Germany, and one in pediatric orthopaedics at Royal National Orthopaedic Hospital in London, England.

Before coming to Geisinger, Dr. Mirenda practiced in Roanoke for 24 years and was an assistant professor in orthopaedics at the University of Virginia. He served as director of the Virginia Crippled Children's Clinic for Southwest Virginia, and was the first medical director of orthopaedics for the Carilion Health System as well as the founding medical director of the Roanoke Ambulatory Surgery Center.

At Geisinger, Dr. Mirenda and his pediatric orthopaedic team manage problems ranging from bumps, bruises and minor growth disturbances to severe spinal deformity, complex neuromuscular syndromes and multisystem trauma. More complicated problems are often managed in conjunction with Geisinger pediatric neurologists, neurosurgeons, rheumatologists and infectious diseases specialists.

Clinical interests
Dr. Mirenda devotes his clinical time primarily to the management of congenital problems, such as clubbed feet and hip dysplasia, growth disturbance and deformity, neuromuscular diseases and syndromes and fractures.

Marcus Riedhammer, MD

Marcus Riedhammer, MD, is chair of Wound Care for the Geisinger Musculoskeletal Institute. In 2009, he came to Geisinger to develop a new wound care program, which is now recognized as a regional center of excellence.

Dr. Riedhammer attended medical school at the University of South Florida, where he also completed a residency in family medicine and served as chief resident. Prior to dedicating his full-time practice to wound care, he practiced family medicine and emergency medicine, serving as medical director of Lock Haven Hospital’s Emergency Department.

He is board certified by the American Board of Family Medicine and the American Board of Wound Management. He has current certification in basic life support with prior certifications in both advanced life support and advanced trauma life support.

Dr. Riedhammer is the author of the book Algorithms in Internal Medicine, and has collaborated on a number of other peer-reviewed publications. He has significant experience in speaking on wound-related topics.

Clinical interests
Although Dr. Riedhammer treats patients with all types of nonhealing wounds, his areas of clinical interest include diabetic ulcers, venous leg ulcers, ischemic/arterial ulcers, pressure ulcers and nonhealing traumatic/surgical wounds. He has carried out extensive research on the advancement of venous leg ulcer treatment and compression therapy and has collaborated with research partners at both Bucknell and Wilkes universities. Dr. Riedhammer has also participated in several pressure ulcer prevention committees and served as expert advisor to the Pennsylvania State Department of Health’s Pressure Ulcer Committee.

Sam S. H. Wu, MD, MA, MPH, MBA

Dr. Sam Wu is a physiatrist (a medical doctor who specializes in restoring function) and chair of the Department of Physical Medicine & Rehabilitation for the Geisinger Musculoskeletal Institute.