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Founded in 2017, Xtremity has followed an intentional path to develop thermoformable socket technology and cost-efficient fabrication processes that will have a life-changing impact on prosthetic care for individuals with transtibial limb loss/difference, as well as the prosthetists who care for them.

A Humanitarian History

Xtremity’s founders were humanitarians living in Aspen, Colorado who participated in medical mission trips to impoverished communities around the world (including Nepal, Haiti, Liberia, and Sierra Leone) with limited healthcare and economic resources.

During these journeys, they were exposed to the hardships experienced by children and adults who were living with limb loss and no access to prosthetic care. They began talking to experts in the O&P industry and joined forces with fellow Aspen resident Mark Joseph, an inventor with expertise and prior success creating medical devices. Mark became one of the company’s founders and began the process for creating a prosthetic socket that could be fabricated in remote locations with less equipment and expertise required to make traditional carbon fiber laminated sockets.

Xtremity’s founders recruited prosthetists, engineers, material scientists and expert manufacturing consultants who collaborated to develop a thermoformable carbon reinforced polymer that can be injection molded to create socket technology that can be efficiently manufactured and heat adjusted.



Maynard Carkhuff

President & CEO

Maynard Carkhuff, a highly respected executive with more than 30 years experience in the prosthetic industry, joined Xtremity as President and CEO in 2021. Carkhuff previously held the same position at Flex-Foot, Inc. (acquired by Ossur) and Freedom Innovations (acquired by Ottobock). He was instrumental in helping the company secure additional investor funding and guided efforts to commercialize the XtremityTT® Socket System. 

bob kerrey

Bob Kerrey

Chairman, Board of Directors

Bob Kerrey is a recipient of the Congressional Medal of Honor for heroism in combat and has worn transtibial sockets and prosthetic devices for more than 50 years. Kerrey is the former Governor and Senator for the state of Nebraska. After leaving public service, he served as the President of the New School in New York City from 2001 to 2010. Kerrey currently serves as Managing Director for Allen & Company, a private investment and advisory firm, and as  Chair Emeritus of the Minerva Institute for Research and Scholarship, where he advocates for broad reform in higher education.

Sean Smith

Sean Smith

VP of Operations & Product Development

Sean Smith was one of the early recruits to the Xtremity team and has had a critical role in the product development process and establishing the operations, quality system, customer service and order fulfillment capabilities. Prior to joining Xtremity, Sean had product management and R&D roles at UNYQ, SOLS, UCSF and the Steadman Research Institute.

Tres Wright

Tres Wright

Clinical Director

Tres Wright was the first prosthetist hired by Xtremity, providing early insights to the company’s founders. Tres had an instrumental role in every step of the development of the XtremityTT® Socket System, including the fitting and care of Patient Testers who were recruited to wear evolving iterations of the product. Tres serves as one of the company’s Clinical Specialists, providing education and training to prosthetists and technicians, and also has a critical ongoing role in the company’s product development, testing, and participation in mission-driven initiatives. 

valerie eason

Valerie Eason

Administrative Director

Valerie was one of the core team of early employees who brought a unique combination of financial and administrative skill sets that helped the startup company stay on course and viable. 

Her education in English, Communications and Social Sciences enabled Valerie to have an essential role in creating the necessary infrastructure and contribute to efforts to communicate with investors about the company’s intentions to have a global impact on the care available to persons with limb loss and limb difference, including in countries where there is limited access to prosthetic care. Valerie has administrative responsibilities related to personnel, accounting, insurance, documentation and resource management. She is passionate about fulfilling the mission of the company’s founders.

marco santini

Marco Santini

R&D Engineer

Marco Santini is a graduate of Cal Poly who joined the Xtremity team as a key member of the research and development team – contributing engineering expertise that contributed to the final design and commercialization of the XtremityTT® Socket System. His experience in biomedical engineering and prosthetics, as well as his analytical mindset, enable Marco to be a critical interface between R&D and the company’s clinical team. He is inspired to help Xtremity have a transformational impact on prosthetic care in the United States and throughout the world. 

Mark Joseph

Mark Joseph

Inventor/Product Designer

Mark Joseph was one of the founders of Medical Creations, Inc., and is the inventor of the XtremityTT® Socket System and continues to work as the lead product designer. Mark has been a designer of products that fit the body for more than four decades. He was the inventor and founder of Exos, and thermoformable casting and bracing system purchased by DJO Global. He has developed over 100 products licenses to a wide range of companies and has over 30 issued patents. 

Gary Berke

Gary Berke, MS, CP, FAAOP

Chief Clinical Officer

Gary Berke is a certified prosthetist who has had an instrumental role in the development processes and testing of the XtremityTT® Socket System prior to its commercial release. As Chief Clinical Officer, Gary leads Xtremity’s team of Clinical Specialists and has responsibilities for clinical research and education.

Gary is the owner of Berke Prosthetics and is an Adjunct Clinical Associate Professor at Stanford University in the Department of Orthopaedic Surgery. He has lectured nationally and internationally on prosthetic design and fitting, has published papers and book chapters, and his passion for prosthetic technology carries forward the mission of the company’s founders to improve prosthetic care for persons with limb loss/difference in developed and developing countries. 

mark clary

Mark Clary, CPO

Clinical Specialist

Mark Clary joined the Xtremity team in 2022 as one of the company’s Clinical Specialists, offering education and training support to prosthetists and technicians who are introducing XtremityTT® into their clinic. 

Mark has over 27 years of experience working in the O&P industry, including two years as a technician before completing his clinical training at Northwestern University and the University of Michigan. He worked at Yanke Bionics in Cleveland for more than 10 years prior to his decision to be a clinical educator for Xtremity. Mark is a Fellow of the American Academy of Orthotists and Prosthetists, and Immediate Past President of the Ohio Chapter, and currently serves as the Vice-Chair of the National Commission on O&P Education.

Ty Hanners

Ty Hanners

National Sales Director

Ty Hanners joined the Xtremity team in 2022 to serve the company’s sales organization. Ty has over ten years of experience in the O&P industry, serving customers in both upper and lower extremity with Freedom Innovations, Touch Bionics and Ossur. His additional experience includes business consulting in the upper extremity segment and service offerings in the workers compensation arena.

Coryn Olpin

Coryn Olpin, CP

Director of Marketing

Coryn is a CP with 20 years of experience in the O&P field. From patient care to R&D and product testing, to education and training, to marketing, she’s used her education and skills to improve the way we educate patients and clinicians. With her Master’s in Instructional Design and Technology, she works with the team of clinicians to help organize, visualize, and simplify product use and creates educational content and videos that are interactive and easily digestible.

Clinical Team

Tres Wright

Tres Wright, Cp

Clinical Director

Tres brings a lifelong passion for prosthetics to Xtremity. With 20+ years of experience in the prosthetics, Tres has brought his unique expertise to the development of the XtremityTT Socket System. He’s been with Xtremity for X years and has been the lead clinician in the development and testing of the Xtremity Socket, bringing it to the outstanding product that it is right now. Tres continues to focus on clinical education as well as research and development of future product iterations and new products.

Gary Berke

Gary Berke, CPO

Chief Clinical Officer

Gary is an Academic and Prosthetist with 35 years of clinical experience and currently an Adjunct Clinical Associate Professor at Stanford University, in the Department of Orthopaedic Surgery. He is also the Owner and Director of Prosthetics at Berke Prosthetics & Orthotics in San Mateo, CA. Gary has been with Xtremity since X. He led us through a 38 subject IRB Clinical Trial in 2021/2022 prior to product launch. He continues to drive scientific evidence as part of Xtremity’s primary focus.

Tres Wright

Mark Clary, CPO

Clinical Specialist

Mark is a certified Prosthetist and Orthotist with twenty-seven years of clinical and technical experience in the profession. After working in the field as a technician for two years, he completed his clinical training at Northwestern University and the University of Michigan. He has provided patient care in a variety of settings, the last ten plus years at Yanke Bionics in Cleveland, Ohio. Mark is a Fellow of the American Academy of Orthotists and Prosthetists (AAOP) and Immediate Past President of the Ohio Chapter; he also currently serves as the Vice-chair of the National Commission on O&P Education (NCOPE). Mark is excited to bring these skills and outlook to Xtremity during a time of evolution in the field.