The NorCal Arthroplasty Fellowship
The NorCal Arthroplasty Fellowship is an evolving program supported by the Hipster Foundation, offering a comprehensive clinical experience with multiple high-volume private practice surgeons throughout the San Francisco Bay Area. Under the direction of Dr. Nicholas H. Mast and Dr. John N. Diana, the fellowship provides advanced exposure to cutting-edge minimally invasive techniques in hip and knee arthroplasty.
Dr. Diana, a double board-certified orthopaedic surgeon and founding partner of Napa Valley Orthopaedic Medical Group, brings over two decades of leadership in joint replacement and reconstructive surgery to the program. As Medical Director of Joint Replacement and Orthopedic Service Lines at Adventist Health–St. Helena Hospital and Queen of the Valley Medical Center, his expertise in robotic-assisted surgery, anterior hip arthroplasty, and rapid recovery protocols complements the program’s mission of clinical excellence.
Through hands-on surgical mentorship and multi-site collaboration, fellows will gain experience in kinematically aligned primary and revision knee arthroplasty, unicompartmental knee arthroplasty, arthroscopic and open hip preservation, hip fracture management, anterior approach hip arthroplasty, resurfacing, and revision anterior hip procedures. Together, Drs. Mast and Diana will guide fellows in the art of efficient, patient-centered, and evidence-based arthroplasty that reflects the innovation and collaborative spirit of Northern California’s leading orthopaedic community.
Welcome NorCal Fellows
The Surgeon Trainee will receive training at the true leading edge of modern arthroplasty. Over the past decade, two minimally invasive approaches have reshaped lower-extremity joint replacement. In hip arthroplasty, the anterior approach has demonstrated clear benefits for patients, including reduced pain, faster recovery, and fewer complications compared to traditional approaches. In knee arthroplasty, emerging evidence supporting kinematically aligned total knee replacement has shown superior soft-tissue preservation, leading to less postoperative pain and swelling, faster return to function, and reduced physical therapy requirements. These techniques directly address the historically reported dissatisfaction associated with mechanically aligned knee arthroplasty.
For more than 15 years, Dr. Nicholas Mast has been at the forefront of anterior hip arthroplasty innovation. His experience includes national teaching roles, peer-reviewed publications, and contributions to the development of novel techniques and instrumentation. Under his leadership, fellows will receive unparalleled exposure to modern hip arthroplasty, including primary, complex, and revision anterior-approach surgery.
Joining him in co-directing the curriculum, Dr. John N. Diana brings over two decades of extensive expertise in knee and hip reconstruction. A founding partner of Napa Valley Orthopaedic Medical Group and long-serving Medical Director of Joint Replacement and Orthopedic Service Lines at Adventist Health–St. Helena, Dr. Diana offers deep clinical and academic experience in robotic-assisted knee arthroplasty, rapid-recovery protocols, and contemporary alignment philosophies. His publications and national and international presentations reflect a career-long commitment to advancing joint replacement science and improving patient outcomes. Under Dr. Diana’s guidance, fellows will receive high-volume, hands-on training in advanced knee reconstruction, including kinematic alignment, unicompartmental knee arthroplasty, and complex revision procedures, as well as anterior hip arthroplasty and hip preservation.
The emphasis of the fellowship is the development of a hands-on, minimally invasive surgical skillset paired with strong clinical reasoning in the diagnosis and management of complex arthroplasty problems. With over 1,000+ annual arthroplasty cases performed across the clinical faculty, the fellow will gain comprehensive exposure to the full breadth of primary and revision hip and knee surgery—ensuring a robust and highly practical foundation for independent practice.
Unlike most arthroplasty fellowships that are focused on a hospital environment, the NorCal Arthroplasty Fellowship provides invaluable private practice context encompassing first-hand experience of all aspects of the procedures – from patient optimization to effective outpatient procedures and post-operative care.
Standing on the shoulders of giants
Education and mentorship is about creating a bridge between generations of surgeons – by taking what has been learned by one generation and passing it to the next to build on it. The NorCal Arthroplasty fellowship program is designed to share best practices in joint replacement surgery with the next generation of surgeons.
“Having mentors in surgery shapes you, it ends up to be your surgical DNA, it’s unique to you but you have inherited it from your mentors”
James Church MD
Method of Formal Evaluation
The fellow on intake to the program will develop in conjunction with the Program Director an Individual Learning Plan (ILP) to adequately assess the fellow’s long-term and short-term goals, specific objectives, career plans, self-identified strengths and weaknesses, development of strategies to achieve the goal and objectives, assessment of progress on goal and objectives, and incorporate feedback from faculty/mentor/advisor.
Assessments will be made by faculty-guided direct observation of clinical care. Formative guidance will be offered on a quarterly basis. Growth and development of relevant Knowledge Base, Technical skills, and Professionalism will be guided by input from Faculty and staff.
Faculty
PROGRAM DIRECTORS
Dr. Nicholas Mast
After completing his orthopedic residency, Dr. Mast undertook extensive additional surgical training in the form of international Fellowships and that allowed him to learn from international leaders in the field of hip and pelvis surgery – including:
- Dr. Reinhold Ganz (whose countless achievements include developing the peri-acetabular osteotomy (PAO) procedure for hip preservation),
- Dr. Michael Leunig (a foremost authority in hip preservation and pelvic surgeries)
- Dr. Frédéric Laude (one of the most influential surgeons in the development of the anterior approach worldwide),
- Dr. Joel Matta (a leader in the field for evaluating, diagnosing, and treating complex orthopaedic hip disorders and the godfather of the anterior approach in the US)
- and of course, his father Dr. Jeffery Mast who collaborated with Dr. Ganz on the PAO technique to treat developmental dysplasia of the hip.
Read more about Dr. Mast’s own training.
Dr. Stephen Howell
The Fellowship distills this expertise in anterior hip surgeries and combines it with an opportunity to learn from a pioneer in knee replacements – Dr. Stephen Howell.
Dr. Howell developed a revolutionary new approach to knee replacement in 2005 – known as kinematic alignment, this innovative technique improves the placement of the orthopedic implants that form the new knee, resulting in more consistency and reliability in patient outcomes. The approach enables shorter lengths of stay and quicker return to prior function. According to ProPublica, Dr. Howell’s readmission, complication and infection rates after total knee replacement are among the lowest in the nation and he is considered among the Top 3% of California knee replacement surgeons.
Dr. Howell has published more than 140 scientific articles in peer-reviewed journals and frequently shares his clinical experiences and research findings as a presenter and invited speaker at national and international meetings and at universities worldwide. He regularly hosts experienced orthopedic surgeons from around the world who seek education in his techniques by observing patient care in the office, hospital, and operating room.
Other Faculty
Dr. Alexander Nedopil and Dr. Robert Mayle.
Research Initiatives and Innovation
The aim of the fellowship is to further educational goals in training and application of minimally invasive techniques of primary and revision arthroplasty.
Current studies include:
- Outcomes following anterior approach total hip arthroplasty
- Outcomes following kinematically aligned total knee arthroplasty
- Anterior Approach for Revision Total Hip Arthroplasty
- Outcomes following simultaneous bilateral knee and hip arthroplasty
- Reduction of infection in total knee and total hip arthroplasty
- Cost and Value as they relate to primary joint arthroplasty
- Improving safety and access for arthroplasty in the ASC setting.
To Apply
Please send your CV and three letters of recommendation to doctormast@sfhips.com
