Our Physician Partners

We have one the most robust physician networks in the Region, with specialists known around the country and the world for quality and the innovative care they provide.

dr. mark tuttle denver orthopedic surgeon
DR. Mark Tuttle

Hip and Knee Replacement/Anterior Hip Expert

Mark S. Tuttle, MD, is a fellowship-trained, board-certified orthopedic surgeon specializing in hip and knee replacement, joint replacement revision, fracture care, and general orthopedics, with special interest in direct anterior total hip arthroplasty and minimally invasive total joint replacement. Dr. Tuttle received his medical degree in 2001 from the University of New Mexico School of Medicine in Albuquerque, where he was valedictorian of his graduating class. Dr. Tuttle also received the faculty award for Outstanding Graduating Medical Student. Upon graduation, Dr. Tuttle completed his orthopedic surgery residency at the University of Colorado Health Sciences Center in Aurora, Colo., where he earned the Outstanding Resident Research Award. Following his residency, he also completed a fellowship in adult reconstruction at the University of Colorado. Dr. Tuttle is a member of the International Congress for Joint Reconstruction, an organization that focuses on orthopedic education. He has co-authored multiple scientific publications and presentations, including research on femoral shaft fractures in multiple-injury patients. Dr. Tuttle is a Diplomat of the American Board of Orthopaedic Surgery, is a member of the American Academy of Orthopaedic Surgeons, and is a member of the American Association of Hip and Knee Surgeons.

DR. Daniel C. allison

Oncology Complex Hip and Knee Reconstruction

Daniel C. Allison, MD, FACS, is board certified in orthopedic surgery with expertise in musculoskeletal oncology, complex hip and knee joint reconstruction, and anterior hip replacement. He is Assistant Director of Orthopedic Oncology at Cedars-Sinai Medical Center, Associate Clinical Professor of Orthopedic Surgery at University of Southern California, and Co-Director of Pediatric Orthopedic Oncology at Children’s Hospital of Los Angeles (CHLA). Dr. Allison is a Fellow of the American College of Surgeons (FACS) and the American Academy of Orthopedic Surgeons (AAOS). He is also a member of the Musculoskeletal Tumor Society (MSTS), the Orthopedic Trauma Association (OTA), the American Association of Hip and Knee Surgeons (AAHKS), and the American Orthopedic Association (AOA). Learn more.

Dr. Ron Hillock

Oncology Complex Hip and Knee Reconstruction

Dr. Hillock is focused on the diagnosis and treatment of musculoskeletal disease and adult joint reconstruction surgery. Dr. Hillock currently serves as Chief of Surgery at Centennial Hills Hospital and Medical Center in Las Vegas and on the Board of Directors of the Nevada State Orthopedic Society. Dr. Hillock received his Bachelor of Science degree in Biology from the University of California, Riverside. He received his Doctor of Medicine degree from Loma Linda University in California. He completed a transitional internship in orthopedic surgery at Walter Reed Army Medical Center, Washington, D.C. He then completed his orthopedic surgery residency at Texas Tech University Health Science Center in El Paso. Dr. Hillock completed his fellowship in orthopedic oncology at the University of California, Los Angeles, School of Medicine in Santa Monica. Dr. Hillock has served as the Chief of Surgery for the 67th Combat Support Hospital during Operation Iraqi Freedom and Chief of Orthopedic Surgery Rehabilitation Service at the U.S. Army Hospital in Heidelberg, Germany. Learn more.

DR. Earl Brien

Oncology Complex Hip and Knee Reconstruction

Dr. Brien earned a bachelor’s degree from the University of California at Berkeley and a medical degree from Howard University School of Medicine, Washington, DC. He completed an internship in general surgery at St. Luke’s-Roosevelt Hospital, Columbia University, New York City, and a residency in orthopedic surgery at King/Drew School of Medicine, Los Angeles. Thereafter he completed a fellowship in orthopedic oncology at the Sloan-Kettering Cancer Center in New York City. From 1993-2004, he served as Director of Musculoskeletal Tumor Service at the Orthopedic Hospital in Los Angeles. From 2004 – 2007 he served as Fellowship Coordinator, Sarcoma Service, John Wayne Cancer Institute / St. John Health Center, Santa Monica, CA. Since 2008, he has served as Surgical Director, Sarcoma Service at Cedars-Sinai Medical Center in Los Angeles. Learn more.

DR. David So

Hip and Knee Replacement

Dr. David So is an orthopedic surgeon in Orange, CA. He earned his medical degree from Wayne State University and then completed his internship and residency training, both in orthopedic surgery at the Henry Ford Hospital. Later, he completed his fellowship at the University of Pennsylvania in adult reconstruction. Currently, Dr. So is affiliated with UCI Health Orthopedic Surgery Services and the UCI Health Orthopedic & Sports Medicine Center. He specializes in joint replacements of the knee and hip as well as other orthopedic procedures. Learn more.

DR. Lindsey Rolston

Knee Replacement

Dr. Lindsey Rolston’s surgical expertise has led him to develop new and better ways to perform knee implants. He pioneered the development of a bicompartmental knee for which he holds a patent. He also has played an important role in the development of four other knee implant systems. Dr. Rolston is a board-certified orthopedic surgeon. He received his undergraduate from Bradley University and MD degree from the University of Illinois and completed his orthopedic residency at Michigan State University, Kalamazoo, where he was also the Chief Orthopedic Resident. He is a member of the following societies: Indiana Orthopedic Society, American Academy of Orthopedic Surgeons, Indiana State Medical Society and American Association of Hip and Knee Surgeons, and Bradley University Centurion Society. Learn more.

Dr. Afshin Masoof

Total Joint Replacement Sports Medicine

Dr. Afshin Mashoof grew up locally in Southern California. He completed undergraduate degree in Engineering before focusing his attention to a career in medicine. At Creighton University School of Medicine, he was awarded multiple awards including research scholarship for work on bone healing and cartilage regeneration. He then continued his training in orthopedic surgery at Kingsbrook/Beth Israel Medical Center in New York City where he trained with the leading surgeons in the country. Dr. Mashoof has over 20 years of experience in treating a variety of orthopedic and sports-related injuries and problems. He has extensive expertise in arthroscopic and minimally invasive reconstructive (Total joint replacement) of the knee/shoulder/Hip, including ligament/tendon injuries, cartilage regeneration and arthritis. Learn more.

DR. Craig Tingey

Total Joint Replacement Sports Medicine

Dr. Tingey specializes in sports medicine and arthroscopic surgery, as well as total joint replacement surgery of the knee, hip, and shoulder. He is skilled in the latest surgical techniques including arthroscopic rotator cuff repairs and minimally invasive hip and knee replacement surgery. He was also part of the orthopedic trauma group that provides care for patients with orthopedic injuries at the University Medical Center, a Level 1 Trauma center. Dr. Tingey served as the chief of orthopedic surgery at Mountain View Hospital. Dr. Craig Tingey earned his Bachelor of Science from Brigham Young University, followed by his Doctor of Medicine from Wake Forest University in North Carolina. He completed his surgical internship and orthopedic surgical residency at Loma Linda University School of Medicine in Southern California where, as chief resident, he was awarded the Leonard Marmor Award for “Excellence in Orthopedic Surgery,” as well as multiple awards for his medical research. Learn more.

Dr. Brian Moss

Total Joint Replacement Sports Medicine

Dr. Brian Moss joined Orthopedic Associates after completing his Orthopedic Sports Medicine fellowship in San Diego. During fellowship, Dr. Moss worked with a wide variety of elite athletes in sports ranging from NFL football, to WWE wrestling, professional rodeo, MMA, rugby, and skate boarding. He completed his residency at Michigan State University where he was exposed to a wide range of orthopedic surgical cases. He enjoys the variety of general orthopedic surgery but has special interest in sports medicine procedures including knee and shoulder arthroscopic reconstruction and repair. He enjoys trauma procedures and additionally specializes in knee and shoulder arthroplasty. Learn more.


Total Joint 
Board-Certified Orthopedic Surgeon

Dr. Patel is a board-certified orthopedic surgeon specializing in Total Joint Replacement and Adult Reconstructive Surgery. Dr. Patel is an attending surgeon at both Hoag Orthopaedic Institute in Irvine as well as St. Joseph’s Hospital in Orange. His area of expertise includes both primary and revision surgical procedures of the hip and knee. He also brings expertise in new surgical techniques including minimally invasive surgical procedures, anterior approach hip replacement surgery, computer navigation, as well as robotic joint replacement.


Dr. Patel is an active member of the American Academy of Orthopaedic Surgeons and the American Association of Hip and Knee Surgeons. He has published on multiple areas of orthopedic research, including computer navigation systems for total joint replacement, revision of complex hip and knee replacement surgery, and orthopedic clinical outcomes. Dr. Patel enjoys spending time with his wife and young children as well as cycling, hiking, and skiing. Learn more.