Hip Morphology Pilot Study Under Way at University Hospitals
January 05, 2025
Innovations in Orthopaedics |Spring 2025
Pediatric orthopaedic surgeon Raymond Liu, MD, is leading a pilot study of cam morphology in adolescents at University Hospitals Rainbow Babies & Children’s Hospital.
![Raymond Liu, MD](/-/media/images/physician-headshots/l/liu-raymond-ortho.jpg)
“This is a significant clinical question because hip cam is responsible for the majority of hip arthroscopy surgery and a portion of total hip replacements,” says Dr. Liu, the Victor M. Goldberg Endowed Chair in Orthopaedics at University Hospitals.
Cam morphology is present in 10 to 15 percent of the overall population and is associated with pain and the development of osteoarthritis. “Even though most people who develop the condition are not negatively affected long term, it is well known that cam morphology predisposes a certain percentage of individuals to future problems,” Dr. Liu says. “We hope to learn more about the process to prevent young people from putting undue stress on the hip during times of development that appear to exacerbate cam formation.”
Dr. Liu and researchers at University Hospitals have contributed to the current understanding that cam morphology originates in the hip’s growth plate, presumably secondary to physical activity during puberty. Pathogenesis appears to coincide with periods of rapid growth and skeletal maturation and is thought to be affected by repetitive mechanical loading of the hip during activities such as running, jumping and pivoting.
Origins of Cam Morphology
Slipped capital femoral epiphysis (SCFE) is a condition that occurs inside the hip joint. “Within the hip socket, the capital femoral epiphysis forms the joint surface,” Dr. Liu says. “The epiphyseal tubercle is the key stabilizer in the growth plate and locks the epiphysis with the metaphysis. During puberty, this area can become vulnerable and shift out of position.”
For a combination of biological and mechanical reasons that are not yet fully understood, the ball at the head of the femur slips off the neck of the bone in a backward direction. “This can cause substantial problems with the hip, including pain, limp and bony deformity,” Dr. Liu says. “Patients almost always require surgery to keep the condition from worsening.”
As they studied SCFE and cam development, Dr. Liu and UH researchers recognized that the epiphyseal tubercle becomes smaller during puberty, resulting in less stability in the proximal femur. The body’s natural response is to build bone to protect itself from the additional force. That stability must come from somewhere, so the edges of the epiphysis begin to grow and extend around the metaphysis.
“We call it cupping because it looks like the epiphysis is forming a little ledge or cup as it grabs around the metaphysis,” Dr. Liu says. “After reviewing multiple orthopaedic studies, we know that most kids are perfectly good at this cupping and are able to protect themselves, but there are some kids who are not able to make that little ledge of bone and end up developing a SCFE.”
Long thought to affect boys more than girls because of differentiated activity levels, Dr. Liu suggests the reality may have more to do with the age when students participate in highly competitive sports. “I think the larger reason we see cam morphology more in males is not because they are necessarily engaging in higher activity levels but because females are vulnerable about two years earlier and fortunately in a state where their hips are generally safe by the time they compete in high school athletics.”
Pilot Study Underway
“Because cam is such a common phenomenon, it is amenable to a natural history study, meaning that we could follow hundreds of children through puberty and theoretically watch this happen,” Dr. Liu says.
University Hospitals researchers are recruiting healthy 12-year-old females and 14-year-old males for the pilot study, which aims to enroll 20 adolescents who are at a vulnerable age for cam development. MRIs will track hip changes over time, and participants will need to keep an activity journal. They will also be asked to wear an ActiGraph medical-grade activity monitor. The sophisticated ActiGraph device gathers accelerometry data in three dimensions, providing a multiaxial sense of movement.
“Ideally, this study will allow us to gather the information we need to go into the community and make recommendations to young athletes and their parents about when they are most vulnerable,” Dr. Liu says. “Like pitch counts in baseball, if individuals limit their activity during the crucial time window, they will have healthier hips for the rest of their lives.”
For more information, contact Dr. Liu at Raymond.Liu@UHhospitals.org.
Contributing Expert:
Raymond Liu, MD
Pediatric Orthopaedic Surgeon
UH Rainbow Babies & Children's Hospital
Victor M. Goldberg, MD, Chair in Orthopaedic Surgery
University Hospitals
Professor of Orthopaedics and Pediatrics
Case Western Reserve University School of Medicine