Hip dysplasia is a deformity in which the hip socket inadequately covers the ball side of the joint, frequently leading to early-onset hip arthritis in young adults (25-50 years of age), even after surgical correction to improve the congruency of the joint.
Holly Aitken’s doctoral studies focused on using 3D patient-specific computer models to identify surgical corrections designed to reduce the chances of developing hip arthritis or needing future hip replacement surgery.
“When a 16-year-old has corrective surgery for hip dysplasia, sometimes their hips still end up developing arthritis by their early 30s. They even may need a hip replacement by age 30,” Aitken says. “We want to try to prevent the need to have to go down that road. We’re looking at what’s going wrong from a mechanical standpoint that’s causing these joints to continue to degenerate even after corrective surgery.”
The native of Sugar Grove, Ill., Aitken earned her doctorate in biomedical engineering at the University of Iowa in summer 2021. Her dissertation was the first doctoral project focusing on hip dysplasia in her lab, which primarily conducts musculoskeletal biomechanics research of joint injuries and post-traumatic osteoarthritis. Aitken received additional time to finish her dissertation writing and statistical analysis after receiving a Ballard and Seashore Fellowship from the Graduate College.
Aitken studied patients’ clinical CT scans taken preoperatively and postoperatively. She isolated the bone geometry from the CT scans to create a 3D model of each patient’s hip joint. She then statistically analyzed the relationship between the lab’s mechanical measures of the hip joint and patients’ long-term outcomes.
Generally, Aitken’s output data looked at the stress on the hip socket.
“I noticed that in these dysplastic joints, patients tend to have higher stresses and decreased contact area between the femur and the socket,” Aitken says. “Joints that continually experience these higher stresses over a long period of time are more likely to develop osteoarthritis. And then we've also found that in these post-operative hips, surgical reorientation of the hip socket does not necessarily always get the stress back to normal levels.”
Stress maps were created to help visually understand the mechanical differences between dysplastic hips and normal hips and further make sense of why some dysplastic hips undergoing corrective surgery still developed arthritis.
Aitken currently works as an assistant research scientist/engineer in the UI Orthopedic Biomechanics Laboratory. In the lab, her research projects address joint injuries and post-traumatic osteoarthritis, high-energy limb trauma, and articular contact stresses as they relate to joint degeneration.
“My research interests are primarily in developmental deformities, how they alter joint mechanics, and how that relates to development of arthritis,” Aitken says. “There's other types of hip deformities that can happen; you can get deformities that are on the ball side of the joint, such as additional bone growth on the head or neck of the femur, flattening of your femoral head, or movement of the femoral head away from the rest of the femur, all of which can also cause mechanical issues and future arthritis.”
“Another area that I'm interested in is the spine and looking at what happens with abnormal development in the spine, like with scoliosis or other deformities, and mechanical factors that contribute to that abnormal development.”