Studying Femoral Head Translation in Healthy Hips To Better Understand Microinstability

April 26, 2022

A team of researchers, led by UPMC Children’s Hospital of Pittsburgh Division of Pediatric Orthopaedic Surgery assistant professor Michael P. McClincy, MD, director of the Adolescent and Young Adult Hip Preservation Program, published results from a new study designed to assess femoral head translation during weight-bearing apprehension to help better understand normal translation and rotation movement in the hips of healthy adolescents. Data from the study may be useful in helping to assess hip microinstability, which often can lead to pain and other symptoms.

Dr. McClincy collaborated with department colleagues, including William Anderst, PhD, assistant professor of Orthopaedic Surgery and director of the Orthopaedic Biodynamics Laboratory (BDL), on the investigation. Dr. Anderst's laboratory uses a bi-plane radiography imaging system that captures stereoscopic radiographs of joint and bone motion. When combined with high-resolution CT imaging of a subject's anatomy is able to create three-dimensional models showing joint movements and dynamics with sub-millimeter accuracy.

The new study captured images of a group of 22 male and female young adults with no history of hip issues or previous surgery, i.e., healthy hips. Imaging studies were performed, capturing the individuals standing and performing static weight-bearing apprehension positions.

Data from the motion captures and 3-D modeling found, in female subjects, translation during weight-bearing apprehension was a mean of 0.9mm, while in male subjects, the mean was 1.3 mm. Side-to-side translation of the performed movements was nearly identical for females and males, 1.4mm and 1.3mm, respectively.

"Understanding what normal joint kinematic patterns look like, as captured in a study such as ours, can then help us understand when and to what degree hip instability or microinstability is occurring in patients with symptoms or dysfunction," says Dr. McClincy. "A clear understanding of what 'normal' joint motion is can more effectively tell us what pathological disturbances look like when they occur, and perhaps allowing correlation of kinematics with severity or prognosis.”


Ruh E, Johnson C, Frankston N, Charles S, Anderst W, McClincy M. Does Femoral Head Translation Vary by Sex and Side in Asymptomatic Hips During a Weightbearing Apprehension Test? Clin Orthop Relat Res. 2022 Feb 23. Online ahead of print.