Functional Hip Joint Center Determination in Obese Subjects

Principal Investigator: Thomas P. Andriacchi, PhD

The purpose of this pilot study is to develop a technique to quantify in vivo joint function and joint loads that is valid for use in patient populations with osteoarthritis of the hip, knee, and ankle in overweight and obese healthy populations.

Specific Aims

Aim 1: To functionally determine the hip joint center for gait analysis in normal-weight and obese subjects

Aim 2: To test the accuracy of functional hip joint center estimate using dual plane radiographs relative to traditional methods

Progress during 2006

Work Accomplished

• Designed and built rig to support subject during dual plane oblique angle radiographs that allows the accurate placement of the subject in two positions relative to the x-ray source
• Implemented several different methods to calculate the functional hip joint center location
• Processed pilot data for 10 normal weight and 10 obese subjects
• Performed pilot analysis on performance of different algorithms to calculate the functional hip joint center
• Established protocols with x-ray technologists at the VA Palo Alto Health Care System

Main Findings

• None to date

Plan for Subsequent Years

• Collect pilot data with pelvis phantom
• Implement algorithm to determine 3D marker positions from 2D radiographs
• Recruit and collect motion and x-ray data for 10 normal weight and 10 obese subjects
• Process motion and x-ray data for all subjects

Data Analysis

• Compare performance of different algorithms to calculate the functional hip joint center
• Compare performance of different motions and marker clusters to calculate the functional hip joint center
• Validate functional hip joint centers from different algorithms, motions, and marker clusters to radiographically determined joint center
• Compare the performance of different algorithms, motions and marker clusters between normal weight and obese subjects
• Submit two abstracts and two manuscripts on subsets of data

Funding Source: Department of Veterans Affairs – Merit Review