Obesity-specific joint center estimation in gait analysis

Gait analysis aims at gathering quantitative information about the mechanics of the musculo-skeletal system during the execution of a motor task. Typically, in gait analysis, variables such as kinematics, joint moments, and powers are determined. This information is used to evaluate pathological gait patterns. Errors in locating the three-dimensional (3D) position of the hip joint center (HJC) can strongly affect the calculation of typical clinical 3D gait analysis variables. This consequentially leads to incorrect interpretations. The problem of inaccuracy in HJC location increases significantly in patients where bony landmarks are difficult to identify, such as in obese or overweight participants. Nevertheless, gait analysis remains as the state of the art method for clinicians as well as for research purpose. Often medical imaging-based methods are recommended to identify the 3D HJC localization. However, these methods typically expose patients to radiation and are often expensive and time- consuming due to long post-processing times. To estimate the position of the HJC several none- invasive predictive methods, based on experimental data, and functional models were introduced to gait analysis in recent years. Research has attempted to determine which of these methods best determine the HJC most accurately in various populations. Among those, only a few studies recruited children or clinically diagnosed patients. To date, no study aimed at identifying the accuracy of the proposed HJC location methods in a population of overweight or obese children and adolescents. However, all currently available non-invasive methods are strongly affected by the amount of subcutaneous fat present (wobbling mass), thus great inaccuracies are introduced. A study to identify how well existing HJC estimation methods work for this very specific population is strongly recommended. Therefore, the primary aim of this study is to evaluate and to compare current non- invasive HJC estimation methods for clinical 3D gait analysis in a population of overweight children and adolescents. In addition, new approaches will be evaluated and tested. Consequentially this may increase the accuracy and reliability of clinical gait analysis in overweight patients.