Hip joint is one of the most stable joints in human body. It has intrinsic stability provided by its relatively rigid ball and socket configuration. The hip joint also has a wide range of motion, which allows normal locomotion and daily activities. Location of hip joint center (HJC) is an important parameter in gait analysis, biomechanical and clinical research laboratories to calculate human lower extremity kinematics and kinetics. Inaccuracies in estimation of hip joint center are shown to propagate errors in kinematic and kinetic calculations of lower extremities
Hip joint is one of the most stable joints in human body. It hasintrinsic stability provided by its relatively rigid ball and socket configuration.The hip joint also has a wide range of motion, which allows normal locomotionand daily activities. Location of hip joint center (HJC) is an importantparameter in gait analysis, biomechanical and clinical research laboratories tocalculate human lower extremity kinematics and kinetics. Inaccuracies inestimation of hip joint center are shown to propagate errors in kinematic andkinetic calculations of lower extremities.In literature there are different methods to determine HJC. Although invasivemethods like radiography, computed tomography and magnetic resonanceimaging may be used to determine the location of HJC, in gait analysislaboratories, non-invasive functional and/or predictive methods are generallyfound to be more advantageous. Calculation of gait parameters fromstereophotogrammetric data requires utilization of classical mechanicstogether with biomechanical models which represents human body as amechanical system. Obviously, procedures employed in these calculations aredirectly associated with the experimental protocol. Adaptation of various jointcenter estimation methods to Middle East Technical University (METU) gaitanalysis system Kiss (Kinematic Support System in English, Kas İskelet Sistemiin Turkish) and investigation of the effects of joint center location on kinematicresults undoubtedly require modifications to be introduced to theexperimental protocol, and consequently, to the calculation methodology.METU gait analysis system, utilizes one of the predictive methods, the Davismethod to determine hip joint center location. This method is verystraightforward and easy to use. However, in this method, the determination ofthe positions of anatomical landmarks depends on the experience of theconductor and anatomical properties of the specimens (any anatomicalvariations of the specific subject will cause errors). One of the major sources oferror propagation in kinematic and kinetic calculations is due to misplacementof hip joint center.This study aims to experimentally verify different HJC estimation methodswith those obtained from MRI in healthy subjects for the purpose ofdemonstrating and validating the contribution of MRI procedure in METU gaitanalysis system. Also combination of Bell's method in posterior direction,Davis method in distal direction and Bell's method in medial direction wasanalyzed and the results were criticized for the accuracy.