- Email: [email protected]
Changing the length vector between sacrum and the hip joint center during a gait cycle
Gait & Posture 49S (2016) 264
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
P118 presented in PS04: Poster teaser: Gait, technical and upper-limb
Changing the length vector between sacrum and the hip joint center during a gait cycle Sebastian Durstberger *, Andreas Kranzl Orthopeadic [1_TD$IF]Hospital Speising, Laboratory for Gait and Human Movements, Vienna, Austria
Introduction: In the determination of the hip joint center it may due to the fact that they are calculated by various parameters, lead to errors. In addition, there may be inaccuracies in the detection of the ASIS markers by skin and soft tissue artefacts. Assuming that the basin is a rigid unit, the distance between [2_TD$IF]sacrum marker and hip joint center is expected to change only slightly. Research question: The aim of this study is to determine how much this distance during a gait cycle changes and whether changes in the distance occur at a certain time. Methods: For retrospective study the kinematic gait data were used by 413 people (body mass index: 23.7 6.7, age 32.4 21.6, marker set: Cleveland Clinical). This group includes both people with physiological and pathological gait (malalignment in frontal and transverse plane, knee pain). The group was not isolated, because the effects of skin and tissue shifts are equally present in both groups. Patients with leg length differences, neuro-motor disorders and pelvic deformities were excluded. In each case, the left side and the right-side calculated separately. Thus, a sample size of n = 826 was available. The reference position for the hip joint was determined in a static position and served as a reference for the variations in the dynamic measurements over a gait cycle. The length vector between
* Corresponding author. http://dx.doi.org/10.1016/j.gaitpost.2016.07.317 0966-6362/
sacrum and hip joint center was calculated and the time of the max. excursion was calculated. Additionally we analysed whether there is a correlation between BMI/Age/walking speed and the difference between the largest distances. All analyses were performed using MATLAB (R2011a, MathWorks, Inc.). Results: We found between 0 and 20% (n = 386) and between 50 and 60% (n = 182) the largest distances between sacrum and hip joint center. The shortest distances are clearly at the end of the gait cycle (90–100%: n = 399) to find. The difference between the largest and the smallest distance is on average 4.8 3.1 mm (maximal distance 19.7 mm). The correlation coefficient between BMI and the difference is 0.36, between the age and the difference: 0.3 and between walking speed and the difference: 0.04. Discussion: From the results it can be clearly seen that the calculated position of the hip joint center is not stationary within the pelvis coordinate system. Interestingly we could not find any correlation with BMI. It would be interesting to investigate whether an alternative marker set with markers only on the back provides less variation in the position of the hip joint center. Also the clinical impact should be addressed for these changes. First results with an alternative marker set look promising.
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
P118 presented in PS04: Poster teaser: Gait, technical and upper-limb
Changing the length vector between sacrum and the hip joint center during a gait cycle Sebastian Durstberger *, Andreas Kranzl Orthopeadic [1_TD$IF]Hospital Speising, Laboratory for Gait and Human Movements, Vienna, Austria
Introduction: In the determination of the hip joint center it may due to the fact that they are calculated by various parameters, lead to errors. In addition, there may be inaccuracies in the detection of the ASIS markers by skin and soft tissue artefacts. Assuming that the basin is a rigid unit, the distance between [2_TD$IF]sacrum marker and hip joint center is expected to change only slightly. Research question: The aim of this study is to determine how much this distance during a gait cycle changes and whether changes in the distance occur at a certain time. Methods: For retrospective study the kinematic gait data were used by 413 people (body mass index: 23.7 6.7, age 32.4 21.6, marker set: Cleveland Clinical). This group includes both people with physiological and pathological gait (malalignment in frontal and transverse plane, knee pain). The group was not isolated, because the effects of skin and tissue shifts are equally present in both groups. Patients with leg length differences, neuro-motor disorders and pelvic deformities were excluded. In each case, the left side and the right-side calculated separately. Thus, a sample size of n = 826 was available. The reference position for the hip joint was determined in a static position and served as a reference for the variations in the dynamic measurements over a gait cycle. The length vector between
* Corresponding author. http://dx.doi.org/10.1016/j.gaitpost.2016.07.317 0966-6362/
sacrum and hip joint center was calculated and the time of the max. excursion was calculated. Additionally we analysed whether there is a correlation between BMI/Age/walking speed and the difference between the largest distances. All analyses were performed using MATLAB (R2011a, MathWorks, Inc.). Results: We found between 0 and 20% (n = 386) and between 50 and 60% (n = 182) the largest distances between sacrum and hip joint center. The shortest distances are clearly at the end of the gait cycle (90–100%: n = 399) to find. The difference between the largest and the smallest distance is on average 4.8 3.1 mm (maximal distance 19.7 mm). The correlation coefficient between BMI and the difference is 0.36, between the age and the difference: 0.3 and between walking speed and the difference: 0.04. Discussion: From the results it can be clearly seen that the calculated position of the hip joint center is not stationary within the pelvis coordinate system. Interestingly we could not find any correlation with BMI. It would be interesting to investigate whether an alternative marker set with markers only on the back provides less variation in the position of the hip joint center. Also the clinical impact should be addressed for these changes. First results with an alternative marker set look promising.