Soft tissue displacement over pelvic anatomical landmarks during 3-D hip movements

Abstract

The position, in a pelvis-embedded anatomical coordinate system, of skin points located over the following anatomical landmarks (AL) was determined while the hip assumed different spatial postures: right and left anterior superior and posterior superior iliac spines, and the sacrum. Postures were selected as occurring during walking and during a flexion-extension and circumduction movement, as used to determine the hip joint centre position (star-arc movement). Five volunteers, characterised by a wide range of body mass indices (22-37), were investigated. Subject-specific MRI pelvis digital bone models were obtained. For each posture, the pose of the pelvis-embedded anatomical coordinate system was determined by registering this bone model with points digitised over bony prominences of the pelvis, using a wand carrying a marker-cluster and stereophotogrammetry. The knowledge of how the position of the skin points varies as a function of the hip posture provided information regarding the soft tissue artefact (STA) that would affect skin markers located over those points during stereophotogrammetric movement analysis. The STA was described in terms of amplitude (relative to the position of the AL during an orthostatic posture), diameter (distance between the positions of the AL which were farthest away from each other), and pelvis orientation. The STA amplitude, exhibited, over all postures, a median [inter-quartile] value of 9[6] and 16[11]mm, for normal and overweight volunteers, respectively. STA diameters were larger for the star-arc than for the walking postures, and the direction was predominantly upwards. Consequent errors in pelvic orientation were in the range 1-9 and 4-11 degrees, for the two groups respectively.

Accuracy and kinematics consistency of marker-based scaling approaches on a lower limb model: a comparative study with imagery data

“…Segment lengths (mean and standard deviation) for five models: MB, MB l:a:m: , MB a:m à : , EB and EB a:m à : : Friedman's test investigated significant differences between models and Tukey's HSD investigated significant differences with the EB model. à , Ãà , ÃÃà indicated respective p-values < 0.05, < 0.005, < 0.001. local coordinates after optimisation were consistent with respect to the literature because they had the same order of magnitude as the reported STA: 20 mm for the shank, 30 mm for the thigh and 9 mm for the pelvis (Leardini et al 2005;Camomilla et al 2017).…”

A Postural Approach to the Pelvic Diameters of Obstetrics: The Dynamic External Pelvimetry Test

“…Research with optical-electronic instruments evaluates the change of the position in the space of the sensors placed on the external surface of the body [5,11,[13][14], but some studies show that external landmarks move with body movement due to the soft tissue artifact that would affect external markers located above those points during movement analysis [15]. The human hand is a very precise and reliable sensor; the hand is one of the most complex and beautiful pieces of natural engineering and it allows us to manipulate small objects with great precision [16].…”

IMU-based sensor-to-segment multiple calibration for upper limb joint angle measurement—a proof of concept

“…The present study shows some limitations: (i) the measurements were carried out on an upper limb mechanical model taken as a proof-of-concept and only on one healthy subject knowing that STA is subject and task specific [44]. However, it has been demonstrated that a same STA model (a linear function of the joint angle) can be calibrated on different subjects [15,45]; (ii) the performance of the proposed multiple calibration has been investigated on three active movements of the upper limb during which only one angle varies.…”