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Hip joint centre location from anatomical landmarks for automotive seated posture reconstruction J. Peng
abcd
abc
, X. Wang
d
ef
e
, L. Denninger , J. Panda & S. Van Sint Jan
a
Université de Lyon, F-69622, Lyon, France
b
IFSTTAR, LBMC, UMR_T9406, Bron, France
c
Université Lyon 1 Villeurbanne, Villeurbanne, France
d
PSA Peugeot-Citroën, Sochaux, France
e
Laboratory of Anatomy, Biomechanics and Organogenesis (LABO) of Université Libre de Bruxelles (ULB), 1000 Bruxelles, Belgium f
Department of Orthopaedics, University of Lubumbashi, Lubumbashi, Democratic Republic of the Congo Published online: 07 Aug 2013.
To cite this article: J. Peng, X. Wang, L. Denninger, J. Panda & S. Van Sint Jan (2013) Hip joint centre location from anatomical landmarks for automotive seated posture reconstruction, Computer Methods in Biomechanics and Biomedical Engineering, 16:sup1, 195-197, DOI: 10.1080/10255842.2013.815895 To link to this article: http://dx.doi.org/10.1080/10255842.2013.815895
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Computer Methods in Biomechanics and Biomedical Engineering, 2013 Vol. 16, No. S1, 195–197, http://dx.doi.org/10.1080/10255842.2013.815895
Hip joint centre location from anatomical landmarks for automotive seated posture reconstruction J. Penga,b,c,d, X. Wanga,b,c*, L. Denningerd, J. Pandae,f and S. Van Sint Jane a Universite´ de Lyon, F-69622 Lyon, France; bIFSTTAR, LBMC, UMR_T9406, Bron, France; cUniversite´ Lyon 1 Villeurbanne, Villeurbanne, France; dPSA Peugeot-Citroe¨n, Sochaux, France; eLaboratory of Anatomy, Biomechanics and Organogenesis (LABO) of Universite´ Libre de Bruxelles (ULB), 1000 Bruxelles, Belgium; fDepartment of Orthopaedics, University of Lubumbashi, Lubumbashi, Democratic Republic of the Congo
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Keywords: hip joint centre; anatomical landmarks; seated posture
1.
Introduction
Measuring hip joint centre (HJC) for seated posture in an automotive environment is a difficult task, because only a very limited number of anatomical landmarks (ALs) can be measured. There exist two classes of methods for estimating HJC location (see Bull et al. 2012 for a short review): regression method and functional method. However, they are not well suited to be directly applied to automotive seated posture. Recently, Bull et al. (2012) showed that the uncertainty in HJC by these two methods applied to automotive seated posture could be up to 4 cm due to errors in AL manual palpation and soft tissue artefacts. Interestingly, Bush and Gutowski (2003) proposed a method of locating HJCs for seated postures only using the right and left anterior superior iliac spines ([R/L]IAS) and the right or left femoral lateral epicondyles of the knee by assuming that the distances between HJC and these three ALs remained constant when changing posture. These distances needed to be firstly determined in an initial reference posture by Seidel’s method. However, one strong limitation of Seidel’s method is that the palpation of the pubic joint landmark (IPJ) is required, which usually causes volunteers to feel uncomfortable. Similar to the method by Bush and Gutowski, the aim of this study was to explore other ALs than IPJ for determining HJC. More specifically, the ilium ischial tuberosity (IIT) could be an alternative candidate as it can be indirectly estimated with the help of a pressure map by assuming that the highest pressure point corresponds to IIT when seated on a flat hard surface. In this study, data collected by Universite´ Libre de Bruxelles (ULB) from 48 adult cadaveric specimens were used for establishing regression equations. The proposed equations were compared with other existing bony landmark-based methods.
*Corresponding author. Email:
[email protected] q 2013 Taylor & Francis
2.
Methods
2.1 ULB anatomical data Data were firstly collected from CT-scanned non-dissected cadavers at the Laboratory of Anatomy, Biomechanics and Organogenesis of ULB. Forty-eight pairs of pelvis and femurs were used after examining obvious abnormalities. Gender information was not available. All ALs were virtually palpated from the 3D pelvis and femoral models. HJCs were approximated as the centres of femoral heads at each side. The left side of each pelvis was symmetrically transferred to the right according to the xy plane (sagittal) to increase the database. The main characteristics of the 48 pelvises used in this study are summarised in Table 1. The two different pelvis local coordinate systems (LCS) are defined and shown in Figure 1.
2.2
HJCs location from RIAS and RIIT
In Table 1, the ratios between HJC – RIIT and RIAS – RIIT in the x, y and z of the pelvis LCS O1X1Y1Z1 (Figure 1) as well as their correlation coefficients are calculated. One can see that HJCx and HJCy are strongly correlated with RIITx and RIITy, respectively. As already observed by Seidel et al. (1995), HJC in the x and y directions are not well correlated with pelvis width (PW), while only PW was used in Bell’s prediction equations. For HJCz, a higher coorrelation between (HJCz –RIASz) and (RIITz– RIASz) was observed than the correlation between (RIASz– HJCz) and PW. Therefore, we suggest the following regression equation: HJCi ¼ k*i ðRIITi 2 RIASi Þ þ RIASi ; i ¼ x; y; z:
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Table 1.
Main characteristic (in mm) of 48 pelvises.
PW PH PD HJCx HJCy HJCz RIITx RIITy RIASz – RIITz HJCx/RIITx HJCy/RIITy (HJCz –RIASz)/(RIITz – RIASz) HJCx/PW HJCy/PW HJCx/PD HJCy/PW HJCz/PH
LCS
Mean
SD
N
r
1 1 1 1 1 1 1 1 1 1 1 2 2 2
238.7 87.8 163.7 2 42.6 2 74.9 84.7 2 73.8 2 142.8 66.2 58.0% 52.6% 52.6% 2 18.0% 2 31.5% 33.9% 14.5% 78.3%
18.1 9.7 9.0 7.2 6.5 5.5 12.8 9.1 13.9 5.4% 2.7% 7.4% 3.6% 3.4% 3.2% 2.9% 7.0%
48 48 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96
0.864 0.814 0.854 0.194 20.116 0.431 0.811 0.783
Notes: Only the data for the right side are given. PW is defined as the interdistance between LIAS and RIAS. Pelvis height (PH) is the shortest distance from the pubic symphysis IPJ to the inter RIAS–LIAS line, and pelvis depth (PD) is the distance between R(L)IAS and R(L)IPS. r is the correlation coefficent between two variables for ration calculation.
Table 2. Means (standard deviations) of the errors between the estimated and the true HJC for the three methods in the x, y and z as well as their distance DHJCd. Method
DHJCx
DHJCy
DHJCz
DHJCd
Bell et al. (1990) 22.5(8.5) 3.4(7.8) 1.4(6.9) 12.5(6.4) Seidel et al. (1995) 0.3(5.1) 2 0.1(5.6) 1.4(6.9) 9.2(4.5) Seidel revised 0.1(5.1) 0.45(5.6) 0.1(6.9) 9.2(4.4) Present work 0.1(3.8) 0.2(3.8,) 0.3(4.5) 6.5(2.4) Notes: All the coordinates are transfered to LCS1 (O1X1Y1Z1) for comparison. Revised Seidel’s method is the modified version of Seidel’s method with the ratios based on the data of this study.
Figure 1. Main ALs and definition of the two pelvis LCS: O1X1Y1Z1 used in this article and O2X2Y2Z2 defined by Seidel et al. (1995). LCS1 has the same definition as recommended by the International Society of Biomechanics, but with origin at the midpoint between RIAS and LIAS and Y1 being normal to the plane RIAS–LIAS–IPS. IPS is the mid-point between RIPS and LIPS. In LCS2, the frontal plane is defined by RIAS, LIAS and IPJ.
Three regression coefficients were calculated by the least square fitting: kx ¼ 57.6%, ky ¼ 52.5% and kz ¼ 52.6%. Note that they are slightly different from the average ratios. 3.
Results and discussion
Table 2 compares the results by the regression equations proposed in this study with those by Seidel et al. (1995) and Bell et al. (1990). Clearly, the smallest error in HJC location
was obtained by the proposed method with an average error of 6.5 mm. For comparison, the ratios defined by Seidel et al. were also calculated using the data of this study and given in Table 1. Note that Seidel et al. used a different pelvis LCS (O2X2Y2Z2 in Figure 1). The ratios in the x, y and z from our data are very close to Seidel’s ratios. Seidel’s method gave a better prediction than Bell’s method. 4.
Conclusions
In this study, we suggested the use of ALs of the ischial tuberosity of the ilium (IIT) and anterior superior illac spine for locating HJC. Corresponding regression equations were obtained from 48 cadaveric specimens. Results showed that the proposed method gave a better prediction of HJCs than Bell’s and Seidel’s methods. The proposed method requires the location of R(L)IIT with the help of a position-calibrated pressure map, implying that subjects have to keep an erect torso posture sitting on a hard surface. Therfore, their measuremnt may be affected by siting posture variation, in particular along the
Computer Methods in Biomechanics and Biomedical Engineering anterior –posterior direction. A further investigation is needed for checking the accuracy of locating R(L)IIT using a pressure map.
References
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Bell AL, Pedersen DR, Brand RA. 1990. A comparison of the accuracy of several hip center location prediction methods. J Biomech. 23:617– 621.
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Bull J, Beurier G, Wang X, Compigne S. 2012. Comparing hip joint centre location methods in an automotive driving position. Int J Hum Factors Model Simul. 3:294– 311. Bush TR, Gutowski PE. 2003. An approach for hip joint center calculation for use in seated postures. J Biomech. 36:1739 – 1743. Seidel GK, Marchinda DM, Dijkers M, Soutas-Little RW. 1995. Hip joint center location from palpable bony landmarks – a cadaver study. J Biomech. 28:995– 998.
