An online repository of body segment parameter models wspr.io/body-segment-param/ Will Robertson, School of Mechanical Engineering, 2016 Introduction Body segment parameter estimates of mass, moment of inertia, &c., is a requirement for biomechanical analyses. Errors in parameters propagate to calculated joint moments and muscle forces [1], in some cases leading to considerable sensitivity in results to segment parameter errors [2]. However, subject-speciﬁc modelling is time- consuming and there have been few studies on the variety of extant body segment pa- rameter models. These consist originally of cadaver studies completed before the 1970s, after which time medical scanning and photo- graphic approaches began to be used in more comprehensive studies. This work collates such studies into a pub- lic repository for general use and historic interest. The repository currently contains over twenty separate body segment param- eter models in studies conducted from 1860 to 2011. Relative mass models The relative mass models provide a scaling factor for the mass of each segment relative to the total mass of the subject. The repos- itory current includes eighteen such models, brieﬂy described in Table 1. – Only whole-body models with complete analysis of masses for all major segments and divisions are included. – Trunk mass is combined from up to four subsegments for cross-model comparison. – The model closest to the mean (RMSE = 8.0%) was the male data from Pavol et al. [3], a study on an older population. – Large ranges (±30%) gives credence to the approach of subject-speciﬁc modelling. The mean segment masses from the sixteen non-juvenile studies are shown in Figure 1. Figure 1: Average mass per segment for the rela- tive mass models for adults. 7.4 % 46.6 % 3.0 % 1.6 % 0.7 % 11.9 % 4.4 % 1.5 % Figure 2: Relative masses for each segment of each model, excepting models eight and nine, which deviate signiﬁcantly from the others. -40 -30 -20 -10 0 10 20 30 40 Percentage difference from mean HEADNECK RMS = 7.5% 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 18 TRUNK RMS = 6.3% 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 18 ARM RMS = 14.6% 1 2 3 45 6 7 10 11 12 13 14 15 16 17 18 FOREARM RMS = 16.0% 1 2 3 4 56 7 10 11 12 13 14 15 16 17 18 HAND RMS = 18.8% 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 18 THIGH RMS = 13.6% 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 18 LEG RMS = 7.3% 1 2 3 4 56 7 10 1112 13 14 15 16 1718 FOOT RMS = 18.5% 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 18 A visualisation of the non-juvenile models is shown in Figure 2, in which segment mass for each is compared to the mean. A deviation of at least ±10% is seen for each segment, indi- cating a large degree of variation in diﬀerent populations and with diﬀerent techniques. Mass–height regression models The repository also includes two comprehen- sive works that deﬁne segment parameters using mass and height as regression variables [16, 17]. These works describe six models, respectively: Chinese F & M, German F & M, and Russian F & M. Each contains data for mass, centroid, and moments of inertia. Figure 3 shows variation in segment mass be- tween models, for three heights per subject. High variability (e.g., head–neck segment for model 2, Chinese M) indicates caution should be used when applying these models outside of their original subject population ranges. Table 1: Relative mass models in the repository. Ref. Name Pop. Method Sex N SDev CoM 1. Harless (1860) Cadaver M 2 2. Braune et al. (1889) Cadaver 3 3. Dempster (1955) Cadaver M 8 ◦ 4. Fujikawa (1963) Japan Cadaver 6 5. Clauser (1969) Cadaver M 13 ◦ ◦ 6. Zatsiorsky et al. (1979) Russia CT F 15 ◦ 7. Zatsiorsky et al. (1979) Young adult CT M 100 ◦ 8. Jensen (1986) 12 yr Photo M 12 9. Jensen (1989) 6 yr Photo M 8 10. Jensen (1989) 18 yr Photo M 8 11. Jensen et al. (1994) Photo F 12 ◦ 12. Jensen et al. (1994) Elderly Photo M 7 ◦ 13. Cheng et al. (2000) China MRI M 8 ◦ ◦ 14. Pavol et al. (2002) Geometric F 50 ◦ ◦ 15. Pavol et al. (2002) Older G