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Scaling and kinematics optimisation of the scapula and thorax in upper limb musculoskeletal models.

Prinold JA, Bull AM - J Biomech (2014)

Bottom Line: These rely on thorax scaling to effectively define the scapula's path but do not consider the area underneath the scapula in scaling, and assume a fixed conoid ligament length.The scapula and clavicle kinematics are optimised with the constraint that the scapula medial border does not penetrate the thorax.This method is simulated in the UK National Shoulder Model and compared to four other methods, including the standard technique, during three pull-up techniques (n=11).

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Affiliation: Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.

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Differences between average optimised scapulothoracic rotations and measured kinematics for (a) front, (b) wide and (c) reverse configuration pull-ups using various scaling and kinematics optimisation strategies (described in Table 1), including the 95% confidence intervals of the differences. Scapulothoracic measurement errors are shown as a dashed horizontal line. These values are the average absolute error plus three SDs (note not RMS) found for each rotation in a previous study (Prinold et al., 2011). The measurement error calculated in upward rotation was 5.6° (compared to 8.4° RMS error in abduction or forward flexion in a bone-pin study: Karduna et al., 2001), the value in internal rotation was 5.8° (compared to 3.8° RMS error in Karduna et al. (2001)) and for posterior tilt 4.9° (compared to 6.2° RMS error in Karduna et al. (2001)). ⁎indicates p<0.05, ⁎⁎p<0.01, ⁎⁎⁎p<0.0001. All trials were included in the statistical analysis. The abbreviations used for the optimisation methods are described in Table 1. Additional simulations using homogeneous scaling of all segments based on segment length (including the thorax) and the FCC method constraints, found average differences across the three pull-up configurations of: 9.0±2.8° (ST posterior tilt), 9.0±2.8° (ST internal) and 9.0±2.8° (ST upward). The same values, with homogeneous scaling of all segments, but without a constrained conoid ligament length were smaller: 4.6±1.9° (ST posterior tilt), 2.2±0.7° (ST internal) and 5.5±2.3° (ST upward).
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f0010: Differences between average optimised scapulothoracic rotations and measured kinematics for (a) front, (b) wide and (c) reverse configuration pull-ups using various scaling and kinematics optimisation strategies (described in Table 1), including the 95% confidence intervals of the differences. Scapulothoracic measurement errors are shown as a dashed horizontal line. These values are the average absolute error plus three SDs (note not RMS) found for each rotation in a previous study (Prinold et al., 2011). The measurement error calculated in upward rotation was 5.6° (compared to 8.4° RMS error in abduction or forward flexion in a bone-pin study: Karduna et al., 2001), the value in internal rotation was 5.8° (compared to 3.8° RMS error in Karduna et al. (2001)) and for posterior tilt 4.9° (compared to 6.2° RMS error in Karduna et al. (2001)). ⁎indicates p<0.05, ⁎⁎p<0.01, ⁎⁎⁎p<0.0001. All trials were included in the statistical analysis. The abbreviations used for the optimisation methods are described in Table 1. Additional simulations using homogeneous scaling of all segments based on segment length (including the thorax) and the FCC method constraints, found average differences across the three pull-up configurations of: 9.0±2.8° (ST posterior tilt), 9.0±2.8° (ST internal) and 9.0±2.8° (ST upward). The same values, with homogeneous scaling of all segments, but without a constrained conoid ligament length were smaller: 4.6±1.9° (ST posterior tilt), 2.2±0.7° (ST internal) and 5.5±2.3° (ST upward).

Mentions: The effect of different optimisation parameters are compared through mean differences to measured rotations and 95% confidence intervals (C.I.) of those optimised rotations (Figs. 2 and 3). The PCC optimisation method is closest to the measured values – with significantly smaller errors in many cases. All the other methods fall outside the scapulothoracic measurement errors (Fig. 2).


Scaling and kinematics optimisation of the scapula and thorax in upper limb musculoskeletal models.

Prinold JA, Bull AM - J Biomech (2014)

Differences between average optimised scapulothoracic rotations and measured kinematics for (a) front, (b) wide and (c) reverse configuration pull-ups using various scaling and kinematics optimisation strategies (described in Table 1), including the 95% confidence intervals of the differences. Scapulothoracic measurement errors are shown as a dashed horizontal line. These values are the average absolute error plus three SDs (note not RMS) found for each rotation in a previous study (Prinold et al., 2011). The measurement error calculated in upward rotation was 5.6° (compared to 8.4° RMS error in abduction or forward flexion in a bone-pin study: Karduna et al., 2001), the value in internal rotation was 5.8° (compared to 3.8° RMS error in Karduna et al. (2001)) and for posterior tilt 4.9° (compared to 6.2° RMS error in Karduna et al. (2001)). ⁎indicates p<0.05, ⁎⁎p<0.01, ⁎⁎⁎p<0.0001. All trials were included in the statistical analysis. The abbreviations used for the optimisation methods are described in Table 1. Additional simulations using homogeneous scaling of all segments based on segment length (including the thorax) and the FCC method constraints, found average differences across the three pull-up configurations of: 9.0±2.8° (ST posterior tilt), 9.0±2.8° (ST internal) and 9.0±2.8° (ST upward). The same values, with homogeneous scaling of all segments, but without a constrained conoid ligament length were smaller: 4.6±1.9° (ST posterior tilt), 2.2±0.7° (ST internal) and 5.5±2.3° (ST upward).
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f0010: Differences between average optimised scapulothoracic rotations and measured kinematics for (a) front, (b) wide and (c) reverse configuration pull-ups using various scaling and kinematics optimisation strategies (described in Table 1), including the 95% confidence intervals of the differences. Scapulothoracic measurement errors are shown as a dashed horizontal line. These values are the average absolute error plus three SDs (note not RMS) found for each rotation in a previous study (Prinold et al., 2011). The measurement error calculated in upward rotation was 5.6° (compared to 8.4° RMS error in abduction or forward flexion in a bone-pin study: Karduna et al., 2001), the value in internal rotation was 5.8° (compared to 3.8° RMS error in Karduna et al. (2001)) and for posterior tilt 4.9° (compared to 6.2° RMS error in Karduna et al. (2001)). ⁎indicates p<0.05, ⁎⁎p<0.01, ⁎⁎⁎p<0.0001. All trials were included in the statistical analysis. The abbreviations used for the optimisation methods are described in Table 1. Additional simulations using homogeneous scaling of all segments based on segment length (including the thorax) and the FCC method constraints, found average differences across the three pull-up configurations of: 9.0±2.8° (ST posterior tilt), 9.0±2.8° (ST internal) and 9.0±2.8° (ST upward). The same values, with homogeneous scaling of all segments, but without a constrained conoid ligament length were smaller: 4.6±1.9° (ST posterior tilt), 2.2±0.7° (ST internal) and 5.5±2.3° (ST upward).
Mentions: The effect of different optimisation parameters are compared through mean differences to measured rotations and 95% confidence intervals (C.I.) of those optimised rotations (Figs. 2 and 3). The PCC optimisation method is closest to the measured values – with significantly smaller errors in many cases. All the other methods fall outside the scapulothoracic measurement errors (Fig. 2).

Bottom Line: These rely on thorax scaling to effectively define the scapula's path but do not consider the area underneath the scapula in scaling, and assume a fixed conoid ligament length.The scapula and clavicle kinematics are optimised with the constraint that the scapula medial border does not penetrate the thorax.This method is simulated in the UK National Shoulder Model and compared to four other methods, including the standard technique, during three pull-up techniques (n=11).

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.

Show MeSH
Related in: MedlinePlus