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Review
. 2021 Feb 18;22(4):2018.
doi: 10.3390/ijms22042018.

The Effects of Mechanical Scale on Neural Control and the Regulation of Joint Stability

Gil Serrancolí  1 , Cristiano Alessandro  2   3 , Matthew C Tresch  3   4   5   6
Affiliations
Review

The Effects of Mechanical Scale on Neural Control and the Regulation of Joint Stability

Gil Serrancolí et al. Int J Mol Sci. .

Abstract

Recent work has demonstrated how the size of an animal can affect neural control strategies, showing that passive viscoelastic limb properties have a significant role in determining limb movements in small animals but are less important in large animals. We extend that work to consider effects of mechanical scaling on the maintenance of joint integrity; i.e., the prevention of aberrant contact forces within joints that might lead to joint dislocation or cartilage degradation. We first performed a literature review to evaluate how properties of ligaments responsible for joint integrity scale with animal size. Although we found that the cross-sectional area of the anterior cruciate ligament generally scaled with animal size, as expected, the effects of scale on the ligament's mechanical properties were less clear, suggesting potential adaptations in passive contributions to the maintenance of joint integrity across species. We then analyzed how the neural control of joint stability is altered by body scale. We show how neural control strategies change across mechanical scales, how this scaling is affected by passive muscle properties and the cost function used to specify muscle activations, and the consequences of scaling on internal joint contact forces. This work provides insights into how scale affects the regulation of joint integrity by both passive and active processes and provides directions for studies examining how this regulation might be accomplished by neural systems.

Keywords: joint stability; ligament; mechanical scale.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Values of the cross-sectional area (CSA) of knee anterior cruciate ligament for different species from the literature. C: cow, G: goat, H: human, M: monkey, P: pony, R: rabbit, S: sheep. In red, human values (bipeds), and in blue, quadrupeds. Blue and orange lines are the best-fit least-square regressions for humans and quadrupeds.
Figure 2
Figure 2
Stiffness of the anterior cruciate ligament (ACL) versus mass for different species obtained from the literature. C: cows, D: dogs, G: goats, H: humans, M: monkeys, Pi: pigs, Po: ponies, Rab: rabbits. There are two outliers in the plot, the stiffness values of the goats and the cows. The blue line is the best-fit least-square regression for the quadrupeds.
Figure 3
Figure 3
Maximum load before rupture of the ACL versus mass for different species obtained from the literature. C: cows, D: dogs, G: goats, GP: guinea pigs, H: humans, M: monkeys, Pi: pigs, Po: ponies, Rab: rabbits, S: sheep. The blue line is the best-fit least-square regression for the quadrupeds.
Figure 4
Figure 4
Scale factors of inverse dynamic forces (blue dots) and inverse dynamic moments (green dots) with respect to the scale factors of the mass. The line and the equations are fitted from the dots. These joint moments and forces are those that must be produced in order to oppose the perturbation and maintain joint configuration and joint integrity.
Figure 5
Figure 5
Scale factors obtained for rectus femoris (RF), vastus lateralis (VL), vastus medialis (CM), biceps femoris (BF), and semitendinosus (ST). These muscles are illustrated since they reflect the main muscles acting at the knee joint in these simulations. The scale factors are obtained by dividing the maximum values of the variables through the trial by the maximum value at the lowest scale. Note that all scale factors start with a value of 1. The variables analyzed are: (a) muscle activations, (b) knee joint moments produced by each muscle, (c) muscle contribution to the knee joint moment, calculated as a fraction of the total knee joint moment, (d) knee contact forces in x, y, and z directions. b is the exponent of the fitted expression sx=smb, where sx is the scale factor of the corresponding variable. Note that parameter a used for the fits in Figure 1, Figure 2 and Figure 3 is omitted, since it is equal to 1 in each plot here because all values are expressed relative to the simulation with body mass of 100 g.
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References

    1. Minassian K., Hofstoetter U.S., Dzeladini F., Guertin P.A., Ijspeert A. The Human Central Pattern Generator for Locomotion: Does It Exist and Contribute to Walking? Neuroscientist. 2017;23:649–663. doi: 10.1177/1073858417699790. - DOI - PubMed
    1. Duysens J., Van De Crommert H.W.A.A. Neural control of locomotion; Part 1: The central pattern generator from cats to humans. Gait Posture. 1998;7:131–141. doi: 10.1016/S0966-6362(97)00042-8. - DOI - PubMed
    1. Grillner S., Manira A. El The intrinsic operation of the networks that make us locomote. Curr. Opin. Neurobiol. 2015;31:244–249. doi: 10.1016/j.conb.2015.01.003. - DOI - PubMed
    1. Kiehn O. Decoding the organization of spinal circuits that control locomotion. Nat. Rev. Neurosci. 2016;17:224–238. doi: 10.1038/nrn.2016.9. - DOI - PMC - PubMed
    1. Bikoff J.B. Interneuron diversity and function in the spinal motor system. Curr. Opin. Physiol. 2019;8:36–43. doi: 10.1016/j.cophys.2018.12.013. - DOI

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