James, Gregory, Stecco, Carla, Blomster, Linda, Hall, Leanne, Schmid, Annina B., Shu, Cindy C., Little, Christopher B., Melrose, James, and Hodges, Paul W. (2022) Muscle spindles of the multifidus muscle undergo structural change after intervertebral disc degeneration. European Spine Journal, 31. pp. 1879-1888.

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Abstract

Purpose: Proprioceptive deficits are common in low back pain. The multifidus muscle undergoes substantial structural change after back injury, but whether muscle spindles are affected is unclear. This study investigated whether muscle spindles of the multifidus muscle are changed by intervertebral disc (IVD) degeneration in a large animal model.

Methods: IVD degeneration was induced by partial thickness annulus fibrosus lesion to the L3-4 IVD in nine sheep. Multifidus muscle tissue at L4 was harvested at six months after lesion, and from six age-/sex-matched naïve control animals. Muscle spindles were identified in Van Gieson’s-stained sections by morphology. The number, location and cross-sectional area (CSA) of spindles, the number, type and CSA of intrafusal fibers, and thickness of the spindle capsule were measured. Immunofluorescence assays examined Collagen I and III expression.

Results: Multifidus muscle spindles were located centrally in the muscle and generally near connective tissue. There were no differences in the number or location of muscle spindles after IVD degeneration and only changes in the CSA of nuclear chain fibers. The thickness of connective tissue surrounding the muscle spindle was increased as was the expression of Collagen I and III.

Conclusion: Changes to the connective tissue and collagen expression of the muscle spindle capsule are likely to impact their mechanical properties. Changes in capsule stiffness may impact the transmission of length change to muscle spindles and thus transduction of sensory information. This change in muscle spindle structure may explain some of the proprioceptive deficits identified with low back pain.

Item ID:	79186
Item Type:	Article (Research - C1)
ISSN:	1432-0932
Copyright Information:	This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funders:	National Health and Medical Research Council of Australia (NHMRC)
Projects and Grants:	NHMRC APP1091302, NKMRC APP1194937
Date Deposited:	05 Jul 2023 01:29
FoR Codes:	42 HEALTH SCIENCES > 4201 Allied health and rehabilitation science > 420106 Physiotherapy @ 50% 42 HEALTH SCIENCES > 4201 Allied health and rehabilitation science > 420109 Rehabilitation @ 50%
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