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. 2022 Jul;31(7):1879-1888.
doi: 10.1007/s00586-022-07235-6. Epub 2022 May 27.

Muscle spindles of the multifidus muscle undergo structural change after intervertebral disc degeneration

Gregory James  1 , Carla Stecco  2 , Linda Blomster  1 , Leanne Hall  1 , Annina B Schmid  1   3 , Cindy C Shu  4 , Christopher B Little  4 , James Melrose  4   5 , Paul W Hodges  6   7
Affiliations

Muscle spindles of the multifidus muscle undergo structural change after intervertebral disc degeneration

Gregory James et al. Eur Spine J. 2022 Jul.

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.

Keywords: Connective tissue; Intervertebral disc degeneration; Multifidus; Muscle spindle; Proprioception.

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Conflict of interest statement

Conflict interest The authors have no competing interests to declare that are relevant to the content of this article.

Figures

Fig. 1
Fig. 1. Methods for quantification of muscle spindle parameters.
a shows features of an equatorial spindle and associated measures of spindle cross-sectional area (CSA) and capsule thickness at eight equidistant locations. The boundary used for quantification of surrounding muscle and connective tissue (two times CSA of muscle spindle is shown. b shows features of a polar spindle with no nuclear chain fibers and narrowed ends of nuclear bag fibers
Fig. 2
Fig. 2. Location of muscle spindles. The multifidus muscle was divided into 3 regions in the dorsolateral and 3 regions in the mediolateral dimension.
a and b show the proportion of muscle spindles in each of the regions for the control and IVD degeneration groups in sections with Van Gieson’s staining. c and d show the proportions in each third in the dorsolateral and mediolateral axes. There was no difference between groups in any location measure. D—dorsal; V—ventral; M—medial; L—lateral; IVD—intervertebral disc
Fig. 3
Fig. 3. Location of muscle spindles in each muscle sample.
Data are shown for all animals in the (a) control and (b) intervertebral disc (IVD) degeneration groups. Using Van Gieson’s stain connective tissue elements are pink and muscle is orange. D—dorsal; V—ventral; M—medial; L—lateral; Black star—single spindle; Blue star—compound spindle
Fig. 4
Fig. 4
Location of muscles spindles relative to connective tissue for representative animals in the (a) control and (b) intervertebral disc (IVD) degeneration groups. Using Van Gieson’s stain connective tissue elements are pink and muscle is orange. The left panels show the location of each numbered spindle or cluster of spindles and the right panel shows each at higher magnification. Note the close proximity of most spindles to dense connective tissue in the muscle. D—dorsal; V—ventral; M—medial; L—lateral; IVD—intervertebral disc. Calibration—150 μm
Fig. 5
Fig. 5
Number and cross-sectional area of intrafusal fibers for muscle spindles in control and (b) intervertebral disc degeneration (IVD degen.) groups. Data are shown for (a) and (c) nuclear bag and (b) and (d) nuclear chain fibers
Fig. 6
Fig. 6. Connective tissue, capsule collagen and surrounding tissue measures.
Data are shown for control and intervertebral disc (IVD) degeneration groups. a Connective tissue thickness averaged over measures and eight equidistant sites. b Muscle spindle capsule thickness. c Muscle tissue and d connective tissue proportion surrounding the muscle spindles. e Collagen I expression. f Collagen II expression. IVD—intervertebral disc
Fig. 7
Fig. 7. Collagen I (blue) and collagen III (red) staining of muscle spindle capsules.
Images are shown for representative animals from the control (a and b) and intervertebral disc (IVD) degeneration (c and d) groups. The dashed lines delineate the inner and outer border of the connective tissue capsule. The boxed regions in (a to d) are magnified in (e to h) Calibration—50 μm
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References

    1. Hoy D, March L, Brooks P, Blyth F, Woolf A, Bain C, Williams G, Smith E, Vos T, Barendregt J, Murray C, et al. The global burden of low back pain: estimates from the Global Burden of Disease 2010 study. Ann Rheum Dis. 2014;73:968–974. doi: 10.1136/annrheumdis-2013-204428. - DOI - PubMed
    1. Hodges PW, James G, Blomster L, Hall L, Schmid A, Shu C, Little C, Melrose J. Multifidus muscle changes after back injury are characterized by structural remodeling of muscle, adipose and connective tissue, but not muscle atrophy: Molecular and morphological evidence. Spine (Phila Pa 1976) 2015;40:1057–1071. doi: 10.1097/BRS.0000000000000972. - DOI - PubMed
    1. James G, Klyne DM, Millecamps M, Stone LS, Hodges PW. ISSLS Prize in Basic science 2019: Physical activity attenuates fibrotic alterations to the multifidus muscle associated with intervertebral disc degeneration. Eur Spine J Off Publ Eur Spine Soc Eur Spinal Deform Soc Eur Sect Cerv Spine Res Soc. 2019 doi: 10.1007/s00586-019-05902-9. - DOI - PubMed
    1. Hodges P, Holm AK, Hansson T, Holm S. Rapid atrophy of the lumbar multifidus follows experimental disc or nerve root injury. Spine. 2006;31:2926–2933. doi: 10.1097/01.brs.0000248453.51165.0b. - DOI - PubMed
    1. Brown SH, Gregory DE, Carr JA, Ward SR, Masuda K, Lieber RL. ISSLS prize winner: Adaptations to the multifidus muscle in response to experimentally induced intervertebral disc degeneration. Spine (Phila Pa 1976) 2011;36:1728–1736. doi: 10.1097/BRS.0b013e318212b44b. - DOI - PubMed

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