Microstructural analysis on the innervation of the anterior, medial, and lateral human hip capsule: Preliminary evidence on its neuromechanical contribution

Joanna C L Tomlinson; Johann Zwirner; Dorothy E Oorschot; Markus Morawski; Benjamin Ondruschka; Ming Zhang; Niels Hammer

doi:10.1016/j.joca.2023.07.009

Microstructural analysis on the innervation of the anterior, medial, and lateral human hip capsule: Preliminary evidence on its neuromechanical contribution

Osteoarthritis Cartilage. 2023 Nov;31(11):1469-1480. doi: 10.1016/j.joca.2023.07.009. Epub 2023 Aug 12.

Authors

Joanna C L Tomlinson¹, Johann Zwirner², Dorothy E Oorschot³, Markus Morawski⁴, Benjamin Ondruschka⁵, Ming Zhang³, Niels Hammer⁶

Affiliations

¹ School of Anatomy, University of Bristol, Bristol, United Kingdom; Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, Otago, New Zealand. Electronic address: jcltomlinson@hotmail.co.uk.
² Institute of Legal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Oral Sciences, University of Otago, Dunedin, Otago, New Zealand.
³ Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, Otago, New Zealand.
⁴ Paul Flechsig Institute for Brain Research, Medical Faculty, University of Leipzig, Leipzig, Saxony, Germany.
⁵ Institute of Legal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
⁶ Division of Macroscopic and Clinical Anatomy, Gottfried Schatz Research Center, Medical University of Graz, Graz, Styria, Austria; Division of Biomechatronics, Fraunhofer Institute for Machine Tools and Forming Technology (Fraunhofer IWU), Dresden, Saxony, Germany; Department of Orthopaedic and Trauma Surgery, University of Leipzig, Germany.

PMID: 37574111
DOI: 10.1016/j.joca.2023.07.009

Abstract

Objective: Capsular repair aims to minimize damage to the hip joint capsular complex (HJCC) and subsequent dislocation risk following total hip arthroplasty (THA). Numerous explanations for its success have been advocated, including neuromuscular feedback loops originating from within the intact HJCC. This research investigates the hypothesis that the HJCC contributes to hip joint stability by analyzing HJCC innervation.

Method: Twenty-nine samples from the anterior, medial, and lateral aspects of the midportion HJCC of 29 individuals were investigated stereologically and immunohistochemically to identify encapsulated mechanoreceptors according to a modified Freeman and Wyke classification, totaling 11,745 sections. Consecutive slices were observed to determine the nerve course within the HJCC.

Results: Few encapsulated mechanoreceptors were found in the HJCC subregions and overlying tissues across the cohort studied. Of regions studied, no significant regional differences in the density of mechanoreceptors were found. No significant difference in mechanoreceptor density was found between sides (left, 10.2×10^-4/mm³, 4.0×10^-4 - 19.0×10^-4/mm³; right 12.9×10^-4/mm³, 5.0×10^-4 - 22.0×10^-4/mm³; mean, 95% confidence intervals) sexes (female 10.4×10^-4/mm³, 4.0×10^-4 - 18.0×10^-4/mm³; male 11.6×10^-4/mm³, 5.0×10^-4 - 20.0×10^-4/mm³; mean, 95% confidence intervals), nor in correlation with age demographics. Myelinated nerves coursed consistently within the HJCC in various orientations.

Conclusion: Sparse mechanoreceptor density suggests that the HJCC contributes to a limited extent to hip joint stabilization. HJCC nerve terminals may potentially contribute to neuromuscular feedback loops with associated muscles to mediate joint stability in tandem with the active and passive components of the joint.

Keywords: Capsular repair; Hip joint; Immunohistochemistry; Neuromechanics; Stability; Total hip arthroplasty.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Arthroplasty, Replacement, Hip*
Female
Hip Dislocation* / surgery
Hip Joint
Humans
Joint Capsule
Joint Dislocations*
Male