Immunohistochemical Investigation of Mechanoreceptors Within the Injured Scapholunate Ligament

Oliver Miles; Stephen Tham; Wayne Morrison; Eugene Ek; Jason Palmer; David McCombe

doi:10.1016/j.jhsa.2023.10.002

Immunohistochemical Investigation of Mechanoreceptors Within the Injured Scapholunate Ligament

J Hand Surg Am. 2023 Dec 1:S0363-5023(23)00546-4. doi: 10.1016/j.jhsa.2023.10.002. Online ahead of print.

Authors

Oliver Miles¹, Stephen Tham², Wayne Morrison³, Eugene Ek⁴, Jason Palmer⁵, David McCombe⁶

Affiliations

¹ Plastic, Reconstructive and Hand Surgery Unit, St. Vincent's Hospital Melbourne, Fitzroy, Australia; O'Brien Institute, St. Vincent's Institute of Medical Research, Fitzroy, Australia. Electronic address: olivermiles91@gmail.com.
² Plastic, Reconstructive and Hand Surgery Unit, St. Vincent's Hospital Melbourne, Fitzroy, Australia; O'Brien Institute, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Victorian Hand Surgery Associates. St Vincent's Hospital, Fitzroy, Australia.
³ O'Brien Institute, St. Vincent's Institute of Medical Research, Fitzroy, Australia; University of Melbourne Department of Surgery, St. Vincent's Hospital, Fitzroy, Australia.
⁴ Mebourne Orthopaedic Group, Windsor, VIC, Australia.
⁵ O'Brien Institute, St. Vincent's Institute of Medical Research, Fitzroy, Australia.
⁶ O'Brien Institute, St. Vincent's Institute of Medical Research, Fitzroy, Australia; Victorian Hand Surgery Associates. St Vincent's Hospital, Fitzroy, Australia; University of Melbourne Department of Surgery, St. Vincent's Hospital, Fitzroy, Australia.

PMID: 38043032
DOI: 10.1016/j.jhsa.2023.10.002

Abstract

Purpose: Scapholunate ligaments (SLLs) play a well-established role in maintaining carpal alignment and kinematics, and are innervated with sensory mechanoreceptors located within the ligaments. They are involved in the afferent arc of dynamic wrist stability. The aim of this study was to describe the changes in these mechanoreceptor populations in injured SLLs.

Methods: Injured SLLs were collected from human wrists at the time of SLL reconstruction or limited wrist fusion, where the ligament remnants would otherwise be discarded. These specimens were formalin-fixed and paraffin-embedded for immunohistochemical analysis to identify mechanoreceptors, which were then classified by type and location within the ligament.

Results: A total of 15 ligaments were collected, with the interval from injury ranging from 39 days-20 years. Eleven ligaments were collected less than one year after injury, and four ligaments were collected two years or more after injury. A total of 66 mechanoreceptors were identified, with 50 mechanoreceptors identified in nine of the 11 specimens collected less than one year after injury. In this group, 54% of the mechanoreceptors resided in the volar subunit, 20% in the dorsal subunit, and 26% in the proximal subunit. Two of the four specimens collected two years or later after injury contained mechanoreceptors, all of which were located in the dorsal subunit. Increasing time from injury demonstrated a decline in mechanoreceptor numbers within the volar subunit.

Conclusions: Mechanoreceptors were consistently located in the SLL, particularly in the volar subunit of specimens collected less than one year after injury.

Clinical relevance: Ligament reconstruction techniques aim to primarily reconstitute the biomechanical function of the disrupted SLL; however, re-establishing the afferent proprioceptive capacity of the SLL may be a secondary objective. This suggests the need to consider the reconstruction of its volar subunit particularly in those managed within one year of injury.

Keywords: Biomechanics; Hand; Proprioception; Wrist.