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An Anatomical Study of Nerves at Risk During Minimally Invasive Hallux Valgus Surgery
15:04

An Anatomical Study of Nerves at Risk During Minimally Invasive Hallux Valgus Surgery

Published on: February 17, 2018

Joint capsule pathology as a contributor to pain in hallux valgus: a histological study

Saori Ishibashi1, Tomoyuki Nakasa2, Yasunari Ikuta1

  • 1Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi Minamiku, Hiroshima City, 734-8551, Hiroshima, Japan.

Scientific Reports
|June 10, 2026
PubMed

Insights

Pain in hallux valgus (HV) is linked to calcitonin gene-related peptide (CGRP) expression in the medial capsule, not just deformity severity. Higher CGRP levels correlate with less pain, suggesting CGRP as a potential therapeutic target for bunion pain.

Area of Science:

  • Orthopedics
  • Molecular Biology
  • Pain Research

Background:

  • Hallux valgus (HV) pain often originates from the first metatarsophalangeal (MTP) joint's medial aspect.
  • The precise mechanisms driving this pain, particularly within the medial capsule (MC), remain incompletely understood.

Purpose of the Study:

  • To investigate the histological and molecular characteristics of the hallux valgus medial capsule.
  • To determine the association between these features and the severity of pain experienced by patients.

Main Methods:

  • Histological and immunohistochemical analysis of the medial capsule from 50 feet of 49 HV patients undergoing surgery.
  • Evaluation of calcitonin gene-related peptide (CGRP), matrix metalloproteinase-3 (MMP3), and collagen types I/III.
  • Correlation of capsular degeneration scores and CGRP expression with pain severity assessed by the Self-Administered Foot Evaluation Questionnaire (SAFE-Q).

Main Results:

  • Medial capsule degeneration severity correlated significantly with hallux valgus deformity severity.
  • CGRP expression was notably high around vessels and chondrocyte-like cells within the MC.
  • CGRP levels showed a positive correlation with MMP3 and a negative correlation with pain scores, with higher CGRP in feet exhibiting bunion tenderness.

Conclusions:

  • Bunion pain in hallux valgus appears more strongly associated with CGRP expression than with the degree of skeletal deformity.
  • Calcitonin gene-related peptide (CGRP) emerges as a significant factor in hallux valgus pain mechanisms.
  • CGRP represents a promising molecular target for future therapeutic interventions aimed at alleviating pain in hallux valgus patients.

Keywords:
CGRPChondrocytesHallux valgusMMP3Medial capsule

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