Menstrual Cycle Hormone Relaxin and ACL Injuries in Female Athletes: A Systematic Review

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Menstrual Cycle Hormone Relaxin and ACL Injuries in Female Athletes: A Systematic Review

Parker et al., 2024 | Iowa Orthop J | Systematic Review

Citation

Parker Emily A, Duchman Kyle R, ... Westermann Robert W. Menstrual Cycle Hormone Relaxin and ACL Injuries in Female Athletes: A Systematic Review. Iowa Orthop J. 2024;44(1):113-123

Abstract

BACKGROUND: Female athletes are at increased risk for anterior cruciate ligament (ACL) injuries. The influence of hormonal variation on female ACL injury risk remains ill-defined. Recent data suggests that the collagen-degrading menstrual hormone relaxin may cyclically impact female ACL tissue quality. This review aims to identify any correlation between menstrual relaxin peaks and rates of female ACL injury. METHODS: A systematic review was performed, utilizing the MEDLINE, EMBASE, and CINAHL databases. Included studies had to directly address relaxin/female ACL interactions. The primary outcome variable was relaxin proteolysis of the ACL, at cellular, tissue, joint, and whole-organism levels. The secondary outcome variable was any discussed method of moderating relaxin levels, and the clinical results if available. RESULTS: AllThe numerous relaxin receptors on female ACLs upregulate local collagenolysis and suppress local collagen production. Peak serum relaxin concentrations (SRC) occur during menstrual cycle days 21-24; a time phase associated with greater risk of ACL injury. Oral contraceptives (OCPs) reduce SRC, with a potential ACLprotective effect. CONCLUSION: A reasonable correlative and plausible causative relationship exists between peak relaxin levels and increased risk of ACL injury in females, and further investigation is warranted. Level of Evidence: III.

Key Findings

AllThe numerous relaxin receptors on female ACLs upregulate local collagenolysis and suppress local collagen production. Peak serum relaxin concentrations (SRC) occur during menstrual cycle days 21-24; a time phase associated with greater risk of ACL injury. Oral contraceptives (OCPs) reduce SRC, with a potential ACLprotective effect.

Outcomes Measured

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Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition See abstract

MeSH Terms

  • Humans
  • Relaxin
  • Female
  • Anterior Cruciate Ligament Injuries
  • Menstrual Cycle
  • Athletic Injuries
  • Athletes

Evidence Classification

  • Level: Systematic Review
  • Publication Types: Systematic Review, Journal Article
  • Vertical: collagen

Provenance

  • PMID: 38919370
  • DOI: (not available)
  • PMCID: PMC11195904
  • Verified: 2026-04-09 via PubMed E-utilities API

Source extracted via PubMed E-utilities API on 2026-04-09