title: Surgical menopause initiates molecular changes that do not result in mechanical changes in normal and healing ligaments.
abstract: OBJECTIVE
  Ligaments which heal spontaneously have a healing process that is similar to skin wound healing. Menopause impairs skin wound healing and may likewise impair ligament healing. Our purpose in this study was to investigate the effect of surgical menopause on ligament healing in a rabbit medial collateral ligament model.
  
  
  METHODS
  Surgical menopause was induced with ovariohysterectomy surgery in adult female rabbits. Ligament injury was created by making a surgical gap in the midsubstance of the medial collateral ligament. Ligaments were allowed to heal for six or 14 weeks in the presence or absence of oestrogen before being compared with uninjured ligaments. Molecular assessment examined the messenger ribonucleic acid levels for collagens, proteoglycans, proteinases, hormone receptors, growth factors and inflammatory mediators. Mechanical assessments examined ligament laxity, total creep strain and failure stress.
  
  
  RESULTS
  Surgical menopause in normal medial collateral ligaments initiated molecular changes in all the categories evaluated. In early healing medial collateral ligaments, surgical menopause resulted in downregulation of specific collagens, proteinases and inflammatory mediators at 6 weeks of healing, and proteoglycans, growth factors and hormone receptors at 14 weeks of healing. Surgical menopause did not produce mechanical changes in normal or early healing medial collateral ligaments. With or without surgical menopause, healing ligaments exhibited increased total creep strain and decreased failure stress compared with uninjured ligaments.
  
  
  CONCLUSIONS
  Surgical menopause did not affect the mechanical properties of normal or early healing medial collateral ligaments in a rabbit model. The results in this preclinical model suggest that menopause may result in no further impairment to the ligament healing process. Cite this article: Bone Joint Res 2015;4:38-44.
authors.affiliation: University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta T2N 4Z6, Canada.
authors.forename: G M
authors.initials: GM
authors.lastname: Thornton
authors.affiliation: University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta T2N 4Z6, Canada.
authors.forename: C R
authors.initials: CR
authors.lastname: Reno
authors.affiliation: University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta T2N 4Z6, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Achari
authors.affiliation: University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: D W
authors.initials: DW
authors.lastname: Morck
authors.affiliation: University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta T2N 4Z6, Canada.
authors.forename: D A
authors.initials: DA
authors.lastname: Hart
keywords: Healing; Ligament; Mechanical properties; Surgical menopause; mRNA levels