October 2020

Intra- and inter-evaluator reliability of the MyotonPRO for the assessment of the viscoelastic properties of caesarean section scar and unscarred skin

Authors: Isabelle Gilbert 1, 2, Nathalie Gaudreault 1, Isabelle Gaboury 2


  1. School of Rehabilitation, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
  2. Department of Family Medicine and Emergency Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada

Journal: Skin Research & Technology - May 2021, Volume27, Issue 3, Pages 370-375 (DOI: 10.1111/srt.12956)

  • The MyotonPRO is a reliable and objective tool to measure the viscoelastic properties of Caesarean section scars before and after treatment.
  • The MyotonPRO tool can discriminate between the viscoelastic properties of C-Section scar and unscarrred skin.
  • The MyotonPRO is a tool can be used for research purposes to explore the association of viscoelstic properties of scars with clinical signs and symptoms.

Background: The clinical evaluation of viscoelastic properties of the Caesarean section (C-section) scar, such as stiffness and elasticity, is usually carried out using subjective scales and palpation techniques. There is currently no reliable and valid tool that objectively quantifies these properties. The MyotonPRO could fill this gap.

Materials and methods: Nineteen healthy women aged between 21 and 40 years with C-section scars participated in this reliability study. Two points, one on the scar and one on unscarred skin, were measured four times successively with the MyotonPRO by three independent evaluators on the same day. The intra-class correlation (ICC) coefficients were estimated using a two-factor ANOVA to determine the inter- and intra-rater reliability. The capacity of the MyotonPRO to discriminate the viscoelastic properties of the C-Section scar against unscarred skin was assessed using the Wilcoxon signed-rank test.

Results: The intra- and inter-rater reliability of the viscoelastic property measurements was good to excellent (ICC 0.99-1.00 and 0.87-0.98, respectively). There was no significant difference between C-section scar and unscarred skin in terms of elasticity (P = .737). Significant differences between C-section scars and unscarred skin tissue were observed for tone (P < .001), stiffness (P < .001), creep (P < .001), and mechanical stress relaxation time (P < .001).

Conclusion: The MyotonPRO is a reliable tool for an objective measurement of the viscoelastic properties of the C-section scar and unscarred skin. The MyotonPRO can discriminate the viscoelastic properties of the C-section scar against the unscarred skin, for tone, stiffness, creep and relaxation times, but not for elasticity.


Keywords: Caesarean section scars, reliability, skin, viscoelastic properties

The MyotonPRO is a portable and reliable tool for measuring the viscoelastic properties of healthy skin and Caesarean section scars. This study fills a gap in providing evidence to support the use of this tool to evaluate the potential effects of interventions proposed to treat C-section scars complications. Further studies should investigate whether there is a correlation between viscoelastic properties and clinical manifestations like pain.