Introduction: Caesarean section is one of the most common inpatient surgical procedures. Complications of obstetric wounds are estimated to account for 2.8-26.6% of cases. Between 11 and 15% of women would develop pain and discomfort following a Caesarean section. Manual therapies may be an interesting non-pharmacological approach to treating the signs and symptoms of scarring complications following a Caesarean section. However, the current literature with an in vivo perspective remains modest results for the effects of tissue physiology and their effects on pain.

Method: Using an exploratory "proof of concept" type descriptive design with before and after measurements, the immediate and 7-day effects following the application of soft tissue manual therapy on the Caesarean section scar will be evaluated. The objectives are to describe and explore differences from the effects of soft tissue manual therapy on the viscoelastic properties, pressure sensitivity and touch sensitivity of the Caesarean section scar. Thirty-eight women aged between 18 and 40 years with a Caesarean section scar who attend first-line or specialized obstetrics and perinatal clinics will be recruited.

Anticipated results This project will document the viscoelastic characteristics, pressure sensitivity and touch sensitivity of the C-section scar and surrounding unhealed tissue to improve our understanding of the plausibility of the effects of manual therapy, an approach used to treat the signs and symptoms associated with C-section scarring.

Methods of manual treatment of scars have demonstrated some effectiveness, although the effects and physiology by which mechanical forces of the therapist's hand provide benefits are poorly understood. This research will improve understanding of certain tissue characteristics and physiology elicited during treatment, and provide better conceptual explanations of the effects of manual therapies.

This study consists of 2 steps. The first step consists of the reliability of the Myoton Pro. The second step consists to describe and explore the effects of the soft tissue manual therapy on viscoelastic properties, touch sensibility and pressure sensibility on the Caesarean scar and the unscarred skin.

Objective(s)

The main objective of this project is to evaluate the effects of the application of mechanical force by the therapist's hand on the Caesarean section scar. The specific objectives are to document the following, prior to and following the application of mechanical force by the therapist's hand:

1. Determine the reliability and discrimination of the Myoton Pro.
2. The viscoelastic properties of the Caesarean section scar and surrounding healthy tissues;
3. The sensitivity of the Caesarean section scar to pressure compared with surrounding healthy tissues;
4. The touch sensitivity of the Caesarean section scar compared with surrounding healthy tissue; and
5. Differences in viscoelastic properties, pressure sensitivity and touch sensitivity before and after the independent variable.

Recruitment Recruitment will be recruited women attending primary care and specialized obstetrics and perinatal clinics in the Vaudreuil-Soulanges region, Candiac on the south shore of Montreal, Repentigny located in the Lanaudière region and community organizations with a perinatal orientation located in the Montreal region. Posters will be put up and announcements will be made on the research centre's Facebook page as well as the page dedicated to the project. Interested will be able to communicate directly with the student researcher via digital platform. A brief description of the implications will be sent using digital platform. They will then be asked if they are still interested in participating and if they agree to be contacted by the student researcher in order to verify the eligibility criteria. The student-researcher will request contact information such as email address and a valid telephone number in order to make contact. During this telephone contact, the student-researcher will explain the elements of the study, reiterate the free nature of their participation and verify the eligibility criteria. The student-researcher will then suggest an appointment.

Data collection Phase 1: Reliability of the Myoton Pro The experimental procedure will take place at the Longueuil Campus of the Université de Sherbrooke located in Longueuil. Three evaluators will perform the measurements. The investigator will call them Evaluator 1 (E1), Evaluator 2 (E2) and Evaluator 3 (E3). E1 will invite participants to lie supine on a treatment table. E1 will place a pillow under the participants' knees to reduce the lower extremity strain. They will be asked to undress their abdomen to make the scar visible. The E1 will locate a point in the centre of the scar and a healthy control point about 2 cm above the scar and identify them with an indelible black pencil. The E1 will take four measurements of each point alternately using the MyotonPro. E2 will then take four measurements at the same points using the MyotonPro using the same procedure. Finally, this procedure will be repeated by E3.

Phase 2:

The experimental procedure will take place at the AXiO sports medicine clinic in Vaudreuil-Dorion, the FDL massage therapy and osteopathy clinic located in Candiac, the Parent-aise osteopathy clinic located in Repentigny and the ENOSI osteopathy centre located in Montreal. Measurements of the dependent variables with the MyotonPro, Von Frey's algometer and microfilaments will be taken by a research assistant. She will be trained beforehand on the following elements: 1) the use of Von Frey's microfilaments, 2) the use of the algometer, 3) the use of the Myoton Pro, 4) their application on the tissue and scar points previously identified by the student researcher, 5) computer data entry. The POSAS questionnaire will be administered by the student researcher, who will explain it to the participants.

Upon their arrival, participants will be greeted by the student researcher. The student researcher will give them the consent form, reiterate the free and informed nature of the questionnaire and make sure they understand it. She will ensure that the form is signed. She will then give them the POSAS questionnaire to which will be annexed to the socio-demographic and clinical data questionnaire.

The student-researcher will invite the participants into a room and they will then lie supine on a treatment table. She will then invite the participants to undress the lower abdominal area. The student-researcher will make sure that the Caesarean section scar and the area around it are clearly visible. She will place a pillow under the participants' knees for maximum reduction of any tension surrounding the scar, which will lengthen the lower limbs.

The student-researcher will identify five points on the Caesarean scar, five points on the upper scar border, five points on the lower scar border and five additional points about 2 cm above the scar in the healthy surrounding tissue and mark them with a nontoxic pencil. She will then leave the room.

Using Von Frey's microfilaments, the research assistant will make an initial assessment of the sensitivity to touch of the five points of the Caesarean scar and the healthy tissue. Using the Myoton Pro, the research assistant will make an initial measurement of the viscoelastic properties of the healthy, scarred tissue points and the upper and lower scar edges (for a total of 20 points). Then, the research assistant will use the algometer placed perpendicularly to each identified point and will make a first measurement of pressure sensitivity on the surrounding tissue surfaces and on the Caesarean section scar (T0). In order to ensure reproducibility, 3 measurements per point will be taken before the manual technique is applied. The measurements will be recorded in the participant's file, without the knowledge of the student researcher.

The student-researcher will enter the room. She will place the glove with the force sensor on the thumb of her right hand. She will evaluate the Caesarean section scar and identify the most rigid scar areas when compression is applied. In these identified areas, the student-researcher will apply the manual therapy procedure described in the independent variable (compression + shear) section. This procedure will be applied to all identified rigid areas of the Caesarean section scar.

This procedure will take 20 minutes (approximately 2 minutes per rigid area). After this time, the student-researcher will remove the force sensor and leave the room. The research assistant will perform the evaluation of Von Frey's microfilaments, measurements of viscoelastic properties using the Myoton pro and pressure sensitivity using the algometer at the same tissue and scar points (T1). This same procedure will be performed again seven days later, before (T2) and after the procedure (T3). Following the last measurement time, a complete treatment of the scar area and surrounding tissues will be offered to the participants. Note that an anonymous code will be assigned to each participant and their information. The research assistant will collect the data using an Excel file. The data from the MyotonPro will be collected and automatically saved in a computer folder and later merged into the Excel file.

Sampling The sample of the accessible population will be drawn from a non-probabilistic convenience sample.

Sample size

Phase 1:

The sample size was determined by assuming a predetermined intra-participant standard deviation (Bland and Altman, 1996). Using Bland's formula for repeatability studies, the following parameters were considered: 1) an intra-participant standard deviation of 10%; 2) four measurements at a point on the scar and four measurements at a healthy control point two centimetres above the scar per participant and per evaluator; and 3) three evaluators. Using these parameters, the sample size required to estimate the magnitude of the 95% confidence interval of the precision estimates is 18 participants.

Phase 2:

The exploratory component of this project will provide data with respect to viscoelastic properties, and sensitivity to pressure and touch. Since to our knowledge, no study could inform the sample size calculation, the investigator assume a medium effect size with a power of 80% and a type I error of 5%. Given these assumptions, the sample size requires 32 participants. Anticipating a 10% drop-out rate, the resulting total sample size is 38 participants.

Analysis plan

Phase 1:

In order for the intraclass correlation coefficient (ICC) to be established accurately, the prerequisites of the analysis of variance (ANOVA) must be met. The normality of the observations will be checked using the Kolmogorov-Smirnov test. Using a two-factor ANOVA, the intra-participant standard deviation, repeatability coefficient and ICC will be calculated to establish intra- and inter-rater reliability.

Phase 2:

Descriptive analyses will be conducted based on socio-demographic data and the characteristics of the participants. The continuous variables, if normally distributed, will be summarized using means and standard deviation. The continuous variables, if not normally distributed, will be summarized using medians and intervals. Ordinal and discrete variables will be summarized using percentages.

With respect to the Caesarean section scar, the viscoelastic properties and sensitivity to pre- and post-pressure will be compared using a multi-level longitudinal regression model, if data is normally distributed. Otherwise, nonparametric tests will be performed. The pre- and post-intervention touch sensitivity of the Caesarean section scar will be compared using the Friedman test. A student's paired test will be used to compare POSAS, viscoelastic properties and pressure sensitivity of healthy tissues means. The Wilcoxon rank test will be used for the touch sensitivity of healthy tissues. Finally, the comparison between the Caesarean scar and healthy tissues will be made with the student's test in the case of a normal distribution of data. Otherwise, a nonparametric test will be performed.

Inclusion Criteria:

1. Woman with a caesarean section scar of 6 months or more but less than two years old
2. with one or more caesarean sections
3. between the ages of 18 and 40
4. with a Pfannenstiel or transverse caesarean section.

Exclusion Criteria:

1. one of the following pathologies: diabetes or under treatment for cancer
2. on anti-inflammatory medication at the time of data collection or they have taken this type of medication in the month prior to data collection
3. applied a product or cream to their scar on the day of data collection
4. contraindications to their skin inductions
5. had a treatment (e.g., a treatment to prevent the development of cancer)
6. undergoing treatment (e.g. laser, massage or other local intervention) for their scar in the three months prior to the data collection.