Behavioral Indicators of Pain Representation

Movements of the center of pressure (COP) are recorded using a force plate, and the SD-COP-AP is calculated after recording and is an indicator of the postural response.

Measured by electromyography, RMS normalized to maximum voluntary contraction.

Measured by electromyography, RMS normalized to maximum voluntary contraction.

Measured by electromyography, RMS normalized to maximum voluntary contraction.

Kinesiophobia was evaluated with the Tampa Scale for Kinesiophobia (TSK), a self-administered questionnaire validated in French. The TSK measures the fear of movement and is used in various painful conditions. It includes 17 items evaluated on a 4-point Likert scale. The total score range is 17-68 and a high score indicates a greater fear of movement.

Pain was assessed with the Brief Pain Inventory (BPI), a reliable self-administered questionnaire about pain severity (4 items) and interference with daily living (7 items) validated in French. Each item is evaluated on a numerical scale from 0 to 10. A high score indicates significant pain or significant interference in daily living.

The EQ-5D-5L is a standardized questionnaire used as a measure of health-related quality of life. The first part assesses 5 dimensions (mobility, self-care, usual activities, pain/discomfort, anxiety/depression, on a five-level scale (no problem, slight problems, moderate problems, severe problems, unable to). The second part consist in a visual analogic scale about global health of the participant and provide a value from 0 to 100 with high value representing a good health.

The fear-avoidance component scale is used to measure the major fear-avoidance signs in painful conditions. It includes 20 items evaluated on a 5-point Likert scale. The total score is from 0 to 100 with 5 severity levels: 0-20 subclinical, 21-40 low, 41-60 moderate, 61-80 severe, and extreme 81-100.

Catastrophism was evaluated with the pain catastrophizing scale. It includes 13 items evaluated on a 4-point Likert scale and divided into 3 dimensions: magnification, rumination, and helplessness. A high score corresponds to a high level of catastrophism. The total score ranges from 0 to 52 with a cut-off score of 30 for a significant catastrophism level.

The Hospital Anxiety and Depression scale (HAD) includes 14 items, 7 for anxiety and 7 for depression validated in French. Each item is rated from 0 to 3 and the scores for each dimension range from 0 to 21. Cut-off scores were established with 8-10 being uncertain symptomatology and above 10 being definite symptomatology.