The Central Sensitization Inventory (CSI) was used to assess symptoms of central sensitization. CSI was developed as a tool to evaluate somatic and emotional complaints associated with central sensitization syndrome. The CSI consists of 25 questions and can be divided in four sections that focus on physical symptoms, emotional distress, headache and jaw symptoms and urological symptoms (Mayer et al. 2012). Each question is answered on a 0-4 scale by choosing the intensity that best describes their symptoms or emotions. The individual answers are added to form a total score that can range from 0 to 100.

The Numerical Rating Scale (NRS) was used to assess pain intensity. NRS has been widely used to measure and assess pain levels in adults, including chronic pain patients (Hawker et al. 2011). The scale consists of a segmented numeric version of the Visual Analog Scale (VAS) in which subjects choose a number (0-10) that best describes their pain intensity.

Pain catastrophizing was assessed by the Pain Catastrophizing Scale (PCS). PCS was created in an effort to measure inability to cope with pain due to catastrophizing. The scale was developed on the construct that catastrophizing involves three subsequent dimensions, rumination, magnification and helplessness (Craner et al. 2016). It is a self-report questionnaire which includes 13 items about the above three dimensions of pain catastrophizing. Every item is answered on a Likert scale ranging from 0 to 4. A final total score will range between 0 and 52 points with minimal detectable change being 9 points.

Kinesiophobia was assessed using the Tampa Scale for Kinesiophobia (TSK). TSK is a questionnaire which consists of 17 questions and is used to assess fear of movement and re injury. The questions are answered by choosing the statement that most accurately represents the subjects state, these answers vary from "strongly agree" to "strongly disagree". The final score of the questionnaire will range from 17-68 and is made up by scoring each answer in a Likert scale (Lundberg et al. 2011).

Anterior Cruciate Ligament - Return to Sport after Injury (ACL-RSI) questionnaire was used to assess willingness and ability to return to play. The ACl-RSI scale focuses on three main psychosocial areas, emotions, confidence and risk appraisal, that can affect willingness and ability to return to sport safely. The scale has high internal consistency, Cronbach's alpha 0.96 and inter-item correlations were high with a mean of 0.69 (min 0.49, max 0.83) (Webster et al. 2008). The ACL-RSI consists of a unidimensional 12-question scale that measures the three psychosocial domains mentioned above, 5 questions focus on emotions, 5 on confidence in performance and 2 on risk appraisal. The questions are answered on a scale from 0 to 100 in 10-point increments and the total score is represented by the mean total of the answers' given (Webster et al. 2008).