Table 2

Patient-reported outcome measures

Outcome	Assessment tool	Procedures
Knee pain during the last 24 hours	Visual Analogue Scale16	Patients provide feedback on knee pain intensity by marking a point on a 100 mm straight horizontal line. The beginning of the line represents ‘no pain’, while the end represents the ‘worst possible pain’. A ruler measures the distance (millimetres) from 0 to the patient’s marking. A numerical value and Wong-Baker faces scale will also be presented to the patient for reference.
Knee pain during the last week	Knee Injury and Osteoarthritis Outcome Score (KOOS)22	Patients provide feedback on the severity of their knee pain using a standard 5-point Likert scale. Each response option is assigned a numerical value (0 for none, 1 for mild, 2 for moderate, 3 for severe and 4 for extreme). A score of 0 indicates no pain, while a score of 32 (based on 8 questions) indicates extreme pain.
Knee symptoms and stiffness during the last week	KOOS22	Patients are asked to rate their knee symptoms and stiffness using a standard 5-point Likert scale, with each response option assigned a numerical value (0, 1, 2, 3, 4). A score of 0 indicates total absence of symptoms, while a score of 20 (based on 5 questions) indicates constant symptoms. For knee stiffness, a score of 0 indicates total absence, while a score of 8 (based on 2 questions) indicates extreme stiffness.
Knee-related physical function during the last week	Knee Injury and Osteoarthritis Outcome Score—Physical Function Short Form23	Patients use a standard 5-point Likert scale to provide feedback on their knee-related physical function. Each response option is assigned a numerical value (0 for none, 1 for mild, 2 for moderate, 3 for severe and 4 for extreme). A score of 0 indicates no difficulties, while a 28 (based on 7 questions) indicates extreme difficulties.
Knee function (daily living, sports and recreational activities) during the last week	KOOS22	Patients are asked to rate their knee function in daily living, sports and recreational activities using a 5-point Likert scale. Each response option is given a numerical value (0 for none, 1 for mild, 2 for moderate, 3 for severe and 4 for extreme). For knee function in daily living, a score of 0 indicates no difficulties, while a score of 68 (based on 17 questions) indicates extreme difficulties. Similarly, for knee function in sports and recreational activities, a score of 0 indicates no difficulties, while a score of 20 (based on 5 questions) indicates extreme difficulties.
Knee-related quality of life during the last week	KOOS22	Patients using a standard 5-point Likert scale to provide feedback on their knee-related quality of life. Each response option is given a numerical value (0, 1, 2, 3, 4), and a raw score is determined based on their responses. A score of 0 indicates no impact, while a score of 4 (based on 4 questions) indicates extreme impact on the quality of life.
Pain catastrophising	Pain Catastrophizing Scale24	Patients are asked to provide feedback on their thoughts, feelings or perceptions related to pain using a standard 5-point Likert scale. Each response option is assigned a numerical value (0 for ‘not at all’, 1 for ‘a slight degree’, 2 for ‘moderate degree’, 3 for ‘great degree’ and 4 for ‘all the time’). A score of 0 indicates a total absence of catastrophic thinking, while a score of 52 (based on 13 questions) indicates a persistent tendency towards catastrophising thoughts about pain.
Anxiety, depression and stress during last week	Depression Anxiety Stress Scales (DASS-21) short-form25	Patients use a standard 4-point Likert scale to report their levels of depression, anxiety and stress. Each response option is assigned a numerical value (0 for ‘did not apply to me at all’, 1 for ‘applied to me to some degree or some of the time’, 2 for ‘applied to me to a considerable degree or a good part of the time’ and 3 for ‘applied to me very much or most of the time’). Cut-off scores are used to determine the severity of the patient’s condition. For depression, based on 7 items, scores of 0 to 9 are considered normal, 10 to 13 are mild, 14 to 20 are moderate, 21 to 27 are severe and 28 or higher are extremely severe. For anxiety, based on 7 items, scores of 0 to 7 are normal, 8 to 9 are mild, 10 to 14 are moderate, 15 to 19 are severe and 20 or higher are extremely severe. Based on 7 items for stress, scores of 0 to 14 are normal, 15 to 18 are mild, 19 to 25 are moderate, 26 to 33 are severe and 34 or higher are extremely severe.