Knee injury and Osteoarthritis Outcome Score (KOOS) for symptoms and stiffness. 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 Injury and Osteoarthritis Outcome Score - Physical Function Short Form (KOOS-PS). 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 score of 28 (based on 7 questions) indicates extreme difficulties.

Knee injury and Osteoarthritis Outcome Score (KOOS) for function in daily living, sports, and recreational activities: Patients are asked to rate their knee function in daily living, sports, and recreational activities using a standard 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 injury and Osteoarthritis Outcome Score (KOOS) for quality of life. 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.

Patellar Tap/Ballottement Test. Patients are evaluated for knee effusion while lying supine on an examination table. The assessor applies downward strokes from the thigh to the leg with the non-dominant hand and then grasps the upper portion of the knee just above the patella. Using two fingers of the dominant hand they press the patella against the femur in a posterior direction. A positive test result for knee effusion is indicated by increased patellar waving or a spongy joint sensation. The test is then repeated on the opposite knee for comparison.

Hand-held Goniometry (HHG): Passive knee extension and flexion range of motion are measured using a long-arm goniometer. The goniometer axis is placed at the lateral epicondyle of the femur. The proximal arm is placed alongside the lateral midline of the femur, using the greater trochanter as a reference, while the distal arm is placed alongside the lateral midline of the fibula, using the lateral malleolus and fibular head as references. Passive knee flexion: the patient lies in a supine position on the table with the lower limbs in an anatomical position. The assessor flexes the knee by sliding the patient's foot along the table towards the pelvis and then taking the passive range of motion measurement. Passive knee extension: the patient lies in a supine position on the table with a towel under the ankle with the knee extended as far as possible. The assessor provides added pressure to the knee in the direction of extension and then takes the passive range of motion measurement.

Hand-held Goniometry (HHG): The length of the knee flexors and extensors muscles is measured with a long-arm goniometer. The goniometer axis placed at the lateral epicondyle of the femur. For the flexor muscle length, the patient lies in a prone position with both hips of the lower extremity extended on the table, and the knee to be tested moves to maximal achieved flexion, and the measurement of knee flexion is taken (test side). For the extensors length, the patient lies in a supine position with the hip of the lower extremity to be measured in 90 degrees of flexion on the table. While the assessor helps to maintain the hip position, the patient executes a knee extension, and the measurement of knee flexion is taken (test side).

Hand-held Dynamometry (HHD): The microFET®2 is used to measure the isometric strength of the hamstrings and quadriceps in patients. This measurement is taken on both knees to allow for comparison. The patient is seated with their hips and knees flexed at a 90-degree angle on an examination table. The assessor stabilizes the patient's leg using the leg of the examination table as support for the hand-held dynamometer. The patient is then instructed to apply maximum force against the device. First, the patient is asked to try to extend the knee, and then they are asked to flex the knee. Three repetitions are performed for both extension and flexion.

Pain Catastrophizing Scale (PCS): 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", to 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.

Depression Anxiety Stress Scales (DASS-21) short-form: Patients use a standard 4-point Likert scale. 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 time", and 3 for "applied to me very much or most of the time"). Cut-off scores determine the severity. 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. For stress, based on 7 items, 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.

Patients are instructed to stand on the leg being tested, hop, and then land on the same limb, jumping as far as possible. The distance hopped is measured at the level of the great toe and recorded to the nearest centimetre using a standard measuring tape that is fixed to the floor. Both lower limbs are evaluated for comparison.

Stair Climbing (SC) test: Patients will be timed as they ascend and descend a flight of 12 stairs as quickly as possible. The number of steps they perform in 30-second intervals will also be counted.

Minimal Clinically Important Difference (MCID): The patients will be asked about their opinion on the minimum change in PROM scores that would show a meaningful improvement in their condition. We will use an anchor-based technique to determine the MCID.