Investigation of the Relationship Between Core Muscle Strength, Balance and Dyskinesia in Patients With Unilateral Rotator Cuff Injury: Case Control Study

Grip Strength: Camry brand Digital Hand Dynamometer will be used for measurement. The measurement of hand grip strength will be made in the standard position recommended by the American Hand Therapists Association AETD; sitting position, shoulder adduction and neutral rotation, elbow 90 degrees flexion, forearm mid-rotation and support, wrist in neutral. According to the test procedure, 3 consecutive measurements will be made for hand grip strength and the averages will be recorded in kg. Pain: Visual Analog Scale will be used for pain assessment. This scale consists of a 10 cm horizontally positioned line on the page. The starting point on this line, '0', represents the patient feeling no pain, while the number '10' represents unbearable pain. The patient is asked to mark any place they want on this straight line between 0 and 10 to show the pain they have during the test. Then, the distance from the point marked by the patient to the starting point, 0, is measured with the help of a ruler and the value obtained is recorded. It will be questioned separately for rest and movement.

Core Strength: Measurements were made in 3 different positions with McGill Core Endurance Tests.

1. Trunk Flexion Test: The participant is asked to cross their hands on their chest. They are positioned on the floor with their body at 60° flexion and their knees at 90° flexion. The stopwatch is started. If there is any deterioration in their position, the stopwatch is stopped and the test is terminated. The elapsed time is recorded in seconds.
2. Side Bridge Test: The participant is asked to lie on their right side and place their foot on top of their other foot. They are asked to cross their left arm over their chest and place it on their right shoulder and rest on their right forearm and elbow. The stopwatch is started. If there is any deterioration in their position, the stopwatch is stopped and the test is terminated. The elapsed time is recorded in seconds. The same measurement is repeated for the left side.
3. Trunk Extensor Test: Participants are positioned in a prone position with their anterior superior iliac spines at the edge of the bed. Participants are asked to extend their upper bodies straight forward from the edge of the table. They are fixed on their knees with a belt. The stopwatch is started. If there is any deterioration in the position, the stopwatch is stopped and the test is terminated. The elapsed time is recorded in seconds.

Balance: Balance assessment will be performed with the Biodex Balance System (Biodex Medical Systems Inc., Shirley, New York, USA). The patient will be positioned on a platform with a screen in front of them. In our study, a rigid platform will be used and the patient will be given the appropriate position by holding on to the side bars with their hands while both feet (bare) are on the platform. The foot coordinates are determined while the patient is in the most comfortable position where they can maintain their balance. For the static postural balance measurement, patients are asked to hold the circular ring they see on the screen in the center for 20 seconds. The test is terminated after 3 measurements, each with 10 seconds of rest. Patients will repeat this measurement with their eyes open and closed.

Functionality: Functionality will be assessed with the Shoulder Pain and Disability Index (SPADI), which was developed for use in patients with shoulder pain and has been validated and reliable. Different activities are also used to assess pain and disability. It consists of 2 sections, pain and disability, and 13 questions. There are 5 questions in the pain section and 8 questions in the disability section. The score varies between 0 and 130. A high score indicates a high level of pain and disability.