Participants were randomly divided into two arms. Participants in the activate comparator group will be administered traditional physiotherapy approaches applied after obstetric brachial plexus injury by the researcher physiotherapist.

Participants included in the motor imagery group through randomization will receive a progressive motor imagery approach in addition to the conventional physiotherapy treatment received by the first group. All applications are performed by the same physiotherapist.

All subjects to be included in our study were evaluated before and after treatment by a physiotherapist acting as a blinded evaluator. In the treatment, conventional physiotherapy approaches are applied twice a week for 8 weeks by the physiotherapist conducting the thesis study. In parallel with the initial evaluation, an individualized conventional physiotherapy program is created according to the functional status of the children and the severity and type of the affected area.

The main topics of this program consist of the following: Normal range of motion exercises for shoulder, elbow, wrist and fingers, strengthening exercises for scapulothoracic, shoulder, elbow, hand-wrist joints in all directions, stretching exercises for shoulder, elbow, wrist, fingers (to be selected depending on the patient's involvement), scapulothoracic mobilization, glenohumeral mobilization and elbow according to possible limitations, hand-wrist joint mobilization techniques (myofascial release, gliding

The modified Mallet classification is one of the valid and reliable scales frequently used in the literature to determine the functional status of the extremity in cases with brachial plexus lesions. This classification system aims to evaluate the global characteristics of the extremity rather than evaluating the functions of individual muscles. In this system, the extremity's global abduction, global external rotation, and the adequacy of the hand reaching the neck, mouth and back to the spine are evaluated. A score between 0 and 5 is made according to the position and degree of strain during each movement. The maximum score that can be obtained is 25, and the score obtained gives an idea about the functional status of the extremity.

Prepared by the Brachial Plexus Clinic of The Hospital for Sick Children (Toronto). In the OBPY group, the affected upper extremity was evaluated with 15 joint movements (from the shoulder to the fingers) specified on the scale. The movement is first examined in the position where gravity is eliminated, and if a full score is obtained, it is evaluated in the position against gravity and a score between (0-7) is given.

QUEST is a test that evaluates the child's manual skills and the quality of movement. It was developed by Prof. Dr. Carol De MATTEO for use in the 18-month-8 age group. Later, the validity and reliability study of this test was conducted for 4-12 age groups. There are studies in the literature regarding its use in children between the ages of 2-15. The sections of QUEST are as follows: A. Independent movements B. Grasping C. Weight bearing D. Protective extension E. Hand function rate F. Cooperation rates.

Range of motion will be assessed by measuring the range of motion of the shoulder, elbow and wrist joints with a universal goniometer. Active joint movements of the patients will be measured with a universal goniometer before and after treatment and recorded as degrees.

The Box and Block Test is a test developed to measure gross manual dexterity. It is a good indicator of the severity of upper extremity involvement in OBPY. In the study, the number of blocks collected in 60 seconds is calculated as in the original procedure of the test.