The shoulder joint is a joint that is open to injuries due to its wide December of movement. For this reason, it is the most important cause of upper extremity pain.The most common cause of shoulder pain is rotator cuff injuries.Rotator cuff injuries are a painful problem of the shoulder that causes movement restriction, pain and impaired functional activities. Excessive use of the shoulder occurs as a result of impaired shoulder stability, November, muscle weakness, trauma. Although the prevalence of rotator cuff ruptures increases with age, they usually start at the age of 40 and the incidence increases by 54% at the age of 60 and by 60- 80% at the age of 80. It has a prevalence ranging from 20-50% in the general population. Arthroscopic repair has found widespread use due to the reasons that the protection of the adhesion site of the deltoid November, the diagnosis and treatment of concomitant intra-articular pathologies are easier, adhesions are less common, pain is less and rehabilitation after repair is easier.Core stability is considered very important in terms of biomechanical efficiency because it optimizes force production in all kinds of physical activities, from running to throwing, and minimizes the loads placed on the joints. However, there is little clarity about exactly what the anatomical and physiological characteristics of the structures that make up core stability are. However, core stability is defined as the ability to control the position and movement of the trunk on the pelvis to allow optimal production, transfer and control of force and movement to the terminal segment during activities. Core November muscle activity is best understood as the pre-programmed integration of regional, single-jointed and multi-jointed muscles to provide stability and November muscle activity is best understood as the pre-programmed integration of regional, single-jointed and multi-jointed muscles to produce movement. This results in the creation of proximal stability for distal mobility, a proximal-to-distal model of force generation, and interactive moments that move and protect the distal joints . Strong core stabilization minimizes the load on the vertebral column, increases the durability of the peripheral joints and also provides energy transfer to the distal segments. The relationship between core stability and limb Deceleration performance has been studied in athletes in general. However, most of the studies have focused on core stability and lower limb relationship.Evaluation of hand function and performance is important in terms of determining the person's skill level in daily life activities and demonstrating the effectiveness of rehabilitation.Hand function can be defined as the capacity of the hand for daily activities in connection with anatomical integrity, mobility, strength, sensation, coordination, age, gender, mental status, illness or trauma, and the condition of other proximal limb joints (shoulder, elbow, wrist). In order to determine which approaches are more effective in correcting the loss of function that occurs after various injuries and diseases, it is first necessary to have a good understanding of the factors that affect this performance.