Frozen shoulder (also known as adhesive capsulitis) is a painful condition that affects the shoulder joint. This is a painful condition in which the movement of the shoulder becomes limited. Normally, the soft tissue surrounding the shoulder joint (capsule) is usually stretchy and elastic allowing joint mobility. Frozen shoulder occurs when the capsule around the shoulder joint becomes thickened and inflamed, causing pain, stiffness and reduced range of motion. This painful stiffening over time leads to sleep disturbance and limits ability to use arm in day-to-day activities.

Kinesiophobia (fear of movement) defined as "an excessive, irrational, and debilitating fear of physical movement and activity resulting from a feeling of vulnerability due to painful injury or reinjury" is an important psychological factor in musculoskeletal disorders. Kinesiophobia has been implicated in the transition from acute to chronic pain and in the persistence of pain-related disability even after tissue healing.

The goal of this observational study is to investigate the relationship between kinesiophobia and pain, range of motion, disability, and quality of life in patients with adhesive capsulitis.Participants in the study will only undergo a physical examination and complete some questionnaires; no invasive procedures will be performed.

Adhesive capsulitis is a common shoulder disorder characterized by pain and progressive restriction of both active and passive range of motion, leading to substantial limitations in activities of daily living, occupational performance, and leisure activities. It most frequently affects middle-aged individuals and is more prevalent in women.

Clinically, patients with adhesive capsulitis present with shoulder pain and progressive stiffness. Functional limitations typically include difficulty performing overhead activities and tasks requiring hand-behind-the-back movements, which significantly impair quality of life. Although restriction occurs in all planes of shoulder motion, passive external rotation is generally the most limited, followed by abduction and internal rotation.

The exact etiopathogenesis of adhesive capsulitis remains unclear; however, it is widely accepted that the pathological process primarily involves the joint capsule, particularly the coracohumeral ligament and the anterior-superior capsule. Chronic inflammation, possibly triggered by autoimmune mechanisms, infectious agents, or biochemical mediators, is thought to initiate the process. Subsequent fibroblastic proliferation, collagen deposition, capsular thickening, fibrosis, and adhesion formation lead to restricted joint mobility. In addition to these biological mechanisms, psychological factors have also been suggested to contribute to the development and persistence of adhesive capsulitis.

Kinesiophobia, defined as an excessive, irrational, and debilitating fear of movement due to the expectation of pain or re-injury, is an important psychological factor in musculoskeletal disorders. It is commonly associated with avoidance behaviors and hypervigilance. Kinesiophobia has been implicated in the transition from acute to chronic pain and in the persistence of pain-related disability even after tissue healing. Consequently, higher levels of kinesiophobia have been associated with increased pain intensity, greater disability, reduced range of motion, and poorer quality of life in individuals with chronic musculoskeletal conditions.

Although the relationship between kinesiophobia and clinical outcomes has been extensively studied in various musculoskeletal disorders, evidence in shoulder pathologies remains limited. Previous studies have reported significant associations between kinesiophobia and pain, disability, and functional limitations. For example, Mintken et al. demonstrated a strong relationship between elevated kinesiophobia levels and increased pain and disability. Similarly, Luque-Suarez et al. reported that higher kinesiophobia levels were associated with greater pain intensity and disability. Another study involving 85 patients found that increased kinesiophobia was linked to poorer upper extremity function and higher pain levels.

Understanding the relationship between kinesiophobia and clinical as well as sociodemographic factors in patients with adhesive capsulitis may contribute to improved prognostic evaluation and more effective clinical decision-making. Therefore, the aim of this study was to investigate the relationship between kinesiophobia and pain, range of motion, disability, and quality of life in patients with adhesive capsulitis.

Inclusion Criteria:

• Age between 18 and 65 years
• Clinical diagnosis of adhesive capsulitis according to Vermeulen criteria, defined as ≥50% loss of passive range of motion in at least one of the following planes compared to the contralateral side: abduction, flexion, or external rotation in abduction
• Ability to understand and complete questionnaires Exclusion Criteria
• Presence of other orthopedic, rheumatologic, neurological, or malignant conditions affecting the shoulder
• History of shoulder trauma, fracture, dislocation, or surgery
• Full-thickness rotator cuff tear (e.g., positive drop arm test, significant weakness)
• Cervical radiculopathy or thoracic outlet syndrome
• Receipt of intra-articular injection, physical therapy, or other shoulder treatments within the previous 6 months
• Cognitive impairment or psychiatric/neurological disorders affecting comprehension

Outpatient clinic of the Department of Physical Medicine and Rehabilitation at Necmettin Erbakan University Faculty of Medicine in Konya