This prospective observational cohort study aims to investigate whether baseline central sensitization and psychological factors predict functional outcomes following rehabilitation in individuals with chronic shoulder pain. Participants with chronic shoulder pain will receive a standardized 6-week physiotherapy and rehabilitation program routinely applied in the clinic. Assessments will be performed before and after treatment, including pain severity, shoulder function, central sensitization symptoms, and psychological factors such as pain catastrophizing. The findings of this study may contribute to a better understanding of biopsychosocial factors affecting rehabilitation outcomes in chronic shoulder pain and help improve individualized rehabilitation approaches.

Chronic shoulder pain is one of the most common musculoskeletal disorders and is associated with pain, functional limitations, reduced quality of life, and work disability. Although structural abnormalities are often identified in clinical evaluation and imaging findings, the relationship between tissue pathology and symptom severity is not always clear. Therefore, factors beyond peripheral tissue damage may contribute to persistent shoulder pain and rehabilitation outcomes.

In recent years, central sensitization has become an important concept in chronic musculoskeletal pain conditions. Central sensitization refers to increased responsiveness of the central nervous system to sensory input, resulting in pain hypersensitivity and amplification of pain perception. Previous studies have demonstrated that individuals with chronic shoulder pain may present with symptoms related to central sensitization, which can negatively affect pain severity, disability, and treatment response.

Psychological factors such as pain catastrophizing, fear of movement, anxiety, and depression are also known to influence chronic pain experiences and rehabilitation outcomes. Higher levels of maladaptive psychological responses may contribute to increased pain perception, reduced treatment adherence, and poorer functional recovery. However, prospective studies evaluating the combined influence of central sensitization and psychological factors on rehabilitation outcomes in chronic shoulder pain remain limited.

This study is designed as a prospective observational cohort study. Individuals with chronic shoulder pain attending physiotherapy rehabilitation clinics will be recruited. Participants will undergo baseline assessments before treatment and follow-up assessments after a standardized 6-week rehabilitation program routinely applied in clinical practice.

The primary objective is to determine whether baseline central sensitization and psychological factors predict functional improvement following rehabilitation. The findings may contribute to a better understanding of the biopsychosocial mechanisms underlying treatment response and support the development of more individualized rehabilitation strategies for chronic shoulder pain management.

Inclusion Criteria:

• Adults aged 18 years and older
• Presence of chronic shoulder pain lasting at least 3 months
• Clinical findings consistent with shoulder-related pain
• Willingness to participate in a 6-week physiotherapy rehabilitation program
• Ability to complete study assessments and questionnaires
• Provision of written informed consent

Exclusion Criteria:

• History of shoulder surgery within the previous 6 months
• Major shoulder trauma within the previous 6 months
• Serious pathology affecting the shoulder (e.g., infection, tumor, systemic inflammatory disease)
• Neurological disorders affecting the upper extremity (e.g., cervical radiculopathy, myelopathy, peripheral nerve injury)
• Severe cognitive impairment
• Communication problems preventing participation
• Shoulder injection within the previous 4 weeks
• Pregnancy

Adults with chronic shoulder pain who are referred to physiotherapy and rehabilitation clinics and scheduled to receive a standardized 6-week physiotherapy rehabilitation program. Participants will include individuals with shoulder pain associated with conditions such as rotator cuff-related shoulder pain, subacromial pain syndrome, and adhesive capsulitis.

Individual participant data will not be publicly shared due to privacy and confidentiality considerations. De-identified data may be available from the principal investigator upon reasonable request and with appropriate ethical approval.