Periarticular Soft Tissue Disorders: Enthesopathies, Tendinopathies, and Bursitis-Pathophysiology and Radiotherapeutic Approaches.

Periarticular soft tissue disorders, encompassing enthesopathies, tendinopathies, and bursitis, contribute substantially to musculoskeletal pain and disability, particularly in adult populations. This chapter provides a comprehensive overview of the pathophysiology, clinical manifestations, and radiotherapeutic management of major periarticular syndromes, including painful shoulder syndrome, lateral epicondylitis, greater trochanteric pain syndrome, and plantar fasciitis. We detail how these conditions often present as a continuum of overlapping pathology at the enthesis, tendon, and peri‑tendinous structures, frequently driven by repetitive microtrauma, mechanical overload, degenerative changes, and low-grade inflammation. Emphasis is placed on the clinical and imaging features distinguishing key entities such as calcific tendinitis, enthesopathies, and bursitis. Special focus is given to the role of low-dose radiotherapy (LDRT) as an effective treatment option for refractory symptoms unresponsive or contraindicated to conservative management. Contemporary practice patterns, including patient selection, target volume delineation based on imaging, and technical variations between linear accelerator and orthovoltage techniques, are discussed. Data from recent prospective and retrospective studies are summarized, demonstrating notable pain reduction rates and functional improvement with LDRT, and outlining response rates, optimal dosage regimens, timing of re-irradiation, and age-based treatment considerations. The chapter concludes with practical recommendations for integrating radiotherapy into multimodal care pathways for periarticular soft tissue disorders, underscoring its utility in symptom control and functional restoration.