This lecture provides an in-depth overview of enthesitis, a key clinical and imaging feature of psoriatic arthritis (PsA). It explains the pathophysiology of enthesitis, its role as a biomarker for PsA, and its association with disease activity. The lecture also reviews MRI characteristics of inflammatory enthesitis at common anatomical sites, differentiates inflammatory from degenerative changes, and introduces emerging concepts such as the enthesis organ, functional enthesitis, and ligamentitis.

Learning Objectives

• Define enthesitis and explain its role in the pathogenesis and diagnosis of psoriatic arthritis.
• Recognize the clinical significance of enthesitis, including its relationship to disease activity, risk factors, and progression to PsA.
• Identify the characteristic MRI findings of enthesitis and distinguish inflammatory from degenerative enthesopathy.
• Describe the concepts of the enthesis organ, functional enthesitis, and ligamentitis, and understand their relevance in psoriatic arthritis and spondyloarthritis.