Enthesopathies - Mechanical, inflammatory or both?

Entheses have the challenging task of transferring biomechanical forces between tendon and bone, two tissues that differ greatly in composition and mechanical properties. Consequently, entheses are adapted to withstand these forces through continuous repair mechanisms. Locally specialized cells (mechanosensitive tenocytes) are crucial in the repair, physiologically triggering biochemical processes to maintain hemostasis. When repetitive forces cause "material fatigue," or trauma exceeds the entheses' repair capacity, structural changes occur, and patients become symptomatic. Clinical assessment of enthesopathies mainly depends on subjective reports by the patient and lacks specificity, especially in patients with central sensitization syndromes. Ultrasonography has been increasingly used to improve the diagnosis of enthesopathies. In this article, the literature on how biomechanical forces lead to entheseal inflammation, including factors contributing to differentiation into a "clinical enthesitis" state and the value of ultrasound to diagnose enthesopathies will be reviewed, as well as providing clues to overcome the pitfalls of imaging.

Enthesitis in Spondyloarthritis Including Psoriatic Arthritis-To Inject or Not To Inject?: A Narrative Review.

PURPOSE: Enthesitis is a key manifestation of psoriatic arthritis (PsA) and spondyloarthritis (SpA) and is considered to be the tissue where the disease initiates. Enthesitis leads to pain and substantial limitations in patients with PsA. Treatment is key in achieving remission or minimal disease activity. Whether it is safe to apply injections to entheseal tissue is unknown. This narrative review aimed to summarize the literature on the efficacy and tolerability of entheseal corticosteroid (CS) injections. METHODS: The published literature was searched through PubMed as well as identifying relevant articles from their citations,  for articles on the anatomic location of the injection, tissue characteristics (eg, whether there is a tendon sheath), blind versus imaging-guided and entheseal versus perientheseal injections, and related studies in animals. Given that articles on SpA are limited, those on mechanical enthesopathies were also included. FINDINGS: The literature on the efficacy and tolerability of entheseal CS injection in SpA and PsA are limited. In most articles on entheseal injection, the entheseal tissue has not actually been targeted. The decision of entheseal injection should be made on an individual basis, with consideration of the use of CS injection as the last treatment option following more conservative measures such as NSAIDs, physiotherapy, rest, and lifestyle modifications. Entheseal injection should be avoided in high-risk patients, such as those who have rupture at the enthesis. Diagnostic ultrasound is advised to ensure the presence of inflammation that can potentially benefit from corticosteroid injection, as well as the absence of rupture. In the authors' perspective, perientheseal injections should be tried before intraentheseal injections. Finally, ultrasound guidance for needle placement is strongly encouraged. IMPLICATIONS: The literature on the efficacy and tolerability of entheseal CS injection in SpA and PsA is limited. With the lack of quality data, recommendations on entheseal corticosteroid injection remain expert opinion.