Background: The concept of "enthesis organ" allows a new look at the nature of enthesis involvement in some rheumatic and nonrheumatic systemic disorders.
Objectives: To describe the various presentations of enthesopathy in the course of systemic medical disorders using the available literature data.
Methods: Review of relevant articles from 1996 to 2006 retrieved by a Medline search utilizing the index terms "enthesis," "enthesitis," and "tendonitis." The list of articles reviewed herein is not exhaustive, with preference given, where possible, to studies and surveys over case reports as well as the most recent literature reflecting new developments on the subject.
Results: Enthesis is defined as the site of insertion of a tendon, ligament, fascia, or articular capsule into bone. Pain originating in the free nerve endings enriched entheses (enthesalgia) may represent a potential cause of chronic musculoskeletal pain in some individuals. Enthesis involvement in the disease process is well appreciated in spondyloarthropathies and in rheumatoid arthritis, though overshadowed by synovitis in the latter. Calcium deposition diseases may constitute the most significant articular cause of enthesopathies in the general population. New data may shed light on the possible pathophysiologic role of enthesopathy in the development of osteoarthritis. Various metabolic and endocrine conditions may manifest with enthesopathy features. The pathogenic mechanisms of enthesis involvement are not uniform and differ in the diverse disorders.
Conclusions: The concept of enthesopathy as a variety of syndromes in the course of many rheumatic, metabolic, and endocrine disorders should be appreciated. Exercise of a high level of suspicion toward enthesopathic involvement, and greater knowledge of enthesopathy's characteristic patterns and diagnostic possibilities, may allow better management of many patients in rheumatology practice.