Placing joint hypermobility in context: traits, disorders and syndromes

BACKGROUND: Joint hypermobility (JHM) is a common physical trait. It may occur alone or in combination with musculoskeletal (MSK) pain, outside or within more complex phenotypes. Hypermobility spectrum disorders (HSD) are diagnosed in individuals with JHM and related MSK pain, when an alternative diagnosis cannot be identified. Conversely, the Ehlers-Danlos syndrome (EDS) encompasses a group of rare hereditary connective tissue disorders featuring JHM along with other pleiotropic manifestations. The 2017 EDS Classification identifies 13 different subtypes. Hypermobile EDS (HEDS) is the only EDS variant still lacking a confirmatory test. SOURCES OF DATA: Literature was reviewed searching for the most relevant papers related to key arguments. Particular attention was focused on papers published after the 2017 Classification. AREAS OF AGREEMENT: Definition, epidemiology, assessment tools and patterns of JHM are presented. The morbid nature of the 2017 EDS Classification and of the ‘spectrum’ is also illustrated. AREAS OF CONTROVERSY: We discuss current limitations and disagreements concerning the ‘spectrum’, HSD and HEDS. GROWING POINTS: In the clinical context, elucidation of the pathophysiology of pain related to JHM should develop in parallel with the analysis of pleiotropic manifestations of syndromes with JHM. AREAS TIMELY FOR DEVELOPING RESEARCH: Future challenges concerning classification, nosology, diagnosis and management of JHM, EDS and related disorders are discussed.