Dancers have a high prevalence of generalized joint hypermobility — a condition in which joints can actively or passively move beyond the expected range, an Australian study shows.
The study, “The prevalence of generalized and syndromic hypermobility in elite Australian dancers,” was published in the journal Physical Therapy in Sport.
Many dancers desire increased mobility in select joints to allow for a broader range of movements. Some dancers acquire this type of mobility through many years of training, while others acquire it through traumatic or repetitive injuries, and still others possess genetic mutations that allow joint hypermobility.
Regardless of how it is obtained, the term generalized joint hypermobility (GJH) is used to refer to a person whose joints move beyond the expected range.
While aesthetically pleasing for dancers, the pros and cons of GJH to a dancer is an important debate. While it can be advantageous in terms of selection for training, GJH has been associated with an increased risk of ligament injuries, recurrent dislocations, knee and ankle effusions (swelling), and premature arthritis.
Specifically in dancers, GJH is associated with an increased likelihood of developing musculoskeletal and psychological complications, in addition to reduced physical fitness leading to earlier fatigue.
A genetic cause of hypermobility, known as joint hypermobility syndrome (JHS) or Ehlers-Danlos syndrome-hypermobility type (EDS-HT), is a disorder that affects the production of collagen — the major component of connective tissues.
Dancers diagnosed with JHS/EDS-HT may experience more dance-related injuries and longer healing times than those without the condition.
The prevalence of JHS/EDS-HT in dancers is not known. Furthermore, there is a lack of consistency in the classification of GJH and a lack of standardized criteria for the diagnosis of JHS/EDS-HT.
The most common method to assess GJH is the Beighton score. However, while extensively used, it only measures a small number of joints in a single plane of movement. Furthermore, the Beighton score weights upper limb mobility more heavily, which may invalidate its use in dancers.
The lower limb assessment scale (LLAS), which was developed and validated for lower limb-specific and generalized hypermobility assessment, may be a useful method to measure hypermobility in dancers.
Researchers in Australia set out to conduct a study to determine the prevalence of GJH and JHS/EDS-HT in a group of dancers using these diagnostic tools, and to determine which of these are most clinically applicable in identifying cases of GJH and JHS/EDS-HT.
Researchers conducted an observational cohort study that included 85 pre-professional and professional dancers from two dance institutions. The presence of JHS/EDS-HT was assessed using the Brighton and Villefranche criteria, while GJH was determined using the Beighton and LLAS scores.
Results indicated that 72% of dancers met the Beighton cut-point for GJH, meaning a score of 5 or higher out of 9 points; 38% met the LLAS cut-point for the left lower limb, meaning a score of at least 7 out of 12 points; and 42% met the LLAS cut-point for the right lower limb. This means the Beighton score classified more participants as having GJH.
The Villefranche criteria identified 84% of dancers as having JHS/EDS-HT, while the Brighton criteria identified only 31%.
Overall, the team concluded that, regardless of the criteria used, “there was a high prevalence of both GJH and JHS/EDS-HT among our cohort of elite dancers.”
Concerning the diagnostic tools used, “the Beighton score was likely to over-estimate GJH prevalence,” the researchers wrote, suggesting that “if the Beighton score is to be used in a dance population, we support increasing the cut-point to ≥ 6/9 [equal or greater than 6 out of 9 points].”