No Effect of Generalized Joint Hypermobility on Injury Risk in Elite Female Soccer Players: Response.

Authors’ Response:

We read with great interest the letter to the editor from Nicholson and Chan, including their vision on measuring generalized joint hypermobility (GJH) of the lower extremity. We thank the authors for their valuable contribution. They contest the Beighton score that we used to measure GJH in our prospective cohort study on injuries and risk factors in elite female soccer players.[1] Because injuries of the lower extremity are most frequently reported in soccer players,[4] they advise the use of a more region-specific tool to measure GJH.

In March 2017, a systematic review by Juul-Kristensen and colleagues[5] was published regarding measurement properties of clinical assessment methods for classifying GJH. They found 4 assessment procedures (Beighton score, Carter and Wilkinson, Hospital del Mar, Rotes-Querol) and 2 questionnaires (5-part questionnaire, Beighton score [self-reported]) that are used to classify GJH in children as well as adults. In total, 33 studies were included that reported on the clinimetric properties of these assessments. Only a few of these studies cited the reliability and validity of the Carter and Wilkinson (n = 1), Hospital del Mar (n = 1), and Rotes-Querol (n = 2); therefore, no conclusions could be drawn. Most studies were reported on the reliability and validity of the Beighton score and the 5-part questionnaire. Conflicting evidence was found for the reliability of the 5-part questionnaire, and studies on the validity of this questionnaire showed methodological issues. Although shortcomings were found in studies reporting on the validity of the Beighton score as well, the interrater reliability was categorized as acceptable to be used in clinical practice, provided that uniformity of the testing procedures is included in these measurements. In our prospective cohort study of elite female soccer players, the Beighton score was assessed by 1 person, a sports physician with extensive experience in performing this test. In the 2014-2015 soccer season, when our study was performed, the Beighton score was still the reference standard used in clinical practice and in epidemiologic studies.

A number of studies were recently published that reported on the clinimetric properties of physical assessments for measuring GJH.[7,8] One of these studies concerned the 12-item Lower Limb Assessment Score (LLAS),[7] as mentioned in the letter by Nicholson and Chan. Hypermobility may be located all over the body in the case of GJH; therefore, the LLAS was designed to study GJH of the lower extremity of adults. However, the LLAS was originally designed for a pediatric population[3] and was not validated for an adult population until 2017.[7]

We encourage development and validation of clinical assessments tools such as the LLAS, which concentrates on hypermobility of the lower extremity. Consequently, the LLAS tests multiple lower limb joints, whereas the Beighton score just includes a single lower extremity joint in its testing procedure. However, we assume that in cases of a positive Beighton score, more joints than those examined will probably show increased mobility owing to, among others factors, a genetic component. On the other hand, since lower extremity injuries are the most predominantly reported injuries for athletes such as soccer players4 and runners6, the LLAS may give better insight of GJH in this population.[2]

Nevertheless, when we started our study of female soccer players in 2014, the LLAS was not yet validated as a screening tool for GJH in adults. Therefore, we also assessed the individual item “knee hyperextension” of the Beighton score in relation to knee injury incidence, knowing that knee injuries are most frequently reported for female soccer players. We found that knee hyperextension had no significant effect on the incidence of knee injuries in female soccer players.

Without a doubt, further development and research on measurement properties of assessments for GJH, including physical procedures as the Beighton score or the LLAS, are necessary to make the next step in this area and to make assessment of GJH more accurate and valid.