Age- and sex-related changes in children with and without generalized joint hypermobility: a two-year follow-up study

Background Joint hypermobility provides flexibility and is known to enhance motor performance but can also give rise to musculoskeletal complaints. There is evidence that young people are more flexible than older individuals, and females are more flexible than males. However, information about age- and sex-related changes in the range of motion (ROM) over time is scarce. Method This study followed 126 children over two years; their ROM was measured three times with one year between measurements. The Beighton scoring system and goniometry were used to classify the children into normal mobile, mobile and hypermobile groups. The study included 56 males and 70 females. Mean age was 7.58 (6-9years), 8.58 (7-10years), and 9.60 (8-11years) years at time points 1, 2, and 3, respectively. Results Joint hypermobility based on a Beighton score of 7-9 decreased from 25 to 13% to 6% in the last year. This was caused by a reduction of elbow and knee movement range but not by changes in finger joints or hamstring length. The pattern of decrease was very similar for boys and girls. Four children with hypermobility showed a large increase in ROM (> 10 degrees), of which 2 showed an increase in ROM at the elbow. Of the 53 children classified with normal mobility at measurement one 15 (28.3%) had one hypermobile joint (localized joint hypermobility). Conclusion Children between 6 and 11 years of age get less flexible over 2 years. Mobility changes with age are comparable in boys and girls. Children who are not classified as generalized hypermobile can still have localized hypermobility. An increase in joint mobility is exceptional and may be a warning sign.