Thumb Proprioception in Hypermobile and Non-Hypermobile Adults: An Observational Study

Aims and Background Hypermobility is a common presentation in the community and is reported related to higher rates of injury and musculoskeletal pain, however the mechanism underpinning this relationship remains unclear. Poor proprioception in hypermobile joints has been proposed as a potential mechanism. This study aims to determine if there is a difference in proprioceptive acuity, as measured by joint position reproduction, in adults with generalised joint hypermobility. Design and methods A convenience sample of 26 university students and staff (mean age 29.23 years, range 18-47) were recruited, of which 12 participants displayed generalised joint hypermobility, and 14 did not. A laser light, mounted to the dominant thumb, was used to test joint position reproduction sense by pointing to targets using a unilateral active-active position reproduction protocol. Results/Findings Test reliability across a range of targets was poor to good (intraclass correlation coefficients ranged from 0.1163 to 0.7256), indicating significant variability between participants. No significant differences was found in absolute angle of error between generalised joint hypermobility and non-generalised joint hypermobility participants. For direction of error in relation to the proprioceptive targets, only 30° thumb extension above horizontal was found to be significantly different between the hypermobile and non-hypermobile groups, with hypermobile participants tending to underestimate distance to target. Age and sex were not correlated to thumb proprioception. Application and Conclusion The difference found in direction of error and tendency to underestimate angular distance may be protective against straying into possibly injurious end-ranges; however, larger studies are recommended to confirm this.