The relationship between hallux grip force and balance in people with diabetes

Background: Diabetes accelerates the decline in muscle strength in older people and substantially increases the risk for fall and injury. Weakening of lower extremity muscles, in particular, is a strong predictor for falls, but currently there is no established method for its assessment in clinics. The paper grip test (PGT) offers a qualitative assessment of hallux plantar flexor strength and its usefulness for predicting falls has been demonstrated in non-diabetic populations. Research question: The aim of this study is to test whether the PGT can be used for a quantitative assessment of lower-extremity strength and to investigate its relationship with isometric muscle strength and balance in people with diabetes and peripheral neuropathy. Methods: Isometric muscle strength of all muscle groups of the foot-ankle was assessed using a dynamometer in sixty-nine people with diabetes and neuropathy. Postural sway and the gripping force exerted by the participants during the PGT was measured for the same participants using a plantar pressure assessment system. These measurements were repeated in regular intervals for 18 months in a longitudinal observational cohort study. Results: Cross-sectional analysis of baseline data showed that people who failed the PGT swayed more. Analysis of longitudinal data showed that increasing hallux grip force is significantly associated with reduced postural sway. No significant association was found between dynamometry-based measurements of strength and postural sway. Hallux grip force was significantly correlated to the strength of all muscle groups of the foot-ankle complex. Significance: These results indicate that hallux grip force can assess the strength of the foot-ankle muscles and could potentially be used to identify people at risk of falling. This sets the basis for the development of new screening protocols to assess weakening of the muscles of the foot-ankle and to enhance risk assessment for falls in people with diabetes and peripheral neuropathy.