Clinical signs in the foot that are predictors of ligamentous laxity in the adult population.

OBJECTIVES: This study evaluates the influence of ligamentous laxity on the foot from observation of clinical signs and quantification of certain joint ranges.

METHODS: The sample consisted of 400 subjects - 200 in the non-lax control group (ages 32.49 ± 11.06 years) and 200 in the lax group (ages 29.82 ± 9.41 years). The Beighton criteria were applied to each subject to diagnose laxity or non-laxity after noting their gender, age, and 2 joint ranges and 2 clinical signs for both feet. This was an observational analytical study of cases and controls, in which a multivariate binary logistic regression model was applied.

RESULTS: Extension of the first metatarsophalangeal joint (MTPJ) ≥95°, extension of the 1st toe's interphalangeal joint (IPJ) ≥14°, and the signs 1st "in the plantar footprint, marked and narrowly confined support under metatarsal heads" and 2nd "in the plantar footprint, continuity of the 1st toe to the 1st metatarsal" presented significant differences between the lax and the non-lax groups. These are usable as parameters with which to detect laxity. The Beighton criteria were confirmed as being the most appropriate for diagnosis.

CONCLUSIONS: We propose the use of 2 clinical signs that can be evaluated in plantar footprints ("1st" and "2nd") and 2 exploratory manoeuvres (extension of the first MTPJ ≥95° and extension of the 1st toe's IPJ ≥14°) as factors present in the foot which allow the detection of ligamentous laxity in the adult population, for subsequent confirmation by applying the Beighton criteria.