Asymmetry of the active non-weightbearing foot and ankle range of motion for dorsiflexion-plantar flexion and its coupled movements in adults

Asymmetries in ankle range of motion (ROM) have been reported, but often the uninvolved limb is used as a reference in clinical practice. The study wanted to quantify the intraindividual asymmetries in dorsi-plantar flexion foot and ankle ROM and its coupled foot movements. Active triplanar nonweightbearing ROM of the foot and ankle was recorded in young healthy adults (30 male volunteers, mean age 22.8 years; 35 female volunteers, mean age 23.8 years) using an optoelectronic set-up. The sagittal plane movement (mean ROM female subjects right side 71.3 degrees, left side 71.4 degrees, P > 0.05; mean ROM male subjects right side 69 degrees , left side 68.9 degrees, P > 0.05; sex difference, P < 0.001) was coupled with frontal (mean ROM female subjects right side 16.6 degrees, left side 14.8 degrees, P > 0.05; male subjects right side 17 degrees, left side 15.3 degrees; P > 0.05; no sex difference) and horizontal (mean ROM female subjects right side 19.6 degrees, left side 18.8 degrees, P < 0.001; male subjects right side 17.6 degrees, left side 16.2 degrees, P < 0.001; sex < 0.001) plane motions. Individual fluctuating asymmetries up to 15 degrees (principal movement), and up to 29 degrees (associated movements) were measured. Overall, 20% of female and 34% of male subjects had principal plane asymmetries >5 degrees, and 50% of the subjects had asymmetries >5 degrees in the associated movements. In young adults, individual asymmetries in ankle joint complex dorsi-plantar flexion should be taken into account when using the uninvolved, contralateral limb as a reference for clinical examination.