Normative data for passive ankle plantarflexion--dorsiflexion flexibility.

Objective: To describe the normal distribution parameters for measures of passive ankle plantarflexion-dorsiflexion flexibility obtained from a large sample of able-bodied young adult subjects.

Design: Seven variables were assessed and descriptive analyses were conducted.

Background: While assessment of plantarflexion-dorsiflexion flexibility is an important component of a clinical examination of plantarflexion contracture, there is limited normative data available that can be used as a reference for clinical decision-making.

Methods: Data were collected from 300 able-bodied male and female subjects aged between 15 and 34 years. Both ankles were measured. Load-displacement curves were collected using a manually controlled instrumented footplate. Six variables were extracted from these curves: passive torque at zero and 10 deg, passive stiffness at zero and 10 deg, and two coefficients from an equation fitted to the curve (i.e., k and b). The seventh variable, passive dorsiflexion range of motion, was quantified using a clinical procedure.

Results: Flexibility variables did not differ between the left and right ankles, nor between the dominant and non-dominant legs. All variables were normally distributed. These distributions can, therefore, be adequately described using their mean and standard deviation values.

Conclusions: This study has substantially increased the available database on plantarflexion-dorsiflexion flexibility and forms the basis of norm-referenced clinical tests.