Forearm crutches are frequently used in the rehabilitation of an injury to the lower limb, by enabling the patient to reduce or remove weight-bearing on the affected limb. Both excessive loading and unloading of the limb can slow healing or cause further damage, suggesting a need for a program of graduated weight-bearing and activity. Therefore, a patient is instructed by their physiotherapist to apply a certain fraction of their body weight through the crutch axis as they walk. Instructing patients on partial weight-bearing is a difficult task for the physiotherapist as there are currently few objective means of measuring how much weight is going through the affected lower limb. A patientâs perception of the loading on their leg is often prone to considerable error and clinicians can give only subjective feedback as a result of visual inspection.