Biomechanical investigation of subtalar joint action in normal and pathological gait and the modifications induced by functional orthoses
Current techniques of rearfoot alignment measurement have been reviewed and a new clinical technique of rearfoot measurement in weight bearing stance has been developed. This technique was validated by radiographic and cadaveric anthropometric studies. The relationship between a central heel bisection line and the underlying bone structure was investigated, and showed that the heel bisection line was coincident with the centre of the x-ray image of the calcaneus at its upper margin, but appeared to be skewed to the lateral side of the image of calcaneus (to 40% of its width) at its lower margin. A cadaveric study confirmed that this appearance arose as a result of a calcaneal tubercle that is larger medially than it is laterally. Reliability of rearfoot measurement was investigated and showed good repeatability (within the 0.5" resolution of the instrument) when made by an experienced podiatrist, with intratester repeatability of 0.93 and 0.95.