Measurement of isolated subtalar range of motion: a cadaver study

Fifteen fresh-frozen cadaveric lower extremities were studied to evaluate the reliability of measuring subtalar motion using a bubble inclinometer. There was high intra-observer reliability for manual inversion and eversion of the subtalar joint with the tibiotalar joint locked and unlocked. Poor correlation of radiographic and clinical measurements questioned the validity of bubble inclinometer measurements. The contribution of the tibiotalar joint to apparent subtalar motion, as measured clinically and radiographically, was found to be one-third of the arc of motion, as compared to motion measured clinically and radiographically with the tibiotalar joint locked.