Eighteen patients who had Paget disease were evaluated in our
gait-analysis laboratory. The results were compared with those of ten
healthy age-matched control subjects in order to quantitate the
biomechanical changes and to describe the specific patterns of walking that
occur secondary to bowing of a lower extremity. Kinetic and kinematic data
were acquired using infrared video cameras and force platforms;
electromyographic data were obtained using surface electrodes. Velocity and
cadence were decreased and stride time and double-limb support time were
increased in the patients who had Paget disease compared with the control
subjects. Frequently, the knee of the limb that was affected by Paget
disease was flexed during stance and flexed less during swing. When the
involved knee was in varus angulation it also had an increased adduction
moment, which may be related to the bowing deformity. Although the patterns
of ground-reaction force were similar in the patients and the control
subjects, the magnitudes of forces were reduced in the patients. Phasic
muscle activity was similar in the two groups.