Use of a patella marker to improve tracking of dynamic hip rotation range of motion.

Hip rotation during gait has traditionally been measured using thigh wand markers. Hip rotation data calculated using thigh wands shows large variability between different laboratories and underestimates the rotation movement. This study investigated effectiveness of a patella marker in tracking hip rotation range of motion in comparison with traditional thigh wands. In controlled trials of isolated hip internal-external rotation, the patella marker detected 98+/-8% of the actual range of motion, compared with 53+/-10% for a distal thigh wand and 43+/-13% for a proximal thigh wand. The patella marker produced the smoothest hip rotation curves and the smallest hip rotation range in walking, and results from the patella marker did not depend on walking speed. These results suggest that the patella marker is less vulnerable to wobbling, inertial effects, and soft tissue movement than traditional thigh wands. The use of patella markers with knee alignment devices may therefore allow for more accurate measurement of hip rotations during clinical gait analysis than is currently possible using traditional thigh wands.