Accuracy of an electromagnetic tracking device for measuring hip joint kinematics during gait: effects of metallic total hip replacement prosthesis, source-sensor distance and sensor orientation
The present study sought to investigate the effects of source-sensor distance, sensor orientation and the effects of metallic total hip replacement (THR) prostheses on the accuracy of the 3Space Tracker System (3STS). Using a simulated hip joint, the angles measured by the 3STS with six different source-sensor distances and two source-sensor orientations were recorded. Then the angles measured in the absence and presence of three different THR prostheses were compared. Both source-sensor distance and sensor orientation affects the accuracy of the 3STS. Measurements were only affected by the presence of one type of prosthesis. The 3STS was equally reliable, but less accurate with source-sensor distances of more than 25 cm. The small angular error and insensitivity of this device to the presence of some metallic THR prostheses make it a useful measurement tool for gait studies performed before and after THR surgery.