Angular rate measurement in the assessment of patellar reflex

Clinical evaluation of the patellar reflex is one of the most frequent diagnostic method used by physicians and medical specialists. This test is usually done and is diagnosed manually, resulting in high variability during the assessment. The aim of this work is to determine if there exist a relation between velocity and the magnitude of reflex response. Methodology: It was used a precalibrated hammer designed for this test, to induce the patellar reflex and measure the angular rate of the leg during the course of the reflex test. The measurement system integrate an impact sensor to detect the hammer stroke; and an inertial measurement unit (IMU) to measure the angular rate of the leg response after it receives the hammer stroke on the tendon. The average angular rate signals were grouped based on the corresponding NINDS level. Results: The maximum value reached by the mean signal of 3+ group is 38 degrees per second. This magnitude is attenuated in a 31% to 2+ group, a 76% to 1+ group and 95% to 0+ group. These results are significant due to the relation between the NINDS level and the magnitude of the angular rate of the reflex response, and add features which can be useful in the quantification of the patellar reflex.