Quantitative measurement of hip protector use and compliance

Abstract

Hip protectors are often prescribed to the elderly who are at risk of falling, with the goal of preventing hip fractures. However, determining the effectiveness of hip protectors has been hampered by unreliable compliance data. This study reports a reliable objective method of measuring compliance and the developed method could be used in any climate, regardless of temperature. Custom compliance monitors were built and embedded inside hip protectors. An algorithm was developed to utilize both temperature and acceleration to determine compliance. Seven young volunteers (age 24.6 ± 4.2 years old) wore the protectors for a total of 667 h while closely recording their compliance. One female (77 years old) who had hip fracture history wore the compliance monitors for 91.6 % of the time during a 1-week stay in a hospital. From the volunteers’ trial, using temperature alone overpredicted compliance by 1.2 % and using acceleration alone overpredicted by 5.4 %, but using a combination of the two methods plus a correction factor only underestimated by 0.6 %. From the elderly data, the average compliance recorded from the temperature, acceleration, and combined methods with correction was 94.6, 88.9, and 90.2, respectively. The high accuracy of temperature sensors in this study will not be attainable in hot climates where most of the worldwide increase in hip fractures is occurring. The developed monitor with the algorithm provided high accuracy in determining compliance and was able to determine both the longitudinal and cross-sectional compliance at any time.