Detection of improper postures leading to dislocation of hip prosthesis by a smartphone

The popularity of smartphone is due to its versatile multimedia communication networking that comes along with tools for various data-processing utilities. One of the useful resources in almost all smartphones is a MEMS-based accelerometer which can be used as a motion sensor. This paper considers its application in healthcare support especially as a posture-monitoring device for patients during rehabilitation period after undergoing hip arthroplasty. The accelerometer output can be used to estimate the hip joint angle when the smartphone position and orientation relative to human body is suitably arranged. The implementation procedure for this concept is explained here by the use of a single Android smartphone to detect the hip-joint angles that lead to improper postures and thus having risk of joint dislocation. The warning sound can then be given to the patient. In the experiments conducted, all angles measured were within the expected ranges and the warning sound was timely activated. It is an evidence that a single smartphone can be used as a convenient healthcare device for hip-joint angle detection. The limit of its classification efficiency is however limited to within 72.7% which is due to the wearing position and the number of units used.