Design and development of a smart continuous passive motion device for knee rehabilitation

Abstract

Continuous Passive Motion (CPM) device is widely used for knee rehabilitation to recover the range of motion or to lessen edema and swelling of the knee following injuries or surgeries. The objective of this work was to design and develop a smart continuous passive motion (SCPM) for knee rehabilitation after the total knee arthroplasty (TKA). A microcontroller with built-in 7-inch touch-screen LCD was used to control the developed device. There are 4 main operating modes, which are Manual, Auto Run, Intermittent and Progressive modes. In addition, the developed device is capable of flexing/extending the knee joint in the range of motion from 0 to 120 degrees. A rotary encoder was installed to ensure the accuracy of the knee joint angle. In addition, patient data and operating data can also be stored on a memory card. To verify the performance of the developed SCPM, the degrees of motion were tested by comparing the movement angles of the developed device with the angles measured from goniometer. The results show that the errors were found to be within 1%. The developed SCPM was also evaluated by physiotherapists. The results show that it gives better benefits associated with its conventional counterparts since it provides more user friendly interface for the controller and it also has better operating modes (Intermittent and Progressive modes) for the safety of the patients.