Design and Development of a System for Pressure Measurement in Patients using Lower Limb Prosthetic and Orthotic Appliances

Abstract

Pain and pressure sensation as parts of somatosensory system provides sense of awareness of joint position & body orientation in space. Proprioception works like a constant feedback loop where human beings are very well aware of body position and forces acting on it. Any abnormality in pressure especially for amputees would result in skin break down, joint disorders and noncompliance of prosthetic limb. In order to avoid problems related to skin & joints along with psychological satisfaction of patient, pressure mapping is performed with improved device compliance. Due to unavailability and high cost of MEMS based bubble sensors and TEKSCAN system, an effective and low-cost solution to problems related to pressure mapping before and after prosthetic fittings is introduced wherein a device capable of being incorporated within stump and prosthesis with minimal chances of breakage due to its flexibility is designed. Twelve pressure tolerant & sensitive areas of stump were marked upon silicon-based stump liner of 3mm thickness for TTP socket. FSR are attached to those specified areas and a Bluetooth module is used in PCB to send data through PLX-DAQ into MS-Excel. When a patient wears his/her prosthesis along with specially designed silicon liner having FSR and bears weight or walk, data is sent back into excel sheet recording the pressure values from 12 locations of a stump. Then adjustments can be made in prosthesis on the exact locations that showed increased pressure values so to eliminate pain and pinch and relieve the patient. Data from 7 patients during standing/ loading response of gait cycle was taken at Rehabilitation department of hospitals and required adjustments were made in prosthetic socket and alignment by the clinician/prosthetist. Comparison between means of pressure values before (27N/m2) and after making adjustment in prosthesis was made which showed improved values of pressure on distal tibia (<17N/m2) Data from 1 patient was obtained through all phases of his gait cycle and plotted on MS-Excel to find out exact phase of gait cycle causing more pressure on stump. The results showed significantly increased values of pressure on sensitive regions of stump during mid-stance phases of gait cycle (>75N/m2). While during early stance and swing phases the pressure values were significantly low (<28.7N/m2)