Detection of Hip Infections Using an Injectable Hydrogel Based Synovial Fluid pH Sensor

A hydrogel-based sensor was developed which could be attached to prosthetic hips prior to implantation, to measure pH in the joint fluid in order to detect, monitor, and study infection. A common complication of hip surgeries are post-surgery infections. Delayed diagnosis would lead to reduced function, increased morbidity and may require more complex surgeries. Therefore, early detection of infections is important for successful management of hip infections. In order to detect infection biomarkers, the joint is aspirated and the synovial fluid is analyzed. However, joint aspiration performed by a radiologist under fluoroscopy or ultrasound guidance is painful and is impractical for routine screening or serial monitoring during treatment. The developed synovial fluid sensor provides a method of early detection and monitoring of hip infections using plain radiography. The sensor is made of a pH responsive polyacrylic acid-based hydrogel and the response was determined from the radiograph by measuring the position of a radio-dense tantalum bead embedded in the hydrogel. Thus, the developed sensor could be used as a potential X-ray imaging functional chemical sensor.