Session: Current Topics in Biological Chemistry:

Periprosthetic hip infections are a common complication of hip surgeries and early diagnosis of these infections is extremely challenging. We developed a novel implantable sensor for non-invasive early detection and monitoring of hip infections by measuring synovial fluid pH radiographically. During periprosthetic hip infections, synovial fluid pH decreases from 7.5 to around 6.7. The sensor consists of a polyacrylic acid-based hydrogel which is responsive to pH. The hydrogel was pinned at one end with a metal wire and a radiodense tantalum bead embedded in the other end. The length changes of the hydrogel can be monitored using plain radiography by measuring the movement of the tantalum bead with respect to the metal wire. The pK_a of the hydrogel sensor was determined to be 5.25 with a sensitivity of 0.3 cm/pH unit. It exhibited good reversibility in the pH range of 6.5 and 7.5 in both buffer and bovine synovial fluid. An interobserver precision of 0.03 pH units was reported from an interobserver study of a randomized series of radiographs. The hydrogel sensor could also be developed to detect other markers of infection such as C-reactive protein (CRP) levels. Therefore, the sensor is useful for noninvasive early detection of periprosthetic hip infections.

Sachindra Kiridena

Graduate Student, Clemson University

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