TITLE: Improved Diagnosis of Infection Associated to Osteosynthesis by Use of Sonication

20 Previous studies have shown that sonication-fluid cultures from removed devices improved the 21 microbiological diagnosis of orthopedic implant-associated infections; however, few of these 22 investigations have applied sonication to the removed fracture-fixation devices to evaluate its 23 utility as an adjunctive diagnostic tool for osteosynthesis-associated infection (OAI). We 24 compared sonication fluid to conventional tissue cultures from 180 subjects with different sizes 25 plates and screws (n=156), spinal implants (n=26) and intra-medullary nails (n=3), of which 125 26 and 55 subjects had OAI and noninfected osteosynthesis (NIO), respectively. The sensitivity for 27 detecting OAI was 90.4% for sonication-fluid culture and 56.8% for periprosthetic tissue cultures 28 (P < 0.05), and specificities were 90.9% and 96.4%, respectively. Sonication-fluid culture 29 detected more pathogens than peri-implant tissue culture (113 vs 71; P < 0.001), while 30 polymicrobial infections were diagnosed by sonication-fluid cultures and tissue cultures in 31 20.8% and 8% (P < 0.001), respectively. Microbiologic diagnosis was achieved exclusively by 32 sonication-fluid cultures on 47 (90.4%) subjects, and among them, 18 (38.3%) had previously 33 received antibiotics, whether on five (9.6%) infected subjects, tissue culture was positive and the 34 sonication-fluid culture was negative. Among 39 (31.2%) OAI cases receiving antibiotics, 35 identification of organisms occurred in 38.5% and 82.1% on tissue culture and sonication-fluid 36 culture, respectively (P < 0.049). We demonstrated that sonication-fluid culture from removed 37 osteosynthesis has the potential for improving the microbiological diagnosis of OAI. 38