Stability of fixation of diacapitular fractures of the mandibular condylar process by ultrasound-aided resorbable pins (SonicWeld Rx® System) in pigs

To assess the stability of osteosynthesis in diacapitular condylar fractures we compared fixation using ultrasound-aided resorbable pins with poly-(d,l)-lactide (SonicWeld® Rx, KLS Martin, Tuttlingen, Germany) with that of titanium screws in 20 pig mandibles, 10 in each group. Isolated diacapitular fractures were created using a surgical chisel. Ten fractures were each repositioned and fixed by two pins (17 and 11 mm long, 2.1 mm in diameter), and 10 fractures were fixed by two titanium screws of equal length, 2.0 mm in diameter. Shear tests were done immediately after treatment to measure the maximum force to disrupt the fixation. Fixation with pins resisted mean shear forces of 310 N until the pins fractured, whereas fixation with titanium screws failed at 918 N when the screws pulled out of the bone. Long-term stability and resorption of pins will have to be analysed in an in vivo study.