[Fracture behavior of AO 3.5 mm cortical titanium screws Synthes screws) combined with LC-DCP plates]

It was investigated if AO 3.5-mm titanium cortical screws used in combination with LC-DCP plates for osteosynthesis are likely to break during surgery.

The moments of torque that lead to breakage of the screw were determined experimentally in a hardwood model. The insertion angle was variable: 90 degrees in centric (n = 30) and excentric (n = 30) positioning, 70 degrees (n = 30) and 50 degrees (n = 30). Minimal moments that led to screw breakage were compared to insertion moments that were measured intraoperatively in 7 fracture operations (radial, ulnar, tibial, fibular; 32 screws).

Minimal moments that led to screw breakage were 2.6 Nm (90 degrees centric), 2.8 Nm (90 degrees eccentric), 2.7 Nm (70 degrees) and 2.4 Nm (50 degrees). The maximal intraoperatively measured insertion moment was 2.25 Nm (radius).

In this investigation, minimal moments that led to screw breakage in an experimental setting were higher than maximal insertion moments that were recorded during surgery. It is concluded that screw breakage related to the given implant combination is unlikely if correct surgical technique is performed.