Aims. We compared the accuracy, operating time and radiation exposure of the introduction of iliosacral screws using O-arm/Stealth Navigation and standard fluoroscopy. Materials and Methods. Iliosacral screws were introduced percutaneously into the first sacral body (S1) of ten human cadavers, four men and six women. The mean age was 77 years (58 to 85). Screws were introduced using a standard technique into the left side of S1 using C-Arm fluoroscopy and then into the right side using O-Arm/Stealth Navigation. The radiation was measured on the surgeon by dosimeters placed under a lead thyroid shield and apron, on a finger, a hat and on the cadavers. Results. There were no neuroforaminal breaches in either group. The set-up time for the O-Arm was significantly longer than for the C-Arm, while total time for placement of the screws was significantly shorter for the O-Arm than for the C-Arm (p = 0.001). The mean absorbed radiation dose during fluoroscopy was 1063 mRad (432.5 mRad to 4150 mRad). No radiation was detected on the surgeon during fluoroscopy, or when he left the room during the use of the O-Arm. The mean radiation detected on the cadavers was significantly higher in the O-Arm group (2710 mRem standard deviation (. sd. ) 1922) than during fluoroscopy (11.9 mRem . sd 14.8). (p < 0.01). Conclusion. O-Arm/Stealth Navigation allows for faster percutaneous placement of iliosacral screws in a radiation-free environment for surgeons, albeit with the same accuracy and significantly more radiation exposure to cadavers, when compared with standard fluoroscopy. Take home message: Placement of iliosacral screws with O-Arm/Stealth Navigation can be performed safely and effectively. Cite this article: Bone Joint J 2016;98-B:696–702

We measured the scattered radiation received by theatre staff, using high-sensitivity electronic personal dosimeters, during fixation of extracapsular fractures of the neck of the femur by dynamic hip screw. The dose received was correlated with that received by the patient, and the distance from the source of radiation. A scintillation detector and a water-filled model were used to define a map of the dose rate of scattered radiation in a standard operating theatre during surgery. Beyond two metres from the source of radiation, the scattered dose received was consistently low, while within the operating distance that received by staff was significant for both lateral and posteroanterior (PA) projections. The routine use of lead aprons outside the 2 m zone may be unnecessary. Within that zone it is recommended that lead aprons be worn and that thyroid shields are available for the surgeon and nursing assistants