gms | German Medical Science

Objectives: Broken screws in the sacral region are rare but can hypothecate revision strategies when the sacral corridors are blocked, especially when the revision strategy consists of using transsacral fixation methods. We describe a technique to remove a remnant of a broken iliosacral screw that is positioned in de S1 corridor with the tip in the sacral promontorium.

Methods: The patient was positioned prone on a radiolucent table and fluoroscopic imaging was performed from the contralateral side.The navigation star (Pulse, NuVasive, San Diego, CA, USA) was placed in to the PSIS on the conteralateral side and a cone beam CT using the Cios Spin fluoroscopy (Siemens Healthineers, Erlangen, Germany) was made of the sacral region.

For the removal of the broken screw part that was positioned in the promontorium of the sacrum we placed a navigated pointer on the skin until the pointer trajectory was in line with the broken screw part. This was done to determine the skin incision site. Then, a4.0 mm, navigated drill (Nuvasive) was positioned so that it was perfectly aligned with the broken screw part. A 4.0 mm hole was drilled until there was contact with the broken screw. (Figure 1 [Fig. 1]) The drill was removed and through this trajectory a conventional 2,8mm threaded guide wire (DePuy Synthes, Raynham, MA, USA) was placed and advanced in to the 7,3mm screw remnant.

Then, the threaded guide wire was overdrilled using a 5.0 mm canulated drill bit. The 2.8 mm threaded guide wire was removed and replaced by a 3.0 mm stainless steel Steinman pin. The screw was then turned clockwise under fluoroscopic guidance and it was noted that screw slightly progressed ventrally. Using the Monoblock flexible reamers (Depuy Synthes) the 3.0 Steinman pin was overdrilled and the canal was reamed until a diameter of 7.5 mm. (Figure 2 [Fig. 2]) The canulated screw could then be removed by turning it counter clockwise.

Results and conclusion: Using this technique the broken, the displaced cannulated screw could be removed successfully in a safe and minimally invasive manner. The pelvic reconstructive surgery was continued with the use of transiliac-transsacral bar and SI screw at the level of S1.