CT guidance assisted by electromagnetic navigation system for percutaneous fixation by internal cemented screws (FICS).

PURPOSE: To evaluate electromagnetic navigation system (ENS) for percutaneous fixation by internal cemented screw (FICS) under CT guidance.

BACKGROUND

FICS is a recently developed modality that consists in inserting screws, under imaging guidance, into bone through a minimal skin incision. FICS recently showed good efficacy for the palliation or prevention of pathologic fractures of the pelvic ring and femoral neck.

MATERIALS AND

METHODS

In this single-center retrospective study, we reviewed all consecutive cancer patients treated with percutaneous FICS under ENS-assisted CT guidance for the prevention or palliation of pelvic or femoral neck fractures. The primary endpoint was technical success. Secondary endpoints were screw placement accuracy (defined by proximal deviation p, distal deviation d, and angle deviation θ), radiation dose exposure, number of CT acquisitions, duration of procedures, and complications.

RESULTS

Mean duration of FICS procedures was 111 ± 51 min. Mean post-procedure hospitalization length was 2.1 days. Technical success was achieved in 48 cases (96%) with a total of 76 screws inserted. Mean distance p, mean distance d, and mean angle θ were respectively 8.0 ± 4.5 mm, 7.5 ± 4.4 mm, and 5.4 ± 2°. Angle θ accuracy was higher for screws with a craniocaudal angulation of less than 20° (4.4° vs 6.4°, p = 0.02). The mean number of CT acquisitions during procedures was 6.4 ± 3.0. The mean dose length product was 1524 ± 953 mGy cm and the mean dose area product was 12 ± 8 Gy cm2. Five complications occurred in 4 patients.

CONCLUSION

CT guidance assisted by ENS is an effective approach for percutaneous FICS.

KEY POINTS: • ENS-assisted CT enables screw insertion in the pelvic ring and femoral neck, with a wide range of trajectories, even when a significant craniocaudal angulation is required. • ENS-assisted CT can be used as an alternative to CBCT guidance for percutaneous fixation by internal cemented screw. • ENS-assisted CT provides high technical success rate with excellent placement accuracy.