Proposed alternative revision strategy for broken S1 pedicle screw: radiological study, review of the literature, and case reports

Background contextThere have been many reports outlining differing methods for managing a broken S1 screw. To the authors' best knowledge, the technique used in the present study has not been described previously. It involves insertion of a second pedicle screw without removing the broken screw shaft.Study designRadiological study, literature review, and two case reports of the surgical technique.PurposeTo report a proposed new surgical technique for management of broken S1 pedicle screws.MethodsComputed tomography (CT) scans of 50 patients with a total of 100 S1 pedicles were analyzed. There were 25 male and 25 female patients with an average age of 51 years ranging from 36 to 68 years. The cephalad-caudal length, medial-lateral width, and cross-sectional area of the S1 pedicle were measured and compared with the diameter of a pedicle screw to illustrate the possibility of inserting a second screw in S1 pedicle without removal of the broken screw shaft. Two case reports of the proposed technique are presented.ResultsThe left and right S1 pedicle cross-sectional area in female measured 456.00±4.00 and 457.00±3.00 mm2, respectively. The left and right S1 pedicle cross-section area in male measured 638.00±2.00 and 639.00±1.00 mm2, respectively. There were statistically significant differences when comparing male and female S1 pedicle length, width, and cross-sectional area (p<.05). At 2-year follow-up, the two case reports of the proposed technique showed resolution of low back pain and radicular pain. Plain radiograph and CT scan showed posterolateral fusion mass and hardware in good position with no evidence of screw loosening.ConclusionsThe S1 pedicle dimensions measured on CT scan reviewed in the present study showed that it may be anatomically feasible to place a second screw through the S1 pedicle without the removal of the broken screw shaft. This treatment method will reduce the complications associated with other described revision strategies for broken S1 screws.