Transiliac-transsacral Screws: What is the Required Implant Length for Adequate Percutaneous Fixation of the...

Objective  Brazilian orthopedic surgeons experience the unavailability of long screws allowing percutaneous fixation of the posterior pelvic ring in transiliac-transsacral (TI-TS) configuration. The objective of the present study is to measure the lenght of the osseous fixation pathways available for TI-TS fixation in a population sample to infer the required implant length. Methods  We retrospectively assessed patients undergoing computed tomography (CT), initially identifying the existence of a potential osseous fixation pathway (POFP) in S1, S2 and S3. Each POFP was measured from the external cortex of the iliac bone to the external cortex of the contralateral iliac bone on axial CT images. Results  The analysis comprised a sample of 180 cases. A POFP was identified in S1 in 116 (64.4%) cases, in S2 in 178 (98.9%) cases, and in S3 in 16 (8.9%) cases. The median (interquartile range - IQR) POFP measurement in S1 was 153 (148-161) mm, ranging from 135 mm to 179 mm. In S2, the median (IQR) POFP measurement was 136 (131-144) mm, ranging from 114 to 160 mm. In S3, the median (IQR) POFP measurement was 120.5 (115-126) mm, ranging from 110 to 131 mm. Conclusions  We demonstrated that the maximum lengths of the osseous fixation pathways identified in our sample would require screws up to 180 mm in length, with a clear dissociation between the values measured and the longer screws currently commercialized in our setting.