Evaluation of transverse percutaneous fixation with iliosacral screws via the second sacral vertebra for longitudinal sacral fractures / 中华创伤骨科杂志

ABSTRACT

Objective To explore the safe bone channels for transverse placement of sacroiliac screws via the second sacral vertebra in the fixation of longitudinal fracture of the sacrum by digital analysis and clinical observation.Methods Firstly,abdomen CT scanning was performed in 50 healthy adult volunteers.They were 30 males and 20 females,aged from 18 to 56 years (mean,34.6 years).After their CT images were transformed by software Materialise Mimics Innovation Suite 15.0,three-dimensional (3D) models of the pelvis were generated,stored in stereolithography format,and transferred into software Imageware 12.0.In the standard antero-posterior position,the sacrum was segmented and the points of 2D image coordinate geometric boundary were extracted to generate an optimal channel for transverse placement of sacroiliac screws via the second sacral vertebra.Secondly,we admitted 10 patients with longitudinal fracture of the sacrum.They were 7 men and 3 women,aged from 20 to 51 years (average,38.3 years).By Tile classification,4 cases were type B2 and 6 type C1.All the fractures were Denis region Ⅱ ones.Pubic ramus fracture was complicated in 3 cases.After traction reduction of the tibial tubercle was conducted for patients with obvious displacement,the optimal channel was calculated on the basis of the CT data.On the lateral images of the sacrum acquired before operation by C-arm fluoroscopy,the optimal channel for transverse placement of sacroiliac screws via the second sacral vertebra was located.After the skin was marked,2.5 mm Kirschner wire was drilled and the 6.0 mm hollow screws were fixated along the Kirschner wire.Postoperative CT scanning images and 3D reconstructed models were analyzed to validate the accuracy of screw placement.Results The projection of safety bone channel on the sagittal fluoroscopy of S2 vertebral body displayed an irregular water drop shape;the projection area in males (213.9 ± 52.4 mm2) was significantly larger than that in the females (171.6 ±49.6 mm2) (P ＜ 0.05).The average length of the channel in men (135.2 ± 12.9 mm) was significantly longer than that in women (121.1 ± 10.1 mm);the average diameter of the screw in men (10.2 ± 0.9 mm) was also significantly larger than that in women (9.1 ±0.8 mm) (P ＜ 0.05).The postoperative X-ray and CT scanning images showed satisfactory positions and lengths of the screws.The screw lengths averaged 98.2 mm;the operation time averaged 25.6 min.No nerve or vascular injury,loosening or breakage of the sacroiliac screws occurred in the patients.Follow-ups for 12 to 24 months revealed no other complications.Conclusion The safety channel for transverse placement of sacroiliac screws via the second sacral vertebra can be determined using the lateral 3D reconstruction images of the sacrum in preoperative planning,which facilitates the percutaneous transverse fixation of longitudinal fracture of the sacrum.