3D image-guided surgery for fragility fractures of the sacrum

Objective. Stabilizing sacral fragility fractures without radiation exposure to the surgical team. Indications. Non-displaced or minimally displaced unilateral or bilateral transalar, transforaminal or central sacral fractures in weak and osteoporotic bone. Contraindications. Displaced or highly unstable sacral fractures. Patients under therapeutic anticoagulation. Patients needing fast track orthopedic surgery. Surgical technique. Prone position. Reference clamp installation on posterior iliac crest. Initial 3D scan of posterior pelvic ring. Image-guided virtual determination of 2-3 interforaminal iliosacroiliac trajectories in sacral vertebrae I and II. Lateral transgluteal mini-open approach. 3D image-guided insertion of 2-3 guide wires along planned trajectories. 3D-scan for controlling guide wire positions. Virtual determination of screw lengths. Cortical drilling and cannulated screw insertion along guide wires. Radiological documentation. Follow-up. Clinical and radiological follow-up after 12 weeks, 12 and 24 months including radiographs in anteroposterior, lateral, inlet and outlet views. Results. From October 2011 until October 2016 a total of 124 sacral fracture sites (in sacral vertebrae I and II) were treated with 120 navigated sacral screws in 52 patients (48 females, 4 males; mean age 76 +/- 10 years, range 36-90 years) using 3D image guidance for screw placement. Imageguidance accuracy was 99.2% (119/120 screws correctly placed). Complications comprised revision surgery for subfascial hematoma evacuation (n= 1) and screw removal due to loosening after 12 weeks (n= 2). Four patients died before final follow-up. Mean pain visual analogue scale (VAS) decreased from 8.9 +/- 1.1 (presurgery value) over 3.6 +/- 1.7 (postsurgery value) to 1.8 +/- 1.9 (2-year followup value), mean Oswestry disability index (ODI) improved from 86.2 +/- 4.9% (presurgery value) over 28.5 +/- 9.5% (postsurgery value) to 23.3 +/- 13.7% (2-year follow-up value).