Biomechanical study and preliminary application of percutaneous retrograde sacral alar-iliac screw for fixation of sacroiliac joint with low bone density.

Abstract

The Sacral alar-iliac screw (SAIS) has stronger stability for sacroiliac joint fixation compared to the classical sacroiliac screw, making it particularly suitable for osteoporotic patients. However, the spinous process can hinder its percutaneous implantation. To address this, we developed a percutaneous retrograde SAIS (RSAIS) technique. This study aimed to explore the stability and preliminary application effects of percutaneous RSAIS for fixation of sacroiliac joint with low bone density. A Tile type C fracture was simulated in fifteen artificial pelvises with low bone density and assigned to three groups. Each group received posterior fixation using one of the following: one sacroiliac screw (SIS) on each side, one transsacral-transiliac screw (TSTIS) on both sides, or one RSAIS on each side. Axial stiffness and maximum load to failure were analyzed. Additionally, two patients with sacroiliac joint pain (SIJP) and three patients with Tile type C pelvic fractures were treated with percutaneous RSAIS fixation. Four males and one female, aged 56 to 68 years with a T-value of -1.6 to -2.5 SD. The study observed screw insertion time, X-ray fluoroscopy time, screw position (Smith criterion), pain (VAS), and functional recovery (ODI and Majeed scores). RSAIS stiffness and maximum load were significantly greater than those of TSTIS and SIS (p < 0.05). The average insertion time was 30 min, intraoperative bleeding averaged 16 ml, and fluoroscopy time was 55 s per RSAIS placement. There were no surgery-related complications, and all screw positions were excellent. At 7-20 months postoperative follow-up, the VAS score recovered from preoperative 5.6-1.6, the ODI improved from 50.4 to 17, and the Majeed score for patients with pelvic fractures recovered from 59.7 to 81. No screw loosening was observed. RSAIS fixation stability for sacroiliac joints with low bone density is superior to SIS and TSTIS. The screw placement is simple, safe, and provides satisfactory therapeutic effects, making it suitable for patients with low bone density.