Triangular fixation to prevent proximal screw pullout for adult spinal deformity Surgery: A technical note

Background: Adult spinal deformity (ASD) is caused by spinal malalignment and results in severe low back pain, neurological dysfunction, and severe deformity. Surgical treatment, such as long spinal fusion offers improved patient-reported outcomes compared to conservative treatment. However, surgical complication of proximal screw pullout represents a difficult problem in minimally invasive ASD surgery. We describe a novel technique to prevent screw pullout in ASD. Case presentation: A 71-year-old woman was referred to our hospital with severe low back pain and gait difficulty. Her daily life had been affected by severe lower back pain for more than 6 months. Standing radiograms indicated severe kyphoscoliosis. Two-stage minimally invasive corrective T10-to-pelvis fixation was performed. The first surgery was an L1–S1 image-guided oblique lumbar interbody fusion, with an operation time of 3 h 57 min and an estimated blood loss of 240 mL. After 1 week, the second percutaneous pedicle screw (PPS) fixation was performed and proximal screws were inserted under a transdiscal approach (T11) and with a lower angulation trajectory (T10) to enhance pullout strength. For this second surgery, operation time was 3 h 33 min, and estimated blood loss was 320 mL. No postoperative complications or neurological compromise was reported. In terms of clinical outcomes, Oswestry Disability Index improved from 56% to 24%, and visual analog scale score for lower back pain improved from 62 mm to 24 mm at the 1-year follow-up. Conclusions: Minimally invasive circumferential surgery with triangular fixation is effective for preventing proximal screw back-out and surgical invasiveness. With this new technique, surgeons and operating room staff can avoid the risk of adverse events due to intraoperative radiation exposure.