Life-threatening postoperative hemorrhage caused by lumbar artery injury in asymmetrical pedicle subtraction osteotomy for severe spinal deformity: two case reports.

Purpose: To present two cases of life-threatening hemorrhage related to lumbar artery injury in adult spinal deformity (ASD) patients following S2‑alar‑iliac (S2AI) fixation and asymmetrical pedicle subtraction osteotomy (PSO), and discuss the possible reasons for postoperative hemorrhage in these patients.

Methods: Patient A was a 52-year-old female with degenerative lumbar scoliosis who underwent posterior spinal fusion from T₈-S₂ and one-level PSO at L₂. Patient B was a 24-year-old male with severe kyphoscoliosis due to non-ambulatory cerebral palsy, who underwent posterior spinal fusion from T₃-S₂ and one-level PSO at L₁. Both patients underwent asymmetric PSO, where a larger wedge was resected from the convex side of the vertebral body rather than the concave side.

Results: Both patients occurred a sudden increase in drainage within 3 h postoperatively, who were under anesthesia in AICU. Digital subtraction angiography (DSA) was emergently performed and revealed that the bleeding sites were from the lumbar artery, which was adherent to the convex side of the osteotomized vertebra in both cases. Then successful bleeding control was achieved through vascular embolization. Postoperative CT revealed spike formation at the anterior edges of the open wedge at the PSO level due to sagittal translation (ST), with noticeable derotation of the osteotomized vertebra.

Conclusion: For patients with severe kyphoscoliosis, asymmetrical PSO increases the risk of lumbar artery injury on the convex side, and postoperative ST may further contribute to this risk. In cases where a sudden increase in drainage is observed postoperatively, it is crucial to consider the possibility of lumbar artery injury, particularly on the convex side of the osteotomized vertebra.