Intramuscular Pseudoaneurysm Following Minimally Invasive Pedicle Screw Fixation for Lumbar Fracture Treated With Thrombin Injection: A Report of a Rare Case.

Minimally invasive surgery (MIS) techniques offer reduced tissue disruption and faster recovery, but rare vascular complications such as pseudoaneurysm may still occur. We present the case of a 66-year-old female patient with ankylosing spondylitis who sustained an unstable L2 fracture. Following navigated MIS pedicle screw fixation, she developed delayed paraspinal swelling. Initial CT demonstrated a paraspinal hematoma, and subsequent CT angiography confirmed an intramuscular pseudoaneurysm, which was successfully treated with fluoroscopy-guided thrombin injection. The patient remained asymptomatic with no recurrence at six-week and five-month follow‑up. This case underscores the importance of maintaining a high index of suspicion for vascular injury in postoperative patients with ankylosing spondylitis and demonstrates the effectiveness of fluoroscopy‑guided thrombin injection as a minimally invasive treatment option, contextualized by a brief literature review of diagnostic challenges and evolving management strategies.