A 73-year-old male patient with a medical history of rheumatoid arthritis diagnosed in 2017 has been taking leflunomide, methotrexate, and hydroxychloroquine. He underwent ALIF surgery from L2 to L5 at a Gwangju Wooridul Hospital in April 2021. The purpose of the surgery was to address lumbar spondylolisthesis and spinal stenosis, which were causing low back pain. Immediately after the operation, there were no signs of neurological deficit, and the patient experienced some improvement in low back pain. However, after approximately 6 months, the pain recurred and worsened, ultimately rendering the patient unable to walk due to severe low back pain. Initial treatment involved conservative measures to manage the symptoms, but no significant improvement was observed. Accordingly, radiological examinations, including x-ray and computed tomography (CT), were conducted. These tests confirmed a fracture of the right L5 screw and revealed the presence of pseudoarthrosis with osteolysis at the L4L/5 (Figure 1A, B). SSI was suspected, prompting the performance of contrast-enhanced magnetic resonance imaging, which identified a contrast-enhancing lesion at L5 (Figure 1C). Peripheral blood tests showed white blood cell count of 13,450/mm³ (neutrophils 78.3%, lymphocytes 12.0%, monocytes 0.96%), erythrocyte sedimentation rate (ESR) of 37 mm/hr, and C-reactive protein (CRP) of 2.20 mg/dL. To isolate the pathogen, a CT-guided biopsy was conducted (Figure 2), and the culture test the presence of Aspergillus fumigatus.

The planned approach for the revision surgery at the site of the lesion was OLIF. Following the conventional method [4], the patient was positioned in the right lateral decubitus position, and a layer-by-layer dissection of the abdominal muscles was performed to access the retroperitoneal space. Although there were tissue adhesions resulting from the previous surgery, they were not severe. Therefore, caution was exercised during the approach to the disk space. The psoas muscle was laterally dissected to expose the disk space through the corridor where the discectomy was previously performed during ALIF (Figure 3A). During annulotomy, fluid resembling an abscess was observed, and a specimen was collected for culture testing. To ensure an adequate window, annulotomy was further performed using a Kerrison punch and pituitary rongeur forceps, followed by the removal of the previously inserted cage (Figure 3B). Then, a fibular strut was cut to match the dimensions of the disk space and inserted to provide support within the empty interbody space. An intraoperative O-arm scan confirmed the stable positioning of the graft (Figure 3C).

After allo-bone graft insertion, the patient was changed to the prone position and the screws (65 mm × 4.5 mm) and rods previously placed in L2, 3, 4, and 5 were removed and larger diameter screws (70 mm × 5 mm) were inserted in the same path. Additional screws were inserted in S1 and S2 alar and a cross-link was used for extra stability (Figure 3D).

Following the surgery, the patient experienced a significant improvement in pain, and by the seventh day after the surgery, the patient was able to ambulate with the assistance of a walker. A. fumigatus was confirmed through culture tests conducted on the specimens obtained intraoperatively. The patient received intravenous as an antifungal treatment for 3 weeks, which was later switched to an oral agent. With antifungal agent, CRP exhibited a significant decrease, stabilizing below 0.5 (Figure 4). Subsequently, the patient was discharged. During outpatient follow-up at 6 months postsurgery, the patient demonstrated independent ambulation while wearing only a thoracolumbosacral orthosis brace. Peripheral blood tests showed normal CRP and ESR. Radiological examinations indicated well-maintained structural integrity (Figure 5), and there were no indications of infection recurrence.