SURGICAL TREATMENT OF UNSTABLE SPONDYLODISCITIS WITH POSTERIOR INSTRUMENTATION AND BIOACTIVE GLASS (BAG-S53P4) ALONE: RESULTS AT MEDIUM-TERM FOLLOW-UP

Aim To describe a surgical treatment for unstable pyogenic spondylodiscitis (UPS) based on debridement and irrigation (D&I), posterior instrumentation and bioactive glass BAG-S53P4 insertion alone, without the use of anterior support hardware, and to report the clinical results of the first three patients who underwent this surgery. Method This surgical technique is suitable for patients with UPS presenting uncontrolled pain, spinal instability or progressive deformity despite a correct antibiotic treatment. It is contraindicated in patients with the integrity loss of the posterior wall. Technique: under general anesthesia and in prone position, a posterior incision is made at the selected levels. Pedicle screws are inserted. The intervertebral space is reached by flavectomy, arthrectomy hemilaminectomy/bilateral laminectomy; the annulus fibrosus is incised. D&I are performed, and tissue biopsies sent for cultures. BAG-S53P4 granules (approximately 10-20 cc) are inserted and distributed with a 3-4 mm tip bone pusher, until all the cavity is filled. At the end of the procedure bars are inserted and the wound closed. The results of the first three patients with UPS treated with this technique were retrospectively reviewed. Results Case 1: a 76-year-old female multi-comorbid patient developed a culture-negative L3-L4 hematogenous UPS (from urinary infection), with a preoperative SISS instability score of 11/14. The patient underwent D&I, posterior L2-5 stabilization and cavity filling with 15 cc of BAG-S53P4 because of worsening pain and radiculopathy after conservative treatment. Intervertebral body fusion was reached after 12 months, without signs of infection recurrence after 2 years. Case 2: a 73-year-old male dialyzed multi-comorbid patient developed a MSSA L2-L3 hematogenous UPS (SISS 11/14) from a dialysis vascular catheter, and underwent D&I, L1-L4 posterior stabilization and cavity filling with 10 cc of BAG-S53P4 because of increasing low back pain and bone erosion. Bone fusion was reached after 24 months, without signs of infection recurrence after 3 years. Case 3: a 83-year-old male multi-comorbid patient developed an ESBL+ E.coli T11-T12 hematogenous UPS (from urinary infection), with a SISS score 12/14. He underwent D&I, posterior T9-L3 stabilization and cavity filling with 12 cc of BAG-S53P4 because of progressive spinal instability and pain, with inability to walk and sit. He reached bone fusion after 24 months, without signs of infection recurrence after 2 years. Conclusions This technique was effective in eradicating infection and promoting bone fusion in the treated patients. No anterior hardware was needed despite a preoperative SISS score of 11-12 out of 14.