Direct pedicle screw fixation in infected vertebrae for acute pyogenic spondylitis: short-term outcomes from a single-arm retrospective study.

BACKGROUND

The safety and efficacy of placing pedicle screws within infected vertebral bodies during surgery for acute pyogenic spondylitis remains controversial. The conventional "skip-level" fixation strategy avoids instrumentation at the infected site but may compromise spinal biomechanical stability and alignment. Conversely, fixation that includes the infected vertebrae can provide immediate stability, facilitate deformity correction, and promote bone fusion, although it carries potential risks of infection recurrence and implant failure.

OBJECTIVE

To describe the short-term outcomes of direct pedicle screw fixation in infected vertebrae for acute pyogenic spondylitis, combined with radical debridement and targeted antimicrobial therapy.

METHODS

A retrospective analysis was conducted on 32 patients with pyogenic spondylitis who underwent surgical treatment between January 2021 and January 2025. All patients had a confirmed etiological diagnosis obtained via microbiological culture or next-generation sequencing (NGS) of surgical specimens and received individualized perioperative anti-infective therapy guided by clinical pharmacists. The surgical protocol included debridement of the infectious focus and posterior pedicle screw fixation incorporating the infected vertebrae, performed via single-stage posterior, single-stage combined anterior-posterior, or staged combined anterior-posterior approaches. Primary outcomes focused on perioperative adverse events, including implant-related complications, infection recurrence, and wound healing. Secondary outcomes assessed clinical efficacy and involved comparisons of Visual Analog Scale (VAS) pain scores, Oswestry Disability Index (ODI), inflammatory markers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], and white blood cell count [WBC]), spinal Cobb angle, Frankel neurological grade, and bone fusion rates. Inflammatory markers and Cobb angle were assessed preoperatively and at 1, 3, and 6 months postoperatively; VAS and ODI were assessed preoperatively and at 1, 3, 6, and 12 months postoperatively; and bone fusion was assessed at 6 and 12 months postoperatively. Bone fusion was independently evaluated by two blinded assessors using Bridwell or modified Lenke criteria.

RESULTS

All 32 patients completed the 12-month follow-up. One osteoporotic patient developed asymptomatic minor screw loosening, and one diabetic patient experienced delayed wound healing that resolved after treatment. No implant failure, infection recurrence, or severe neurological complications occurred. Friedman tests demonstrated significant overall time effects for all dynamic indicators (all P < 0.0001): ESR (χ²(3) = 62.87, W = 0.65), CRP (χ²(3) = 67.22, W = 0.70), WBC (χ²(3) = 37.93, W = 0.40), Cobb angle (χ²(3) = 34.71, W = 0.36), VAS (χ²(4) = 95.90, W = 0.75), and ODI (χ²(4) = 127.02, W = 0.99). By 6 months, inflammatory markers had decreased markedly: ESR from 55.19 ± 31.05 to 6.00 (3.50, 12.25) mm/h; CRP from 34.10 (13.97, 85.15) to 2.12 (0.96, 3.90) mg/L; and WBC from 9.08 (5.75, 11.27) to 5.46 ± 1.01 ×109/L. The Cobb angle improved from 7.94 (6.84, 14.22)° to 8.34 ± 2.43°. At 12 months, VAS improved from 4.00 (4.00, 5.00) to 1.00 (0.75, 1.00), and ODI decreased from 28.72 ± 8.82% to 5.00 (2.25, 8.00)%. Neurological function recovered to Frankel grade E in 93.8% (30/32) of patients. The overall descriptive fusion rate (successful fusion in at least one graft site) was 78.13% at 6 months and 93.75% at 12 months postoperatively.

CONCLUSIONS

In this single-arm retrospective study of 32 patients with acute pyogenic spondylitis, direct pedicle screw fixation involving infected vertebrae was performed in conjunction with radical debridement and targeted antimicrobial therapy. At 12 months, patients demonstrated favorable short-term outcomes, including a low incidence of implant-related complications, significant improvements in pain and disability, a high radiographic fusion rate, and no observed infection recurrence. These findings provide preliminary evidence that this comprehensive protocol is a viable strategy for achieving favorable short-term outcomes in selected patients, and may serve as a practical reference for surgeons considering direct instrumentation in infected vertebrae.