gms | German Medical Science

Objectives: Is the novel modular, titanium-coated, carbon-fiber-reinforced poly-ether-ether-ketone (CFR-PEEK) vertebral body replacement (VBR), referred to as Kong^®, a safe and effective option for anterior column reconstruction (ACR) of the thoracolumbar spine?

Methods: A retrospective case series was conducted on patients who underwent ACR of the thoracolumbar spine with Kong^® VBR due to high-energy trauma, osteoporotic fractures, or tumors from 2020 to 2021. Patients with incomplete medical records were excluded. The primary outcome was the bi-segmental kyphotic angle (BKA) using the Cobb method. Secondary outcomes included craniocaudal subsidence [1], cage height coefficient [1] to assess the cage expansion locking mechanism, sagittal tilt, pedicle screw loosening, and spinal fusion status by Bridwell's criteria [2] on plain radiographs and CT scans. Perioperative and long-term complications were recorded. Clinical outcomes were assessed using Odom’s criteria, the Karnofsky Performance Status (tumor group), and the AOSpine PROST-Score (trauma group). Neurological impairments were monitored during follow-up. Paired Student’s t-tests were applied for angular and subsidence measurements comparisons, while the Wilcoxon signed-rank test was used for cage height coefficient and clinical scores assessment.

Results and conclusion: The cohort comprised 28 patients (15 high-energy fractures, 7 osteoporotic fractures, 6 tumors; mean age: 61 ± 19 years; 33% female; mean follow-up duration: 17.7 ± 7.7 months [range 8–36 months]). A postoperative BKA correction of 14.4° (± 23.8°, p=0.010) was observed. At last follow-up, a correction reduction of 2.7° (± 25.2°, p=0.599) was noted, with the correction from baseline sustained at 15.3° (± 30.3°, p=0.036). Mean subsidence did not increase significantly (change: 0.5 ± 0.71 mm [range 0–2 mm], p=0.052), cage height coefficient remained consistent (change: 0.02 ± 0.10 [range 0.0–0.5], p=0.113) until the last follow-up. No significant change was observed in the sagittal tilt over time (change: 0.8 ± 4.4° [range 0–22°], p=0.381). No screw loosening was recorded. Fusion, (Bridwell Grade I or II) was achieved in 95% (CT) and 93% (radiographs) of cases. No implantation complications occurred. In seven of eight patients (88%) with initial deficits, neurological symptoms improved. In the tumor subgroup, the Karnofsky Performance Status improved by 17.9 points (p=0.010). The mean AOSpine PROST-Score for trauma patients was 56.9 at the last follow-up. According to Odom's criteria, 92% of patients were assessed as “excellent” or “good” at final follow-up.

Preliminary data suggest that the Kong^® modular, expandable, titanium-coated CFR-PEEK VBR system is a viable and effective option for ACR in cases of the thoracolumbar spine affected by high-energy and osteoporotic fractures, as well as spinal tumors.