Conversion to hypertrophic vertebral pseudarthrosis following percutaneous vertebroplasty

To determine the role of percutaneous vertebroplasty (PVP) in bone formation and the union of vertebral pseudarthrosis, we analyzed 14 patients with an average follow-up duration of 21 months. Evaluation methods included back pain (visual analog scale: VAS), wedge angle, dynamic mobility, radiographic remodeling including callus and spur formation, and union status. The Student's t test was used for statistical analysis and a probability of less than 0.05 was determined as a significant difference. Back pain improved in all 14 patients with a VAS score of 57.8 ± 23.5 mm (average ± standard deviation) preoperatively and 14.7 ± 16.4 mm at the final follow-up (P < 0.001). The wedge angle decreased from 21.6° ± 8.3° (average ± standard deviation) preoperatively to 13.2° ± 6.9° at the final follow-up (P < 0.001). Callus formation was seen in four patients. Bony spurs were seen in the affected vertebra in preoperative radiographs in all patients, and were further developed to a solidified form during follow up after PVP. Dynamic mobility of the affected vertebrae was 6.9 ± 2.9 mm preoperatively, which decreased to 1.1° ± 0.7° at the final follow-up (P < 0.001). Notably, all patients showed the dynamic vertebral mobility of 2 mm or less. Nevertheless, only two patients exhibited the dynamic vertebral mobility of 0 mm at the final follow-up, which is referred to as bone union. These findings indicate that PVP serves as a mechanical stabilizer for vertebral pseudarthrosis, which leads to immediate pain relief and segmental bony responses.