Balloon kyphoplasty versus KIVA vertebral augmentation--comparison of 2 techniques for osteoporotic vertebral body fractures: a prospective randomized study.

STUDY DESIGN: Prospective, parallel-group, controlled comparative randomized study.

OBJECTIVE: This study compares the efficacy in sagittal vertebral height and wedge deformity restoration, polymethylmethacrylate cement leakage safety, and functional outcome of balloon kyphoplasty (BK) versus KIVA (a novel vertebral augmentation technique) implant for the augmentation of fresh osteoporotic vertebral body fractures.

SUMMARY OF BACKGROUND DATA: Minimally invasive vertebral augmentation procedures have been widely used to treat vertebral compression fractures caused by osteoporosis. The results of these trials are encouraging in augmenting the vertebra and reducing the wedge deformity. However, after BK, polymethylmethacrylate leakage remains common after A3.1 AO type fractures, with a frequency per vertebra into the epidural space up to 9.8% but less common (0.03%-5.6%) in A1.1 AO type fracture. KIVA is a novel percutaneous uniportal vertebral augmentation device that is designed to restore the vertebral body and reduce polymethylmethacrylate leakage.

METHODS: From a total 190 patients with osteoporotic fractures who were initially enrolled in this prospective randomized study, 10 patients were excluded (5 met exclusion criteria, 5 with evidence of metastasis). This study examined 82 patients (69 ± 11 yr) with 133 fractures who received KIVA and 86 patients (72 ± 9 yr) with 122 fractures that were reinforced with BK. Anterior (anterior vertebral body height ratio [AVBHr]), midline (midline vertebral body height ratio [MVBHr]), and posterior (posterior vertebral body height ratio [PVBHr]) vertebral body height ratio and Gardner segmental vertebral wedge deformity were measured preoperatively to postoperatively. New fractures were recorded at the final observation. The baseline anthropometric and roentgenographic parameters did not differ between the 2 groups. Any cement leakage was examined on plain roentgenograms and computed tomographic scan. All patients were followed for an average of 14 months (range, 13-15 mo) postoperatively. RESULTS.: At the final observation, both KIVA and BK restored significantly AVBHr, PVBHr, and MVBHr. However, only KIVA device reduced significantly the Gardner angle (P = 0.002). Residual kyphosis of more than 5° was measured significantly more (P < 0.001) in the BK than in KIVA spines. KIVA showed significantly lower (3%, χ2, P ≤ 0.05) leakage) [corrected] (paravertebral, intradiscal) rate per vertebra than BK (0.098%) in which because of intracanal leakage 2 patients developed acute paraplegia and were reoperated in emergency. New fracture rate was similar in both groups. Back pain scores (visual analogue scale), 36-Item Short Form Health Survey (Physical Function and Mental Health domains), and Oswestry Disability Index scores improved significantly in the patients of both groups.

CONCLUSION: Both KIVA and BK restored in short-term similarly vertebral body height, but only KIVA restored vertebral body wedge deformity. KIVA was followed by significantly lower and harmless always extracanal leakage rate than BK. Longer observation is needed to show whether these radiological changes have any functional impact.