[Comparison of clinical and radiological data in the treatment of patients with osteoporotic vertebral compression fractures using radiofrequency kyphoplasty or balloon kyphoplasty]

Purpose: Since the 1990s, balloon kyphoplasty has been proven as an effective method of treating patients with painful vertebral compression fractures (VCF). The radiofrequency kyphoplasty is an innovative procedure available since 2009, for which an ultra-high viscosity cement is used. For the statistical comparison of the two methods of augmentation, the clinical and radiological data of 2 larger patient groups were evaluated.

Materials and methods: As part of the surgical treatment of patients with conservative therapy-resistant osteoporotic vertebral fractures, a prospective study of radiofrequency kyphoplasty (RFK) was performed between 2009 and September 2010. The treatment was minimally invasive using the StabiliT® Vertebral Augmentation System by DFine for which the StabiliT® multiplex controller, the articulating VertecoR® Midline Osteotome, and the radiofrequency-sensitive StabiliT® ER2 bone cement were applied. From the clinical aspect, measurement parameters for efficacy and safety were the course of pain intensity using a visual analogue scale (VAS: 0 to 100 mm) and the Oswestry disability score (0-100%). For the radiological outcome the increase in the middle and anterior parts of the treated vertebra and also the reduction of kyphosis after surgery and after 6 months were evaluated. Furthermore, the extent of cement extrusion and the duration of operation time were compared. There were 2 groups of patients chosen with the same indication, and with the same average VAS prior to treatment. For the balloon kyphoplasty (BKP) the Kyphon® technology was used. For the BKP group the same parameters as in the first group were evaluated (matched pairs). To compare the data statistically, parametric and non-parametric tests were applied.

Results: For the radiofrequency kyphoplasty group (RFK) 114 patients were recruited, and for the balloon kyphoplasty group (BKP) 114 appropriate patients were selected. In 48% of the RFK patients and in 44% of the BKP patients more than one vertebral body were treated (thoracic or lumbar). Prior to treatment 84 mm on the VAS were calculated in both groups. The decrease in VAS values (RFK vs. BKP) immediately after surgery was 58.8 vs. 54.7 mm (p = 0.02), and 73.0 vs. 58.9 mm after 6 months (p < 0.001). In both groups improvements in the Oswestry scores were registered after 6 months without a statistically significant difference. In both groups, the middle part of the vertebral bodies was increased by an average of 3.1 mm. RFK yielded a decrease in the average kyphosis angle of 4.4, the BKP resulted in about 3.8 degrees. Concerning cement leakage a key difference in favor of the radio frequency kyphoplasty was detected (6.1 % vs. 27.8%; p < 0.0001). For RFK a significant shorter duration of operation time was calculated (28.2 vs. 49.6 min; p < 0.001).

Conclusions: The RFK has proven to be a clinically very effective procedure that does somewhat better than BKP in long-lasting pain relief. No differences could be detected regarding improvement of functioning and the mean restoration of mid- and anterior vertebral height. As far as the safety aspect is concerned the RFK offers the advantage of a statistically significant lower proportion of cement extrusion.