Verbesserung der Wirbelkörperrekonstruktion bei komplexen Wirbelkörperfrakturen durch Verwendung eines Doppelballons – Biomechanischer Vergleich zweier Ballon-Verfahren

Introduction Burstfractures of one or multiple vertebral bodies are one of the most frequent iniuries of the spine. The consequences for the patient are heavy and incorporate pain, reduction of activities and an increase of mortality. Therefor a treatment is necessary. While the treatment of painful osteoporotic compression fractures by Balloon Kyphoplasty is well accepted, the treatment of complex fractures of the vertebral body is still part of discussion in literature. The Balloon inflation or void creation cannot fully be controlled by the surgeon since the Balloon follows the path of least resistance and the reconstruction is limited. Aim of the present study was to compare two Balloon Systems in a complex fracture model using cadaveric spines to test the possibilities of the new method. Material and methods The spines of 5 donors were disected from T9 to L4. Out of every spine 4 pairs of vertebral bodies were harvested (T9+10, T11+12, L1+2, L3+4), after there was a CT Scan of the vertebral bodies to exclude any damage. The discs and ligaments were kept intact. The pairs were imbedded in in Technovit 3040 (firm Kulzer). Using a oscillating saw stress risers were cut in the lower vertebral body to ensure the generation of burst fractures. The fractures were finally generated using a drop tower in which a defined weight was dropped on the vertebral bodies. CT-scans were performed before and after fracture as well as after treatment. After fracture 16 vertebral bodies were matched into two comparable groups and randomized into two treatment arms. One group was treated by conventional bipedicular Balloon-Kyphoplasty (Allevo, Joline, Hechingen), the other group by bipedicular double Balloon (Stop`n GO, Joline, Hechingen). In the CT-Scans there are measured the anterior, central and the posterior height and the volume of the vertebral body. Afterwards the results of the reconstruction of the two methods were compared. Results Initial values before fracture represent 100%. The central height was elevated from 78,5% (65,8-95,8) to 87,7% (80,1-96,2) in the Balloon group and from 77,0% (64,2-87,0) to 98,3% (88,4-98,3) in the double Balloon group. The posterior height of the vertebral body was elevated from 82,3% (63,0-100,7) to 89,2% (82,2-103,1 ; Balloon) and from 85,6% (75,5-99,3) to 98,0% (90,5-107,1; double Balloon). The difference between both groups regarding central and posterior heights was significant in favour of the double Balloon (central p=0,0108; posterior p=0,0047). The volume of the vertebral body was increased by 18,5 % (7,1ml; 1,7-10ml) in the double Balloon group and by 7,3 % (2,6ml; -2,2-7,7ml) in the single Balloon group respectively. This difference was significant as well (Volume in percent p = 0,0301 and Volume in cm3 = 0,0094). Conclusion The use of the double Balloons allowed a better control of the Balloons during inflation. This led to better central and posterior reconstruction of the vertebral body. Hereby significant differences between the conventional and double Balloons were documented in this study. The double Balloon seems to be an improvement of the regular Balloon system. Further biomechanical and clinical studies are needed to understand this better.