Biomechanical in vitro comparison of radiofrequency kyphoplasty and balloon kyphoplasty.

PURPOSE: Balloon kyphoplasty (BK) has emerged as a popular method for treating osteoporosis vertebral compression fractures (OVCFs). In response to several shortcomings of BK, alternative methods have been introduced, among which is radiofrequency kyphoplasty (RFK). Biomechanical comparisons of BK and RFK are very sparse. The purpose of this study was to perform a biomechanical study in which BK and RFK are compared.

METHODS: Each of the two study groups comprised six specimens prepared from two functional spinal units (FSUs) cut from fresh-frozen cadaveric spines (3 of T9-T11 and 3 of T12-L2). VCFs (A1.2 type) were created in the middle VB of each of the FSUs, with a height loss of 30% of the VB. After that, the specimens were subjected to cyclic compression-compression loading. The following parameters were determined: range of motion (ROM), height of the middle VB, augmentation time, cement interdigitation and cement distribution. Also, the cement layer, the trabecular bone in the augmented VB and the bone-cement interface were examined for cracks. All of these parameters were determined at various stages, namely in the intact middle VB and after its fracture, cement augmentation and subject to the cyclic loading protocol.

RESULTS: Fractures caused a significant increase in median ROM and a significant reduction in the height of fractured VB. Cement augmentation significantly stabilized the fractures and led to partial height restoration. ROM and vertebral height, however, were not restored to the intact levels. Cyclic loading led to a further significant increase in ROM and a significant height reduction. There were no significant differences between BK and RFK in terms of any of these parameters.

CONCLUSIONS: BK and RFK achieved similar results for fracture stabilization and restoration of the height of the fractured VB. RFK involved shorter cement augmentation time and less damage to the trabecular bone.