Osteoporosis is the most common cause of vertebral compression fractures (VCFs) which result in debilitating back pain and negatively impact the patient’s quality of life [1]. Conservative treatment of symptomatic VCFs consists of medical therapy, which includes analgesics, anti-osteoporotic drugs, bed rest for a limited time, external bracing, physiotherapy, and rehabilitation. These treatments are only partially effective as they take a longer time and do not prevent further kyphotic deformity [2].

Vertebroplasty and kyphoplasty are minimally invasive percutaneous approaches developed for the treatment of symptomatic VCFs. It is well established that more than 90% of patients with osteoporotic fractures will experience rapid and significant pain relief from these procedures with improved functionality and quality of life. Although not well established, the most likely mechanism for pain relief after kyphoplasty (even without significant restoration of vertebral body height) appears to be mechanical stabilization of the vertebral body [3,4].

The main risk of these minimally invasive techniques is leakage of polymethyl methacrylate (PMMA) into the venous system, which is reported in large prospective randomized trials to be as high as 72% in vertebroplasty and 27% in balloon kyphoplasty. Most leakages are asymptomatic but may result in pulmonary embolism. Leakage through the fracture into the spinal canal or neural foramina may lead to neurologic disorders or other complications like local or systemic reactions to cement or infection [5-7].

Radiofrequency (RF) kyphoplasty is a new method for VCF treatment, approved in the United States in 2007 and in Germany in 2009. Its principle depends on the ex vivo transformation of PMMA cement by RF into a semisolid mass of ultrahigh viscosity. This inactivated cement can be applied in controlled fashion for up to 35 minutes, while its properties remain constant without destroying the cancellous bone that is still existing [8].

In this study, we assessed the effectiveness of a new method of RF kyphoplasty and its benefits over old methods for the treatment of VCFs.

In 30 patients (73%), one level fracture was treated, and the mean operating time was 24 minutes (range, 18–30 minutes). In four patients (10%), two levels were augmented and required a mean operating time of 38 minutes (range, 38–40 minutes). In five patients (12%), three levels were treated requiring an operating time of 55 minutes (range, 54–58 minutes). In two patients (5%), four levels were treated, and the mean operating time was 69 minutes (range, 68–70 minutes). The maximum number of fractures was in the thoracolumbar junction (23 patients, 56%), thoracic fractures (Th5–Th9) constituted 15% (six patients), and lumbar fractures (L2–L5) constituted 29% (12 patients). The main level affected was L1 followed by Th12.

There were 10 patients (24%) who had secondary osteoporosis caused by long-term corticosteroid therapy. The remainder 31 (76%) were assumed to have primary osteoporosis. All patients were mobilized within the first 24 hours after surgery. Thirty-one patients (76%) were hospitalized for 1–3 days. Due to additional injuries, 10 patients (24%) stayed for a maximum of 10 days. The mean preoperative pain score on VAS was 8.7 (range, 5–10; SD, 1.2). Postoperatively, the mean score was 3.3 (range, 2–5; SD, 0.9); VAS 6 months postoperatively, a mean score of 1.07 (range, 0–5; SD, 0.9); and VAS 12 months postoperatively, a mean score of 1.22 (range, 0–7; SD, 1.6). Thus, significant pain relief (p<0.005) was achieved in all three consecutive intervals of follow-up. The mean preoperative ODI score was 85.9, decreasing to 9.6 postoperatively and improving at 10.1 and 18.4 at 6 months and 1-year follow-up, respectively. These results are depicted in Table 1.

The mean local kyphotic angle was 9.04° before the procedure and decreased by a mean of 6.16° after the operation, as well as at 6 months and 1-year follow-up (p<0.005). In 23 fractures (37.7%), the reduction was achieved by less than 2°, while the reduction of 2°–5° occurred in 25 fractures (40.98%). In 13 fractures (21.3%), a reduction of >5°–10° was achieved. The mean vertebral height was 19.16 mm preoperatively, increasing by a mean of 22.50 mm postoperatively and remaining unchanged at 6 months and 1-year follow-up (p<0.005). Results are illustrated in Table 2.

Note that in 25 fractures (41.0%), the reduction was achieved by less than 2 mm, while a reduction of 2–5 mm was achieved in 21 fractures (34.4%). In 13 fractures (21.3%) and two fractures (3.3%), reductions of >5–10 mm and >10 mm were achieved, respectively.

Postoperative complications are as follows. Cement leakage occurred in five (8%) of 61 augmented vertebral bodies. Type S (via the segmental vein) leakage occurred in two cases. Type B (via the basivertebral vein) leakage occurred in two cases. We observed only one case of type C leakage (through a cortical defect). No cement leakage required revision, and no other complication was detected.

VCFs are the most frequent fractures associated with osteoporosis. At 5 years after diagnosis, the estimated survival rate is reported to be 61%; clinically diagnosed vertebral fractures are rarely fatal, and the reduced survival rate is related to comorbid conditions [11].

RF kyphoplasty is a novel vertebral augmentation procedure that consists of non-balloon, bone-sparing cavity creation and targeted delivery of an ultrahigh viscosity cement after activation using RF energy.

The bone cement viscosity and polymerization of energy-responsive bone cement are controlled by a low-power bipolar RF warming source that warms the bone cement to provide consistent ultrahigh viscosity properties over an extended working time. The ultrahigh viscosity cement allows for superior interdigitation with cancellous bone without a destroying effect, and the risk of cement leakage is reduced at high cement viscosity injection. The targeting delivery of a highly viscous cement in the anterior third of a compressed vertebral body has been reported to result in height restoration of VCFs [12-14].

Our study results of RF kyphoplasty demonstrate a significant pain relief in all consecutive follow-up interval periods. A significant back pain and function ODI (p<0.001) was achieved immediately postoperatively and in both 6-month and 1-year follow-up. Compared to other studies of vertebroplasty, balloon kyphoplasty, and RF kyphoplasty, we observed no difference in pain relief between different methods of vertebral augmentation techniques [15-18].

In our study, we measured the kyphotic angle and mean vertebral height. The mean local kyphotic angle was 9.04° preoperatively which decreased to a mean of 6.16° postoperatively with 62% of fractures restored more than 2°. The mean vertebral height was 19.16 mm preoperatively and increased to 22.50 mm postoperatively. Sixty percent of fractures increased more than 2 mm in height postoperatively.

In our study, the mean vertebral body height increased by 3.34 mm and mean local kyphotic angle decreased by 2.88°, comparable to both balloon kyphoplasty and vertebroplasty.

Pflugmacher et al. [12] showed that the average increase in the middle part of the vertebral bodies in both RF kyphoplasty and balloon kyphoplasty was 3.1 mm. Previous work has shown that the average decrease in kyphosis angle is 4.4° in RF kyphoplasty, and balloon kyphoplasty decreases kyphosis by 3.8°; the results of both methods are comparable to ours. The difference in height restoration and local kyphotic angle between the three techniques is generally small [16-18].

The Wilcoxon rank sum test revealed that mean local kyphotic angle and mean vertebral height were successfully achieved (p<0.001)

This RF kyphoplasty procedure provides a unique level of control which addresses the problem of cement leakage due to the combination of controlled delivery of RF-activated (high viscosity) cement at a fixed, low rate of delivery into site-specific channels created using a navigational osteotome. Additionally, based on the unipedicular access. Accordingly, this controlled procedure of remotely controlled cement delivery RF kyphoplasty may decrease procedural invasiveness and cement leakage [12,14].

Our study observed five cases of cement leakage (8%). Yeom et al. [10] observed 74 leaks in 48 osteoporotic vertebral fractures [OVFs] treated by vertebroplasty. Our results are far less compared to vertebroplasty (38%–72.5%) [19].

Our results are comparable to other balloon kyphoplasty and RF kyphoplasty studies. Schulz et al. [20] showed cement leakage in eight out of 46 OVFs treated by balloon kyphoplasty (17.4%). Cement leakage incidence in RF kyphoplasty is less than 50% compared with balloon kyphoplasty [8].

RF kyphoplasty is the newest vertebral augmentation procedure consisting of delivery of ultrahigh viscosity cement activated by RF energy to control cement consistency and minimize cement leakage. It is a good alternative for the treatment of VCFs.