[Assessment of Reduction Abilities of an Expandable Stent in Treating Osteoporosis-Related Fractures of Th/L (Thoracolumbar) Spine]. / Zhodnocení repozicních schopností expandibilního stentu pri osetrení osteoporotických zlomenin Th/L pátere.

PURPOSE OF THE STUDY The method of stabilising the osteoporosis-related spinal fractures using an expandable stent (vertebral body stent - VBS) and bone cement is generally accepted for its minimal invasiveness, a low risk of complications and confirmed analgesic effect. The efficiency of reduction of a compressed vertebra is, however, still discussed in the literature. Our hypothesis was that the stent expansion in the vertebral body can achieve a statistically significant reduction in the anterior, middle and posterior part of the vertebra. MATERIAL AND METHODS The patients in whom the VBS technique was used to treat an osteoporosis-related fracture of Th/L spine in the period 2010-2014 were included in the study, namely 29 patients with 31treated fractures. The following radiographic parameters were monitored - anterior, middle and posterior vertebral body height, kyphotic angle between the upper and lower endplates of the vertebral body. Also, the radiation burden, painfulness according to VAS score and occurrence of complications were monitored. The minimum follow-up was 12 months. RESULTS The mean height of the anterior part of the vertebral body before the surgery, on the 1st postoperative day and at 6 weeks, 3 months, 6 months and 12 months was 23.5/25.4/23.9/23.6/23.6 mm respectively. The mean height of the middle part of the vertebral body at the same intervals was 17.9/24.0/23.4/22.9/22.9/22.9 mm. The mean height of the posterior part of the vertebral body was 29.6/29.8/29.4/29.3/29.2/29.2 mm. The kyphotic angle between the endplates of the vertebral body was 8.6/5.3/7.4/7.9/8.0/8.0°. The mean VAS values were 8.2/2.4/2.0/1.9/1.8/1.7. The mean duration of surgery was 54.3 minutes. The mean time of fluoroscopy was 33.4 s. The mean radiation dose was 443.1 cGycm2. The observed complications comprised 2 cases of dilatation balloon rupture, one case of a failure to expand the stents in a healed fracture due to incorrect indication. In total, four cases of cement leakage outside the vertebral body were reported, always with no clinical response. DISCUSSION All the authors agree that the method brings immediate analgesic effect, comparable to kyphoplasty or vertebroplasty. In our cohort, good reduction ability of the implant in the middle part of the vertebral body was confirmed. This has been confirmed also by other authors. Nonetheless, at a longer time interval the loss of correction was observed, which was reported only by Hartmann (5). The other authors mostly did not take into account the longer-term outcomes. CONCLUSIONS The hypothesis that the stent is capable of a statistically significant reduction in the anterior, middle and posterior portion of the vertebral body was only partially confirmed. A statistically significant reduction was seen only in the middle portion of the vertebral body. In the anterior portion of the vertebral body the reduction was demonstrable only immediately after the surgery, while the later follow-up checks revealed the loss of correction. The statistically significant improvement of the kyphotic angle between the endplates of the injured vertebra was also seen only on the first postoperative radiographs and at later follow-up checks the improvement was no more significant. The change in the height of the posterior portion of the vertebral body was not statistically significant at any of the follow-up intervals. Key words:osteoporosis, vertebral fracture, vertebral body augmentation, stentoplasty, vertebral body stent.

[Management of Odontoid Fractures with Compression Screw and Anterior Transarticular Screw Fixation in Elderly Patients]. / Osetrení zlomeniny zubu cepovce u starsích pacientu metodou kompresní osteosyntézy a prední transartikulární stabilizací.

PURPOSE OF THE STUDY In the management of dens axis fractures in patients older than 65 years of age the posterior approach is preferred due to osteoporosis and the risk of a failure of anterior osteosynthesis. The posterior approach, however, is associated with a higher incidence of complications. A combination of anterior transarticular fixation of C1/2 (ATS) with compression osteosynthesis of dens axis significantly increases the stability of osteosynthesis. MATERIAL AND METHODS In the period from 2009 to 2015 our hospital admitted 13 patients older than 65 years of age with a diagnosed type III dens axis fracture based on AO classification. 8 patients sustained a dens axis fracture combined with a stable atlas fracture. The cohort consisted of 13 women aged 67 to 90 years, with the mean age of 82.3 years. None of the female patients were affected neurologically. The dens axis fracture was treated by anterior approach. Once the screw was inserted in the dens axis, two more screws were added, the entrance points of those screws were medial and lateral to the odontoid screw and direction was divergently via C1/2 joints in order to reinforce stability. The patients were monitored at 6-week, 3-, 6- and 12-month follow-ups. Bone healing was confirmed by CT scan. RESULTS No complications were recorded during the surgery in any of the 13 patients. In one female patient the stabilization failed in the early postoperative period. A reoperation from anterior approach with the use of the same method was necessary. In eleven patients bone healing occurred after 6 to 12 months. In two patients pseudoarthrosis was formed with no clinical symptoms. No neurological deterioration or a patient s death was reported in the monitored period within 12 months after the treatment. DISCUSSION Where dens axis fractures in elderly patients are managed operatively, the posterior approach and transarticular fixation of C1/2 with sublaminar loop are preferred. This procedure is considered more reliable, owing to the fears of a failure of osteosynthesis by anterior approach. The most frequent cause of a failure is the pulling out of the screw through the anterior wall of dens axis base in patients with osteoporosis. Concurrently, the anterior approach is regarded as more considerate. The ATS fixation increases stability compared to isolated compression osteosynthesis, which makes it possible to manage the dens axis fractures by a more considerate anterior approach. CONCLUSIONS The ATS is a method that increases stability of compression osteosynthesis in managing dens axis in elderly patients. Key words: dens axis, upper cervical spine fracture, elderly, triple screw technique, anterior transarticular C1/2 stabilization.