Introduction: In recent years, navigated surgical procedures in spinal surgery have been established due to an increasing demand for precision. Especially 3D-C-arms connected with navigation systems are being used more often and can be utilized intraoperatively for planning as well as controlling of screw positions. This study analyses our experiences with 3D-based navigation in the posterior cervical and high thoracic spine.

Methods: A 3D-C-Arm (Vision Vario 3D, Ziehm) was connected with a navigation system (Vector vision, Brainlab) and since 10/2007 used for the placement of overall 350 Screws at 51 Patients. Of those 9 Patients had to undergo operations in the posterior cervical spine, of 53 screws Judet- (n=8), Massa lateralis- (n=27) and pedicle-screws (n=18) were placed. Indications for instrumentation were traumatic fractures (n=3), spon-dylodiscitis (n=1), multiple metastases with high-grade instability (n=4), and degenerative rheumatic stenosis of the spinal canal (n=1). Concerning the high thoracic spine (T1–10) 42 interventions were made with the method, 297 pedicle- screws were implanted. Indications in this area were traumatic fractures (n=24), metastases (n=14) and spondylodiscites (n=4).

Results: Scan-time intraoperatively took 60 seconds on average, data-transfer to the navigation-system another 10 seconds. Application-time including anti-collision-check needs approx. 6 minutes [5;18]. In total 260/350 (74%) screws could be inserted assisted with navigation, 194/350 (55%) were controlled intraop-eratively. Regarding the cervical spine in 44/53 (89 %) of the screws the navigation procedure was uneventful. Positioning of 37/53 (70%) of the screws was checked immediately postoperatively. In the upper thoracic spine 216/297 (73%) could be placed with navigation, 157/297 (53%) were controlled intraoperatively. Occasionally, scan-setup was problematic, in addition, we experienced technical problems. Correct placement was seen for each screw, thus correlating well with the intraoperative findings.

Conclusions: The application of the combination of intraoperative 3D-imaging and navigation for posterior instrumentation of the cervical and the upper thoracic spine is technically feasible and reliable in clinical use. User- and software-dependant sources of error could be solved during the first course of the series. Image-quality at the cervical spine is depending on individual bone density, and possible metal artifacts. With undisturbed visibility of the vertebral body, the reliability of 3D-based navigation at the cervical spine is comparable to that of CT-based procedures. Additionally, it has the advantage of skipping preoperative acquisition of data as well as the matching-process. Furthermore, exposure to radiation is reduced due to the possibility of sparing pre- and postoperative CT.

Introduction: In kyphoplasty and vertebroplasty, polymethyl methacrylate (PMMA) is currently the standard in augmentation materials but it is characterized by a lack of osseointegration and limited biocompatibility. At the same time, calcium phosphate cements are not currently considered an alternative due to their insufficient mechanical stability against shear, compression and extension forces. This prospective study examines the suitability of a new calcium alumiate ceramic (Xeraspine^®, Doxa) for augmentation of vertebral fractures treated with balloon-kyphoplasty.

Methods: The operation technique follows the standard protocol for a bilateral percutaneous balloon-kypho-plasty (Kyphon). Exclusion criteria were: additional instrumentation, age > 90 years, as well as cardiac arrhythmia. The following clinical and radiological data were collected pre and post op, as well as after 6 weeks: Visual-Analogue-Score, Oswestry-Index, bisegmental endplate angle, and vertebral hight. A CT- scan was provided to show possible cement extrusion and disintegration.

Results: 20 vertebrae were included so far. The fractures could be classified as: type A1.3 (n=11), A3.1 (9). They were located at Th9 - L3. All 20 patients reported pain relief immediately post op. Restoration of endplate angles was 6,2° on average. There was no case of cement disintegration. No loss of correction was observed radiologically.

Discussion: The calcium aluminate ceramic used in balloon-kyphoplasty is an alternative to PMMA. Due to comparable shear, compression and extension strengths, there is no risk of cment breakage and following loss of correction. On the other hand the calcium aluminate ceramic shows better biocompatibility if compared to PMMA.

Endoscopic techniques lead to higher numbers of anterior procedures to the vertebral column. Navigation systems can assist to more precision using less x-rays. We registered prospectively more than 100 cases of anterior stabilization of the thoracic and lumbar spine using minimally invasive technique, endoscopic assistance and CT-based navigation. Patients were observed continuously over a time period of at least 12 month according to a standardized protocol.

135 patients were recorded prospectively between January 2002 September 2004. All patients recieved anterior procedures using endoscopical assistance. Operations were performed in prone position using Synframe® and navigation system by BrainLab®. The follow up of at least one year consisted in clinical investigations and radiographs 6 weeks, 3, 6, 9 and 12 months post OP.

87 male and 48 female patients were recorded with a mean age of 41 (16–77) years. 47 isolated anterior and 88 combined antero-posterior spondylodeses were performed with the described technique. In 101 cases thoracoscopy was used. For the instrumentation of L3, mini-lumbotomy was necessary which was also combined with Synframe® and endoscopical assistance. Isolated anterior procedures were completed under navigation control in 29 and combined antero-posterior procedures in 71 cases. Image intensifier times were reduced up to 85%, op-times were shortened using navigation for a mean of 22 minutes.

Navigation procedures showed initial learning curve. However, after this initial time it was a useful techique to enlarge precision and reduce op-times as well as x-ray exposition. The further standardization of the procedure lead to the development of advantageous instruments that further on will lead to even higher acceptance of this new technique.