Ausrissfestigkeit implantierter Pedikelschrauben in konventioneller und fluoroskopisch-navigierter Technik

The Surgical Treatment Principles of Atlantoaxial Instability Focusing on Rheumatoid Arthritis

OBJECT

This retrospective review was conducted to determine the surgical treatment principle for rheumatoid arthritis (RA) patients with atlantoaxial instability (AAI).

METHODS

Thirteen patients with AAI, including 5 RA patients, received preoperative computed tomography- (CT-) based image-guided navigation system (IGS) in C1 lateral mass-C2 pedicle screw-rod system fixation (LC1-PC2 fixation). These 13 patients were analyzed for 52 screws inserted into C1 and C2. We defined these patients as non-RA group (8 patients, 32 screws) and RA group (5 patients, 20 screws). The neurological status for RA group was evaluated using the Ranawat classification. The causes of AAI, surgical indications, complications, surgical method revolution, and CT-based navigation application are discussed.

RESULTS

None of the 13 patients expressed neurological function deterioration. The non-RA group screw accuracy was 100%. In the RA group, 1 RA patient developed left C2 screw loosening at 1(+) months after operation due to screw malposition. The screw accuracy for this group was 95%.

CONCLUSIONS

Higher intraoperative surgical complication rate was described in RA patients. Preoperative CT-based IGS in LC1-PC2 fixation can provide good neurological function and screw accuracy results. However, for higher screw accuracy in RA patients, intraoperative CT-based IGS application may be considered.

Radiographic comparison of cross-sectional lumbar pedicle fill when placing screws with navigation versus free-hand technique

BACKGROUND

Pedicle screws are often used for spinal fixation. Increasing the percentage of pedicle that is filled with the screw presumably yields greater fixation. It has not been shown whether spinal navigation helps surgeons more completely fill their instrumented pedicles.

METHODS

Fifty consecutive patients from each arm (navigated and free-hand) were retrospectively reviewed. The cross-sectional area of each instrumented lumbar pedicle and screw were measured using an automatic area calculation tool. The coronal images and measurements were blinded to the surgeons.

RESULTS

The instrumented pedicles in the navigated patients were significantly more filled by screws than the pedicles in the non-navigated patients (P < 0.001).

CONCLUSION

Obtaining a higher cross-sectional percentage fill of the pedicle with a screw is expected to provide greater spinal fixation in instrumented fusion surgery. This study shows that utilizing spinal navigation helps to more completely fill the pedicles that are being instrumented. Copyright © 2015 John Wiley & Sons, Ltd.

Role of the O-arm and Computer-assisted Navigation of Safe Screw Fixation in Children with Traumatic Rotatory Atlantoaxial Subluxation

Study Design

A retrospective analysis of 7 patients with traumatic rotatory atlanto-axial subluxation.

Overview of Literature

Cases of traumatic rotatory atlantoaxial subluxation in children are difficult to be stabilized. Surgical challenges include: narrow pedicles, medial vertebral arteries, vertebral artery anomalies, fractured pedicles or lateral masses, and fixed subluxation. The use of O-arm and computer-assisted navigation are still tested as aiding tools in such operative modalities.

Purpose

Report of clinical series for evaluation of the safety of use of the O-arm and computed assisted-navigation in screw fixation in children with traumatic rotatory atlantoaxial subluxation.

Methods

In the present study, 7 cases of rotatory atlantoaxial traumatic subluxation were operated between December 2009 and March 2011. All patient-cases had undergone open reduction and instrumentation using atlas lateral mass and axis pedicle screws with intraoperative O-arm with computer-assisted navigation.

Results

All hardware was safely placed in the planned trajectories in all the 7 cases. Intraoperative O-arm and computer assisted-navigation were useful in securing neural and vascular tissues safety with tough-bony purchases of the hardware from the first and only trial of application with sufficient reduction of the subluxation.

Conclusions

Successful surgery is possible with using the intraoperative O-arm and computer-assisted navigation in safe and proper placement of difficult atlas lateral mass and axis pedicle screws for rotatory atlantoaxial subluxation in children.

Placement of thoracolumbar pedicle screws using three-dimensional image guidance: experience in a large patient cohort

OBJECT

The goal of this study was to analyze the placement accuracy and complications of thoracolumbar pedicle screws (PSs) inserted using 3D image guidance in a large patient cohort.

METHODS

The authors reviewed the charts of 220 consecutive patients undergoing posterior spinal fusion using 3D image guidance for instrumentation placement. A total of 1084 thoracolumbar PSs were placed using either the BrainLAB Vector Vision (BrainLAB, Inc.) or Medtronic StealthStation Treon (Medtronic, Inc.) image guidance systems. Postoperative CT scanning was performed in 184 patients, allowing for 951 screws to be graded by an independent radiologist for bone breach. All complications resulting from instrumentation placement were noted. Using the intraoperative planning function of the image-guided system, the largest diameter screw possible in each particular case was placed. The screw diameter of instrumentation placed into the L3-S1 levels was noted.

RESULTS

No vascular or visceral complications occurred as a result of screw placement. Two nerve root injuries occurred in 1084 screws placed, resulting in a 0.2% per screw incidence and a 0.9% patient incidence of nerve root injury. Neither nerve root injury was associated with a motor deficit. The breach rate was 7.5%. Grade 1 and minor anterolateral "tip out" breaches accounted for 90% of the total breaches. Patients undergoing revision surgery accounted for 46% of the patients in this study. Accordingly, 154 screws placed through previous fusion mass could be evaluated using postoperative CT scanning. The breach rate in this specific cohort was 7.8%. A total of 765 PSs were placed into the L3-S1 levels in this study; 546 (71%) of these screws were > or = 7.5 mm in diameter. No statistical difference in breach rate was noted in PSs placed through revision spinal levels versus nonrevision spinal levels (p = 0.499). Additionally, no increase in breach rate was noted with placement of 7.5-mm-diameter screws.

CONCLUSIONS

Three-dimensional image guidance is a useful adjunct to placement of spinal instrumentation. The complication rate in this study was low, and accurate placement of instrumentation was achieved despite the high percentage of revision surgery cases in our patient population. Additionally, because active fluoroscopy was not used for instrumentation placement, there was minimal to no radiation exposure to the surgeon or operating room staff.