Posterior atlantoaxial three-point fixation: comparison of intraoperative performance between open and percutaneous techniques.
BACKGROUND
Atlantoaxial instabilities, which require surgical fixation follow a variety of clinical disorders. Different surgical procedures are used for stabilization of the atlantoaxial complex, mainly posterior wiring techniques and transarticular screw fixation. Nowadays, often a combination of transarticular screws and a posterior one-point fixation is used to achieve a three-point fixation, with superior biomechanical stability and good clinical results. Different modifications were developed to improve this technique. In 1995, a percutaneous approach for atlantoaxial stabilization was introduced. In clinical studies, the technique showed a tendency towards better outcome. Beside the outcome, the intraoperative performance is of special interest for minimal invasive approaches. We therefore compared the operation time, screw angulation and blood loss, between the open and percutaneous posterior atlantoaxial techniques.


METHODS
Two groups, each consisting of 17 patients, with either open (group 1) or percutaneous (group 2) atlantoxial stabilization, were compared. The operation time was retrospectively acquired from the patient's charts. The data for blood loss was provided by our anaesthesiological department, separated for intraoperative, postoperative and total blood loss. Screw angulation was measured on the postoperative x-ray by an orthopaedic surgeon.


RESULTS
The percutaneous group showed an average intraoperative blood loss of 239.7 ml, compared to 929.4 ml for the open group (p< or =0.001). The analogue values for the postoperative blood loss were 142.9 ml and 379.4 ml for group 2 and group 1, respectively (p=0.008). Consecutively, the total blood loss showed also a statistically significant difference (p< or =0.001). The operation time was significantly different (p< or =0.001), with average values of 175.3 min (group 1) and 110.6 min (group 2). Screw angulation showed a trend towards a steeper angulation in the percutaneous group with an average angle of 56.8 degrees , compared to 53.9 degrees (group 1), although this was not statistically significant (p=0.053).


CONCLUSIONS
The percutaneous technique for atlantoaxial stabilization with a three-point fixation has clear intraoperative benefits, with shorter operation time and reduced blood loss. A trend towards steeper screw angulation was found and shows at least equal feasibility for transarticular screw placement with the percutaneous technique, compared to the standard open approach.
Schmidt
René
R
Department of Orthopedics and SCI, Orthopädische Klinik mit Querschnittgelähmtenzentrum, University of Ulm, Oberer Eselsberg 45, 89081 Ulm, Germany. rene.schmidt@gmx.de
Richter
Marcus
M
Gleichsner
Franziska
F
Geiger
Peter
P
Puhl
Wolfhart
W
Cakir
Balkan
B
D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena; D016063:Blood Loss, Surgical; D001863:Bone Screws; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods*; D016896:Treatment Outcome