ABSTRACT
Posterior transarticular C1-C2 screw fixation is the most popular technique for instrumented atlantoaxial fusion. The construct is usually augmented by a sort of sublaminar C1-C2 wire fixation. In spite of this augmentation, construct failure with pseudarthrosis still can be encountered and presents a real challenge. to introduce a new technique for C1-C2 fusion in which a special plate is used for fixing the arch of Cl to the lateral mass of C2. The transarticular screw fixation is done through the caudal hole in the plate. The author designed a plate [Lotus Cervical Plate, LCP] for posterior C1-C2 fixation [Intraplant Company, Germany]. The proximal end of the plate is U-shaped. Fixation to the atlas is achieved by contouring the u-shaped end of the plate to seize the arch of C1. A locking mini-screw is inserted in the arch of C1. The transarticular C1-C2 screw fixation is done through the distal hole of the plate. The plate was applied in 10 patients with atlantodental instability due to rheumatoid arthritis. Two of them were revision cases and presented with pseudarthrosis and metal failure after attempted transarticular fixation [Magerl technique] augmented with sublaminar fixation. Two plates of suitable lengths were used for the C1-C2 fixation. A corticocancellous bone graft was fixed between the decorticated posterior arch of C1 and the lamina of C2. The period of follow up ranged between 12 months and 20 months [mean: 15.20 months, sd.2.49] The technique was safe. Fusion was evident 3 months after the operation. Apart from remodelling of the graft, no metal failure occurred. From the biomechanical point of view C1-C2 plating is stiffer than transarticular C1-C2 fixation even when the latter is augmented by sublaminar fixation. The introduced technique can supplant the traditional augmentation of Magerl technique using wire or cable particularly in severe C1-C2 instabilities