To introduce the design, modification and clinical application of Jefferson-fracture reduction plate (JeRP), which was designed for the surgical treatment of Jefferson-fracture of the atlas, and evaluate the clinical effects.

JeRP system was designed for the treatment of patients with Jefferson fractures without rupture of the transverse ligament. Eight patients were treated operatively with the JeRP system for reduction and fixation of the fracture. Three-dimensional spiral CT was used to determine the integrity of the transverse ligament. During the preliminary clinical application, the clinical results were satisfied. But there were some disadvantages. The entry point of the superior screw of the mass was much too high, causing the screw penetrate into the atlantooccipital joint. Three-dimension Computed tomography images were used to analyze the anatomic characters of atlas. The relative anatomic parameter of the atlas was obtained. According to it, the Jefferson-fracture reduction plate was modified. The modified JeRP was applied clinically in another 4 patients. Extension and flexion X-ray were used to determine whether there was atlatoaxial dislocation after the operation. CT was used to determine whether there was bony fusion.

Eight patients with Jefferson fractures without rupture of the transverse ligament were treated with the original JeRP. The mean follow-up time was 6.3 months. Neck pain was significantly alleviated after surgery in all patients. There was no infection or wound breakage. The reduction of the fracture was satisfied in all patients. Bony fusion was achieved in 3 months. No atlantoaxial dislocation was found in all patients during follow-up. Of the 8 patients, three complained about the movement restriction of the neck. The radiological examination found the upper screw of lateral mass breaking into the atlas-occipital joint. Anatomic structure of C₁ lateral mass was measured using 1 mm CT scans. The optimal entry points and other parameters for the screws of the mass were determined. According to the anatomic parameters, we modified the JeRP. Another 4 patients with Jefferson fractures without rupture of the transverse ligament were treated operatively using this modified JeRP system. The preliminary clinical results were satisfactory. No screw penetrating into the atlas-occipital joint happened.

Although the preliminary results of the application of JeRP were satisfactory, there was a highratio of atlas-occipital joint violated during lateral mass screw insertion. The modified JeRP can avoid this complication.

Cervical atlas; Spinal fractures; Internal fixators; Fracture fixation, internal