[Bone screw osteosynthesis of dens fractures. Technical surgical aspects and results].

Twenty cases of Anderson and d'Alonzo type II and "shallow" type III fractures of the dens were treated by anterior screw fixation: the results were reviewed and compared with previously published results obtained in series of such fractures treated non-surgically, by posterior C1-C2 arthrodesis or anterior screw fixation. The complication rate of 25% in our series is comparable to those reported in a previously published review of studies on posterior wiring for C1-C2 arthrodesis. Three of our cases in which complications occurred (15%) were recognized in retrospect as inappropriate for the use of this technique: in one of these patients there was confirmed non-union, and the other two had markedly osteoporotic bone. A meticulous operative technique and the use of special instruments may improve the success rate. The anterior screw fixation method, however, allows for maximal post-treatment cervical motion, since it makes arthrodesis unnecessary and minimizes the degree and duration of postoperative external immobilization. It also reduces the iatrogenic trauma since an anterior rather than a posterior cervical approach is taken and supplementary bone grafting is not required. Anterior screw fixation of type II dens fractures appears to be the ideal method of treatment for these injuries, but since it is difficult to perform its use should be limited only to experienced spine surgeons with access to the appropriate surgical facilities.