Posterior stabilization with Halifax interlaminar clamps in traumatic atlanto-axial instability. A report of 12 cases

From May 1989 to July 1992, 20 consecutive cases of traumatic atlanto-axial (C1-2) fracture-dislocations and subluxations, treated at this Hospital, were reviewed. Among them, the 12 cases undergoing Halifax interlaminar clamping and fusion procedures for C1-2 instability were analysed. There were 8 male and 4 female patients whose ages ranged from 15 to 56 years, with an average of 33 years. In a mean follow-up period of 31.7 (range, 12-48) months, there was no operative mortality. In two patients, C1-2 fracture could not be completely reduced and resulted in malaligned fusion. Another two had malaligned fusion because of overcorrection and posterior motion of C1 on C2. In functional and imaging study, all 12 patients had stable C1-2 structure. Loosening of the screw was noted in 2 cases (2/12). The present series seems to indicate the Halifax interlaminar clamping techniques provide an excellent alternative for posterior fusion in traumatic C1-2 instability. Proper case selection is indispensable to clinical success. To achieve good results, the ideal alignment of the instability must be reduced before clamping and fusion procedures.