SA Orthopaedic Journal
On-line version ISSN 2309-8309
Transarticular screw fixation offers acceptably high fusion rates but is not possible in 18% of patients due to a high riding vertebral artery. It also requires pre-operative anatomical reduction which is not always possible. The Harms technique utilises a posterior C1 lateral mass and C2 pedicle screw. This allows easier access due to the angle of drilling and has become an increasingly popular surgical technique. AIM: The aim of this study is to review and compare the above techniques with regard to surgery, complications and outcome. METHODS: A retrospective case note and radiographic review of 42 patients undergoing posterior C1-2 fusion in a single institution during the period 2003 to 2011, identified on a prospectively maintained database, was performed. The indication for surgery was atlanto-axial instability with post-traumatic and rheumatoid arthritis the commonest aetiologies. There was no difference in age and gender between the two groups. RESULTS: The Harms method had a slightly higher mean blood loss compared to the transarticular method. The surgical time was no different. The transarticular technique was abandoned in three cases due to inability to place the screw safely. The Harms technique was successfully completed in all cases. There were four unilateral vertebral artery injuries in the transarticular group and one in the Harms group. There were three intra-operative unintentional durotomies in the transarticular group with one in the Harms. All but one transarticular case fused, with five transarticular cases taking more than 9 months. CONCLUSION: Although the Harms technique had an increased blood loss, the incidence of vertebral artery and dura injury was lower. Fusion was similar in both groups with the only non-union occurring in the transarticular group. The Harms technique offers the advantage of intra-operative reduction and a smaller exposure due to the direction of access but at a higher instrumentation cost.
Keywords : atlanto-axial fusion; Harms; transarticular.