Atlanto-axial fusion: Transarticular versus Harms techniques

HJ Stander, RN Dunn


Purpose of study 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.

The aim of this study is to review and compare the above techniques with regard to surgery, complications and outcome.

Description of methods This study is a retrospective chart and radiographic review of patients undergoing posterior C1-2 fusion in a single institution in the period 2003 to 2011. The most common aetiology was rheumatoid arthritis and post-traumatic instability. All atlanto-axial instability patients that came to surgery are included in this study, and only cases with less than six months follow-up were excluded. We report on surgical indications, surgical outcomes, complications and radiographic outcomes.

Summary of results No statistically significant differences were found in blood loss (p=0.47) or surgical time (p=0.44) using the Mann-Whitney U test. Complications in patients undergoing transarticular screw fixation included the need to abandon transarticular screws in two cases due to technical difficulty, metalware failure in two cases and intra-operative cerebrospinal fluid leaks in 2 cases. The Harms technique was associated with a single case of cerebrospinal fluid leak.

Conclusion There is no significant difference in surgical time and blood loss between the two techniques. Both are reliable in terms of fusion. The Harms technique offers the advantage of intra-operative reduction and a smaller wound due to the direction of access. The decision to use one or the other is based on the surgeons skill levels, ability to pre-operative reduce the joint and possibly the cost.