C1-C2 fixation techniques under the spotlight
MedWire News: Two widely used C1-C2 fixation techniques are effective for stabilizing the atlanto-axial complex, but show some differences in safety and long-term robustness, say researchers.
The findings, from a retrospective comparison of the Magerl's and Harms' techniques, are reported by Pierluigi Vergara (l'Università degli Studi di Napoli Federico II, Italy) in the journal Neurosurgery.
Vergara's team reviewed outcomes in 122 patients with atlanto-axial instability who underwent Harms' or Magerl's fixation. These are "probably the most effective and commonly used techniques," say the researchers, yet there is little evidence to help surgeons decide between the two.
The patients' mean age was 53.6 years, 75 were female, and the indication for surgery was degenerative instability in 57.8% (mostly rheumatoid arthritis), acute post-traumatic instability in 23.7%, and chronic post-traumatic instability in 8.9%.
All patients were treated with C1-C2 posterior fixation and most used a postoperative cervical orthosis. Among 106 evaluable patients, the mean duration of follow-up was 34 months.
Vergara et al found no differences between the Magerl's and Harms' techniques with respect to duration of surgery, intraoperative and postoperative blood loss, postoperative hospital stay, and postoperative pain.
However, complications were significantly more frequent in the Magerl's versus the Harms' group, at 21.0% versus 2.1%. This difference was driven by a 10-fold higher rate of vertebral artery (VA) injury with the Magerl's procedure, along with higher rates of procedure-related complications such as fracture of the k-wire, fracture of C2 lateral mass, fracture of the hip from graft site, and loss of somatosensory evoked potential.
The VA injuries did not typically lead to neurologic symptoms or deficits, note the researchers. Just three patients developed serious sequelae; these included one case of transient ischemic attack (TIA), one case of mild hemiparesis complicated by TIA, and one death.
In terms of clinical outcomes, neck pain and C2 radiculopathy improved dramatically after surgery, with no significant difference between the two techniques. There were also modest improvements in neurologic function of the hands and difficulties in walking, which again did not differ between groups.
With regard to radiologic outcomes, fusion rates at the end of follow-up were numerically but not statistically higher in the Harms' surgery group while the range of movement in flexion/extension between C1 and C2 was significantly lower in the Harms' group as compared with Magerl's.
Commenting on their findings, the researchers admit that retrospective studies are always subject to bias and confounding; nevertheless, they believe their data represent "a comprehensive comparison of the Magerl's and Harms' techniques."
Vergara and team conclude: "Harms' technique and Magerl's technique with posterior wiring are both effective options for stabilizing the atlanto-axial complex. They are, in many ways, very similar and achieve similar clinical results."
They add: "Within the limitations of a retrospective study we found that Harms' technique seems to be more practical, less dependent on reduction or anatomical variations of vertebral artery, safer (lower incidence of VA injury and complications), and stronger (lower incidence of screw breakage and greater reduction of movements)."
By Joanna Lyford