J Korean Neurosurg Soc.  2012 Jul;52(1):21-26. 10.3340/jkns.2012.52.1.21.

Posterior Cervical Fixation with a Nitinol Shape Memory Loop for Primary Surgical Stabilization of Atlantoaxial Instability: A Preliminary Report

• Kim DG
• Eun JP
• Park JS

• KMID: 2190518
• DOI: http://doi.org/10.3340/jkns.2012.52.1.21

Abstract

OBJECTIVE
To evaluate a new posterior atlantoaxial fixation technique using a nitinol shape memory loop as a simple method that avoids the risk of vertebral artery or nerve injury.
METHODS
We retrospectively evaluated 14 patients with atlantoaxial instability who had undergone posterior C1-2 fusion using a nitinol shape memory loop. The success of fusion was determined clinically and radiologically. We reviewed patients' neurologic outcomes, neck disability index (NDI), solid bone fusion on cervical spine films, changes in posterior atlantodental interval (PADI), and surgical complications.
RESULTS
Solid bone fusion was documented radiologically in all cases, and PADI increased after surgery (p<0.05). All patients remained neurologically intact and showed improvement in NDI score (p<0.05). There were no surgical complications such as neural tissue or vertebral artery injury or instrument failure in the follow-up period.
CONCLUSION
Posterior C1-2 fixation with a nitinol shape memory loop is a simple, less technically demanding method compared to the conventional technique and may avoid the instrument-related complications of posterior C1-2 screw and rod fixation. We introduce this technique as one of the treatment options for atlantoaxial instability.

Keyword

Atlantoaxial stabilization; Posterior cervical surgery; Nitinol shape memory loop

MeSH Terms

Alloys
Follow-Up Studies
Humans
Memory
Neck
Retrospective Studies
Spine
Vertebral Artery
Alloys

Figure

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  Fig. 1 A: Intraoperative findings after fixation of the C1 ring, mesh cage (arrow) and C2 lamina with a nitinol loop. B: Postoperative simple radiograph shows nitinol loop hooking the C1 ring and C2 lamina.

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  Fig. 2 A: Preoperative cervical computed tomography shows orthotopic type of os odontoideum. B: Magnetic resonance image shows severe cervical canal stenosis with spinal cord contusion (arrow). C: Six months postoperative cervical computed tomography shows solid bridging bone formation between C1 and C2 across the graft. D: Preoperative lateral radiograph shows orthotopic type of os odontoideum. E: Six months postoperatively, lateral radiograph demonstrates improvement of the lordotic curve and an increase in PADI from 16.00 mm to 18.53 mm. PADI: posterior atlantodental interval.

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