Direct C1 lateral mass screw for cervical spine stabilisation

# Guidance
Current evidence on the safety and efficacy of direct C1 lateral mass screw for cervical spine stabilisation appears adequate to support the use of this procedure, provided that the normal arrangements are in place for consent, audit and clinical governance.
This procedure should be performed only in specialist units where surgery of the cervical spine is routinely undertaken.# The procedure

# Indications
Atlantoaxial instability (excessive movement between the first and second cervical vertebrae) can be caused by trauma, malignancy and inflammatory or congenital defects. It can present with local pain, but if the spinal cord is compressed it can cause clumsiness, lack of coordination, difficulty walking and, rarely, paralysis or death. Treatment is by stabilisation of the C1 (atlas) on to the C2 (axial) vertebra.
Traditional methods of atlantoaxial fusion involve using wires and bone grafts, but these require external support in the postoperative period, including halo devices. Methods of rigid fixation with transarticular screws between C1 and C2 have been described. These do not require external fixation, but are not appropriate for every patient.

# Outline of the procedure
Under general anaesthesia, the patient is placed in the prone position and standard posterior exposure of the cervical spine is performed. Screws are inserted into the lateral masses of C1 and fixed by rods corresponding to screws in the lateral masses or pedicles of C2. The posterior arch of bone compressing the spinal cord may be removed. An onlay graft of bone permits a permanent fusion between C1 and C2.

# Efficacy
The primary endpoint in the literature was successful fusion. In two case series of 37 and 160 patients and one case report, immobilisation of C1 on C2 was achieved in 196 patients (in the remaining two patients the intent was not to procure fusion, see Sources of evidence for more information).
In a case series of 157 patients, clinical and neurological recovery was documented in 100% but assessment measures were not described.
A case series investigating a lateral mass and plate system reported that 6% (9/157) of procedures could not be completed because of inadequate exposure of the atlantoaxial region. For more details refer to the Sources of evidence.
The Specialist Advisors considered this to be a variation on existing fusion techniques.

# Safety
In two case series of 157 and 37 patients, there were no reports of implant failure. No vertebral artery injuries occurred in the three case series (n = 212) or in the one case report where safety outcomes were reported.
In a case series, sensory loss in the distribution of the C2 nerve root was reported by 11% (18/157) of patients undergoing screw and plate fixation. In the same series, six screws were found to be penetrating more than 4 mm from the anterior cortex of C1 but with no clinical complications. One screw was found to be broken at 18 months' follow-up. In another case series, deep wound infection was reported in 3% (1/37) of patients. For more details refer to the Sources of evidence.
The Specialist Advisors stated that potential adverse events include haemorrhage from the vertebral venous plexus and screw failure or loosening. Less common but more serious complications may include injury to the vertebral artery, and spinal cord injury caused by screw misplacement.

# Other comments
It was recognised that the evidence on this procedure was limited, but it was considered sufficient in the context of the conditions requiring treatment.
These recommendations are based on evidence from studies using two different techniques  the plate system and the more recent polyaxial screw and rod systems.
Andrew DillonChief ExecutiveDecember 2005# Further information

# Sources of evidence
The evidence considered by the Interventional Procedures Advisory Committee is described in the following document.
'Interventional procedure overview of direct C1 lateral screw procedure for cervical spine stabilisation', February 2005.

# Information for patients
NICE has produced information on this procedure for patients and carers. It explains the nature of the procedure and the guidance issued by NICE, and has been written with patient consent in mind.# About this guidance
NICE interventional procedure guidance makes recommendations on the safety and efficacy of the procedure. It does not cover whether or not the NHS should fund a procedure. Funding decisions are taken by local NHS bodies after considering the clinical effectiveness of the procedure and whether it represents value for money for the NHS. It is for healthcare professionals and people using the NHS in England, Wales, Scotland and Northern Ireland, and is endorsed by Healthcare Improvement Scotland for implementation by NHSScotland.
This guidance was developed using the NICE interventional procedure guidance process.
We have produced a summary of this guidance for patients and carers. Information about the evidence it is based on is also available.
Changes since publication
January 2012: minor maintenance.
Your responsibility
This guidance represents the views of NICE and was arrived at after careful consideration of the available evidence. Healthcare professionals are expected to take it fully into account when exercising their clinical judgement. This guidance does not, however, override the individual responsibility of healthcare professionals to make appropriate decisions in the circumstances of the individual patient, in consultation with the patient and/or guardian or carer.
Implementation of this guidance is the responsibility of local commissioners and/or providers. Commissioners and providers are reminded that it is their responsibility to implement the guidance, in their local context, in light of their duties to avoid unlawful discrimination and to have regard to promoting equality of opportunity. Nothing in this guidance should be interpreted in a way which would be inconsistent with compliance with those duties.
Copyright
 National Institute for Health and Clinical Excellence 2005. All rights reserved. NICE copyright material can be downloaded for private research and study, and may be reproduced for educational and not-for-profit purposes. No reproduction by or for commercial organisations, or for commercial purposes, is allowed without the written permission of NICE.
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