Atlanto-axial Rotational Instability

Pathology

 

Paediatric populations predisposed

- due to lateral mass anatomy and ligamentous laxity

- both alar ligaments and facet capsules must be torn to occur

 

Aetiology

 

Due to forced rotation and lateral tilt

Can be spontaneous

 

Presentation

 

Most patients have torticollis and limited rotation

 

Cock robin position 

- lateral flexion and rotation to other side

 

Fielding Classification

 

1. Rotatory fixation without anterior displacement

 

2. Rotatory fixation with anterior displacement 3 - 5 mm

 

3. Rotatory fixation with anterior displacement > 5mm

- indicates disruption of both facet joints and transverse ligament

 

4. Rotatory fixation with posterior displacement

 

Associations

 

Downs

RA

Klippel Feil

Morquio

SED

Achondroplasia

 

DDx

 

Torticollis

Atlantoaxial rotatory fixation

Ondontoid fracture

Os Ondontoid

 

Grisel's syndrome

 

Pyogenic atlanto-axial subluxation

- after upper respiratory tract infection

- inflammation induced ligamentous laxity

- can be post tonsillectomy

 

Present with painful torticollis and limited rotation

 

Xray

 

Widened atlanto - lateral mass interval

 

Dynamic CT

 

Head turned to left then to right

- demonstrate fixed subluxation

 

Management

 

Atlanto-axial instability

 

1.  Early presentation

- i.e. first day or two

- trial soft collar / analgesics

- see 1 week later

 

2.  Reduce any anterior displacement with halter traction

- add sequential weight

- check X-ray to ensure no C0/1 displacement

- valium and Phenergan

- if successful apply HTB

- flexion extension views out of HTB for residual instability

 

3.  Failure halter traction / Trial skeletal traction

 

4.  Failure skeletal traction / Open reduction and fusion

 

Residual instability

 

C1/2 Gallie fusion

 

Chronic

 

> 3/12

- consider fusion in situ

 

Grisel's

 

Usually will reduce spontaneously

 

First week

- NSAIDS and hard collar

 

Failure or > 1 week symptoms

- soft halter traction

 

> 4 weeks

- skeletal traction and HTB once reduced