- See: Anatomy of
C1 /
C2
- Discussion:
- classically described as a 4 part burst frx of the
atlas, w/ combined anterior and posterior arch fractures;
- frx variants: include two and three part fractures;
-
pediatric frx:
- frx proceeds thru open synchondroses, and may occur w/ minimal trauma;
- posterior synchondroses fuses at age 4;
- anterior synchondroses fuses at age 7;
-
mechanism:
- original description in 1920 noted role of axial compression;
- may also be caused by hyperextension, causing a posterior arch fracture;
-
associated injuries:
- approx 1/3 of these fractures are associated with a
axis fracture;
- approx 50% chance that some other
C-spine injury is present;
- low rate of neurologic deficits is due to large breadth of
C1 canal;
- Exam:
- pts usually complain of upper neck pain;
- pts are usually neurologically intact;
- in cases of vertebral artery injury, neurologic injury can occur;
- neurologic injury may manifiest as Wallenberg's syndrome w/ ipsilateral loss of cranial nerves,
Horner's syndrome, ataxia, and loss of contra-lateral pain and temp. sensation;
- Radiographs: 
- Odontoid view:
- open mouth odontoid view shows overlapping of
C1 facets on
C2 facets;
- if sum of lateral mass displacement over articular
surfaces of
axis is > 7 mm,
transverse ligament is likely to be torn;
- this fracture is therefore considered unstable & should be rx'ed in
halo for 3 months;
-
children:
- overlapping lateral masses can be a normal variant in children and therefore this view
may not allos assessment of whether frx is stable or unstable;
- Lateral view:
- shows
prevertebral soft tissue widening
- if atlantodental interval is
> 4 mm, there may be a rupture of the
transverse ligament;
- if antantal dens interval is > 6 mm,
transverse ligament is presummed to be disrupted and the injury is unstable;
- fusion anomalies of the
Atlas differ from a burst frx in that fusion defect has
well corticated margins and is associated w/ no soft tissue swelling;
- Flexion and Extension Views:
- usually required to determine whether there is
transverse ligament disruption;
- atlantodens interval > 3 mm indicates hypermobility;
- may detect concomitant anterior hypermobility;
- CT Scan:
- probably should be ordered for all children suspected of having Jefferson frx,
since the odontoid view may be difficult to interpret;
- additional information may be provided by a CT scan, which may detect
ligament avulsion frx, even if displacement is < 7 mm;
- CT of
C1 is often helpful in further delineating exact displacement of fragments;
- Treatment of Stable Frx:
- by definition stable fractures are those w/ intact
transverse ligament;
- nondisplaced or minimally displaced frx is rx'ed w/ orthosis;
- soft-collar treatment is sufficient for isolated posterior arch frx;
- w/ minimally displaced fracture (and overhang is < 7 mm), then frx is stable and should be
treated in a rigid support, such as a cervicothoracic brace, for 3 month;
- although late subluxation of C-1 is not common, it should be looked for following bony healing;
- Treatment of Unstable Frx:
- separation of lateral masses implies that
transverse ligament is ruptured, and is therefore unstable;
- prolonged cranial traction is only method that will reduce lateral mass displacement, because
halovest will not dependably produce sustained traction;
- w/ adequate reduction following traction,
halovest can be worn although
late atlantoaxial instability may occur;
-
halo or skeletal traction is necessary for a total of 3 months;
- w/ greater than 5 mm of C1-C2 subluxation consider C1-C3 fusion;
References
Fractures of the atlas
Non-union of fractures of the atlas
Injuries of the atlas and axis. A follow-up study of 85 axis and 10 atlas fractures.
Jefferson fracture in a 2-year-old child.
