- See:
Hyperflexion Injuries
- Discussion:
- partial or complete tear of posterior ligaments w/ varying
degrees in widening of the interspinous and interlaminar spaces,
as well as subluxation, but not dislocation of
Facet Joint;
- hyperflexion sprain injury may include mild anterior subluxation of
involved vertebral body;
- this subluxation may be so subtle that it may only be appreciatted on
lateral films obtained in flexion;
- that stable injuries to
Anterior column include compression
frx of < 25% loss of vertebral body height & anteroinferior avulsion
frxs where the fragment width is < 20% of vertebral body width;
- that unstable injuries to
Anterior column include
compression frxs
w/ > 25% loss of ht indicating posterior ligament rupture,
and fractures thru vertebrae;
- frx lines seen on lateral radiographs or CT scans, which extend thru
vertebral body centrum in coronal plane represent
anterior column failure;
- Subluxation in RA:
- anterior subluxation occurs as the result of
Facet Joint disease and
is most commonly seen at C5/6 level, which is level of greatest mobility;
- any level may be affected, however, and it is common to see several
levels showing anterior subluxation in a stepwise fashion;
- subaxial involvement in R.A. in less common than atlantoaxial lesions;
- Powers Ratio:
- identifies anterior subluxation and is described as ratio of BC/OA
- BC is distance from basion to midvertical portion of posterior laminar
line of the
Atlas;
- OA is distance from opisthion to midvertical portion of posterior
surface of anterior ring of
Atlas;
- if this ratio is greater than 1, anterior subluxation exists;
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Upper cervical instability in rheumatoid arthritis.
