Fielding Classification for Atlanto-Axial Subluxation

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The Fielding classification is commonly used to categorize atlantoaxial subluxation based on the degree of displacement and the associated neurological or ligamentous damage. This classification system is primarily used to assess subluxations that occur due to trauma or inflammatory diseases, particularly in cases of rheumatoid arthritis or other conditions that lead to instability in the cervical spine.

### Fielding Classification for Atlanto-Axial Subluxation:

The Fielding classification consists of four types based on the extent of displacement between the atlas (C1) and axis (C2):

1. Type I:

1. Description: Mild subluxation.
2. Displacement: No significant displacement or very minimal displacement between the C1 and C2 vertebrae (less than 5 mm).
3. Treatment: Conservative management with physical therapy, neck immobilization, and close monitoring.
4. Instability: Minimal to no instability.

2. Type II:

1. Description: Moderate subluxation.
2. Displacement: Moderate anterior displacement of the C1 on C2 (between 5 mm and 10 mm).
3. Treatment: May require more aggressive conservative management or surgical intervention if instability persists or neurological symptoms develop.
4. Instability: Mild to moderate instability with possible neurological compromise.

3. Type III:

1. Description: Severe subluxation.
2. Displacement: Significant displacement of the C1 on C2 (greater than 10 mm).
3. Treatment: Surgical stabilization is often required to avoid spinal cord compression and neurological deterioration.
4. Instability: Severe instability with potential neurological deficits.

4. Type IV:

1. Description: Severe subluxation with rotational deformity.
2. Displacement: C1 may be displaced and rotated relative to C2.
3. Treatment: Surgical intervention is urgently required to restore alignment and stabilize the cervical spine.
4. Instability: High risk of neurological injury due to rotation and displacement.

### Key Considerations: - The Fielding classification focuses on displacement and instability of the atlanto-axial joint. - Treatment strategies vary significantly based on the degree of displacement, ranging from conservative management in mild cases (Type I) to urgent surgical intervention in severe cases (Type III and IV). - This classification is useful for trauma, rheumatoid arthritis, and other conditions affecting the cervical spine, but it is not typically used for congenital atlanto-axial subluxation.

In summary, the Fielding classification provides a framework for evaluating atlanto-axial subluxation, which helps guide treatment decisions and prognostic planning based on the extent of displacement and associated instability.