Anterior Shear Test: Assessing Upper Cervical Stability

The Anterior Shear Test is a critical provocative test used to evaluate the stability of the upper cervical spine, particularly the atlantoaxial segment (C1-C2). It is primarily used to check the integrity of the transverse ligament.

1. Purpose

The primary purpose of the Anterior Shear Test is to **assess the stability** of the upper cervical spine, specifically the integrity of the transverse ligament and the dens (odontoid process). It checks for anterior instability of the atlantoaxial joint (C1-C2).

2. How to Perform

Warning: This test applies stress to the spinal cord area. It must be performed with extreme caution and only if no fracture is suspected.

1. The patient is positioned in supine (lying on their back) with the head in a neutral position, supported by the examiner.
2. The examiner palpates the C2 spinous process and transverse processes to identify the level.
3. The examiner places their index fingers (or hands) on the posterior arch of C1 (atlas).
4. The examiner applies a firm, controlled anterior force (shearing force) to C1, lifting it forward relative to C2, while keeping the head stable.

3. Positive & Negative Sign

Positive Sign (Test is POSITIVE):
A positive test (indicating instability) is:

• Reproduction of symptoms such as a "lump" in the throat.
• Lip parasthesia (numbness/tingling) or extremity paresthesia.
• Nystagmus (involuntary eye movement) or dizziness.
• Excessive anterior translation or a "soft" end-feel.

Negative Sign (Test is NEGATIVE):
A negative test is when no symptoms are produced and there is a firm end-feel.