Purpose of Alar Ligament Stress Test: To test the stability of the upper cervical spine and the integrity of the supporting alar ligaments.

Patient position: Supine lying with the head rested on the examination table (supported by a pillow) in neutral alignment.

Examiner position: Standing behind the patient on the head side.

Lateral Procedure (performed while the patient is in a supine position)

Gently lift the patient’s head/neck while providing adequate support to the head & neck. Stabilize the axis vertebra with a wide pinch grip around the lamina and spinous process. Attempt passive side flexion of the head while stabilizing the axis.

Outcome:

If the alar ligament is intact, with adequate stabilization of the axis, there will be minimal side flexion of the head with a strong capsular end feel followed by a firm stop.

If excessive movement is present, proceed with the same test in all three planes: neutral, flexion and extension; and on both directions: left and right (to test both alar ligaments).

Additional Notes:

Dvorak and Panjabi reported that the alar ligament occurs in one of three planes: caudocranial, horizontal, and craniocaudal (1).

The variation in the height of dens was suggested to account for the observed variation in the orientation of the alar ligament (1). It is thus recommended to test this ligament in all three planes to accommodate for the orientation of alar ligaments (2).

However, the variation in dens height as a cause of variation in ligament orientation is not supported by OA Rawson et al (3). With regards to the lateral flexion stress test, the test is performed in 3 positions in the sagittal plane, and laxity in all 3 positions is required to confirm the presence of instability due to alar ligament laxity/rupture (4).

Rotational Procedure (performed while the patient is in sitting or supine position)

Gently lift the patient’s head/neck while supporting the posterior aspect of the head with a wide palm support. Stabilize the axis vertebra with a lumbrical grip (between thumb and finger) around the lamina and spinous process. Attempt passive rotation of the head (left or right) to the end of the available range, while stabilizing the axis.

Outcome:

If the alar ligament is intact, there will be minimal rotation of the head. If excessive movement is present (more than 20 to 30 degrees of rotation, without moving axis vertebra), injury to the opposite side alar ligament is suspected. Proceed to perform lateral flexion alar ligament stress test in the same direction to confirm your finding.

Additional Notes:

Osmotherly et al. (5) reported that the range of craniocervical rotation during rotation stress testing of intact alar ligaments should typically be 21 degrees or less. The clinicians may consider rotational instability beyond this range.

Reference:

1. Dvorak J, Panjabi MM. Functional anatomy of the alar ligaments. Spine. 1987;12(2):183-9.
2. Aspinall W. Clinical Testing for the Craniovertebral Hypermobility Syndrome. Journal of Orthopaedic & Sports Physical Therapy. 1990;12(2):47-54.
3. Osmotherly PG, Rawson OA, Rowe LJ. The relationship between dens height and alar ligament orientation: a radiologic study. Journal of manipulative and physiological therapeutics. 2011;34(3):181-7.
4. Beeton K. Instability in the upper cervical region; clinical presentation, radiological and clinical testing. Manipulative Physiotherapist. 1995;27(1):19e32.
5. Osmotherly PG, Rivett D, Rowe LJ. Physical therapy. 2013;93(7):986-92.