The Sharp Purser Test is performed if atlanto-axial instability is suspected, indicating subluxation of the atlas on the axis and probable damage to the transverse ligament.
Execution: The examiner places one hand over the patient’s forehead, while the thumb of the other hand is placed over the spinous process of C2 (axis) to stabilize. The patient is then asked to slowly flex the head while the examiner presses backward with the palm on the forehead.
Outcome: A backward slide of the head, felt by the examiner during the movement. The slide backwards indicates that the subluxation of the atlas has been reduced. The slide might also be accompanied by a “clunk”.
Note: This test should be performed with extreme caution.
(Uitvlugt et al. 1988)
See THESIS, section “Sharp Purser Test” for further discussion.