What is the mechanism of injury for a unilateral facet lock injury?

• A. Extension with rotation
• B. Flexion with lateral bending
• C. Rotation with flexion
• D. Severe distraction with straightening

Answer: (C)

A unilateral facet lock injury typically occurs as a result of a combination of rotation and flexion forces. During this injury mechanism, the vertebrae can become misaligned, leading to a locking of the facet joints on one side. In this scenario, when the spine is flexed and simultaneously rotated, it places undue stress on the facet joints, causing one side to become trapped or locked due to the positional change and the forces exerted.

This mechanism is particularly significant because it highlights how certain movements can predispose the spine to injury. In such an event, the flexion component contributes to compressive forces on the spinal column, while the rotational aspect increases the likelihood of one facet joint engaging improperly with its counterpart. This combined effect is central to understanding how a unilateral facet lock can occur in clinical scenarios, leading to pain, restricted movement, and potential neurological complications depending on the severity of the injury.

Understanding this mechanism aids in both diagnosis and treatment, as recognizing the need for appropriate therapeutic interventions or alignment techniques can prevent further complications and promote healing.