The human cervical spine is an extremely mobile part of the body. It
allows us to flex, extend and rotate our head with significant degrees
of motion. The ability to flex comes from the numerous joints that connect
each vertebra to each other.
Patients with abnormal motion (also called cervical instability) will
often complain of significant neck, shoulder and arm pain. Occasionally
cervical instability can result from such conditions as traumatic
fractures, tumors, inflamed rheumatoid arthritis.
We can visualize this normal motion on special x-rays which are called flexion and extension x-rays. Examples are below:
The flexion and extension x-rays allows the physician to visualize the motion of all joints of the cervical spine. Abnormal motion refers to either excessive or reduced amount of flexibility of one of the joints in the spine. This can result in abnormal alignment in the bones of the neck.
The treatment for cervical instability (or abnormal motion) usually requires a cervical fusion. The fusion surgeries attempt to lock together two vertebras which have exhibited abnormal motion by treating the instability in bones. This can significantly improve the patient's pain.
Conversely, Artificial Cervical Discs are used to replace a problematic cervical disc while at the same time while preserving the normal spinal motion. A patient with cervical instability generally is not a candidate for an Artificial Cervical Disc Replacement.