As i said before, the Coflex device is not something I would use due to the basic theory of its use. This device is designed to wedge between the two vertebra at the spinous processes. This causes the two vertebra to be forced into flexion which in turn causes deleterious effects on the rest of the lumbar spine. In addition, this device can erode into the spinous processes which can cause lower back pain and will lose its effectiveness when it erodes.
Flexion does reduce the pressure on whatever structure is being compressed (lateral recess stenosis, foramina stenosis or central stenosis) but why not just decompress these structures in the first place? The surgeon should not just throw this device in. Take care of the structural problem and don’t put a bandaid on it.
If the problem is back pain and instability, this device does not take care of this problem. The problem with instability is failure of the disc and facets. Putting this device in does not solve that problem.