Radiology Coding Alert

Anatomy:

Clue in to Facet Joint Structure

Each vertebra has a total of four facet joints -- two joints that articulate (loosely connect) with the vertebra above and two that articulate with the vertebra below. For example, the C5 vertebra has right and left facet joints that articulate with the C4 vertebra above. The C5 vertebra also has right and left facet joints that articulate with the C6 vertebra below.

Two paravertebral facet joint nerves (medial branches) provide the sensory innervation for each facet joint. For example, the C4 and C5 medial branches provide the sensory innervation from the C4-C5 facet joint back to the spinal cord. The provider could potentially treat either one or two joints at the same level. Because of this, the 2011 codes with descriptors focusing on vertebral levels didn't adequately reflect the work performed. Codes 64633-64636 more accurately describe the situation by focusing on joints instead of nerves.