Radiology Coding Alert

Ankylosing spondylitis is an inflammatory process that affects the spine. The cause of ankylosing spondylitis is not precisely known. It is a genetic condition and most, but not all, patients test positive for gene HLA-B27. Patients affected are usually young adults who may be late twenties or early thirties. It is a systemic disease which can present with fever, fatigue, and loss of appetite.

Although the spine is the most common site affected, other joints can also be involved including the sacroiliac joints. Any region in the spine can be affected and the patient typically complains of pain and stiffness. The vertebrae may fuse together resulting in spinal stiffness and limitation in mobility. The patient may develop a stooped posture and may face challenges performing daily routine activities.“Modest traumatic injuries can result in fractures through the ankylosed disc space. The radiographic findings in these injuries can be subtle,” says Gregory Przybylski, MD, director of neurosurgery, New Jersey Neuroscience Institute, JFK Medical Center, Edison.

Radiographic findings: Your physician will depend upon radiographs to detect, diagnose, and follow up a patient with ankylosing spondylitis. You will find clinical note specifying subchondral bony erosions in the iliac side of the sacroiliac joint. Other findings may include bony proliferations and subchondral sclerosis. In the late stages, the sacroiliac joint may show bony fusion.

Your radiologist will typically specify that the changes were symmetrical and bilateral. In rare cases, the asymmetrical changes are found. Look for terms like ‘squaring of vertebrae, bamboo spine, Romanus lesion, shiny corner sign, syndesmophyte formation, chalk stick fractures, pseudoarthrosis, Andersson lesion, and enthesopathy. Your physician may also like to confirm the findings on CT or MRI.