A 22 year old man with history of chronic backache presents to your office. The patient has a history of progressive low back pain for 3 years. He relates his pain to a motor vehicle accident that happened to him 3 years ago. X-rays of the spine were performed three years ago at the start of his symptoms and were normal. He reports that his pain is worst in the morning but gradually improves towards the end of the day. The patient has been using over the counter ibuprofen and tylenol with out any relief. He was recently started by his primary care doctor on oxycodone which he takes 6 times daily as needed for pain. This did not relieve his pain either. The patient is here to see you for a second opinion. The most appropriate next step in management is :
A. Plain X-ray of lumbar spine and pelvis
B. MRI of the lumbar spine
C. Prescribe long acting narcotic
D. Physical Therapy
E. HLAB27 testing
Archer USMLE Step 3 Blog 
a
b
aaaaa?
a
First A, then B based on the findings; XR can also identify joint space loss, subchondral sclerosis, and osteophytes of OA which may be a ddx for his back pain.
b
Ans.A.
Patient has clinical presentation consistent with Ankylosing spondylitis. According to modified New York Criteria, diagnosis of AS can be confirmed if it meets one radiological criterion and one clinical criterion. Plain X-rays of the lumbar spine and pelvis will help us to know if this is inflammatory arthritis associated with sacroileitis . Then, proceed to E
Modified New York criteria for ankylosing spondylitis. Includes Clinical and radiological parameters:
Clinical parameters:
Low back pain and stiffness for more than three months that improves with exercise, but is not relieved by rest
Limitation of motion of the lumbar spine in both the sagittal and frontal planes
Limitation of chest expansion relative to normal values correlated for age and sex
Radiological parameters :
Sacroiliitis grade ≥2 bilaterally
Sacroiliitis grade 3 to 4 unilaterally
AS is confirmed if patient fulfills at least one radiological parameter plus at least one clinical parameter
answer A
Radiographs are the single most important imaging technique for the detection, diagnosis, and follow-up monitoring of patients with ankylosing spondylitis. Overall bony morphology and subtle calcifications and ossifications may be demonstrated well radiographically. The diagnosis may be reliably made if the typical radiographic features of ankylosing spondylitis are present. Radiographs are limited in detecting early sacroiliitis and in demonstrating subtle changes in the posterior elements of the vertebrae.
Magnetic resonance imaging (MRI) is useful in assessing early cartilage abnormalities and bone marrow edema. MRI is limited by its relatively poor ability to detect calcification, ossification, and cortical bony changes.
But, because cost benefits, always start with plain X ray and then MRI.
thx