This is Barry Belosis, one of the musculoskeletal radiology fellows at Stanford University. 21 year old female with history of lumbosacral spondylolisthesis presented with this right shoulder pain. Concerned for HLA-B27 spondyloarthropathy. The patient in this case presented with this imaging. On our most left-hand side here we can see a right shoulder MRI coronal T2 fat set imaging showing some soft tissue edema and capsular edema of the acromioclavicular joint. There is no significant joint effusion. The ankle MRI of the same patient demonstrate this tibial tail joint effusion and also this non-specific bone marrow edema at the posterior margin of the talus. The imaging of the spine here we can see a spondylolisthesis of L5 over S1 which was reported to be secondary to bilateral parse defect, which is not depicted on this image. This is a different patient with ankylosing spondylitis. Ankylosing spondylitis typically affects males 15 to 35 years of old and largely affects the spine in the sacroiliac joint. The peripheral joints are affected later including the hips, shoulders, and the knees. Here is a normal sacroiliac joint. We have a preserved joint space with no bone erosions. One of the earliest signs of ankylosing spondylitis is sacroiliitis. On our CT, we see this irregularity predominantly at the iliac side of the sacroiliac joint bilaterally. These are consistent with erosions and are typically seen in acute phase of sacroiliitis. On the late stage of ankylosing spondylitis, we can see that there is fusion of the sacroiliac joint or ankylosis consistent with patient's history of ankylosing spondylitis. This is the MRI of the sacroiliac joint depicting the sacroiliitis. Here on our Axial T1 imaging, we can see this hypo-intense band predominantly on the iliac side. Also, we can see a little bit of hypo-intense band on the left iliac margin of the sacroiliac joint. On our Axial T2 FATSAT imaging, we can see this bone marrow edema or bright signal predominantly in the iliac side bilaterally. These are all consistent with sacroiliitis in the acute phase. After the sacroiliac joint, the thoracolumbar spine is the second most commonly affected. Here we can see the squaring of the vertebral bodies and also some flowing syndesmophytes which are typical of ankylosing spondylitis. In here, we can see what we call a bamboo spine. Bamboo spine can predispose the patient to trauma. It is basically a stiff spine, so any kind of little trauma can cause major fracture subluxation in the spine because they are stiff. These are all in three different patients where we can see there is fracture dislocation of the vertebral bodies. Also here in the thoracolumbar junction and in this patient where we can see that there is posterior subluxation on the upper thoracic spine. Other imaging findings associated with ankylosing spondylitis includes this dagger sign which is basically a single central radiodense line typically seen in the frontal radiographs related to ossification of the interspinous ligament which is secondary to enthesitis. Enthesitis is also another imaging findings of ankylosing spondylitis. Enthesitis is basically an inflammation at the attachment of a ligament or tendon to bone. Here, we can see some enthesitis at the attachment of the Achilles tendon and also at the plantar fascia. On our MRI of this patient, we can see this bone marrow edema both at the attachment of the Achilles tendon here and the plantar fascia attachment here. In advanced cases of patients with ankylosing spondylitis, we do affect the peripheral joints including the hips where we can see that there is complete loss of joint space bilaterally left greater than right.

2nd Edition, CASE 46

2nd Edition

Rheumatology

spondylolisthesis

HLA-B27

ankylosing spondylitis

sacroiliitis

bamboo spine