A 52 y.o. male presents with back pain so severe he has to crawl on the floor and cannot walk.
What do you see on the L side of this image that would explain his pain?
Our patient had sacroiliitis which is inflammation of the SI joint resulting in pain. The SI joint is one of the largest joints in the body and it is estimated that 10% of all back pain is actually from the SI joint. In those patients 50% have radiation of the pain into the leg. The causes of sacroiliitis are both degenerative and inflammatory. Some of the inflammatory conditions leading to sacroiliitis are ankylosing spondylitis, psoriatic arthritis , hyperparathyroidism and bacterial infections.
Sacroiliitis in ankylosing spondylitis
One of the most common causes of inflammation of the SI joint is pregnancy. The hormone relaxin leads to the relaxation causing stretching and widening of the SI joint. The increased weight of pregnancy causes extra mechanical stress on the joint.
A mimic of sacroiliitis is a sacral insufficiency fracture. Osteoporosis is the predominant risk for sacral insufficiency fractures. They are a type of stress fracture associated with normal stress applied to a weakened bone. Steroid induced osteopenia, RA, multiple myeloma , hip replacement Paget’s disease and renal osteodystrophy are all risk factors for these fractures.
SPECIFIC TESTS FOR THE SI JOINT
FABER test-reproduction of pain after flexing the hip while also abducting and externally rotating the hip.
Sacral distraction test- Applying pressure to the anterior superior iliac spine.
Iliac compression test- reproduction of pain after applying pressure downward on the superior aspect of the iliac crest.
THE SI JOINT IN ANKYLOSING SPONDYLITIS
Classic ankylosing spondylitis occurs in young males and is associated with HLA-B27 and often affects the SI joint. They develop a “bamboo spine” which is a result of vertebral body fusion by syndesmophytes. Patients have an increased risk of fractures both because of the rigidity of the spine and osteoporosis. They often have cervical spine injuries which is not characteristic of osteoporosis alone.
A patient from last week with ankylosing spondylitis and an odontoid fracture
Our patient was diagnosed on MRI with sacroiliitis secondary to arthritis and was treated with NSAIDS In spite of physical therapy he developed difficulty walking and was diagnosed with cervical myelopathy. He is currently recovering from surgery.
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Ziade N. HLA B27 antigen in Middle Eastern and Arab countries: systematic review of the strength of association with axial spondyloarthritis and methodological gaps. BMC Musculoskelet Disord. 2017 Jun 2
Kao F, Hsu Y, Liu P, et al. Osteoporotic sacra insufficiency fracture an easily neglected disease in elderly patients Medicine Dec 2017 Vol 96 Issue 51p e9100 doi:10.1097/MD.0000000000009100.
Hatgis J, Granvillle M, Jacobson R, et al. Sacral insufficiency fractues: recognition and treatment in patients with concurrent lumbar vertebral compression fractures. Cureus 2017;9:e1008.