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Sacroiliitis (rare plural: sacroiliitides), is an inflammation of one or both sacroiliac (SI) joints, and a common cause of buttocks or lower back pain. Sacroiliitis can be a manifestation of a wide range of disease processes.
Symptoms of sacroiliitis can vary. People with sacroiliitis commonly present with ipsilateral or bilateral buttock and/or midline lower lumbar area pain. Up to 50% may have pain radiating to the lower extremity.
The causes of sacroiliitis can be divided into unilateral or bilateral. See article: sacroiliitis (differential)
Conventional radiography remains the first line of imaging despite its poor sensitivity and specificity in early disease. Specific sacroiliac joint views are helpful in the evaluation and comparing both sides of sacroiliac joints.
Radiograph findings include:
sclerosis of the endplates particularly on the iliac side
irregular joint end plates
widening of joint spaces
ankylosis (end stage)
CT examinations offer greater sensitivity, accuracy and detailed information compared to plain radiography. However, due to higher radiation exposure, it is not advisable to use CT for diagnosis or follow-up purposes.
Bone scans demonstrate increased radioisotope activity of the joints and helpful in localizing the source of the pain. It is also valuable in excluding stress fractures and other bone pathologies.
Though not routinely used for evaluating the sacroiliac joints, MRI is capable of identifying early inflammatory changes of joints when other imaging is negative and excludes other differential causes such as disc prolapse which may resemble clinical symptoms of sacroiliitis.
MRI features of sacroiliitis can be divided into inflammatory and structural lesions 6,7:
subchondral sclerosis: bands of low signal (on all sequences) paralleling the joint margins, at least 5 mm from the joint space
erosions: marginal foci of articular bone loss
low T1 signal
high T2/STIR signal if active
more prominent anteroinferiorly and on the iliac side of the SIJ
when confluent may appear as joint space widening
backfill: intra-articular high T1 signal filling up excavated bone erosions
fat metaplasia: periarticular fat deposition
Treatment and prognosis
Treatment depends on the underlying cause of the sacroiliitis. Physiotherapy may also be helpful in strengthening the pelvic muscle and increase the mobilization of the SI joint. Analgesics such as NSAIDs may be useful in symptomatic management. Corticosteroid injection to the affected sacroiliac joint can be performed to reduce inflammation and pain.
Surgical fusion of the SI joint is only considered as a last resort when conservative management is ineffective.
The following conditions may mimic sacroiliitis:
- 1. Protopopov M, Poddubnyy D. Radiographic progression in non-radiographic axial spondyloarthritis. (2018) Expert review of clinical immunology. 14 (6): 525-533. doi:10.1080/1744666X.2018.1477591 - Pubmed
- 2. Bernard SA, Kransdorf MJ, Beaman FD, Adler RS, Amini B, Appel M, Arnold E, Cassidy RC, Greenspan BS, Lee KS, Tuite MJ, Walker EA, Ward RJ, Wessell DE, Weissman BN. ACR Appropriateness Criteria Chronic Back Pain Suspected Sacroiliitis-Spondyloarthropathy. (2017) Journal of the American College of Radiology : JACR. 14 (5S): S62-S70. doi:10.1016/j.jacr.2017.01.048 - Pubmed
- 3. Tsoi C, Griffith JF, Lee RKL, Wong PCH, Tam LS. Imaging of sacroiliitis: Current status, limitations and pitfalls. (2019) Quantitative imaging in medicine and surgery. 9 (2): 318-335. doi:10.21037/qims.2018.11.10 - Pubmed
- 4. Benjamin K. Buchanan, Matthew Varacallo. Sacroiliitis. (2019) Pubmed
- 5. Van der Heijde D, Ramiro S, Landewé R, Baraliakos X, Van den Bosch F, Sepriano A, Regel A, Ciurea A, Dagfinrud H, Dougados M, van Gaalen F, Géher P, van der Horst-Bruinsma I, Inman RD, Jongkees M, Kiltz U, Kvien TK, Machado PM, Marzo-Ortega H, Molto A, Navarro-Compàn V, Ozgocmen S, Pimentel-Santos FM, Reveille J, Rudwaleit M, Sieper J, Sampaio-Barros P, Wiek D, Braun J. 2016 update of the ASAS-EULAR management recommendations for axial spondyloarthritis. (2017) Annals of the rheumatic diseases. 76 (6): 978-991. doi:10.1136/annrheumdis-2016-210770 - Pubmed
- 6. María Navallas, Jesús Ares, Brigitte Beltrán, María Pilar Lisbona, Joan Maymó, Albert Solano. Sacroiliitis Associated with Axial Spondyloarthropathy: New Concepts and Latest Trends. (2013) RadioGraphics. 33 (4): 933-56. doi:10.1148/rg.334125025 - Pubmed
- 7. Laloo F, Herregods N, Jaremko JL, Carron P, Elewaut D, Van den Bosch F, Verstraete K, Jans L. MRI of the axial skeleton in spondyloarthritis: the many faces of new bone formation. (2019) Insights into imaging. 10 (1): 67. doi:10.1186/s13244-019-0752-4 - Pubmed