Frequency of pertinent MRI abnormalities of the sacroiliac joints of patients without spondyloarthropathies: a systematic review of the literature

Infectious sacroiliitis: MRI- and CT-based assessment of disease extent, complications, and anatomic correlation

OBJECTIVE

To describe the frequency of MR and CT features of infectious sacroiliitis (ISI) and assess its extent and complications MATERIALS AND METHODS: This retrospective study included patients with ISI who were evaluated between 2008 and 2021 in a single center. Two radiologists reviewed MRI and CT images to determine the anatomical distribution (unilateral/bilateral, iliac/sacral bone, proximal/middle/distal), severity (bone marrow edema [BME]/periostitis/erosions), concurrent infection (vertebral/nonvertebral), and complications (abscess/probable adjacent osteomyelitis/cavitation/devitalized areas/sequestrum/pelvic venous thrombosis) of ISI. Interobserver reproducibility was assessed. Correlation analysis evaluated the effect of the causative microorganism on severity. Two human bodies were dissected to outline possible ways that ISI can spread.

RESULTS

Forty patients with ISI (40 years ± 22; 26 women) were evaluated. Ten patients had bilateral ISI. Concurrent vertebral infection was associated in 15% of cases. Reproducibility of sacral BME, periostitis, and reactive locoregional abnormalities was perfect (κ = 1). Reproducibility was low for erosion count (κ = 0.52[0.52-0.82]) and periarticular osteopenia (κ = 0.50[0.18-0.82]). Inflammatory changes were BME (42/42 joints), muscle edema (38/42), and severe periostitis along the ilium (33/37). Destructive structural changes occurred with confluent erosions (iliac, 20/48; sacral, 13/48), sequestrum (20/48), and cavitation (12/48). Complications occurred in 75% of cases, including periarticular abscesses (n = 30/47), probable adjacent osteomyelitis (n = 16/37), and pelvic thrombophlebitis (n = 3). Tuberculous ISI (6/40) correlated with sclerosis (rs = 0.45[0.16; 0.67]; p < 10-2) and bone devitalization (rs = 0.38[0.16; 0.67]; p = .02). The anatomical study highlighted the shared venous vascularization of sacroiliac joints, pelvic organs, and mobile spine.

CONCLUSION

Complications of ISI are frequent, including abscesses, adjacent osteomyelitis, and periostitis. ISI had bilateral involvement nonrarely and is commonly associated with another spinal infection.

What You Need to Know About Sacroiliac Dysfunction

Low back pain is the leading cause of disability worldwide, and sacroiliac dysfunction is estimated to occur in 15%-30% of those with nonspecific low back pain. Nurses are in the unique position to support and provide education to patients who may be experiencing sacroiliac dysfunction or possibly apply this knowledge to themselves, as low back pain is a significant problem experienced by nurses. A patient's clinical presentation, including pain patterns and characteristics, functional limitations, common etiologies and musculoskeletal system involvement, current diagnostic tools, and realm of treatments, are discussed along with their respective efficacy. Distinction is made between specific diagnosis and treatment of joint involvement and that of sacroiliac regional pain, as well as other factors that play a role in diagnosis and treatment for the reader's consideration.

Frequency and anatomic distribution of magnetic resonance imaging lesions in the sacroiliac joints of spondyloarthritis and non-spondyloarthritis patients

Background

Lesions detected by magnetic resonance imaging (MRI) of the sacroiliac joints are critical to the diagnosis of non-radiographic axial spondyloarthritis. However, inflammatory and structural lesions may be encountered in other conditions.

Objectives

The objective of this study was to evaluate and compare the frequency and localization of inflammatory and structural lesions on MRIs of the sacroiliac joint of spondyloarthritis (SpA) and non-spondyloarthritis (non-SpA) patients.

Design

This is a retrospective study including 200 patients, each having undergone an MRI of the sacroiliac joints.

Methods

Two experienced readers evaluated the whole set of images to detect erosions, subchondral sclerosis, fatty lesions, bone marrow edema (BME) and ankylosis according to the definitions established by the ASAS MRI working group. We divided sacroiliac joints into five segments: upper, antero-middle, intermediate-middle, postero-middle and lower.

Results

A total of 96 subjects with SpA (mean age 37.4 ± 11.8 years) and 104 without SpA (mean age 39.9 ± 11.6 years) were included. Of the 96 SpA patients, 65% had inflammatory buttock pain compared with 25% in the non-SpA group. BME was seen in 65% of SpA patients, mainly in the intermediate-middle segment, and in 20% of non-SpA patients, predominantly in the antero-middle segment. Subchondral sclerosis occurred in 44% of non-SpA patients, mostly in the antero-middle segment, and in 36% of SpA patients. Fatty lesions were present in 34% of SpA and in 21% of non-SpA patients. Erosions were seen in 25% of non-SpA and in 60% of SpA patients. BME and structural lesions were minimally observed in the postero-middle segment in non-SpA patients.

Conclusion

Inflammatory and structural lesions were observed in all segments of the joint in SpA, mainly in the middle segments, while lesions predominantly affected the antero-middle segment in non-SpA, and were uncommon in the postero-middle segment.

Main Diagnostic Pitfalls in Reading the Sacroiliac Joints on MRI

Magnetic resonance imaging of the sacroiliac joints is now frequently performed to help identify patients with early axial spondyloarthritis. However, differential diagnoses exist and should be recognized. The aim of this article is to review the most frequent differential diagnoses that may mimic inflammatory sacroiliitis in clinical practice.