Infectious sacroiliitis: a retrospective, multicentre study of 39 adults

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.

Imaging of Sacroiliac Pain: The Current State-of-the-Art

Pain in the sacroiliac (SI) region is a common clinical manifestation, often caused by diseases involving the SI joints. This is typically due to inflammation or degenerative changes, while infections or cancer are less frequent causes. The SI joint is challenging to image accurately because of its distinct anatomical characteristics. For an accurate diagnosis, conventional radiography often needs to be supplemented with more precise methods such as magnetic resonance imaging (MRI) or computed tomography (CT). Sacroiliitis, a common presenting feature of axial spondyloarthritis (axial SpA), manifests as bone marrow edema, erosions, sclerosis, and joint space narrowing. Septic sacroiliitis and repetitive stress injuries in sports can also cause changes resembling inflammatory sacroiliitis. Other conditions, such as osteitis condensans ilii (OCI), can mimic the radiologic characteristics of sacroiliitis. Inflammatory lesions are diagnosed by concurrent erosions, hyperostosis, and ankylosis. Ligament ossifications or mechanical stress can also result in arthritic disorders. Determining the exact diagnosis can be aided by the distribution of the lesions. Inflammatory lesions can affect any part of the articulation, including the inferior and posterior portions. Mechanical lesions, such as those seen in OCI, often occur in the anterior middle region of the joint. In cases of idiopathic skeletal hyperostosis, ligament ossification is found at the joint borders. This pictorial essay describes common SI joint problems, illustrated with multimodal imaging data. We, also, discuss strategies for selecting the best imaging modalities, along with imaging pitfalls, key points, and approaches for treating patients with suspected inflammatory back pain.

MRI predictors of infectious etiology in patients with unilateral sacroiliitis

BACKGROUND

Unilateral presentation of sacroiliitis is a diagnostic dilemma, especially between infection and inflammatory sacroiliitis associated with spondyloarthritis, requiring an early and accurate diagnosis.

OBJECTIVE

To assess the utility of magnetic resonance imaging (MRI) in differentiating infective versus inflammatory etiology in unilateral sacroiliitis.

MATERIALS AND METHODS

Retrospective review of the MRI of 90 patients with unilateral sacroiliitis, having an established final diagnosis. MR images were evaluated for various bone and soft tissue changes using predefined criteria and analyzed using univariate and multivariate regression analysis.

RESULTS

Among the 90 patients, infective etiology was diagnosed in 66 (73.3%) and inflammatory etiology in 24 (26.7%). Large erosions, both iliac and sacral-sided edema, joint space involvement with effusion or synovitis, soft tissue edema, elevated ESR/CRP, and absence of capsulitis and enthesitis were associated with infection (p < .001). The independently differentiating variables favoring infection on multivariate analysis were-both iliac and sacral-sided edema (OR 4.79, 95% CI: 0.96-23.81, p = .05), large erosions (OR 17.96, 95% CI: 2.66-121.02, p = .003), and joint space involvement (OR 9.9, 95% CI: 1.36-72.06, p = .02). Exclusive features of infection were osteomyelitis, sequestra, abscesses, sinus tracts, large erosions, and multifocality. All infective cases had soft tissue edema, joint space involvement, elevated ESR, and no capsulitis.

CONCLUSION

MRI evaluation for the presence and pattern of bone and joint space involvement, soft tissue involvement, and careful attention to certain exclusive features will aid in differentiating infectious sacroiliitis from inflammatory sacroiliitis.

A rare case presentation of septic sacroiliitis caused by staphylococcus xylosus and complicated with abscess formation: A case report

Septic sacroiliitis is one of the infectious causes of sacroiliitis and it is seen rarely. In current literature, cases of septic sacroiliitis caused by several microorganisms have been reported so far. This case report presents the first case of septic sacroiliitis caused by Staphylococcus xylosus and also complicated with an abscess formation.

Infectious Sacroiliitis as a Rare Postpartum Complication: A Case Report

Infectious sacroiliitis is a rare and challenging diagnosis. Sacroiliac joint changes related to pregnancy and puerperium can predispose to this condition. However, its clinical presentation can often mimic common causes of lower back pain and delay the diagnosis. We report the case of a 31-year-old pregnant woman with twins who presented at 29 weeks of gestation with lower back and right buttock pain that radiated down to the thigh. Although initially interpreted as sciatica pain, the diagnosis of psoas hematoma complicated with infectious sacroiliitis was made. With this case, we aim to bring awareness to this condition in order to raise suspicion among clinicians for an earlier diagnosis.

A case report on the development of sacroiliitis post laparoscopic appendicectomy for acute appendicitis: a rare cause of sacroiliitis in an adult

INTRODUCTION AND IMPORTANCE

Acute appendicitis is the most common abdominal surgical emergency in the world and often requires surgical intervention. One of the complications of appendicitis is abscess formation. In rare cases, a localised abscess can occur in the adjacent organs, such as the iliac and psoas muscles. Sacroiliitis occurring secondary to, or concomitant with, acute appendicitis is extremely rare. However, a missed diagnosis of either or both conditions can lead to serious complications, including mortality.

CASE PRESENTATION

A 27-year-old male patient presented to the emergency department with a history of acute severe right hip pain that was aggravated by movement and associated with nausea and vomiting. CT suggested acute uncomplicated appendicitis with no localised contamination. He underwent an emergent laparoscopy which showed mild appendiceal inflammation and appendicectomy was performed. He became septic a few hours after the operation, resulting in admission to the high dependency care unit for close observation. On review the following day, he reported ongoing right hip pain and lower back pain with a new onset inability to weight-bear. An MRI scan was performed which showed features of infection around the right sacroiliac joint and Staphylococcus aureus grew in his blood culture. A diagnosis of acute pyogenic sacroiliitis was then made. The patient was treated with IV antibiotics for a total of four weeks, followed by two weeks of oral antibiotics.

CLINICAL DISCUSSION

Acute pyogenic sacroiliitis is one of the rarer conditions seen that can mimic the acute abdomen, in this case acute appendicitis. MRI is the best diagnostic modality in sacroiliitis, in comparison to CT for appendicitis. In most cases of acute appendicitis, mixed bacteria including aerobes and anaerobes are seen in the blood culture while staphylococcus aureus is seen mostly in acute pyogenic sacroiliitis. Staphylococcus aureus-induced appendicitis is reported in less than 3.7 % of cases. An early diagnosis of either or both conditions can significantly reduce complications and, more importantly, expedite implementation of appropriate treatment.

CONCLUSION

In our case we present a combination acute appendicitis, acute sacroiliitis and staphylococcus aureus septicaemia and provide proof that acute pyogenic sacroiliitis can be a rare complication of acute appendicitis. Thus, a high clinical index of suspicion should be considered in the appropriate clinical scenario.

SPILF update on bacterial arthritis in adults and children

In 2020 the French Society of Rhumatology (SFR) published an update of the 1990 recommendations for management of bacterial arthritis in adults. While we (French ID Society, SPILF) totally endorse this update, we wished to provide further information about specific antibiotic treatments. The present update focuses on antibiotics with good distribution in bone and joint. It is important to monitor their dosage, which should be maximized according to PK/PD parameters. Dosages proposed in this update are high, with the optimized mode of administration for intravenous betalactams (continuous or intermittent infusion). We give tools for the best dosage adaptation to conditions such as obesity or renal insufficiency. In case of enterobacter infection, with an antibiogram result "susceptible for high dosage", we recommend the requesting of specialized advice from an ID physician. More often than not, it is possible to prescribe antibiotics via the oral route as soon as blood cultures are sterile and clinical have symptoms shown improvement. Duration of antibiotic treatment is 6 weeks for Staphylococcus aureus, and 4 weeks for the other bacteria (except for Neisseria: 7 days).

Diagnostics of Sacroiliac Joint Differentials to Axial Spondyloarthritis Changes by Magnetic Resonance Imaging

The diagnosis of axial spondyloarthritis (axSpA) is usually based on a pattern of imaging and clinical findings due to the lack of diagnostic criteria. The increasing use of magnetic resonance imaging (MRI) of the sacroiliac joints (SIJ) to establish the diagnosis early in the pre-radiographic phase has resulted in a shift in the paradigm with an increasing frequency of axSpA diagnoses and a changed sex distribution. Non-radiographic axSpA affects males and females nearly equally, whereas ankylosing spondylitis predominantly occurs in males. The MRI-based increasing frequency of axSpA in women is mainly due to the presence of subchondral bone marrow edema (BME) on fluid-sensitive MR sequences, which may be a non-specific finding in both women and men. Due to the somewhat different pelvic tilt and SIJ anatomy, women are more prone than men to develop strain-related MRI changes and may have pregnancy-related changes. Awareness of non-specific subchondral BME at the SIJ is important as it can imply a risk for an incorrect SpA diagnosis, especially as the clinical manifestations of axSpA may also be non-specific. Knowledge of relevant MRI and clinical features of differential diagnoses is needed in the diagnostic workout of patients with suspected axSpA considering that non-SpA-related SIJ conditions are more common in patients with low back or buttock pain than axSpA sacroiliitis. The purpose of this review was to present current knowledge of the most frequent differential diagnoses to axSpA sacroiliitis by MRI taking the clinical characteristics into account.

Sacroiliac joint beyond sacroiliitis-further insights and old concepts on magnetic resonance imaging

The sacroiliac joint (SIJ) is an amphiarthrosis composed of a posterior syndesmosis and an anterior cartilaginous portion, with limited yet present mobility. Its main function is to transmit the load from the axial skeleton to the lower limbs and vice-versa; it is susceptible to early mechanical and degenerative changes which are much more common than inflammatory sacroiliitis. Magnetic resonance imaging (MRI) has increasingly been used to evaluate these changes, and while subchondral bone marrow edema (BME) is a common finding related to both, care must be taken when applying the ASAS research MRI definition for sacroiliitis without considering lesion BME topography, size and depth, concomitant structural damage and, of course, the clinical picture. In this review, we will discuss the anatomy and biomechanics of the SIJ, the noninflammatory causes of SIJ subchondral BME, and how these concepts combined can be used to increase our diagnostic confidence.

Differentiating nonradiographic axial spondyloarthritis from its mimics: a narrative review

Background

Optimal treatment of nonradiographic axial spondyloarthritis depends on accurate and timely diagnosis of the underlying disease; however, patients present with common symptoms that, in the absence of radiographic changes, may confound diagnosis.

Methods and findings

In this narrative review, a PubMed literature search was conducted through January 2021, with no date limits, to identify English-language publications discussing classification of nonradiographic axial spondyloarthritis, with an emphasis on clinical features and presentation, differential diagnoses, and mimics of disease. This review describes the epidemiology, clinical features, and burden of disease of nonradiographic axial spondyloarthritis as it relates to the overall axial spondyloarthritis spectrum and discusses mimics and differential diagnoses of nonradiographic axial spondyloarthritis that should be considered when evaluating patients with suspected nonradiographic axial spondyloarthritis in clinical practice.

Conclusions

Recognition of clinical features of nonradiographic axial spondyloarthritis, along with an understanding of comorbid conditions such as fibromyalgia, allows for differentiation from its mimics. Appropriate diagnosis of nonradiographic axial spondyloarthritis is important for aggressive management of disease to reduce pain, avoid loss of function, and improve quality of life.

Clinical Manifestations and Diagnosis of Axial Spondyloarthritis

BACKGROUND

Axial spondyloarthritis (axSpA) is a chronic, rheumatic disease characterized by inflammation of the sacroiliac joint, spine, and entheses. Axial spondyloarthritis affects up to 1.4% of adults in the United States and is associated with decreased quality of life, increased mortality, and substantial health care-related costs, imposing a high burden on patients, their caregivers, and society.

SUMMARY OF WORK

Diagnosing axSpA can be difficult. In this review, we seek to help rheumatologists in recognizing and diagnosing axSpA.

MAJOR CONCLUSIONS

A discussion of challenges associated with diagnosis is presented, including use and interpretation of imaging, reasons for diagnostic delays, differences in disease presentation by sex, and differential diagnoses of axSpA.

FUTURE RESEARCH DIRECTIONS

The early diagnosis of axSpA and advances in available therapeutic options have improved patient care and disease management, but delays in diagnosis and treatment remain common. Additional research and education are critical for recognizing diverse axSpA presentations and optimizing management early in the course of disease.

Non-typhoidal, Non-paratyphoidal Salmonella Species Causing Sacroiliitis and Pyomyositis in a Healthy 19-Year-Old Athlete

Salmonella is a gram-negative bacterium, subdivided into typhoidal and non-typhoidal Salmonella. It is usually caused by eating raw or undercooked meat, poultry, eggs, or egg products. The clinical manifestations of Salmonella infection can be divided into five syndromes: enterocolitis (food poisoning), enteric (typhoid) fever, bacteremia/septicemia, focal infection, and a chronic carrier state, which is usually asymptomatic. The most common clinical presentation is diarrhea. Salmonella osteomyelitis occurs most frequently in patients with sickle-cell disease; other risk factors include other hemoglobinopathies, immunocompromised status, and chronic Salmonella carrier state. The incidence of Salmonella osteomyelitis/septic arthritis in otherwise healthy individuals is rare. The duration of symptoms can range from a few months to several years, and multifocal involvement occurs in 15% of reported cases of Salmonella osteomyelitis. The symptoms of Salmonella osteomyelitis are pain and variable swelling of the affected limb; high temperatures are rarely noted. Our patient is a 19-year-old boy with no known past medical history who presented with severe right-sided sacroiliitis with extensive surrounding osteomyelitis on both sides of the sacroiliac joint with non-typhoidal, non-paratyphoidal Salmonella bacteremia.

Case Report: Multimodality Imaging of Infectious Sacroiliitis and Retroperitoneal Abscess Causing Hindlimb Ataxia in a Young Dog

A 3-month-old intact male Labrador Retriever was presented for falling trauma and hindlimb ataxia. Radiography indicated radiolucent left sacroiliac joint with irregular margin. Computed tomography revealed thickened sublumbar muscles and hypoattenuated sacroiliac joint while magnetic resonance imaging demonstrated abscess at retroperitoneum and gluteal muscle. Ultrasonography showed lytic left sacroiliac joint with retroperitoneal fluid, and fine needle aspiration resulted Staphylococcus aureus. Hindlimb ataxia was attributed to infectious sacroiliitis and its secondary retroperitoneal abscess. As far as the authors' knowledge, this is the first report of multimodality imaging of infectious sacroiliitis with retroperitoneal abscess caused by S. aureus in a dog.

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.

Perinatal sacroiliitis diagnostic challenges

Lumbo-pelvic pain is a common and non-specific problem during pregnancy and postpartum. Although perinatal pyogenic sacroiliitis is uncommon during this time, it might be difficult to distinguish from reactive sacroiliitis in women who are experiencing significant lower back and pelvic girdle pain, as the symptoms and signs are not clear and the tests are not definitive. A 34-year-old primigravida went to the emergency department with severe lower back pain radiating to the right gluteal region and down to the back of the right thigh. This pain began 12 days prior to her presentation and eventually worsened to the point that she could not stand or walk. Her vital signs were within normal ranges, and she was experiencing a fever. Apart from a slight widening of the symphysis pubis, her pelvic and lumbo-sacral pain X-rays revealed no important findings. With the clinical impression of right lumbo-pelvic pain, the patient was admitted for pain management and further inquiries. Despite the fact that the antibiotherapy was prescribed to treat a urinary tract infection, the significant recovery of the patient's symptoms, even in the absence of a definitive culture of aspirate from the right sacroiliac joint, supported the diagnosis of pyogenic sacroiliitis.

Septic sacroiliitis in the post-partum period with haematogenous spread

Pelvic pain is a very common gynaecological complaint especially during the puerperium. It is rarely associated with development of septic sacroiliitis or haematogenous spread to other sites within the body. The case below demonstrates a 30 year old female 10 days post-partum presenting with left hand cellulitis secondary to development of septic sacroiliitis. Her case supplements a small cohort of reports among literature identifying septic arthritis in the postpartum period, recognises the delay to diagnosis and increased morbidity of this condition.

Axial Spondyloarthritis: Mimics and Pitfalls of Imaging Assessment

Axial spondyloarthritis (axSpA) is a chronic inflammatory disorder that predominantly involves the axial skeleton. Imaging findings of axSpA can be divided into active changes, which include bone marrow edema, synovitis, enthesitis, capsulitis, and intra-articular effusion, and structural changes, which include erosions, sclerosis, bone fatty infiltration, fat deposition in an erosion cavity, and bone bridging or ankylosis. The ability to distinguish between imaging lesions suggestive of axSpA and artifacts or lesions suggestive of other disorders is critical for the accurate diagnosis of axSpA. Diagnosis may be challenging, particularly in early-stage disease and magnetic resonance imaging (MRI) plays a key role in the detection of subtle or inflammatory changes. MRI also allows the detection of structural changes in the subchondral bone marrow that are not visible on conventional radiography and is of prognostic and monitoring value. However, bone structural changes are more accurately depicted using computed tomography. Conventional radiography, on the other hand, has limitations, but it is easily accessible and may provide insight on gross changes as well as rule out other pathological features of the axial skeleton. This review outlines the imaging evaluation of axSpA with a focus on imaging mimics and potential pitfalls when assessing the axial skeleton.

MRI nomenclature for musculoskeletal infection

The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.

Suspected Septic Sacroiliitis Following Recent Cesarean Section Under Spinal Anesthesia

Septic sacroiliitis is sacroiliac (SI) joint inflammation secondary to microbial invasion of the synovial space characterized by tenderness over the sacroiliac joint, difficulty walking, and lower back pain that can radiate to the buttocks. Clinicians can easily overlook septic sacroiliitis as a potential diagnosis due to its rare occurrence and non-specific symptoms. A 30-year-old female (G2P2A0) who presented acutely to the ED nine days after an uncomplicated Cesarean section performed under spinal anesthesia. The patient experienced progressive lancinating, electric-shock pain originating from the coccyx radiating to the right buttock and lower back with the inability to bear weight. MRI pelvis demonstrated edematous changes of the right SI joint, indicative of septic sacroiliitis. Patient's condition improved after empiric intravenous antibiotics and was discharged home on the continued intravenous course. Rapid empiric administration of intravenous antibiotics may have prevented the onset of severe complications of an infective SI joint.

Management of Instability following Pyogenic Sacroiliitis: Technical Case Report

Background

Septic arthritis of the sacroiliac joint (SI-joint) is a rare and often delayed diagnosis. Management usually consists of intravenous antibiotics and debridement of infected tissue. However, very few reports consider the management of the secondary instability of the sacroiliac joint. Case Presentation. We report a case of a 16-year-old girl diagnosed with S. aureus pyogenic sacroiliitis who benefited from aggressive surgical debridement and primary arthrodesis for infection-related SI-joint instability in the acute infection phase.

Conclusion

Diagnosis of pyogenic sacroiliitis is often delayed. Destruction of the joint can lead to chronic pain and instability. In cases of obvious intraoperative instability, primary arthrodesis could be considered in young patients.

Arthrodesis Using Bilateral Dual Iliac Screws with Autologous Iliac Bone Transfer for the Treatment of Pyogenic Sacroiliitis

Pyogenic sacroiliitis is a relatively rare condition that often leads to surgical treatment, including debridement and arthrodesis. Here we introduce a new surgical technique using bilateral dual iliac screws to secure early ambulation and maximal fusion success rate for the treatment of pyogenic sacroiliitis. We retrospectively reported a case and technical reports of pyogenic sacroiliitis treated by a new bilateral dual iliac screw fixation arthrodesis technique using radiologic outcomes, including plain X-rays and MRI scans, as well as outcomes based on the visual analogue scale for pain measurement. This technique improved uncontrolled pyogenic sacroiliitis with immediate stability that enabled ambulation and secured firm fixation for extensive evacuation of infected debris and subsequent autograft bone arthrodesis. In conclusion, we recommend bilateral dual iliac screw fixation for the treatment of pyogenic sacroiliitis, as this technique can improve uncontrolled pyogenic sacroiliitis with immediate stability.

[Differential diagnosis of axial spondyloarthritis-axSpA mimics]

The classification of axial spondyloarthritis (axSpA) comprises the classical ankylosing spondylitis (AS), which is characterized by already existing structural changes in the sacroiliac joints, and the so-called non-radiographic axSpA (nr-axSpA), in which by definition such changes are not present. This distinction is based on the ASAS classification criteria for axSpA, which are however not suitable for a diagnosis. According to the current classification, spondyloarthritis (SpA) includes axSpA, which can be associated with psoriasis and/or chronic inflammatory bowel diseases (CED), such as Crohn's disease and ulcerative colitis, and peripheral SpA, which is further divided into SpA associated with psoriasis, partially synonymous with psoriatic arthritis (PsA), reactive SpA, partially synonymous with reactive arthritis (ReA) and SpA associated with CED, partially synonymous with arthritis associated with CED (e.g. Crohn's disease, ulcerative colitis) and peripheral undifferentiated SpA, which by definition is not associated with any of the above. In this article only the most important differential diagnoses are discussed, i. e. diffuse idiopathic skeletal hyperostosis (DISH), fractures and infections in the axial skeleton. In addition, the frequency of certain musculoskeletal findings in the normal population examined by magnetic resonance imaging (MRI) are also discussed.

Analysis of the early signs of septic sacroiliitis on computed tomography

OBJECTIVE

Septic sacroiliitis is a difficult diagnosis rarely considered in an emergency in case of pelvic pain associated with fever. In these cases, a computed tomography (CT) is classically performed to exclude digestive or gynecological disorder, but the sacroiliac joint is not systematically analyzed. The aim of the present study was to detect the early signs of septic sacroiliitis on CT.

METHODS

In a monocentric retrospective study, the characteristics, biology, and imaging of patients with septic sacroiliitis were analyzed.

RESULTS

Seven cases of septic sacroiliitis were included in the study. For all patients, a CT scan with contrast-enhanced acquisitions of the pelvis was performed. The 4 early signs of septic sacroiliitis frequently not evocated by a radiologist in an emergency were highlighted as follows: fat infiltration in front of the sacroiliac joint (83%), anterior bulging of the sacroiliac capsule (46%), and piriformis and iliac muscles swelling (71% for both). All patients had at least one of these signs; 86% had at least 2 signs. Magnetic resonance imaging was performed for 5 out of 7 patients and confirmed the aspect of infectious sacroiliitis.

CONCLUSION

Systematic analysis of the sacroiliac joint and adjacent muscles on pelvic CT scan is necessary to avoid the unrecognition of septic sacroiliitis in case of pelvic pain with fever.

Diagnostic imaging characteristics of canine infectious sacroiliitis

Infectious sacroiliitis has not been described in dogs. This retrospective case series describes the presentation, diagnostic imaging characteristics, and outcomes of 2 canine patients with infectious sacroiliitis. Selection criteria included presentation with back pain from 2010 to 2017, diagnostic imaging of the sacroiliac joints, and short- and long-term response to antibiotic therapy. Medical records, and magnetic resonance imaging (MRI) were reviewed by a Board-certified veterinary radiologist, a neurologist, and a small animal intern. Two dogs met the inclusion criteria. Magnetic resonance imaging revealed unilaterally wide and irregular sacroiliac joint spaces, with juxta-articular soft tissue contrast enhancement and bone marrow edema. One patient had a communicating abscess of the psoas muscle, which cultured positive for Pasteurella canis. Following treatment with pain relief medications and antibiotics, both patients made a complete clinical recovery, with no signs of lameness 2 to 4 weeks after cessation of treatment, and no lameness reported by the owner afterwards. Infectious sacroiliitis should be considered when dogs are presented with lumbosacral pain.

A case report of melioidosis complicated by infective sacroiliitis in Sri Lanka

Background

Melioidosis is an infection caused by a facultative intracellular Gram-negative bacterium, Burkholderia pseudomallei. It can present as septicemia, localized infection with/without septicemia, asymptomatic infections, ulcers, pneumonia, visceral abscesses, neurological infection, musculoskeletal infections and can involve any organ.

Case presentation

A 56 year old Sri Lankan diabetic female presented with fever, chills and rigors for 2 weeks. She also had malaise and loss of appetite, but no other features. On examination, she was febrile (temperature was 101.4 ⁰ F) and rest of the examination was unremarkable. Her blood culture was positive for Burkholderia pseudomallei and she was started on IV antibiotics, on day 3. During her 2nd week of hospital stay, she developed right sided low back pain with buttock pain, right hip joint pain and restricted hip joint movements suggestive of right sacroiliitis. CE CT and MRI scans confirmed the diagnosis of right iliopsoas abscesses and right sacroiliitis.

Incision and drainage was performed and a pigtail catheter was left in place for continuous drainage of abscesses. Her intensive phase was initiated with IV ceftazidime 2 g every 6 h for 12 days, then changed over to IV meropenem 2 g every 8 h together with oral co-trimoxazole. 2 weeks later, oral co-trimoxazole was replaced by oral doxycycline for another 6 weeks (due to transient pancytopaenia). She made a complete and uneventful recovery with oral co-trimoxazole for another 6 months, in her eradication phase.

We report this case to show the importance in early diagnosis of melioidosis, and to consider it in the differential diagnosis of multiple abscesses and to emphasize the importance in suspecting melioidosis as a causative agent in infective sacroiliitis.

Discussion

Melioidosis can have 2 major presentations; acute infection (symptoms lasting less than 2 months) and chronic infection (symptoms lasting more than 2 months). Musculoskeletal melioidosis is a well-recognized manifestation of the disease, which can manifest as soft tissue abscesses, septic arthritis, spondylitis, sacroiliitis and osteomyelitis.

Management of melioidosis consists of 2 phases. The intensive phase and the eradication phase. These are aimed at the importance of rapidly treating the septicemia, the need of eradication of the persistent disease and the prevention of recurrent infections or relapses. The intensive phase consists of minimum 10–14 days of IV antibiotics: IV ceftazidime or IV carbapenem (meropenem/ imipenem). Eradication phase should be followed by 3–6 months of oral co-trimoxazole alone or in combination with oral doxycycline/ oral amoxiciliin-clavulanic acid.

Klebsiella pneumoniae sacroiliac septic arthritis: First case report

Infective sacroiliitis is a rare disease with misleading clinical signs that often delay diagnosis. We report a case of pyogenic sacroiliac joint septic arthritis caused by Klebsiella pneumoniae that has not been reported in the literature highlighting its importance especially among diabetics.

Unilateral sacroiliitis: differentiating infective and inflammatory etiology by magnetic resonance imaging and tissue studies

PURPOSE

Unilateral sacroiliitis (US) is an uncommon disease with varied etiology. The differentiation between infective and inflammatory causes for US based on MRI alone is often difficult. We studied the efficacy of MRI findings in comparison with tissue studies in the diagnosis of US.

METHODS

A retrospective analysis of patients who presented with US and evaluated with MRI, biopsy for histopathology and tissue cultures was performed. Patients with bilateral sacroiliitis, traumatic and postpartum sacroiliitis were excluded. Based on defined MRI criteria, the patients were divided into two groups-infective (group A) and inflammation (group B).

RESULTS

In total, 33 patients (mean age-33.4 ± 17.2 years) with MRI features of US had presented with unilateral gluteal pain (100%) and positive Patrick's test (91.9%). Based on the MRI features of severe subchondral marrow edema, widening of joint space, intra-articular abscess and periarticular muscle abscess, infective sacroiliitis (A) was diagnosed in 20/33 (60.6% cases). A total of 13/33 (39.3%) patients had features of inflammation (B), based on the following MRI criteria-subchondral sclerosis with minimal edema, erosions, maintained joint space without abscess/destruction. Tissue evidence of infection was positive in 13/20 (65%) patients in group A while it was negative in all group B patients.

CONCLUSION

MRI had high sensitivity (71%) and 100% specificity in diagnosing inflammatory sacroiliitis while it had low specificity, but 100% sensitivity for diagnosing infective sacroiliitis. Hence, patients diagnosed as inflammatory sacroiliitis in MRI are unlikely to benefit from further tissue studies while percutaneous biopsy is recommended in patients diagnosed in MRI as infective sacroiliitis.

Acute Streptococcus mitis Sacroiliitis in a Teenager with Unclear Source of Bacteremia: A Case Report and Literature Review

Septic arthritis is an orthopedic emergency that is commonly caused by Staphylococcus aureus. Old age, diabetes mellitus, rheumatoid arthritis, prosthetic joint, and recent surgery are the main predisposing risk factors. Most cases of septic arthritis are caused by hematogenous spread of infection. Infectious sacroiliitis is a rare form of septic arthritis which is often clinically challenging to diagnose due its various and nonspecific presentations. Streptococcus mitis belongs to viridans group streptococci (VGS) bacteria, which is a component of body flora that is commonly involved in bacterial endocarditis. VGS in general and S. mitis specifically is an uncommon cause of osteoarticular infections. Here, we report a case of spontaneous Streptococcus mitis bacteremia complicated by septic sacroiliitis in a healthy teenager in the absence of infective endocarditis or a clear source of bacteremia.

Postpartum Bone Marrow Edema at the Sacroiliac Joints May Mimic Sacroiliitis of Axial Spondyloarthritis on MRI

OBJECTIVE

The objective of our study was to compare MRI findings in the sacroiliac joints of postpartum women (as a model of mechanical changes) and women with known axial spondyloarthritis (as an inflammatory model).

SUBJECTS AND METHODS

For this prospective multicenter age-matched, case-control study, sacroiliac joint MRI examinations of 30 healthy women (mean age, 34.0 years) in the early postpartum period (mechanical group) and 30 age-matched women (mean age, 33.8 years) with known axial spondyloarthritis (retrospective inflammatory group) were compared. Blinded to clinical information, readers assessed MR images using the following scoring systems: Spondyloarthritis Research Consortium of Canada (SPARCC) MRI index, Berlin method, Assessment of Spondyloarthritis International Society (ASAS) criteria, and SPARCC MRI structural score. Descriptive statistics as percentages of the different findings (i.e., bone marrow edema [BME], erosion, fatty bone marrow replacement, backfill, ankylosis) and scores between groups and between delivery modes were compared.

RESULTS

In the postpartum group, 63.3% (19/30) of women showed BME around the sacroiliac joints compared with 86.7% (26/30) of women in the spondyloarthritis group (based on ASAS criteria). Erosions were uncommon in the postpartum group (10.0% [3/30] postpartum vs 56.7% [17/30] spondyloarthritis). Fatty bone marrow replacement, backfill, and ankylosis were not seen in the postpartum group. In subjects with positive MRI findings for sacroiliitis based on ASAS criteria, the SPARCC MRI index (mean ± SD, 13.6 ± 14.5 vs 13.0 ± 10.7; p = 0.818) and Berlin method (4.5 ± 3.0 and 5.5 ± 3.5, p = 0.378) were not different between the postpartum and spondyloarthritis groups. Scores were not different between birth modalities.

CONCLUSION

Pregnancy-induced BME at the sacroiliac joints, as a result of prolonged mechanical stress, was present in 63.3% of women who underwent MRI during the early postpartum period and may mimic sacroiliitis of axial spondyloarthritis.

Septic Sacroiliitis in a 53-Year-Old Adult: A Case Report

A 53-year-old woman with no significant medical history presented with 10/10 right buttock pain that radiated to the right groin. With no reported recent injury, the absence of fever, and no identifiable risk factors, an infectious etiology, including septic sacroiliitis (SSI), is at the end spectrum of the differential. SSI is a rare condition with nonspecific findings that can lead to major complications, including death. To our knowledge, there are only 4 recent major literature reviews on SSI, with most cases reported to have at least 1 risk factor or clinical sign indicating the possibility of an infectious etiology. The patient reported in this case had no identifiable risk factors; therefore, high clinical suspicion is needed to prevent debilitating consequences from prolonged infection. LEVEL OF EVIDENCE: V.

Percutaneous CT-guided sacroiliac joint sampling for infection: aspiration, biopsy, and technique

OBJECTIVE

To evaluate methods of CT-guided sacroiliac joint sampling in patients with suspected infection.

MATERIALS AND METHODS

All CT-guided sacroiliac joint sampling procedures for suspected infection were reviewed for sampling type (aspiration, lavage aspiration, biopsy), microbiology results, and clinical and imaging follow-up. The primary gold standard was anatomic pathology. If pathology was not available, then positive blood culture with the same organism as SIJ sampling, imaging and clinical follow-up, or clinical follow-up only were used. Anterior and posterior joint distention was evaluated by MRI within 7 days of the procedure.

RESULTS

A total of 34 patients (age 39 ± 20 (range, 6-75) years; 21 F, 13 M) were included. Aspiration samples only were obtained in 13/34 (38%) cases, biopsy samples only in 9/34 (26%) cases, and both samples in 12/34 (35%) cases. There was an overall 54% sensitivity and 86% specificity. For the aspiration samples, sensitivity and specificity were 60 and 81%, respectively, compared to 45 and 90% for the biopsy samples. In cases with both samples, biopsy did not add additional microbial information. Seventeen (17/34, 50%) patients had an MRI. The anterior joint was more distended than the posterior joint in 15/17 (88%) of patients, and this difference was significant (P = 0.0003). All of these 17 patients had an attempted aspiration by a posterior approach; 6/17 (35%) resulted in a successful aspiration.

CONCLUSIONS

Aspiration of the sacroiliac joint has a higher sensitivity than biopsy and should always be attempted first. MRI may be helpful for procedure planning.

Septic arthritis of the sacroiliac joint

Septic arthritis is an inflammation of a joint caused directly by various microorganisms. It is often characterized by many unspecific symptoms. Bacteria is the most often etiological factor.

We present a case report of a 76-years old woman with a unilateral septic arthritis of the sacroiliac joint. Bacterial sacroiliitis should be taken into account in patients with sacroiliitis and fever onset.

Proper diagnosis can be very often difficult and delayed but fast implementation of antibiotic therapy is extremely important in the treatment process. Diagnostic imaging is crucial to the diagnosis and monitoring of septic arthritis. Magnetic resonance imaging is the most relevant tool for the detection of sacroiliitis, allowing the institution of therapeutic strategies to impede the progression of the disease.

Successful Treatment of Mycobacterium gordonae Sacroiliitis Using a Novel Minimally Invasive Sacroiliac Joint Arthrodesis: A Case Report

CASE

A 43-year-old man with a history of well-controlled HIV (human immunodeficiency virus) infection presented with sacroiliac joint destruction from a Mycobacterium gordonae infection. A sacroiliac joint arthrodesis was performed using a minimally invasive technique utilizing both biologic fusion (allograft bone with rhBMP-2 [recombinant human bone morphogenetic protein-2]) and fixation with titanium ingrowth rods.

CONCLUSION

To our knowledge, this is the first reported case of infectious sacroiliitis from a nontubercular mycobacterium (M. gordonae) treated with a combination of joint debridement, biologic fusion with bone graft, and nonbiologic functional fusion using titanium ingrowth rods, all performed in a minimally invasive fashion. This strategy effectively alleviated pain and preserved function at 2 years of follow-up.

A Rare Case of Isolated Salmonella Species Group B Sacroiliitis in a Healthy Collegiate-Level Swimmer: A Case Report

CASE

We present a case of isolated Salmonella species group B sacroiliitis in a healthy 19-year-old collegiate-level swimmer with no known risk factors. To our knowledge, there are no similar cases described in the current literature.

CONCLUSION

Pyogenic sacroiliitis (PS) is a rare form of septic arthritis, especially in adults. PS is most commonly seen in the setting of intravenous drug use or in an immunocompromised patient. If a patient does not fit either of these demographics, PS initially can be a difficult diagnosis because of its rarity and vague symptomatology.

A young female presenting with unilateral sacroiliitis following dengue virus infection: a case report

BACKGROUND

Dengue is a common arthropod-borne viral infection in Sri Lanka which is spread by the mosquitos of the genus Aedes. The clinical features of dengue include high-grade fever associated with arthralgia and myalgia. However, dengue virus is not considered an arthritogenic virus. We report a case of a previously healthy young female who presented with imaging-confirmed right-sided sacroiliitis 10 days after developing dengue fever. This is the first reported case that shows a possible link between dengue infection and development of arthritis.

CASE PRESENTATION

A 14-year-old Sri Lankan female presented to our medical unit with right buttock and hip pain of 3 weeks' duration. She had serologically confirmed dengue infection 10 days prior to the onset of buttock pain. A clinical examination revealed features of right sacroiliitis. An X-ray of her sacroiliac joint showed joint space widening and reactive bone changes. Magnetic resonance imaging of her pelvis and sacroiliac joint confirmed the diagnosis of acute sacroiliitis. She had an erythrocyte sedimentation rate of 110 mm first hour with a normal C-reactive protein. Her human leukocyte antigen-B27, rheumatoid factor, antinuclear antibody, chikungunya antibody, hepatitis serology, Brucella serology, and tuberculin skin test were negative. She was treated with nonsteroidal anti-inflammatory drugs and showed gradual improvement.

CONCLUSIONS

After excluding possible causes for sacroiliitis, we postulated that sacroiliitis in the index case could have been caused or triggered by dengue virus infection. However there is a possibility that the sacroiliitis merely coincided with the dengue virus infection. This case illustrates the possibility that dengue virus could have a link with the development of arthritis in the same manner as other arthritogenic viruses; possible mechanisms for this include direct invasion of the synovium and the joint tissue by the virus, immune complex formation and deposition in the joint tissue, and immune dysregulation. Further studies are needed in this field to gain more knowledge, as dengue infection is highly prevalent in Sri Lanka.

Sacroiliitis mimics: a case report and review of the literature

BACKGROUND

Radiographic sacroiliitis is the hallmark of ankylosing spondylitis (AS), and detection of acute sacroiliitis is pivotal for early diagnosis of AS. Although radiographic sacroiliitis is a distinguishing feature of AS, sacroiliitis can be seen in a variety of other disease entities.

CASE PRESENTATION

We present an interesting case of sacroiliitis in a patient with Paget disease; the patient presented with inflammatory back pain which was treated with bisphosphonate. This case demonstrates comorbidity with Paget disease and possible ankylosing spondylitis. We also present a review of the literature for other cases of Paget involvement of the sacroiliac joint.

CONCLUSIONS

In addition, we review radiographic changes to the sacroiliac joint in classical ankylosing spondylitis as well as other common diseases. We compare and contrast features of other diseases that mimic sacroiliitis on a pelvic radiograph including Paget disease, osteitis condensans ilii, diffuse idiopathic skeletal hyperostosis, infections and sarcoid sacroiliitis. There are some features in the pelvic radiographic findings which help distinguish among mimics, however, one must also rely heavily on extra-pelvic radiographic lesions. In addition to the clinical presentation, various nuances may incline a clinician to the correct diagnosis; rheumatologists should be familiar with the imaging differences among these diseases and classic spondylitis findings.

Aggregatibacter aphrophilus Sacroiliitis Following Gastroscopy in a Young Sportsman

We report a case of Aggregatibacter aphrophilus sacroiliitis in a young sportsman, presenting 48 hours after endoscopy and biopsy. Microbiological diagnosis was made only after repeated attempt at joint aspiration. The patient was cured after radiologically guided drainage and a prolonged course of directed antibiotics.

A Case Report of Infectious Sacroiliitis in an Adult Presenting to the Emergency Department with Inability to Walk

BACKGROUND

Infectious sacroiliitis (ISI) is an uncommon cause of back and hip pain in which the sacroiliac joint, either unilateral or bilateral, is inflamed from an infectious source. Historically, this has been an easily missed diagnosis due to nonspecific presenting symptoms along with subtle nondistinguishable laboratory abnormalities.

CASE REPORT

We describe an injection drug user presenting with right-sided ISI who presented with hip and back pain and inability to walk. The patient had tenderness over his right sacroiliac joint, and despite negative plain radiographs, a magnetic resonance imaging (MRI) scan was obtained from the Emergency Department (ED) given the patient's risk factors for infection. Concerning findings of ISI on this MRI led to a computed tomography-guided biopsy during the patient's hospital admission, which revealed alpha-hemolytic Streptococcus as the responsible pathogen. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Infectious sacroiliitis is a rare condition that is difficult to diagnose, and carries increasing morbidity when diagnosis is delayed. We aim to increase awareness through a case report of a patient encountered in the ED.

[Infectious sacroiliitis in tunisian centre: retrospective study of 25 cases]

Infectious sacroiliitis are rare but they can be complicated by disabling functional sequelae. To describe the clinical and bacteriological characteristics of infectious sacroiliitis among patients treated in Sousse Medical Center, Tunisia. A retrospective, descriptive study, of infectious sacroiliitis among patients hositalized in Sousse between 2000 and 2015. The diagnosis was made on the basis of medical signs, imaging, microbiological indicators. In the study were enrolled twenty five patients, 10 men and 15 women; the average age was 41 years (19-78). Sacroiliitis were due to pyogenic bacteria in 14 cases (56%), brucella bacteria in 6 cases (24%) and tuberculosis bacteria in 5 cases (20%). The mean duration of symptoms was 61, 45 and 402 days respectively. The most common clinical signs were buttock pain (92%) and fever (88%). Standard radiographic evaluation was abnormal in 75% of cases. CT scan and MRI of the sacroiliac joints was performed in all cases. The diagnosis was bacteriologically confirmed in 24 cases (96%). The average duration of antibiotic treatment was 83 days in the pyogenic sacroiliitis, and 102 days in brucellar sacroiliitis. The evolution was favorable in 12 patients (48%), 9 patients (36%) had sequelae of sacroiliac joint pain and 4 patients (16%) died. In our study, time frame of infectious sacroiliitis evolution did not predict the causative bacterium, hence the need for bacteriological documentation in order to prescribe appropriate antibiotic therapy.

MR Imaging of the Lumbosacral Plexus: A Review of Techniques and Pathologies

The lumbosacral plexus is a complex anatomic area that serves as the conduit of innervation and sensory information to and from the lower extremities. It is formed by the ventral rami of the lumbar and sacral spine which then combine into larger nerves serving the pelvis and lower extremities. It can be a source of severe disability and morbidity for patients when afflicted with pathology. Patients may experience motor weakness, sensory loss, and/or debilitating pain. Primary neurologic processes can affect the lumbosacral plexus in both genetic and acquired conditions and typically affect the plexus and nerves symmetrically. Additionally, its unique relationship to the pelvic musculature and viscera render it vulnerable to trauma, infection, and malignancy. Such conditions are typically proceeded by a known history of trauma or established pelvic malignancy or infection. Magnetic resonance imaging is an invaluable tool for evaluation of the lumbosacral plexus due to its anatomic detail and sensitivity to pathologic changes. It can identify the cause for disability, indicate prognosis for improvement, and be a tool for delivery of interventions. Knowledge of proper MR protocols and imaging features is key for appropriate and timely diagnosis. Here we discuss the relevant anatomy of the lumbosacral plexus, appropriate imaging techniques for its evaluation, and discuss the variety of pathologies that may afflict it.

Pyogenic sacroiliitis: diagnosis, management and clinical outcome

OBJECTIVE

The purpose of the present study was to evaluate the role of diagnostic tools and management options for patients with pyogenic sacroiliitis, including potential complications.

MATERIALS AND METHODS

This retrospective study included 16 patients with pyogenic sacroiliitis who were admitted to a single orthopaedic centre between 2007 and 2012. The following data were collected: demographics, history, radiography, magnetic resonance images (MRI), biological data, type of pathogenic agent, abscess formation, type of management, and clinical outcome.

RESULTS

Our study demonstrated that only one-fifth of the patients with lumbogluteal or hip pain had established diagnoses of suspected pyogenic sacroiliitis upon admission. MRIs confirmed this diagnosis in all cases. MRI examinations revealed joint fluid in the sacroiliac joint and significant oedema of the adjacent bone and soft tissues. In 12 of the 16 cases, erosions of the subchondral bone were encountered. Contrast-enhanced MRI revealed that 9 patients had abscesses. All patients received antibiotic therapy. Antibiotic treatment was only successful in 9 cases. The other 7 patients underwent computed tomography (CT)-guided abscess drainage. Drainage was sufficient for 4 patients, but 3 patients required open surgery. One patient required sacroiliac arthrodesis. The clinical outcomes included minimal disability (n = 10), moderate disability (n = 5), and full disability (n = 1) of the spine.

CONCLUSIONS

Contrast-enhanced MRI is mandatory for a reliable diagnosis. Abscess formation was observed in approximately half of the MRI-diagnosed sacroiliitis cases and required minimally invasive drainage under CT guidance or frequently open surgery.