Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow

Likelihood of hip infection with image-guided hip aspiration dry tap: a 10-year retrospective study

OBJECTIVE

To determine the rate of infection in patients with suspected hip septic arthritis who underwent image-guided aspiration (IHA) resulting in dry-tap, diagnostic value of subsequent lavage and re-aspiration, and if pre-aspiration MRI can help prevent a dry tap.

MATERIALS AND METHODS

Retrospective review between 2010 to 2020 identified native hip (NH) and total hip arthroplasty (THA) patients who had a dry-tap following aspiration for suspected infection or periprosthetic joint infection (PJI). Serology tests, lavage/re-aspiration volumes, and aspirate cell-count/culture were assessed. On pre-aspiration MRI, presence/grade of joint effusion (JE), pseudocapsule dehiscence (PD), extraarticular fluid and sinus-tract were recorded.

RESULTS

Out of 215 included dry-taps, 185 (86.0%) were non-infected and 30 (13.9%) infected. In subgroup analysis, 64/71(90.1%) NH and 121/144(84.0%) THA dry-taps were non-infected. Pre-aspiration MRI of THA group with dry-tap showed significant findings; PD with extraarticular fluid (8/12, 66.7%) and sinus tract (7/12, 58.3%) were higher in the infected compared to non-infected group (5/42, 11.9% and 0/42, 0.0%) (both p < 0.001). Among THA group, polymorphonuclear-leukocytes > 80% was present in 8/9 (88.9%) of infected versus 4/28 (14.3%) non-infected group (p < 0.001). Multivariable regression showed PD (p = 0.005) and JE (p = 0.042) being significant independent predictors of PJI, similarly the elevated CRP (p = 0.044) and JE (p = 0.017).

CONCLUSION

Majority of patients suspected of hip joint infection with dry-tap were non-infected. Synovial PMN% following lavage maintains high sensitivity for detection of PJI. In patients with THA, PD and subsequent extraarticular collection can be associated with dry-tap therefore, pre-aspiration MRI can help determine their presence and plan the aspiration.

[Acquired hip joint pathologies in childhood]

A number of different acquired pathologies can affect the pediatric hip joint. The classical and relatively common reactive, inflammatory or traumatic entities have to be differentiated from each other. Rarer and very rare pathologies, such as neoplastic entities or tenosynovial giant cell tumor, must also be considered in the differential diagnostics. The correct diagnosis, treatment planning and follow-up monitoring require close coordination between the departments of pediatric radiology and pediatric orthopedics. Sonography often represents the initial diagnostic step, followed by conventional radiography. Further evaluation of hip joint pathologies requires magnetic resonance imaging. In selected cases computed tomography can also be indicated.

Acute septic arthritis of the acromioclavicular joint caused by Staphylococcus aureus with marked soft tissue collection towards posterior medial aspect of the AC joint: A rare clinical presentation

Primary septic arthritis of the Acromioclavicular joint is an unusual disorder and is seldom seen even in an immunocompromised person. We report a case of primary septic arthritis of the acromioclavicular (A-C) joint caused by Staphylococcus aureus. The patient was admitted with pain in the left shoulder, restricted movements and fever. Laboratory parameters showed elevated C-reactive protein, raised erythrocyte sedimentation rate and leukocytosis. Ultrasound revealed a 32 mm collection at the acromioclavicular joint. Patient underwent incision and drainage of abscess. Culture and sensitivity revealed moderate growth of Staphylococcus-aureus. Patient was started on appropriate intravenous antibiotics. Magnetic resonance imaging (MRI) done after 2 weeks revealed marked erosion in the lateral end of clavicle with soft tissue collection along the posteromedial aspect A-C joint. The patient had to undergo repeat drainage of the abscess along with the decompression of lateral end of clavicle. The patient was successfully treated with 8 weeks of appropriate antibiotics with complete resolution of infection.

Post-arthrogram synovitis: MRI and histopathologic findings

A 57-year-old patient developed severe, persistent pain following MR arthrography with iodinated contrast. MRI 1 week later showed synovitis which was new compared to the prior MRI. Arthroscopy showed severe synovitis. Histopathology showed synovitis characterized by lymphocytes, neutrophils, and necrosis. One out of 4 intraoperative cultures was positive, but ultimately believed to be due to contaminants. CRP normalized within 1 month. Repeat MRI 2 years later showed progressive degenerative findings, but no evidence of ongoing infection, or stigmata of previous infection. We believe this to be an unusually severe case of reactive synovitis. The purpose of the report is to add to knowledge of reactions to intra-articular contrast injection.

Usefulness of MRI findings in differentiating between septic arthritis and transient synovitis of hip joint in children: A systematic review and meta-analysis

Purpose

Septic arthritis (SA) of the hip joint is a serious infection which can lead to more irreversible complications. Differentiating Septic arthritis from Transient synovitis (which is the most common cause of painful hip in children) is difficult and very important to prevent serious complications which can occur with Septic arthritis. The aim of this study was to find out the MRI findings which can differentiate between these two conditions.

Methods

Systematic literature search was conducted according to the PRISMA guidelines on MEDLINE(PubMed), Google Scholar, ScienceDirect, and world Health Organization Virtual Health Library, up to April 2022. Studies that compared MRI findings between Septic Arthritis and Transient Synovitis of hip joint in children were included. The pooled sensitivity and specificity estimates of these findings were calculated using MetaDTA version 2.0.

Results

Six studies were included in qualitative analysis and five were included in quantitative analysis. Pooled sensitivity and specificity of synovial enhancement were 94.2 % (95 % CI, 45.2–99.7 %) and 60.6 % (95% CI, 6–97.4 %) respectively. Soft tissue changes had pooled sensitivity and specificity of 75 % (95% CI, 57.5–86.9 %) and 69.9 % (95 % CI, 46.5–86.2 %) respectively. Pooled sensitivity and specificity of femoral head changes were 41.5 % (95 % CI, 15.9–72.7 %) and 87.3 % (95 % CI, 75.5–93.8 %) respectively. Bone marrow changes had pooled sensitivity and specificity of 70 % (95 % CI, 26.8–93.7 %) and 99.9 % (95 % CI, 28.7–100 %) respectively.

Conclusion

MRI findings especially bone marrow changes were found to be useful in differentiating septic arthritis from transient synovitis among children presented with painful hip after exclusion of other causes.

Prediction of High-Grade Hip Joint Effusion With Simple Radiographs in Children: A Comparative Study With Magnetic Resonance Imaging

OBJECTIVES

The objective of this study was to investigate the predictive value of asymmetric joint space widening on simple radiographs for the presence of hip joint effusion in children with unilateral hip pain.

METHODS

Sixty-eight patients aged 6 to 17 years with both simple radiograph and magnetic resonance imaging of both hips were retrospectively reviewed. We evaluated the predictive effects of radiographic surrogates for joint space widening on the presence of high-grade hip joint effusion. We also sought to investigate a predictive model for the presence of hip joint effusion with the patients' clinical and radiological data.

RESULTS

Radiographic values showed high specificity but low sensitivity for the presence of high-grade joint effusion. On multivariate analysis, sex and the difference ratio of medial and superior gaps were independent predictive factors for unilateral high-grade hip joint effusion.

CONCLUSIONS

For children 6 years and older with asymmetric hip joint space widening on simple radiographs, further evaluations for the presence of hip joint effusion should be considered because of its high specificity. The predictability can improve if both medial and superior gaps, and sex are included in the evaluation. In girls, hip joint effusion seems to widen the joint space more easily than in boys, which may be owing to the more ligamentous laxity of and less musculature around the hip in girls. However, the risk of joint effusion should not be underestimated even if a child presents symmetry on the simple radiograph because of its low sensitivity and the possibility of bilateral involvements or early stage of diseases.

Test characteristics of history, examination and investigations in the evaluation for septic arthritis in the child presenting with acute non-traumatic limp. A systematic review

BACKGROUND

Septic arthritis is an uncommon but potentially significant diagnosis to be considered when a child presents to the emergency department (ED) with non-traumatic limp. Our objective was to determine the diagnostic accuracy of clinical findings (history and examination) and investigation results (pathology tests and imaging) for the diagnosis of septic arthritis among children presenting with acute non-traumatic limp to the ED.

METHODS

Systematic review of the literature published between 1966 and June 2019 on MEDLINE and EMBASE databases. Studies were included if they evaluated children presenting with lower limb complaints and evaluated diagnostic performance of items from history, physical examination, laboratory testing or radiological examination. Data were independently extracted by two authors, and quality assessment was performed using the Quality Assessment Tool for Diagnostic Accuracy Studies 2 tool.

RESULTS

18 studies were identified, and included 2672 children (560 with a final diagnosis of septic arthritis). There was substantial heterogeneity in inclusion criteria, study setting, definitions of specific variables and the gold standard used to confirm septic arthritis. Clinical and investigation findings were reported using varying definitions and cut-offs, and applied to differing study populations. Spectrum bias and poor-to-moderate study design quality limit their applicability to the ED setting.Single studies suggest that the presence of joint tenderness (n=189; positive likelihood ratio 11.4 (95% CI 5.9 to 22.0); negative likelihood ratio 0.2 (95% CI 0.0 to 1.2)) and joint effusion on ultrasound (n=127; positive likelihood ratio 8.4 (95% CI 4.1 to 17.1); negative likelihood ratio 0.2 (95% CI 0.1 to 0.3)) appear to be useful. Two promising clinical risk prediction tools were identified, however, their performance was notably lower when tested in external validation studies.

DISCUSSION

Differentiating children with septic arthritis from non-emergent disorders of non-traumatic limp remains a key diagnostic challenge for emergency physicians. There is a need for prospectively derived and validated ED-based clinical risk prediction tools.

Differential MRI findings of transient synovitis of the hip in children when septic arthritis is suspected according to symptom duration

We investigated the differential MRI findings in children with transient synovitis of the hip in whom septic arthritis was suspected. Under the hypothesis that disease progression can alter representative MRI findings, we stratified these findings in accordance with symptom duration as this can correlate with disease progression. We analyzed 65 children who underwent MRI for acute hip pain and who were suspected of having a septic condition (i.e. presented with fever or increased inflammatory markers) when the imaging was performed. Symptom duration was defined as the interval from the first presentation of hip pain to the MRI scan. We divided the patients into two subgroups according to symptom duration: patients with short symptom duration (≤2 days, short-term subgroup, n = 30) and those with long symptom duration (≥3 days, long-term subgroup, n = 35). Twenty-eight (43.1%) of the study subjects were diagnosed with septic arthritis. Whereas only a high-grade joint effusion was a significant MRI finding differentiating septic arthritis from transient synovitis in the whole cohort, the presence of contralateral joint effusion in the short-term subgroup (P = 0.024) and the absence of a change/enhancement of the signal intensity of soft tissue in the long-term subgroup (P < 0.001) were significant predictors of transient synovitis. The significances of differential MRI findings for septic arthritis and transient synovitis seem to change according to symptom duration. We suggest that symptom duration, which may correlate with disease progression, should also be considered when interpreting MRIs of children under suspicion of septic arthritis.

Imaging musculoskeletal soft tissue infections

Musculoskeletal soft tissue infections are not uncommonly encountered in both the clinic and Emergency Department setting. The clinical diagnosis is not always evident as these infections can have variable presentations depending on the duration and depth of disease extension through the soft-tissue layers. Imaging often plays an important role in diagnosing the infection, defining the extent of involvement, directing tissue sampling, and in monitoring treatment response. After initial radiographs, ultrasound (US) is often the next modality utilized to evaluate patients with suspected soft tissue infections given its low cost, availability, portability, and potential for real-time guidance of fluid aspiration. The widespread use of cross-sectional imaging with magnetic resonance imaging (MRI) and computed tomography (CT) has greatly increased the radiological diagnosis in conditions where US may be limited. In addition, CT and MRI allow a thorough evaluation of disease extension, including assessment of joint spaces, tendons, and osseous changes indicative of bone involvement. This review will focus on the radiological findings of soft tissue infections on US, CT, and MRI.

Femoral Neck Aspiration Aids in the Diagnosis of Osteomyelitis In Children With Septic Hip

BACKGROUND

The role of femoral aspiration (FA) in the treatment of septic arthritis of the hip is controversial. The purpose of this study was to determine if FA conducted concomitantly with irrigation and debridement (I&D) of the septic hip aids in microorganism and osteomyelitis identification and alters the treatment plan, or if the risks of the procedure outweigh its potential benefit. We also compare preoperative magnetic resonance imaging (MRI) with FA for diagnosis of osteomyelitis cooccurring with septic arthritis.

METHODS

Retrospective review was performed of all patients treated at a single institution between January 2003 and June 2014 for suspected septic hip arthritis. Eighty-three patients were identified with suspected or confirmed septic arthritis and 28 patients (33%) had cooccurring osteomyelitis. Demographic and clinical data were recorded for each patient. The sensitivity and specificity of FA and MRI for diagnosing osteomyelitis were determined.

RESULTS

Among the 83 patients with confirmed or suspected septic arthritis, 31 patients (37%) had a FA performed at the time of the hip I&D, resulting in positive cultures in 17 patients. All of these patients had other positive cultures (blood and/or joint fluid) that grew the same organism. 54 patients (65%) had a preoperative MRI. The MRI was falsely negative in 10 patients, 6 of whom had a positive FA resulting in appropriate management of osteomyelitis. Missed or delayed diagnosis of osteomyelitis resulted in significant morbidity in 3 patients (avascular necrosis and femoral neck fracture, extensive lower extremity osteomyelitis, and subtrochanteric fracture with malunion). No complications associated with FA were identified. FA and MRI were found to have sensitivity/specificity for osteomyelitis of 100%/100% and 38%/95%, respectively.

CONCLUSIONS

Although FA did not improve microorganism identification, it did aid in the diagnosis of cooccurring osteomyelitis when treating children with septic arthritis, especially in patients with false negative MRI findings for osteomyelitis. We recommend FA at the time of septic hip I&D as its benefits appear to far outweigh its risks.

LEVEL OF EVIDENCE

Level III-diagnostic study.

Irritable Hip as the Inaugural Symptom for Neuroblastoma

CASE REPORT

A four-year-old girl presented with fever and a painful limp in the left hip. Pain characteristics and anemia detected in the blood analyses were the first warning signs that the hip process was not standard. Although the primary suspicion was of septic arthritis, a CT scan of the abdomen revealed an adrenal neuroblastoma.

CONCLUSION

The presenting signs of neuroblastoma are commonly atypical. About 25% of presentations are orthopedic and mimic a variety of severe orthopedic conditions. The most important clinical dilemma is distinguishing benign and self-limiting disorders from septic or malignant processes.

JOURNAL CLUB: Can Coronal STIR Be Used as Screening for Acute Nontraumatic Hip Pain in Children?

OBJECTIVE

The objective of this study is to evaluate whether coronal STIR MRI can be used as a screening test for nontraumatic acute hip pain in children.

MATERIALS AND METHODS

From 2008 to 2012, we identified all patients younger than 18 years at our tertiary care facility who underwent pelvic MRI including coronal STIR for the following indications: acute hip pain, limping, or refusal to bear weight. Patients with a history of trauma were excluded. Each MR image was independently reviewed by four radiologists who were blinded to the clinical outcome. After first reviewing the coronal STIR images only, they then reviewed the full MRI studies in a random order different from that used for review of the coronal STIR images. The sensitivity and specificity of STIR-only images in identifying the presence of abnormality and specific diagnoses were calculated, with the full MRI study considered as the reference standard. Kappa values were calculated for STIR-only and full MRI studies.

RESULTS

A total of 127 patients (67 female patients and 60 male patients; median age, 9 years; range, 5 months to 17 years) were identified. The most common abnormalities (calculated as the mean of frequency values noted by four readers) were hip effusion (52%; range, 46-58%), osteomyelitis (42%; range, 29-48%), and myositis (32%; range, 20-40%). For the detection of any abnormality, STIR-only images had a mean sensitivity of 95% and a mean specificity of 67%. For approximately one-third of STIR-only studies with true-positive results, additional abnormalities were found on full MRI studies.

CONCLUSION

Coronal STIR imaging of the pelvis has high sensitivity (95%) in the detection of abnormalities associated with acute nontraumatic hip pain in children, but it often misses additional abnormalities.

A guideline for differential diagnosis between septic arthritis and transient synovitis in the ED: a Delphi survey

OBJECTIVE

Among the causes of limping gait in children, septic arthritis (SA) and transient synovitis (TS) are the 2 most likely etiologies. The aim of this study was to determine the medical histories, physical examinations, and other studies to use to create a clinical guideline for differential diagnosis between SA and TS in children in the emergency department (ED). The pediatric orthopedic emergency committee of our institution addressed the issue of developing a guideline for differential diagnosis.

METHODS

Two rounds of the modified Delphi survey were conducted, and a face-to-face committee meeting was held after each survey round. Delphi survey panelists included 10 pediatric orthopedic surgeons and 8 emergency physicians including 3 pediatric emergency physicians.

RESULTS

Response rates were 100% in each round. The panelists used a 6-point Likert scale to rate the clinical diagnostic guideline contents as having high (5 or 6), moderate (3 or 4), or low importance (1 or 2). Twenty-eight questionnaire items were included in the first round; and 18 items, in the second round. Factors for concern were selected, and a flowchart of the diagnostic guideline development process was based on the results of the survey.

CONCLUSION

A diagnostic guideline for evaluating SA and TS in children in the ED was achieved using combined empirical evidence together with expert opinion, potentially resulting in a diagnostic strategy to be incorporated into existing guidelines or used on its own.

Is MRI Necessary for Skeletal Evaluation in Sickle Cell Disease

BACKGROUND

More than 50% of the world's cases of sickle cell anaemia are in India with an estimated population of 1.27 billion as against estimated world's population of 7.24 billion.

AIM

MRI of 103 patients of sickle cell disease were evaluated to assess the skeletal changes in proven cases of sickle cell disease and to find the incidence of bony infarcts in such patients. The conversion of red marrow to yellow marrow in these patients were also studied.

MATERIALS AND METHODS

Sickle cell patients with musculoskeletal pain as well as asymptomatic sickle cell patients were evaluated by MRI. The standard sequences used wereT1WI, T2WI, STIR, T1WI + Gd Contrast.

RESULTS

Persistent Red marrow was seen in axial and appendicular skeleton (62 cases). Extramedullary haematopoiesis was found in 4 cases, avascular necrosis of femur head (32 cases) and bone infarcts (46 cases) were also observed in our study. Osteomyelitis, septic arthritis and tubercular infections were associated with sickle cell disease in our study.

CONCLUSION

MRI is very sensitive in detecting early stages of avascular necrosis, red marrow persistence, extramedullary haematopoiesis, changes of arthritis, infections and joint effusion.

Concomitant septic arthritis and osteomyelitis of the hip in young children; a new pathophysiological hypothesis suggested by MRI enhancement pattern

Background

In children, septic arthritis (SA) of the hip is either primary or concomitant with acute haematogenous osteomyelitis (AHO). However, seldom, patients with isolated SA at presentation, may later show osteomyelitis in the metaphysis. The aim of this study was to elaborate a physiopathological hypothesis based on the peculiar MRI findings to explain the onset of AHO after SA.

Methods

Cases of acute infection of the hip admitted between January 2010 and December 2013 were retrospectively reviewed to assess radiographic and MRI features, as well as bacteriological findings. Only children with isolated SA were included in this study, whereas cases of concomitant SA and AHO at presentation were excluded.

Results

Ten patients met the inclusion criteria. Six (1–11 months) demonstrated, on the initial MRI, decreased perfusion on gadolinium enhanced fat-suppressed T1-weighted sequence of the femoral epiphysis and developed one month later metaphyseal AHO. Four (5–14 years) did not show decreased perfusion and did not develop AHO on follow-up. The type of germ involved influenced neither the type of enhancement pattern nor the outcome.

Conclusions

Age under one year and decreased perfusion of the affected femoral epiphysis increases the risk of secondary AHO. Our study is the first report in human medicine supporting the physiopathological hypothesis described by Alderson et al. in an animal model: primary infection can originally affect the joint, then penetrate the epiphyseal cartilage, and finally spread into the metaphyseal region through transphyseal vessels present only in the first 12/18 months of life.

The use of ultrasound in the management of septic arthritis of the hip

In the assessment of septic arthritis of the hip in a pediatric population, ultrasound is a safe and easily conducted method to confirm an effusion. The need for MRI to further evaluate the patient for adjacent infection before treatment is debatable. Once an effusion is confirmed on ultrasonography, we have found that septic arthritis of the hip does not need advanced imaging before arthrotomy and debridement. Patients who fail to clinically respond to an initial hip arthrotomy and appropriate antibiotics may benefit from an MRI for the identification of concomitant infections that may require surgical intervention.

Septic arthritis of the neonatal hip: acute management and late reconstruction

Septic arthritis of the hip in neonates is rare but can have devastating consequences. Presenting signs and symptoms may differ from those encountered in older children, which may result in diagnostic challenge or delay. Many risk factors predispose neonates to septic arthritis, including the presence of transphyseal vessels and invasive procedures. Bacterial infection of the joint occurs via hematogenous invasion, extension from an adjacent site, or direct inoculation. A strong correlation exists between younger age at presentation and severity of residual hip deformity. Diagnosis is based on clinical examination, laboratory markers, and ultrasound evaluation. Early management includes parenteral antibiotics and surgical drainage. Late-stage management options include femoral and pelvic osteotomies, trochanteric arthroplasty, arthrodesis, pelvic support procedures, and nonsurgical measures. Early diagnosis and management continues to be the most important prognostic factor for a favorable outcome in the neonate with septic arthritis.

Magnetic resonance imaging of pressure sores in spinal cord injured patients: accuracy in predicting osteomyelitis

OBJECTIVE

Identify key magnetic resonance imaging (MRI) features that have a significant correlation with osteomyelitis of pressure ulcers in spinal injury patients.

DESIGN

Retrospective review study.

PARTICIPANTS

Adult patients admitted to the National Spinal Injuries Centre with spinal cord injury (SCI) and signs of pressure ulceration investigated with MRI.

METHODS

Analysis of MRI examinations and clinical records collected over a 4-year period. Images were independently assessed by 2 experienced radiologists for osteomyelitis based on assigned predictive indicators including cortical bone erosion, soft tissue edema, deep collections, heterotopic new bone, hip effusion, and abnormal signal change of the marrow.

RESULTS

Thirty-seven patients underwent 41 MRI scans. The prevalence of osteomyelitis was highly correlated with cortical bone erosion (r = 0.84) and abnormal bone marrow changes on T1-weighted images (r = 0.82).

Usefulness of dynamic contrast-enhanced MRI in differentiating between septic arthritis and transient synovitis in the hip joint

OBJECTIVE

The purpose of this study was to show the usefulness of dynamic contrast-enhanced MRI (DCE-MRI) and to determine the optimal time window in MRI for differentiating between septic arthritis and transient synovitis in painful hip joints.

MATERIALS AND METHODS

Eighteen patients who underwent DCE-MRI were enrolled, and the final diagnoses were septic arthritis (n = 7) and transient synovitis (n = 11). The enhancement patterns of DCE-MRI were dichotomized according to the shape of the time-signal intensity curves. The time at the maximal difference in the signal intensity between two time-signal intensity curves of both femoral heads was recorded. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated. Receiver operating characteristic curves were calculated.

RESULTS

Six of seven patients with septic arthritis in the hip joint had decreased enhancement during the early phase of DCE-MRI. The enhancement difference between the two patient groups was statistically significant (p = 0.0498). The time at the maximal difference in the signal intensity between two time-signal intensity curves of both femoral heads was approximately 3.5 minutes. The area under the receiver operating characteristic curve for predicting septic arthritis was 0.792.

CONCLUSION

DCE-MRI is useful in differentiating between septic hip arthritis and transient synovitis. If static contrast-enhanced coronal MRI is used, the optimal time for the acquisition of contrast-enhanced coronal MRI is approximately 3.5 minutes.

Spectrum of synovial pathologies: a pictorial assay

The synovium, a specialized vascular tissue, lines the diarthrodial joints, bursae, and tendon sheaths of the body. It helps in nourishment of articular structures. The synovium is affected by a variety of disorders that can be either localized or systemic. Although normal synovium is barely perceptible on magnetic resonance imaging, it provides an excellent imaging modality for the evaluation of pathologic processes involving the synovium. The pathologic processes affecting the synovium include 1 of the following etiologies: inflammatory, infectious, degenerative, traumatic, or neoplastic and tumor-like conditions. In this article, we discuss the magnetic resonance imaging technique and the sequences used in the evaluation of synovial pathologies and review the characteristic imaging findings of specific conditions thus narrowing the differential diagnoses.

Differences in MRI findings between subgroups of recent-onset childhood arthritis

BACKGROUND

MRI is sensitive for joint inflammation, but its ability to separate subgroups of arthritis in children has been questioned. Infectious arthritis (IA), postinfectious arthritis (PA), transient arthritis (TA) and juvenile idiopathic arthritis (JIA) are subgroups that may need early, different treatment.

OBJECTIVE

To determine whether MRI findings differ in IA, PA/TA and JIA in recent-onset childhood arthritis.

MATERIALS AND METHODS

Fifty-nine children from a prospective study of incidence of arthritis (n = 216) were, based on clinical and biochemical criteria, examined by MRI. Joint fluid, synovium, bone marrow, soft tissue and cartilage were scored retrospectively and analysed by Pearson chi-square test and logistic regression analysis.

RESULTS

Fifty-nine children had MRI of one station. IA was suggested by bone marrow oedema (OR 7.46, P = 0.011) and absence of T1-weighted and T2-weighted low signal intensity synovial tissue (OR 0.06, P = 0.015). Furthermore, soft-tissue oedema and reduced contrast enhancement in the epiphyses were more frequent in children with IA. JIA correlated positively with low signal intensity synovial tissue (OR 13.30, P < 0.001) and negatively with soft-tissue oedema (OR 0.20, P = 0.018). No significant positive determinants were found for PA/TA, but bone marrow oedema, soft-tissue oedema, irregular thickened synovium and low signal intensity synovial tissue was less frequent than in IA/JIA.

CONCLUSION

In children with high clinical suspicion of recent onset arthritis, there was a significant difference in the distribution of specific MRI features among the diagnostic groups.

Subchondral bone marrow lesions are highly associated with, and predict subchondral bone attrition longitudinally: the MOST study

OBJECTIVE

Subchondral bone attrition (SBA) is defined as flattening or depression of the osseous articular surface. The causes of attrition are unknown, but remodeling processes due to chronic overload that are reflected as bone marrow edema-like lesions (BMLs) on magnetic resonance imaging (MRI) might predispose the subchondral bone to subsequent attrition. The aim of this study was to evaluate the cross-sectional and longitudinal association of BMLs with SBA in the same subregion of the knee.

DESIGN

The Multicenter Osteoarthritis (MOST) study is a longitudinal observational study of individuals who have or are at high risk for knee osteoarthritis. Subjects with available baseline and 30-months follow-up MRI were included. Patients with a recent history of trauma or findings suggestive of post-traumatic bone marrow changes were excluded. Subchondral BMLs and SBA were scored semiquantitatively from 0 to 3 in 10 tibiofemoral subregions. We evaluated the association of prevalent BMLs at baseline with the presence of prevalent and incident SBA on a per-subregion basis using logistic regression. We also cross-sectionally evaluated the association of BML grade severity and presence of baseline SBA.

RESULTS

One thousand and twenty-five knees were included. 8.9% of the analyzed knee subregions showed SBA present at baseline and 9.2% of subregions exhibited prevalent subchondral BMLs. The adjusted odds ratio (OR) for prevalent SBA for subregions with prevalent BMLs was 18.8 [95% confidence intervals (CI) 15.9-22.4]. A larger BML size was directly associated with an increased risk of prevalent SBA. 195 (2.2%) subregions exhibited incident SBA at follow-up. The adjusted OR for incident SBA was 5.3 [95% CI 3.6-7.7] when compared to subregions without BMLs as the reference.

CONCLUSIONS

Prevalent and incident SBA is strongly associated with subchondral BMLs in the same subregion. One explanation for the presence and development of SBA is subchondral remodeling due to increased stress, which is reflected as BMLs on MRI.

The management of septic arthritis in children

We performed a systematic review of the optimal management of septic arthritis in children as recommended in the current English literature using MEDLINE, EMBASE, CINAHL, the Cochrane Library and reference lists of retrieved articles without date restrictions up to 31 January 2009. From 2236 citations, 227 relevant full-text articles were screened in detail; 154 papers fulfilled the inclusion criteria, from which conclusions were drawn on the management of infected joints in children.

Our review showed that no single investigation, including joint aspiration, is sufficiently reliable to diagnose conclusively joint infection. The roles of aspiration, arthrotomy and arthroscopy in treatment are not clear cut, and the ideal duration of antibiotic therapy is not yet fully defined. These issues are discussed. Further large-scale, multi-centre studies are needed to delineate the optimal management of paediatric septic arthritis.

MRI-detected subchondral bone marrow signal alterations of the knee joint: terminology, imaging appearance, relevance and radiological differential diagnosis

OBJECTIVE

To discuss terminology, radiological differential diagnoses and significance of magnetic resonance imaging (MRI)-detected subchondral bone marrow lesions (BMLs) of the knee joint.

METHODS

An overview of the published literature is presented. In addition, the radiological appearance and differential diagnosis of subchondral signal alterations of the knee joint are discussed based on expert consensus. A recommendation for terminology is provided and the relevance of these imaging findings for osteoarthritis (OA) research is emphasized.

RESULTS

A multitude of differential diagnoses of subchondral BMLs may present with a similar aspect and signal characteristics. For this reason it is crucial to clearly and specifically define the type of BML that is being assessed and to use terminology that is appropriate to the condition and the pathology. In light of the currently used terminology, supported by histology, it seems appropriate to apply the widely used term "bone marrow lesion" to the different entities of subchondral signal alterations and in addition to specifically and precisely define the analyzed type of BML. Water sensitive sequences such as fat suppressed T2-weighted, proton density-weighted, intermediate-weighted fast spin echo or short tau inversion recovery (STIR) sequences should be applied to assess non-cystic BMLs as only these sequences depict the lesions to their maximum extent. Assessment of subchondral non-cystic ill-defined BMLs on gradient echo-type sequences should be avoided as they will underestimate the size of the lesion. Differential diagnoses of OA related BMLs include traumatic bone contusions and fractures with or without disruption of the articular surface. Osteonecrosis and bone infarcts, inflammation, tumor, transient idiopathic bone marrow edema, red marrow and post-surgical alterations should also be considered.

CONCLUSION

Different entities of subchondral BMLs that are of relevance in the context of OA research may be distinguished by specific imaging findings, patient characteristics, symptoms, and history and are discussed in this review.

Chronic recurrent multifocal osteomyelitis: comparison of whole-body MR imaging with radiography and correlation with clinical and laboratory data

PURPOSE

To describe whole-body magnetic resonance (MR) imaging appearance of chronic recurrent multifocal osteomyelitis (CRMO) and assess the role of MR imaging versus radiography in diagnosis of disease and correlation with clinical findings and laboratory data.

MATERIALS AND METHODS

Institutional review board approved this retrospective HIPAA-compliant study; informed consent was waived. T1-weighted, short inversion time inversion-recovery, and contrast material-enhanced T1-weighted whole-body MR imaging was performed and two-plane radiographs, clinical findings, and laboratory data were reviewed in 13 children (median age, 13 years) with CRMO. Lesion depiction, location, and characterization and extraskeletal abnormalities were evaluated. MR imaging findings were compared with clinical and laboratory data and radiographic results. Data analysis was performed, and diagnostic performance statistics of radiography, physical examination results, and serum inflammatory markers were calculated. General multilevel linear modeling framework was used. Odds ratios were calculated to estimate effect of age, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) level on reliabilities. Associations of ESR and CRP level with total number of lesions were assessed (chi(2) test).

RESULTS

MR imaging depicted 101 ill-defined edemalike osseous lesions. Most frequent anatomic sites were distal femur (21%, 21 of 101), proximal tibia (17%, 17 of 101), and distal tibia and fibula (14% each, 14 of 101). In tubular bones (70 anatomic sites), metaphysis (86%, 60 of 70) and epiphysis (67%, 47 of 70) were involved. Contiguous physeal relationship (89%, 66 of 74), periosteal reaction (48%, 48 of 101), and symmetric involvement (85%, 11 of 13) were present. MR imaging demonstrated multifocality in all patients. There were no extraskeletal abnormalities and no relationship between serum inflammatory markers and number of symptomatic anatomic sites (P = .472). Sensitivity for radiography was 0.13 (70 of 119); physical examination, 0.31 (52 of 299); and serum inflammatory markers, 0.15 (two of 13).

CONCLUSION

Whole-body MR imaging is useful for detection of CRMO, particularly in indeterminate cases, because it is more likely to show abnormalities.

Primary septic arthritis of the acromio-clavicular joint: case report and review of literature

Primary septic arthritis of the Acromio clavicular joint is an uncommon disorder and is rarely seen even in an immunocompromised individual. We report a case of primary septic arthritis of the acromio-clavicular (A-C) joint caused by Staphylococcus aureus without any predisposing factors. The patient was admitted with left shoulder pain, restricted movements and fever. Laboratory parameters showed high C-reactive protein, raised erythrocyte sedimentation rate and leucocytosis. Blood cultures were positive for Staphylococcus-aureus. Magnetic resonance imaging (MRI) using Gadolinium enhancement revealed marked effusion in the A-C joint. Aspiration from the A-C joint revealed a heavy growth of Staphylococcus-aureus. The patient was successfully treated with 8 weeks of appropriate antibiotics with complete resolution of infection and return to full function.

Imaging in pelvic osteomyelitis: support for early magnetic resonance imaging

BACKGROUND

Children with pelvic osteomyelitis may present with symptoms that are nonspecific. Conventional imaging modalities including plain radiographs, ultrasound, technetium bone scan, and computed tomography rarely demonstrate pathology that is diagnostic of this condition. As a result, accurate diagnosis is often delayed, and children may undergo surgical diagnostic or therapeutic procedures that may be avoided. We report the radiographic and magnetic resonance imaging (MRI) findings in 23 children admitted with a suspected diagnosis of pelvic osteomyelitis. We are presenting imaging findings in children with suspected pelvic osteomyelitis with emphasis on MRI abnormalities and to propose an anatomical classification based on the patterns of pelvic involvement.

METHODS

The medical records and imaging reports of all patients admitted to our institution with a history and physical examination suggestive of pelvic osteomyelitis between July 31, 1992, and March 10, 2003 were reviewed. Criteria were defined for the diagnosis of pelvic osteomyelitis based on criteria used by Farley et al in 1985. Specific attention was paid to the imaging strategies used and the influence of each radiographic method on the ultimate diagnosis.

RESULTS

Abnormalities on the MRI included soft tissue inflammation and bone edema. These findings were bright on T2 and short inversion time Short T1 inversion recovery (STIR) images and enhanced after gadolinium administration. Five distinct patterns of pelvic involvement were observed, each corresponding to a cartilaginous epiphysis or apophysis. These were the sacroiliac joint, triradiate cartilage, pubic symphysis, ischium, and iliac apophysis. One patient had a noninfectious cause of presentation with a deep vein thrombosis, whereas another was diagnosed with Hodgkin lymphoma in addition to osteomyelitis of the ischium.

CONCLUSIONS

Magnetic resonance imaging is a sensitive technique for evaluation of pyogenic infections involving the pelvis. In patients presenting with clinical findings and laboratory studies suggesting an infectious process, MRI with gadolinium enhancement should be performed as an early study. Magnetic resonance imaging is also effective in identifying other conditions that may resemble pelvic osteomyelitis.

MRI features of Lyme arthritis of the hips

Diagnosing Lyme arthritis without a history of travel to endemic regions or erythema migrans can be a challenge. Radiographic and ultrasonographic findings are nonspecific for the diagnosis of Lyme arthritis. We present the MRI features of Lyme disease of the hip in a 4-year-old boy who presented with hip pain and was found to have Lyme disease by Western blot. Our findings include bilateral hip effusions and synovial enhancement, normal bone marrow signal intensity without enhancement, minimal adjacent muscular and soft-tissue edema, and bilateral inguinal lymph nodes measuring up to 1 cm.

Septic Arthritis Versus Transient Synovitis of the Hip: Gadolinium-Enhanced MRI Finding of Decreased Perfusion at the Femoral Epiphysis

OBJECTIVE

The purpose of this study was to identify differences in the MRI findings of septic arthritis and transient synovitis in patients with nontraumatic acute hip pain and hip effusion.

MATERIALS AND METHODS

The MRI findings in nine patients with septic arthritis and 11 with transient synovitis were reviewed retrospectively. This study was approved by our institutional review board. The diagnoses were based on findings at physical examination, laboratory studies, and joint aspiration and bacteriologic study. The MRI findings were analyzed with emphasis on the grade of joint effusion, alterations in signal intensity in the soft tissues and bone marrow, and the presence of decreased perfusion at the femoral head.

RESULTS

Low signal intensity on fat-suppressed gadolinium-enhanced T1-weighted coronal MRI suggesting decreased perfusion at the femoral head of the affected hip joint was seen in eight of nine patients with septic arthritis and in two of 11 patients with transient synovitis. Statistically reliable differences (p = 0.005) were found between the two groups. Alterations in signal intensity in the bone marrow were seen in three patients with septic arthritis but in none of the patients with transient synovitis. Decreased perfusion on fat-suppressed gadolinium-enhanced coronal T1-weighted MRI was seen in the six patients with septic arthritis who did not have alterations in signal intensity involving the bone marrow.

CONCLUSION

Decreased perfusion at the femoral epiphysis on fat-suppressed gadolinium-enhanced coronal T1-weighted MRI is useful for differentiating septic arthritis from transient synovitis.

The limping child: an algorithm to outrule musculoskeletal sepsis

BACKGROUND

The acutely limping child presents a significant diagnostic challenge.

AIM

The purpose of this study was to create a clinically useful algorithm to allow exclusion of 'musculoskeletal sepsis' as a differential diagnosis in the child presenting with limp.

METHODS

Data were collected on all 286 limping children admitted to our centre over a 3-year-period. Using logistic regression analysis, the predictive model was constructed, to exclude infection.

RESULTS

Duration of symptoms, constitutional symptoms, temperature, white cell count and ESR were significantly different in children with musculoskeletal infection (P < 0.05). Multivariate analysis demonstrated that when all three variables of duration of symptoms >1, <5 days; temperature >37.0 degrees C; and ESR >35 mm/h were present, the predicted probability of infection was 0.66, falling to 0.01 when none were present.

CONCLUSION

This multivariate model enables us to rule out musculoskeletal infection with 99% certainty in limping children with none of these three presenting variables.

Septic arthritis in Western and sub-Saharan African children - a review

This article reviews what is known about the incidence, aetiology, presentation, bacteriology and management of septic arthritis in children. It compares where possible the different presentations and characteristics of this condition in the Western and sub-Saharan African regions.

[MRI of knee tuberculous arthritis]

Tuberculous arthritis is rare and the diagnosis may be confused with inflammatory arthritis. Only few cases, explored by MRI, have been reported in the literature. We report 3 cases of tuberculous arthritis of the knee revealed by insidious pain. The abnormalities revealed by MRI suggested tuberculosis. Diagnosis was confirmed by histology.

MR imaging of transient synovitis: differentiation from septic arthritis

BACKGROUND

Transient synovitis is the most common cause of acute hip pain in children. However, MR imaging findings in transient synovitis and the role of MR imaging in differentiating transient synovitis from septic arthritis have not been fully reported.

OBJECTIVE

To describe the MR findings of transient synovitis and to determine whether the MR characteristics can differentiate this disease entity from septic arthritis.

MATERIALS AND METHODS

Clinical findings and MR images of 49 patients with transient synovitis (male/female 36/13, mean age 6.1 years) and 18 patients with septic arthritis (male/female 10/8, mean age 4.9 years) were retrospectively reviewed.

RESULTS

MR findings of transient synovitis were symptomatic joint effusion, synovial enhancement, contralateral joint effusion, synovial thickening, and signal intensity (SI) alterations and enhancement in surrounding soft tissue. Among these, SI alterations and enhancement in bone marrow and soft tissue, contralateral joint effusion, and synovial thickening were statistically significant MR findings in differentiating transient synovitis from septic arthritis.

CONCLUSIONS

The statistically significant MR findings in transient synovitis are contralateral (asymptomatic) joint effusions and the absence of SI abnormalities of the bone marrow. It is less common to have SI alterations and contrast enhancement of the soft tissues. The statistically significant MR findings in septic arthritis are SI alterations of the bone marrow, and SI alterations and contrast enhancement of the soft tissue. Ipsilateral effusion and synovial thickening and enhancement are present in both diseases.

The role of ultrasound in differentiating septic arthritis from transient synovitis of the hip in children

A total of 154 children admitted with septic arthritis (n=81) or transient synovitis (n=73) were studied retrospectively. Ultrasound findings for 127 patients were correlated with the final diagnosis. Sensitivity, specificity and positive predictive value of ultrasound for the diagnosis of pediatric septic hip were 86.4, 89.7 and 87.9%, respectively. Unsatisfactory outcome occurred more significantly in children, for whom treatment was initiated more than 4 days after the onset of symptoms and those who had a false-negative ultrasound study. Ultrasound cannot be used safely to distinguish between pediatric septic hip and transient synovitis. It may be a method of value to detect minimal hip effusion. A predictive algorithm using clinical, laboratory and ultrasound findings could be beneficial.

Transient Synovitis of the Hip in an Adult

Transient synovitis of the hip is an acute and self-limited disease commonly seen in children. It is the most common cause of acute hip pain in children ages 3 to 10. It is not considered a disease of adults. It usually only affects one hip. The child may complain of pain that is much worse with walking and may actually walk with a limp. The symptoms usually improve in 4 to 5 days. Over-the-counter pain medicines (acetaminophen, ibuprofen) may help. There is usually no associated residual deficit. Currently, three cases in the literature report the same presentation and symptomatology in adults. We report the fourth case of acute hip pain in an adult that behaved in a way parallel to that seen in the pediatric population.

MR Imaging of Congenital/Developmental and Acquired Disorders of the Pediatric Hip and Pelvis

This article reviews the MR imaging findings of some of the more common congenital and acquired disorders of the pediatric hip and pelvis,with the intent of increasing the awareness of radiologists and facilitating early and accurate diagnosis and treatment. The importance of MR imaging in the pediatric population is underscored by its ability to evaluate these disorders well and without the use of ionizing radiation.

MR Imaging of Hip Infection and Inflammation

With its superior anatomical resolution and high sensitivity in depicting pathological processes of the joint, bone marrow and surrounding soft tissue structures, MR imaging is the ideal modality for demonstrating the manifestations and sequelae of the infective and inflammatory conditions common to the hip. Though the imaging features of these conditions may overlap, combining the clinical history and results and other imaging modalities yields a higher degree of specificity, ultimately enhancing the confidence of the radiological interpretation.

Technical Considerations in MR Imaging of the Hip

MR imaging of the hip presents technical difficulties seldom encountered when imaging other joints. The imager is responsible for surrounding bony and soft tissue structures susceptible to many maladies that can mimic hip pain related to an intra-articular derangement. The anatomic nature of the hip and pelvis present difficulties with application and use of local receiver coils. A lack of hip joint capaciousness and distensibility presents obstacles to acquiring diagnostic images with direct and indirect arthrography. Imagers must strive to improve diagnostic accuracy and maximize the information provided to referring clinicians in each MR imaging report in order to help choose the most appropriate therapeutic course. In this article, the authors review technical considerations specific to patient subsets and suspected causalgia of pain or dysfunction about the hip.

Abnormal gait in a child with fever: diagnosing septic arthritis of the hip

The diagnosis of septic arthritis should be considered in all children with hip pain. We review the evaluation of children who present with fever and hip pain, emphasizing features that may assist in distinguishing septic arthritis of the hip from transient synovitis. We also discuss the impact of the increased prevalence of methicillin-resistant Staphylococcus aureus on the management of septic arthritis of the hip.

Radiologic investigation of rheumatic diseases

This article reviews the current use of the wide variety of imaging modalities now available, presenting the imaging features of common and important causes of acute and chronic rheumatic disorders including juvenile idiopathic arthritis, spondyloarthropathies/enthesitis-related arthritis, sepsis, autoimmune diseases, vasculitis, and osteoporosis.