Musculoskeletal infections: US manifestations

Evaluation of the efficacy of pharmacological treatment in patients with temporomandibular joint dysfunctions using ultrasonography

STATEMENT OF PROBLEM

Temporomandibular joint dysfunctions (TMDs) are complex problems affecting the temporomandibular joints (TMJs), masticatory muscles, or both. TMDs are considered muscle pain caused by contraction and ischemia in the masticatory muscles, but evaluation of the efficacy of pharmacological treatment is lacking.

PURPOSE

The purpose of this clinical study was to evaluate the changes in masticatory muscles, joint space, and main arteries supplying the TMJs after pharmacological therapy in patients with TMDs using ultrasonography (USG).

MATERIAL AND METHODS

The TMJ space, masseter and temporal muscles, temporal superficial artery (TSA), and facial artery (FA) were examined using USG in 30 participants with acute TMD pain before and after 10 days of symptomatic treatment with analgesic and myorelaxant. The bilateral masseter and temporal muscle thicknesses, joint space, and end-diastolic minimum velocity (Ved), minimum end-diastolic minimum velocity (Vmin), peak systolic maximum velocity (Vmax), pulsatility index (PI), and resistance index (RI) values of the TSA and FA were measured and compared before and after pharmacological treatment. The relationship between the masseter muscle thickness and the Ved and Vmin values of the TSA and FA before and after pharmacological treatment was analyzed using the paired sample t test; the relationship between the temporal muscle thickness, TMJ spaces, and Vmax, PI, and RI values of the TSA and FA was analyzed using the Wilcoxon signed-rank test (α=.05).

RESULTS

A significant difference was found between the right temporal muscle thickness before and after medication (P=.01), whereas no statistically significant difference was found in the left temporal muscle thickness (P>.05). A significant difference was found between pretreatment and posttreatment bilateral masseter thicknesses at rest (right P=.014; left P=.004). No statistically significant difference was found in the bilateral joint space or Vmax, Vmin, Ved, PI, and RI values of the TSA and FA before and after treatment (P>.05).

CONCLUSIONS

Pharmacological treatment in participants with acute TMD led to a reduction in masseter and temporal muscle thickness but did not significantly affect joint space and local blood flow. USG is a useful diagnostic tool in the diagnosis and follow-up of TMDs.

Diagnostic Performance of Ultrasonography for Diabetic Foot Osteomyelitis

Objective: This study aims to analyze the potential diagnostic capability of ultrasonography (US) in detecting diabetic foot osteomyelitis (DFO) in patients with diabetic foot ulcers (DFUs). Approach: A 1-year prospective study was conducted on 47 consecutive patients with active DFUs and suspicion of DFO at a specialized diabetic foot unit. The following ultrasonographic features were evaluated at baseline: (1) periosteal reaction; (2) periosteal elevation; (3) cortical disruption; (4) sequestrum; and (5) positive power Doppler. The primary outcome measure aimed to establish the effectiveness of ultrasonographic features compared with aseptic bone culture for diagnosing DFO. Receiver operating characteristic (ROC) curves were utilized to evaluate the diagnostic performance of ultrasonographic features. Sample size could not be determined as it is the first study to assess ultrasonographic features for the diagnosis of DFO. The research adhered to the guidelines for diagnostic accuracy studies (Standards for Reporting of Diagnostic Accuracy Studies [STARD] 2015). Results: All patients (n = 24) diagnosed with DFO exhibited positive power Doppler, resulting in a sensitivity (S) and specificity (SP) of 1 and an area under the curve (AUC) of 1 (p < 0.001 [1-1]). Cortical disruption was present in 23 patients (95.8%) with DFO, yielding an S of 0.93, SP of 1, and AUC of 0.96 (p < 0.001 [0.88-1]). Innovation: It validates the diagnostic value of US for DFO as it is the first and largest study of its kind to establish a clear reference standard to guide clinician decision-making. Conclusion: This study demonstrates the effectiveness of cortical disruption and positive power Doppler in assessing DFO through US.

Imaging of MSK infections in the ER

Musculoskeletal infections in the ER are not an uncommon presentation. The clinical context is critical in determining the suspicion for infection and degree of tissue involvement which can involve all layers from the skin to bones. The location, extent, and severity of clinically suspected infection directly relate to the type of imaging performed. Uncomplicated cellulitis typically does not require any imaging. Localized and superficial infections can mostly be evaluated with ultrasound. If there is a diffuse site (an entire extremity) or suspected deeper involvement (muscle/deep fascia), then CT is accurate in diagnosing, widely available, and performed quickly. With potential osseous involvement, MRI is the gold standard for diagnosing acute osteomyelitis; however, it has the drawbacks of longer scan times, artifacts including patient motion, and limited availability.

High-resolution ultrasound in the evaluation of musculoskeletal infections

Soft tissue and osseous musculoskeletal infections are common but can be difficult to diagnose clinically. Signs, symptoms, and physical examination findings may be nonspecific, and laboratory values can be inconclusive. The extent of disease may also be underestimated on physical examination. Soft tissue infections most commonly occur secondary to direct inoculation from broken skin and less frequently due to the seeding of the soft tissues from hematogenous spread, while osseous infections are more commonly due to hematogenous seeding. Infections may also be iatrogenic, following surgery or other procedural interventions. High-resolution ultrasound is an extremely useful imaging modality in the evaluation of musculoskeletal soft tissue and joint infections, and can occasionally be used to evaluate osseous infections as well. Ultrasound can aid in the early diagnosis of musculoskeletal infections, allowing for prompt treatment, decreased risk of complications, and treatment optimization. Ultrasound is sensitive and specific in evaluating soft tissue edema and hyperemia; soft tissue abscesses; joint, bursal and tendon sheath effusions/synovitis; and subperiosteal abscesses. This article describes the typical high-resolution grayscale as well as color and power Doppler ultrasound imaging findings of soft tissue infections including cellulitis, fasciitis, necrotizing deep soft tissue infection, pyomyositis, soft tissue abscess, infectious bursitis, and infectious tenosynovitis. Ultrasound findings of septic arthritis as well as osteomyelitis, such as subperiosteal spread of infection (subperiosteal abscess). are also reviewed. In addition, the use of ultrasound to guide fluid and tissue sampling is discussed.

Imaging of Musculoskeletal Soft-Tissue Infections in Clinical Practice: A Comprehensive Updated Review

Musculoskeletal soft-tissue infections include a wide range of clinical conditions that are commonly encountered in both emergency departments and non-emergency clinical settings. Since clinical signs, symptoms, and even laboratory tests can be unremarkable or non-specific, imaging plays a key role in many cases. MRI is considered the most comprehensive and sensitive imaging tool available for the assessment of musculoskeletal infections. Ultrasound is a fundamental tool, especially for the evaluation of superficially located diseases and for US-guided interventional procedures, such as biopsy, needle-aspiration, and drainage. Conventional radiographs can be very helpful, especially for the detection of foreign bodies and in cases of infections with delayed diagnosis displaying bone involvement. This review article aims to provide a comprehensive overview of the radiological tools available and the imaging features of the most common musculoskeletal soft-tissue infections, including cellulitis, necrotizing and non-necrotizing fasciitis, foreign bodies, abscess, pyomyositis, infectious tenosynovitis, and bursitis.

Ultrasonographic features of diabetic foot osteomyelitis: a case series

OBJECTIVE

Osteomyelitis is a limb-threatening complication of diabetic foot ulcers. Early identification of the disease is key to ensuring successful prognosis. In this study, we describe ultrasonographic features for the identification of osteomyelitis.

METHOD

Patients were screened through clinical, ultrasonographic and probe-to-bone tests.

RESULTS

Ultrasonographic features in three patients that could be used to identify diabetic foot osteomyelitis included periosteal reaction, periosteal elevation, cortical erosions and presence of sequestrum, all of which were confirmed by a plain X-ray.

CONCLUSION

An ultrasonographic examination could be used for the early detection of osteomyelitis, which could help clinicians devise prompt treatment strategies.

Pediatric chest wall masses: spectrum of benign findings on ultrasound

A palpable finding along the chest wall is a frequent indication for pediatric US. Accurate identification of benign lesions can reassure families and appropriately triage children who need follow-up, cross-sectional imaging, or biopsy. In this pictorial essay, we review chest wall anatomy, illustrate US techniques and discuss key US imaging features of common benign lesions and normal variants.

Point-of-Care Ultrasound Identifies Pyomyositis Secondary to Intramuscular Testosterone Injection: Report of Two Cases

BACKGROUND

Intramuscular (i.m.) injections are a commonly utilized route for medication delivery. Intramuscular-associated soft tissue infections are rare and can include pyomyositis and i.m. abscess. Intramuscular testosterone injections have not been previously implicated in causing pyomyositis. Point-of-care ultrasound is an important bedside tool that can identify pyomyositis and differentiate this infection from more common entities such as cellulitis.

CASE REPORTS

We present two cases of i.m. testosterone-associated pyomyositis. In both cases, the physical examination features were consistent with simple cellulitis. However, point-of-care ultrasound evaluation revealed changes consistent with pyomyositis in each case. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although uncommon, i.m. injections such as testosterone carry a risk of soft tissue infection. As demonstrated in the above cases, ultrasound can be helpful in making the differentiation between simple cellulitis and pyomyositis. The emergency physician should be cognizant of this complication of therapeutic i.m. injections, as well as the diagnostic efficacy of point-of-care ultrasound in evaluating the extent and location of the soft tissue infection.

Risk Factors, Clinical Characteristics, Management, and Outcomes of Musculoskeletal Fungal Infection at Thailand’s Largest National Tertiary Referral Center

To investigate the risk factors, clinical characteristics, management, and outcomes of musculoskeletal fungal infection in Thai patients, patients aged ≥18 years definitively diagnosed with musculoskeletal fungal infection by culture and/or histopathology at Siriraj Hospital (Bangkok, Thailand) during 2002–2020 were retrospectively enrolled. Twenty-eight patients (median age: 58.5 years [range: 22–81], 57.1% male) with fungal osteomyelitis (n = 22), septic arthritis (n = 1), or fungal osteomyelitis with septic arthritis (n = 5) were included. Immunocompromised status was common (82%). Most patients had de novo infection from hematogenous spreading that usually presented at a single, non-contiguous site. The median symptom duration prior to diagnosis was 2 months. The tibia and knee were the most common site of osteomyelitis (30%) and septic arthritis (72%), respectively. The most common pathogens were Talaromyces marneffei and Cryptococcus neoformans. Organism identification from tissues at the affected sites was required in all cases. Most patients (82%) required combination surgery and systemic antifungal therapy. Among those with complete follow-up (23/28), 61% and 39% had complete and partial responses, respectively. Musculoskeletal fungal infection is an uncommon disease with insidious onset and non-specific manifestations that requires pathogen identification via tissue cultures and histopathologic studies. Combination surgery and systemic antifungal therapy yielded generally favorable outcomes.

Bone and Joint Infections: The Role of Imaging in Tailoring Diagnosis to Improve Patients' Care

Imaging is needed for the diagnosis of bone and joint infections, determining the severity and extent of disease, planning biopsy, and monitoring the response to treatment. Some radiological features are pathognomonic of bone and joint infections for each modality used. However, imaging diagnosis of these infections is challenging because of several overlaps with non-infectious etiologies. Interventional radiology is generally needed to verify the diagnosis and to identify the microorganism involved in the infectious process through imaging-guided biopsy. This narrative review aims to summarize the radiological features of the commonest orthopedic infections, the indications and the limits of different modalities in the diagnostic strategy as well as to outline recent findings that may facilitate diagnosis.

Imaging update on musculoskeletal infections

The clinical diagnosis of musculoskeletal infections can be challenging due to non-specific signs and symptoms on presentation. These infections include infectious myositis, necrotising fasciitis, septic arthritis, septic bursitis, suppurative tenosynovitis, osteomyelitis, spondylodiscitis and periprosthetic infections. Diagnostic imaging is routinely employed as part of the investigative pathway to characterise the underlying infectious disease pattern, allowing expedited and customised patient management plans to optimise outcomes. This article provides an update on the various imaging modalities comprising of radiography, computed tomography, ultrasonography, magnetic resonance imaging and radionuclide procedures, and incorporates representative images of key findings in the different forms of musculoskeletal infections.

Updates and Advances: Pediatric Musculoskeletal Infection Imaging Made Easier for Radiologists and Clinicians

Infants and children often present with a wide range of musculoskeletal (MSK) infections in daily clinical practice. This can vary from relatively benign superficial infections such as cellulitis to destructive osseous and articular infections and life-threatening deep soft tissue processes such as necrotizing fasciitis. Imaging evaluation plays an essential role for initial detection and follow-up evaluation of pediatric MSK infections. Therefore, a clear and up-to-date knowledge of imaging manifestations in MSK infections in infants and children is imperative for timely and accurate diagnosis that, in turn, can result in optimal patient management. This article reviews an up-to-date practical imaging techniques, the differences between pediatric and adult MSK infections, the spectrum of pediatric MSK infections, and mimics of pediatric MSK infections encountered in daily clinical practice by radiologists and clinicians.

The Utility of Musculoskeletal Ultrasonography in Diagnosing Pyomyositis: A Comparison With Surgically and Conservatively Treated Cases

Objective:

The study aimed to determine the accuracy of sonography in diagnosing pyomyositis.

Methods:

A retrospective review of pyomyositis cases in a government hospital between January 1, 2016 and June 30, 2019 was done. All cases underwent a sonogram for the indication of pyomyositis. Positive purulence for surgical cases and improved laboratory parameters for conservative cases were confirmatory for pyomyositis. Comparison with sonographic results using a 2 × 2 contingency table was done to determine sensitivity and specificity.

Results:

A total of 122 cases were included. The sonographic results corresponded with 95% of surgical cases and 89% of conservative cases. A lack of false and true negatives for surgical cases resulted in a sensitivity of 100% (95% confidence interval [CI] = 93%–100%) and a specificity of 0% (95% CI = 0%–71%). In conservative cases, sonography had a sensitivity of 92% (95% CI = 82%–97%) and a specificity of 0% (95% CI = 0%–84%) due to a lack of true negatives.

Conclusion:

Sonography is not limited to primarily as a screening tool but a capable diagnostic imaging choice for pyomyositis, particularly in low-resource settings. The results show the strength of sonography, particularly in the suppurative stage of pyomyositis. [Box: see text]

CT findings of severe burn injuries after a motor vehicle collision: a case report

Severe burn injuries can complicate management of polytrauma. While CT is the primary imaging modality for evaluation of trauma injuries, CT findings of severe burn are rarely reported. A 31-year-old female was brought to the emergency department after motor vehicle collision in which she sustained a burn injury from contact with the vehicle muffler. Her initial trauma workup was notable for full-thickness burns to her left abdominal wall among other injuries. CT scan showed skin thickening and extensive stranding involving the whole layer of subcutaneous soft tissue. The deep fascia and underlying muscle layer were free from burn injuries. Identification of this finding on the CT scan helps establish appropriate care.

Ultrasound image of malignant bone tumors in children. An analysis of nine patients diagnosed in 2011-2016

Introduction: The diagnostic process of bone tumors, including malignant ones, is based on conventional radiological methods, such as radiography and computed tomography, and with precise assessment of local advancement in magnetic resonance imaging. Ultrasonography is not included in the diagnostic algorithms as a tool suitable to detect this type of pathology. More and more frequent usage of musculoskeletal ultrasound in children as the first imaging method or, in some cases, as the only diagnostic method, makes it necessary to be familiar with sonographic presentation of bone tumors to suggest this diagnosis early enough and, after its verification, start treatment without a significant delay. Aim: The aim of this study was to determine changes in the sonographic image that might indicate a bone malignancy and suggest the need to extend the diagnostic process in this direction. Material and method: This article discusses 10 bone tumors in 9 children who had an ultrasound scan performed at the beginning of the diagnostic process before the histopathological diagnosis was established and treatment initiated. The assessment involved ultrasonographic features indicating the presence of a tumor. Results: In the group of 9 patients, 8 malignant bone tumors were diagnosed in ultrasonography and later verified histopathologically: 4 osteosarcomas and 4 Ewing’s sarcomas. In one case, two bone tumors were detected in ultrasonography without specification of their nature (malignant/benign, primary/secondary). Conclusions: In the analyzed cases, ultrasonography enabled the correct diagnosis of a focal bone lesion, and in most cases (8/9) it presented an image that suggested its malignant nature and the necessity of further diagnosis and treatment.

Spectrum of imaging findings of chronic granulomatous disease: a single center experience

The purpose of this pictorial essay is to present and summarize findings of various images of chronic granulomatous disease (CGD). CGD represents a heterogeneous group of disorders caused by defective generation of respiratory bursts in human phagocytes. This defect results in abnormal phagocytic functions and defective killing of bacteria by phagocytes. CGD may involve many organs and present with recurrent infections and inflammations. Radiologists should consider the possibility of CGD when a patient presents with atypical and recurrent infection. They must also consider other concurrent infections a patient may have.

Ultrasound features of purulent skin and soft tissue infection without abscess

PURPOSE

Ultrasound (US) aids clinical management of skin and soft tissue infection (SSTI) by differentiating non-purulent cellulitis from abscess. However, purulent SSTI may be present without abscess. Guidelines recommend incision and drainage (I & D) for purulent SSTI, but US descriptions of purulent SSTI without abscess are lacking.

METHODS

We retrospectively reviewed pediatric emergency department patients with US of the buttock read as negative for abscess. We identified US features of SSTI with adequate interobserver agreement (kappa > 0.45). Six independent observers then ranked presence or absence of these features on US exams. We studied association between US features and positive wound culture using logistic regression models (significance at p < 0.05).

RESULTS

Of 217 children, 35 patients (16%) had cultures positive for pathogens by 8 h after US and 61 patients (32%) had cultures positive by 48 h after US. We found kappa > 0.45 for focal collection > 1.0 cm (κ = 0.57), hyperemia (κ = 0.57), swirling with compression (κ = 0.52), posterior acoustic enhancement (κ = 0.47), and cobblestoning or branching interstitial fluid (κ = 0.45). Only cobblestoning or interstitial fluid was associated with positive wound cultures in logistic regression models at 8 and 48 h.

CONCLUSIONS

Cobblestoning or interstitial fluid on US may indicate presence of culture-positive, purulent SSTI in patients without US appearance of abscess. Although our study has limitations due to its retrospective design, this US appearance should alert imagers that the patient may benefit from early I & D.

Sporotrichal Tenosynovitis Diagnosed Helpfully by Musculoskeletal Ultrasonography

A 72-year-old man presented with persistent oligoarthritis and positive results for rheumatoid factor and was suspected of having rheumatoid arthritis (RA). However, the musculoskeletal ultrasonography (MSUS) findings were not consistent with those of typical RA. He had undergone surgery for carpal tunnel syndrome, which allowed both histopathological and microbiological examinations to be performed. A synovial tissue culture was positive for Sporothrix schenckii, and he was diagnosed with sporotrichal tenosynovitis. He received anti-fungal therapy, and the sporotrichal tenosynovitis resolved. This case suggests that MSUS is a useful modality, and sporotrichal tenosynovitis, though rare, should be considered in the differential diagnosis of RA.

Ultrasound Examination of Pediatric Musculoskeletal Diseases and Neonatal Spine

Ultrasound (US) is a simple, non-invasive imaging modality which allows high-resolution imaging of the musculoskeletal (MSK) system. Its increasing popularity in pediatrics is due to the fact that it does not involve radiation, has an ability to visualize non-ossified cartilaginous and vascular structures, allows dynamic imaging and quick contralateral comparison. US is the primary imaging modality in some pediatric MSK conditions like infant hip in developmental dysplasia (DDH), hip joint effusion, epiphyseal trauma and evaluation of the neonatal spine. US is the modality of choice in infants with DDH, both in the initial evaluation and post-treatment follow-up. US has a sensitivity equivalent to MRI in evaluation of the neonatal spine in experienced hands and is a good screening modality in neonates with suspected occult neural tube defects. In other MSK applications, it is often used for the initial diagnosis or in addition to other imaging modalities. In trauma and infections, US can often detect early and subtle soft tissue abnormalities and a quick comparison with the contralateral side aids in diagnoses. Dynamic imaging is crucial in evaluating congenital instabilities and dislocations, soft tissue and ligamentous injuries, epiphyseal injuries and fracture separations. High-resolution imaging along with color Doppler (CD) is useful in the characterization of soft tissue masses. This article reviews the applications of US in pediatric MSK with emphasis on conditions where it is a primary modality. Limitations of US include inability to penetrate bone, hence, limited diagnosis of intraosseous pathology and operator dependency.

Is ultrasonography useful in the diagnosis of nasolabial cyst?

Nasolabial cysts are nonodontogenic cysts that occur beneath the ala nasi. Its pathogenesis is uncertain. Because the nasolabial cyst is a soft tissue lesion, plain radiographs are useless. CT and MRI should be evaluated. In this report, a nasolabial cyst is described including its features on ultrasonography (USG) and CT exams.

Musculoskeletal aspiration procedures

With advances in imaging technology, there has been a significant increase in the number and range of interventional musculoskeletal image-guided procedures. One of the most commonly performed image-guided musculoskeletal interventions is the diagnostic and therapeutic percutaneous aspiration and drainage of multiple types of intra-articular, juxta-articular, and intramuscular pathologic fluid collections. These procedures may be performed under fluoroscopic, ultrasound, computed tomography, or even magnetic resonance guidance depending on the location to be accessed, type of pathology, patient characteristics, and operator preference. Musculoskeletal image-guided aspiration and drainage procedures are minimally invasive and generally very safe while offering valuable diagnostic information as well as therapeutic benefit. This article focuses on the appropriate indications, contraindications, and general technique for accessing the major joints via imaging guidance. For each joint, we discuss pertinent anatomy, appropriate imaging modalities, and preferred approaches to gaining intra-articular access. Additionally, the article discusses some of the more frequently encountered juxta-articular and intramuscular fluid collections that can be accessed and aspirated via percutaneous intervention, with mention of the importance of recognizing extremity sarcomas that can mimic these benign collections.

Complications of muscle injuries

Muscle injuries can be classified into strain injuries and contusions. Depending on the type of injury, different complications may occur, which in turn can be divided into early, intermediate and delayed complications. A prompt diagnosis of complications allows early treatment and permits to avoid harmful sequelae. Imaging studies, ultrasonography in particular, allow (recognizing) the assessment of complications whenever clinically suspected. In this article the most frequent complications of muscle injuries are presented.

Magnetic resonance imaging of musculoskeletal infections: systematic diagnostic assessment and key points

Prompt diagnosis and treatment are essential in preventing the complications of musculoskeletal infection. In this context, imaging is often used to confirm clinically suspected diagnoses, define the extent of infection, and ensure appropriate management. Because of its superior soft-tissue contrast resolution, magnetic resonance imaging (MRI) is the modality of choice for evaluating musculoskeletal infections. This article describes the MRI features along the full spectrum of musculoskeletal infections and provides several illustrative case examples.

Necrotizing fasciitis: contribution and limitations of diagnostic imaging

Necrotizing fasciitis is a rare, rapidly spreading, deep-seated infection causing thrombosis of the blood vessels located in the fascia. Necrotizing fasciitis is a surgical emergency. The diagnosis typically relies on clinical findings of severe sepsis and intense pain, although subacute forms may be difficult to recognize. Imaging studies can help to differentiate necrotizing fasciitis from infections located more superficially (dermohypodermitis). The presence of gas within the necrotized fasciae is characteristic but may be lacking. The main finding is thickening of the deep fasciae due to fluid accumulation and reactive hyperemia, which can be visualized using computed tomography and, above all, magnetic resonance imaging (high signal on contrast-enhanced T1 images and T2 images, best seen with fat saturation). These findings lack specificity, as they can be seen in non-necrotizing fasciitis and even in non-inflammatory conditions. Signs that support a diagnosis of necrotizing fasciitis include extensive involvement of the deep intermuscular fascias (high sensitivity but low specificity), thickening to more than 3mm, and partial or complete absence on post-gadolinium images of signal enhancement of the thickened fasciae (fairly high sensitivity and specificity). Ultrasonography is not recommended in adults, as the infiltration of the hypodermis blocks ultrasound transmission. Thus, imaging studies in patients with necrotizing fasciitis may be challenging to interpret. Although imaging may help to confirm deep tissue involvement and to evaluate lesion spread, it should never delay emergency surgical treatment in patients with established necrotizing fasciitis.

Common sonographic findings in the painful hip after hip arthroplasty

Diagnosing the cause of hip pain in patients with hip arthroplasty can be challenging because of the numerous possible causes of pain and artifacts caused by the prosthetic components on computed tomography and magnetic resonance imaging. Sonography plays an important role in the diagnosis and management of these patients because the soft tissues surrounding the prosthetic joint are not obscured by artifacts and because sonography enables hands-on examination of the painful site, dynamic evaluation of moving structures, and comparison with the opposite side. Another advantage of sonography is the ability to perform sonographically guided diagnostic and therapeutic procedures. In this pictorial essay, we highlight commonly encountered sonographic findings in patients with hip pain after hip arthroplasty.

Imaging of musculoskeletal soft tissue infections

Prompt and appropriate imaging work-up of the various musculoskeletal soft tissue infections aids early diagnosis and treatment and decreases the risk of complications resulting from misdiagnosis or delayed diagnosis. The signs and symptoms of musculoskeletal soft tissue infections can be nonspecific, making it clinically difficult to distinguish between disease processes and the extent of disease. Magnetic resonance imaging (MRI) is the imaging modality of choice in the evaluation of soft tissue infections. Computed tomography (CT), ultrasound, radiography and nuclear medicine studies are considered ancillary. This manuscript illustrates representative images of superficial and deep soft tissue infections such as infectious cellulitis, superficial and deep fasciitis, including the necrotizing fasciitis, pyomyositis/soft tissue abscess, septic bursitis and tenosynovitis on different imaging modalities, with emphasis on MRI. Typical histopathologic findings of soft tissue infections are also presented. The imaging approach described in the manuscript is based on relevant literature and authors' personal experience and everyday practice.

Utility of bedside sonography to distinguish soft tissue abnormalities from joint effusions in the emergency department

OBJECTIVE

The purpose of this study was to determine the utility of bedside sonography to differentiate soft tissue abnormalities from joint effusions.

METHODS

We conducted a retrospective review of emergency department (ED) patients presenting with joint pain, erythema, and swelling who received bedside sonography. The ED sonographic examinations were performed by emergency physician sonologists who were not involved in clinical assessment and management of these patients. The treating physician's opinions regarding the probability of joint effusion and need for aspiration were documented in the sonography log before the sonographic examination was performed. The bedside sonograms of all patients included in this study were also reviewed for accuracy. Descriptive statistics were used to summarize the data.

RESULTS

A total of 54 patients (mean age +/- SD, 41 +/- 18.9 years) were identified over a 1-year period. The symptomatic joints in our study subjects were as follows: knee, 24 of 54 (44%); elbow, 21 of 54 (38%); ankle, 8 of 54 (15%); and metatarsophalangeal joint, 1 of 54 (2%). Twenty-two of 54 patients (40.7%; 95% confidence interval [CI], 27.6%-53.8%) were found to have joint effusions on sonography. Sonography altered management in 35 of 54 patients (65%; 95% CI, 52%-77.5%). Joint aspiration was planned in 39 of 54 cases (72.2%; 95% CI, 60.2%-84.1%) before sonography. After sonography, only 20 of these patients (37%; 95% CI, 24.1%-49.9%) underwent joint aspiration. There was a statistically significant difference in treatment plans after the addition of bedside sonographic results (P < .01).

CONCLUSIONS

Our study suggests that bedside sonography is useful in differentiating joint effusions from soft tissue abnormalities and directing appropriate therapy.

Magnetic resonance imaging in the visualization of benign tumors and tumor-like lesions of hand and wrist

The differential diagnosis of benign tumors and tumor-like lesions of the hand and wrist region is important with regard to choosing the therapy (medical versus surgical), or to decide to just follow-up the lesion. In most of the cases the proper analysis of MRI findings in correlation with the patient's history is sufficient to meet a specific diagnosis. However, diagnostic confusion is not uncommon as there are numerous lesions affecting the hand and wrist region. This pictorial essay offers a practical radiological approach to benign tumors and tumor-like lesions of the hand and wrist region based on most frequently observed MRI findings.

Gray-scale and color Doppler ultrasonographic evaluation of reactivated post-traumatic/postoperative chronic osteomyelitis

OBJECTIVE

We aimed to carry out a systematic assessment of gray-scale and color Doppler ultrasonography (CDUS) findings of reactivated post-traumatic/postoperative chronic osteomyelitis (COM) in adults.

MATERIALS AND METHODS

Gray-scale and color Doppler ultrasonography were performed on 40 consecutive patients with a history of long-standing post-traumatic/post-operative chronic osteomyelitis and clinical suggestion of reactivation, in a 32-month-period. All patients had metallic implants: 16 internal fixations, nine external fixations, 11 hip arthroplasties and four knee arthroplasties. The final diagnosis of reactivated COM was based upon biopsy findings, with microbiological and histological examination (n = 27), or a combination of laboratory, clinical and magnetic resonance (MR) findings (n = 13). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of sonographic signs, including fistulous tracts, periosteal thickening, cortical discontinuity, soft tissue abscess and cellulitis, juxtacortical fluid, distension of the pseudocapsule in arthroplasties, and periosteal vascularity, were estimated.

RESULTS

Statistically significant differences between patients with and without reactivated COM were found for fistulous tracts (P < 0.0001), juxtacortical fluid collections (P < 0.001) periosteal thickening (P < 0.01), distension of pseudocapsule (P < 0.05), and periosteal vascularity (P < 0.0001). Low-resistance arterial flow of periosteal vessels presented the highest sensitivity (92%), specificity, and PPV (100%), yielding only two false negative results in two obese patients. Among gray-scale findings, the presence of a fistulous tract yielded the highest specificity and PPV (100%), whereas periosteal thickening was the most sensitive (92%), though not specific, finding (specificity 50%).

CONCLUSION

A constellation of gray-scale and CDUS findings can be highly indicative of reactivated bone infection in patients with long-standing chronic post-traumatic/post-operative osteomyelitis.

Ultrasound in the inflammatory myopathies

Dermato- or polymyositis must be diagnosed or ruled out early because early immunosuppressive therapy prevents irreversible muscle degeneration. Acute poly- and dermatomyositis are accompanied by normal or increased size, low echogenicity, and elevated perfusion of affected muscles, whereas in chronic poly- and dermatomyositis, the size and perfusion of affected muscles are reduced and echogenicity is increased. Although magnetic resonance imaging is more sensitive in detecting edema-like muscular changes and thereby acute myositis, contrast-enhanced ultrasound with its capability of measuring perfusion has become a useful diagnostic tool in diagnosing acute inflammation in poly- and dermatomyositis.

MR imaging of urgent inflammatory and infectious conditions affecting the soft tissues of the musculoskeletal system

Soft tissue infections and inflammatory conditions of the musculoskeletal system are a group of disorders commonly seen by emergency room physicians and radiologists. Many of these entities can either be limb- or life-threatening. Magnetic resonance imaging is currently the best imaging modality to evaluate these conditions. In this review, the characteristic imaging findings of cellulitis, abscess formation, necrotizing fasciitis, pyomyositis, diabetic ischemic infarction, acute and exertional compartment syndromes, and rhabdomyolysis will be emphasized as well as imaging factors that can help to differentiate these disorders.