Ultrasonography of the painful hip. Prospective studies in 204 patients

Pediatric musculoskeletal infections

PURPOSE OF REVIEW

The aim of this article is to review the recent guidelines and literature regarding the diagnosis and the treatment of common pediatric musculoskeletal infections: septic arthritis, osteomyelitis, pyomyositis, and Lyme disease.

RECENT FINDINGS

In the last decade, a better understanding of the causative organisms of common bacterial infections, including Kingella , leads to prompt targeted antimicrobial coverage in all musculoskeletal infections. Prompt diagnosis and treatment continues to be the mainstay in the treatment of children with osteoarticular infections. Efforts to improve early detection have lead to improving rapid lab diagnostic testing; however, more advanced diagnostics such as arthrocentesis for septic arthritis and MRI for osteomyelitis and pyomyositis, remain the gold standard. Shorter and narrowed antibiotic courses, with appropriate transition to outpatient oral treatment provide effective infection clearance and reduction in complications of disease.

SUMMARY

Advances in diagnostics, including pathogen identification as well as imaging continues to improve our ability to diagnose and treat these infections, although still lack ability to provide definitive diagnosis without more invasive nor advanced techniques.

US Evaluation of Juvenile Idiopathic Arthritis and Osteoarticular Infection

Juvenile idiopathic arthritis (JIA) and osteoarticular infection can cause nonspecific articular and periarticular complaints in children. Although contrast material-enhanced magnetic resonance imaging is the reference standard imaging modality, musculoskeletal ultrasonography (US) is emerging as an important adjunct imaging modality that can provide valuable information relatively quickly without use of radiation or the need for sedation. However, diagnostic accuracy requires a systemic approach, familiarity with various US techniques, and an understanding of maturation-related changes. Specifically, the use of dynamic, Doppler, and/or multifocal US assessments can help confirm sites of disease, monitor therapy response, and guide interventions. In patients with JIA, ongoing synovial inflammation can lead to articular and periarticular changes, including synovitis, tenosynovitis, cartilage damage, bone changes, and enthesopathy. Although these findings can manifest in adult patients with rheumatoid arthritis, important differences and pitfalls exist because of the unique changes associated with an immature and maturing skeleton. In patients who are clinically suspected of having osteoarticular infection, the inability of US to evaluate the bone marrow decreases its sensitivity. Therefore, the US findings should be interpreted with caution because juxtacortical inflammation is suggestive, but neither sensitive nor specific, for underlying osteomyelitis. Similarly, the absence of a joint effusion makes septic arthritis extremely unlikely but not impossible. US findings of JIA and osteoarticular infection often overlap. Although certain clinical scenarios, laboratory findings, and imaging appearances can favor one diagnosis over the other, fluid analysis may still be required for definitive diagnosis and optimal treatment. US is the preferred modality for fluid aspiration and administering intra-articular corticosteroid therapy. ^© RSNA, 2017.

Improving diagnostic efficiency: analysis of pelvic MRI versus emergency hip aspiration for suspected hip sepsis

BACKGROUND

Accurately diagnosing and treating childhood hip sepsis is challenging. Adjacent bone and soft-tissue infections are common and can lead to delayed and inappropriate treatment. This study evaluated the effect of early advanced imaging (bone scan, magnetic resonance imaging) in the management of suspected hip sepsis.

METHODS

A retrospective review of pediatric patients admitted between 2003 and 2009 with suspected hip sepsis was performed. Patients were classified into 2 categories: group I-immediate hip aspiration or group II-advanced imaging performed before intervention.

RESULTS

In total, 130 patients (53 in group I and 77 in group II) were included. No significant differences were found between the groups with regard to laboratory values, temperature, number of anesthetics, and length of hospital stay. However, patients in group I were younger than in group II (5.4 vs. 7.3 y, P=0.02) and more patients in group I were unable to bear weight on the affected limb compared with group II (83% vs. 61%, P=0.009). In group I, 36 patients (68%) had a septic hip compared with 35 patients (45%) in group II. In group I, 16 patients (30%) required reoperation versus 13 (17%) patients in group II. Results from the multivariate analysis demonstrated that reoperation was required 2.8 times (95% confidence interval, 1.12-6.78) more often in group I as compared with group II (P=0.03).

CONCLUSIONS

Advanced imaging performed before hip aspiration improves diagnostic efficacy and may decrease the need for reoperation.

LEVEL OF EVIDENCE

III.

Hip ultrasound

In newborns, US has an established role in the detection and management of developmental dysplasia of the hip. Later in childhood, when the limping child is a major diagnostic dilemma, US is extremely helpful in the identification of the varied disease processes underlying this condition, as transient synovitis, septic arthritis, Perthes disease and slipped femoral capital epiphysis. In adolescent practicing sporting activities, US is an excellent means to identify apophyseal injures about the pelvic ring, especially when avulsions are undisplaced and difficult-to-see radiographically. Later on, in the adulthood, US is an effective modality to diagnose tendon and muscle injuries about the hip and pelvis, identify effusion or synovitis within the hip joint or its adjacent bursae and guide the treatment of these findings. The aim of this article is to provide a comprehensive review of the most common pathologic conditions about the hip, in which the contribution of US is relevant for the diagnostic work-up.

Paediatric musculoskeletal US beyond the hip joint

US is a technique particularly suited to the investigation of musculoskeletal disorders in children and adolescents. This review paper describes a range of clinical settings beyond the hip joint where US has a significant role to play, including sports injuries, infectious diseases, inflammatory and degenerative conditions, congenital and developmental disorders, acute trauma of bone and joints, and peripheral nerve injuries. In some circumstances, US can be regarded as the most effective means of diagnostic imaging, whereas in other instances, it is an alternative or supplement to other more comprehensive imaging modalities, like MRI and CT. Although MRI offers superior soft-tissue contrast resolution, US is low-cost, non-invasive and has higher spatial resolution and real-time capability for the assessment of musculoskeletal structures during joint movement and stress manoeuvres.

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.

[Benefit of hip ultrasound in management of the limping child]

OBJECTIVE

To evaluate the contribution of sonography of the hip in the management of nontraumatic limping in children.

PATIENTS AND METHODS

Prospective study including children consulting for nontraumatic limping (n=93). These children had a clinical examination, a biological and imaging workup (pelvis x-rays (n=88), initial sonograph of the hip (n=93), and follow-up sonograph of the hip (n=29)).

RESULTS

Ninety-three children (69 boys, 24 girls) aged from 10 months to 13 years (median, 4 years) were included and divided into two groups: The sensitivity and specificity of sonography in establishing a serious diagnosis was 57% and 59%, respectively.

CONCLUSION

The advantage of systematic hip sonography is challenged in this study because of low sensitivity and specificity. Its main advantage seems to be in its negative results, which prompt other investigations.

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.

Ultrasound in pediatric musculoskeletal disease: techniques and applications

The increased ratio of nonossified cartilage to bone in children makes ultrasound (US) a particularly suitable technique for evaluating pediatric musculoskeletal disorders. US allows the examiner to compare quickly and meticulously an affected to unaffected area of interest in different orthogonal planes without a need for sedation. Developmental dysplasia of the hip is the most common indication for pediatric musculoskeletal US. Sonography is also a cost-effective, useful, and complementary imaging tool for evaluating pediatric musculoskeletal trauma, inflammation-infection, and masses.

Anterior joint capsule of the normal hip and in children with transient synovitis: US study with anatomic and histologic correlation

PURPOSE

To study the anatomic components of the anterior joint capsule of the normal hip and in children with transient synovitis.

MATERIALS AND METHODS

Six cadaveric specimens were imaged with ultrasonography (US) with special attention to the anterior joint capsule. Subsequently, two specimens were analyzed histologically. These anatomic findings were correlated with the US findings in 58 healthy children and 105 children with unilateral transient synovitis.

RESULTS

The anterior joint capsule comprises an anterior and posterior layer, mainly composed of fibrous tissue, lined by only a minute synovial membrane. Both fibrous layers were identified separately at US in 98 of 116 (84%) hips of healthy subjects and in all hips with transient synovitis. Overall, the anterior layer was thicker than the posterior layer. In transient synovitis compared with normal hips, no significant thickening of both layers was present (P = .24 and .57 for the anterior and posterior layers, respectively). Normal variants include plicae, local thickening of the capsule, and pseudodiverticula.

CONCLUSION

Increased thickness of the anterior joint capsule in transient synovitis is caused entirely by effusion. There is no US evidence for additional capsule swelling or synovial hypertrophy.

Ultrasonographic evaluation of the anterior recess in the normal hip: a prospective study on 166 asymptomatic children

PURPOSE

To redefine the ultrasonographic features of the normal hip joint in children and to establish a normal value for the neck-capsule distance (NCD) of its anterior recess.

MATERIALS AND METHODS

332 hips of 166 asymptomatic children were examined sonographically. In a sagittal section plane the maximum distance between the anterior surface of the femoral neck and the anterior limit of the articular capsule (NCD-A) was measured.

RESULTS

The hypoechoic synovial membrane occupying the anterior recess could always be differentiated from the capsule. An additional thin layer of synovial fluid was detected in 12% of probands. The configuration of the capsule varied with different rotation positions of the legs. In small children the mean NCD-A increased from 2.5 mm at 65 cm height to 5 mm at 100 cm height. In larger children the mean NCD-A was 5.5 mm. The mean right-to-left difference was 0.5 mm with a pathological limit of 2 mm.

CONCLUSIONS

The pathological limit of the NCD-A increases from 3.5 to 7.5 mm in relation to the height. Sonographic investigation of the pediatric hip joint must include detailed demonstration of anatomical structures to avoid misinterpretations.

The irritable hip: immediate ultrasound guided aspiration and prevention of hospital admission

A protocol for the management of irritable hip was assessed; this protocol avoids hospital admission while detecting all other serious causes of hip pain, in particular septic arthritis, at the earliest possible opportunity. Fifty children with painful hips were studied prospectively with immediate ultrasound guided aspiration and Gram stain of all hip effusions. Bone scintigraphy performed at an early stage was reserved for patients with unremitting symptoms. Thirty six hips were aspirated. Only two patients were admitted. The final diagnoses were transient synovitis (45 cases), Perthes' disease (three cases), fracture (one case), and septic arthritis (one case). The single case of hip sepsis was diagnosed on presentation. The traditional approach to management is questioned and the advantages of the protocol highlighted, including earliest diagnosis of sepsis and other serious pathology, avoidance of hospital admission, and the relief of pain by joint decompression.

Ultrasound diagnosis of effusion of the hip

This paper reports on two prospective studies of ultrasound examination of the hip in 150 healthy subjects and 50 patients with hip joint diseases. The sagittal distance of the anterior recess of the hip was measured on the sonogram of the sagittal section. The normal value in adults, teenagers and children was 4.54 mm +/- 0.99 mm, 4.27 mm +/- 1.26 mm and 3.40 mm +/- 0.93 mm, respectively. Ultrasound examination of both hips in 50 patients with hip joint diseases showed that the sagittal distance of the anterior recess was significantly widened in the symptomatic side, and the mean value in the symptomatic side and normal side was 12.02 mm +/- 3.68 mm, and 4.12 mm +/- 1.15 mm, respectively. Ultrasound showed echo-free area in anterior recess in 42 hips, hypoecho and medium echo area in 8 hips. Of 50 patients undergoing plain radiography, 33 showed bony changes of the hip, and the remaining 17 no change whatever. The results obtained demonstrated that ultrasound can accurately detect effusion of the hip, what is more, it is easy to operate, inexpensive, noninvasive, convenient for follow-up and without radiation damage.

Acute osteomyelitis and septic arthritis in the neonate, risk factors and outcome

Twenty-two neonates with acute osteomyelitis (AO) or septic arthritis (SA) were included in a study based on a review of medical reports and a long-term clinical and radiological follow up. Clinical symptoms, bacteriology, risk factors, and outcome are discussed. The diagnoses were difficult, the clinical symptoms vague, fever rare and white cell count normal. Detection by plain radiological films was more efficient than by radionuclide bone scan. Staphylococcus aureus was the predominant causative organism and a shift towards group B Streptococcus in recent years was not identified. Risk factors for AO and SA were prematurity (13/22), respiratory distress syndrome (15/22) and perhaps most important: umbilical artery catheterisation (15/22). Severe sequelae were found in only 1 patient, while 3 patients had slight asymptomatic changes. The relatively favourable long-term outcome is unexplained, but may be related to early and appropriate, long lasting antibiotic treatment.

Ultrasonographic evaluation of Legg-Calve-Perthes disease based on sonoanatomic criteria and the application of new measuring techniques

This study attempts an ultrasonographic classification of Legg-Calve-Perthes disease according to sonoanatomic and sonometric criteria. Four stages, similar to standard radiological staging, could reproducibly be found in 29 patients with unilateral disease. The stages could be significantly differentiated according to descriptive sonoanatomic criteria and partially newly introduced sonographic measurements, including epiphysis-metaphysis-index and acetabulum-epiphysis-distance. Sonographic evaluation of Perthes hips is a simple and standardised procedure, which can serve to stage and monitor the course of the disease and hence reduce the amount of X-ray exposure and treatment costs.

Ultrasonography in Legg-Calvé-Perthes disease

Ultrasonography was found to be a valuable investigation in the assessment and management of Legg-Calvé-Perthes disease (LCPD). It was used to assess 23 patients with LCPD in 25 affected hips and was compared with radiographs obtained at the same time. A chronological five-part staging of LCPD is proposed, expressing the degree of flattening and fragmentation as well as reconstitution of the femoral head as seen on ultrasound examination. Thickening of articular cartilage was documented, and associated findings of synovitis and lateral extrusion of the femoral head were evaluated. An intraarticular hip effusion was present in 74% of cases in stages I-II. Lateral extrusion increased from stage II onwards until the healing stage. The phase of reconstitution (stage IV) demonstrated both resorption of the necrotic bone and formation of new immature osteoid tissue. Lateral extrusion and the start of the healing phase can be shown earlier by ultrasonography than by radiography.

Assessment of congenital hip dislocation with real-time ultrasound: a pictorial essay

Real-time ultrasound (US) is the imaging method of choice for diagnosis and follow-up of congenital dislocation of the infant hip (CDH). Clinical aspects and the role of imaging are reviewed. Technique and anatomy, both normal and abnormal, are illustrated, as well as, the use of sonography during treatment with Pavlik harness and spica cast. Correlation of ultrasound findings with clinical examination, other available imaging studies and long-term patient follow-up shows 100% sensitivity and 100% specificity for real-time US diagnosis of CDH.