Legg-Calvé-Perthes disease in the evolutionary period: comparison of magnetic resonance imaging with bone scintigraphy

Role of Advanced Imaging in the Diagnosis and Management of Active Legg-Calvé-Perthes Disease

Since the first description of Legg-Calvé-Perthes disease a century ago, the diagnosis, staging, prognosis, and treatment decisions have been based on plain radiographs. The goal of treatment is prevention of femoral head deformity, yet radiographic prognostic classifications are applied in the fragmentation stage, often after deformity occurs. These classifications are assigned too late in the progression of the disease to maximize the effects of intervention. Thus, alternative mechanisms to determine femoral head involvement earlier in the disease course are warranted. Increasingly, MRI has been used in the study of the disease. Gadolinium-enhanced and diffusion-weighted MRI has shown promising results that correlate with radiographic classifications and the early radiographic outcome. Advanced imaging has improved the assessment of hinge abduction, yet the exact definition remains controversial. The role of imaging in the management of Legg-Calvé-Perthes disease is rapidly evolving. New or refined imaging techniques may eventually allow earlier prognosis and treatment.

Legg-Calvé-Perthes disease

Current knowledge of the causes and risk factors of Legg-Calvé-Perthesdisease (LCPD) does not allow effective preventive strategies. The outcome in adulthood is usually good. Hip osteoarthritis rarely develops before 50 years of age. The risk of osteoarthrosis depends chiefly on the final degree of joint incongruence. Age at onset and the lateral pillar classification are the two main outcome predictors and serve to guide the surgical indications based on the studies by Herring's group. Non-operative treatment is not effective. In contrast, femoral varus osteotomy and Salter's innominate osteotomy provide good outcomes. In severe forms, however, combining these two techniques or performing a triple pelvic osteotomy seem preferable. Surgery is now performed considerably less often than in the past, as it is effective only in patients with lateral pillar group B or B/C disease with onset after eight years of age. In other situations, therapeutic abstention is recommended.

Emergency department evaluation and treatment of pediatric orthopedic injuries

Orthopedic injuries in children are unique when compared to those of adults because of the physiologic differences, especially the growth plates, stronger periosteum, and dynamic state of growth. The approach to the orthopedically injured child requires a gentle yet thorough focus with consideration of the growth plates as a primary area of weakness and growth when the child sustains an injury. Understanding the developmental stages of bones is paramount to being able to manage any injuries. Finally, what appears to be a benign injury may portend more serious issues, because nonaccidental trauma must always be considered in the evaluation of the injured child.

Perfusion MRI in Early Stage of Legg-Calvé-Perthes Disease to Predict Lateral Pillar Involvement: A Preliminary Study

BACKGROUND

Current radiographic classifications for Legg-Calvé-Perthes disease cannot be applied at the early stages of the disease. The purpose of this study was to quantify the perfusion of the femoral epiphysis in the early stages of Legg-Calvé-Perthes disease with use of perfusion magnetic resonance imaging (MRI) and to determine if the extent of epiphyseal perfusion can predict the lateral pillar involvement at the mid-fragmentation stage.

METHODS

Twenty-nine patients had gadolinium-enhanced perfusion MRI at the initial stage or early fragmentation stage of Legg-Calvé-Perthes disease and were followed prospectively. The percent perfusion of the whole epiphysis and its lateral third was measured by four independent observers using image analysis software. The radiographs obtained at the mid-fragmentation stage were used for the lateral pillar classification. Intraclass correlation coefficient (ICC) and logistic regression analyses were performed.

RESULTS

The mean age (and standard deviation) at diagnosis was 7.7 ± 1.7 years (range, 5.3 to 11.3 years). The mean interval between the MRI and the time of maximum fragmentation was 8.2 ± 5.5 months. The interobserver ICC for the percent perfusion of the lateral third of the epiphysis was 0.90 (95% confidence interval [CI]: 0.83 to 0.95). The mean percent perfusion of the lateral third of the epiphysis was 92% ± 2%, 68% ± 18%, and 46% ± 12% for the hips in which the lateral pillar was later classified as A, B, and C, respectively (p = 0.001). When the perfusion level was ≥90% in the lateral third of the epiphysis, the odds ratio of the lateral pillar being later classified as group A, as opposed to B or C, was 72.0 (CI: 3.5 to 1476). With a perfusion level of ≤55% in the lateral third of the epiphysis, the odds ratio of the lateral pillar being later classified as group C, as opposed to A or B, was 33.3 (CI: 2.8 to 392). Similar results were obtained for the whole epiphysis.

CONCLUSIONS

Perfusion MRI measurements of the total epiphysis and its lateral third obtained at the early stages of Legg-Calvé-Perthes disease were predictive of lateral pillar involvement at the mid-fragmentation stage of the disease.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

A comparison of non-contrast and contrast-enhanced MRI in the initial stage of Legg-Calvé-Perthes disease

BACKGROUND

A prognostic indicator of outcome for Legg-Calvé-Perthes disease (LCP) is needed to guide treatment decisions during the initial stage of the disease (stage 1), before deformity occurs. Radiographic prognosticators are applicable only after fragmentation (stage II).

OBJECTIVE

We investigated pre- and postcontrast MRI in depicting stage I femoral head involvement.

MATERIALS AND METHODS

Thirty children with stage I LCP underwent non-contrast coronal T1 fast spin-echo (FSE) and corresponding postcontrast fat-suppressed T1-weighted fast spin-echo (FSE) sequences to quantify the extent of femoral head involvement. Three pediatric radiologists and one pediatric orthopedic surgeon independently measured central head involvement.

RESULTS

Interobserver reliability of percent head involvement using non-contrasted MR images had intraclass correlation coefficient (ICC) of 0.72. Postcontrast MRI improved interobserver reliability (ICC 0.82). Qualitatively, the area of involvement was more clearly visible on contrast-enhanced MRI. A comparison of results obtained by each observer using the two MRI techniques showed no correlation. ICC ranged from -0.08 to 0.03 for each observer. Generally, greater head involvement was depicted by contrast compared with non-contrast MRI (Pearson r = -0.37, P = 0.04).

CONCLUSION

Pre- and postcontrast MRI assess two different components of stage I LCP. However, contrast-enhanced MRI more clearly depicts the area of involvement.

Unexpected MRI findings in clinically suspected Legg-Calvé-Perthes disease

BACKGROUND

In the setting of clinically suspected Legg-Calvé-Perthes (LCP) disease and negative/equivocal radiographs, contrast-enhanced MRI can be performed to confirm the diagnosis.

OBJECTIVE

To determine the frequency of unexpected causes of hip pain as identified by MRI in children with clinically suspected LCP disease and negative/equivocal radiographs.

MATERIALS AND METHODS

All pediatric contrast-enhanced MRI examinations of the pelvis and hips performed between January 2000 and February 2009 to evaluate for possible LCP disease in the setting of negative/equivocal radiographs were identified. MRI examinations performed to evaluate for secondary avascular necrosis were excluded. Imaging reports were retrospectively reviewed for unexpected clinically important causes of hip pain.

RESULTS

Thirty-six pediatric patients underwent contrast-enhanced MRI examinations for clinically suspected LCP disease in the setting of negative/equivocal radiographs. Twenty-two (61%) imaging studies were normal, while four (11%) imaging studies demonstrated findings consistent with LCP disease. Ten (28%) imaging studies revealed unexpected clinically important causes of hip pain, including nonspecific unilateral joint effusion and synovitis (n=7, juvenile chronic arthritis was eventually diagnosed in 3 patients), sacral fracture (n=1), apophyseal injury (n=1), and femoral head subluxation (n=1).

CONCLUSION

MRI frequently reveals unexpected clinically important causes of hip pain in children with suspected LCP disease and negative/equivocal radiographs.

MRI of Legg-Calve-Perthes disease

OBJECTIVE

Legg-Calvé-Perthes disease is a common cause of hip pain in children that may be initially clinically and radiographically difficult to diagnose and stage. The purpose of this article is to describe and illustrate the various MRI appearances of this condition.

CONCLUSION

MRI may show proximal femoral abnormalities before radiography in the setting of Legg-Calvé-Perthes disease, allowing appropriate diagnosis and prompt treatment. MRI can also assess for revascularization, healing, and multiple complications.

Imaging of elbow disorders

Numerous modalities are available for imaging the elbow. Radiographs should be the first imaging procedure performed for evaluation of an elbow abnormality. The use of advanced imaging modalities such as MR imaging, CT, and sonography also is discussed in this article.

Nuclear medicine in pediatric orthopedics

In this presentation, the common clinical pediatric problems (appendicular growth aberrations, hip pain, back pain, some aspects of trauma, and inflammatory and infectious processes that can be addressed by nuclear imaging will be discussed. The accurate interpretation of bone scintigraphy in the evaluation of pediatric orthopedic conditions depends on the use of appropriate radiopharmaceuticals and imaging techniques specific for the pediatric population, a knowledge of physiologic changes in the growing skeleton, as well as the different disease processes peculiar to each age bracket. The physes (growth-plates) will be discussed in detail because they are the most active portion of the pediatric skeleton. Their activity (potential for growth) can be altered by physiologic, developmental aberrations (varus and valgus) and pathologic conditions (trauma, infection, etc.).