You are in: eMedicine Specialties > Radiology > PEDIATRICS Legg-Calve-Perthes DiseaseArticle Last Updated: May 28, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR, LRCP, Chairman of Medical Imaging, Professor of Radiology, NGHA, King Fahad National Guard Hospital, King Abdulaziz Medical City, Riyadh, Saudi Arabia Ali Nawaz Khan is a member of the following medical societies: American Institute of Ultrasound in Medicine, Radiological Society of North America, Royal College of Physicians, Royal College of Physicians and Surgeons of the United States, Royal College of Radiologists, and Royal College of Surgeons of England Coauthor(s): Dare Mutiyu Seriki, MBBS, FRCR, MRCP, Staff Physician, Department of Radiology, Hope Hospital, UK; Charles Edward Hutchinson, MD, FRCR, Senior Lecturer, Department of Diagnostic Radiology, University of Manchester; Sumaira MacDonald, MBChB, PhD, MRCP, FRCR, Lecturer, Sheffield University Medical School; Endovascular Fellow, Sheffield Vascular Institute Editors: Fredric A Hoffer, MD, FAAP, FSIR, Professor of Radiology, University of Washington; Section Chief of Interventional Radiology, Department of Radiology, Seattle Children's Hospital and Regional Medical Center; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Marta Hernanz-Schulman, MD, FAAP, Professor, Radiology, Radiological Sciences, and Pediatrics, Director, Department of Pediatric Radiology, Radiologist-in-Chief, Director, Department of Diagnostic Imaging, Vanderbilt University Medical Center, Vanderbilt Children's Hospital; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington Author and Editor Disclosure Synonyms and related keywords: Legg-Calvé-Perthes, Legg-Perthes disease, Perthes disease, idiopathic avascular necrosis of the proximal femoral epiphysis, pediatric hip disorder, childhood hip disorder, epiphyseal bone infarction, femoral head infarction, Chandler disease, LPD, LCP INTRODUCTIONSection 2 of 12
  BackgroundLegg-Calvé-Perthes (LPD) disease is a childhood hip disorder that results in infarction of the bony epiphysis of the femoral head. LPD represents idiopathic avascular necrosis of the femoral head. The disease is bilateral in 10-20% of patients and usually affects children aged 4-8 years. When both hips are involved, they are usually affected successively, not simultaneously. A family history is present in 6% of patients. In adults, the corresponding condition is termed Chandler disease. Although the etiology is unclear, certain risk factors have been identified in children, including sex, socioeconomic group, and the presence of an inguinal hernia and genitourinary tract anomalies. More specifically, boys are affected 3 to 5 times more often than girls, and the incidence increases in low socioeconomic groups and in children with low birth weight. Determining the prognosis is important at the time of presentation because more than 50% of patients with LPD do not require treatment.1, 2, 3 PathophysiologyThe primary pathologic abnormality in patients with LPD is osteonecrosis resulting in flattening and collapse of the femoral head. The articular cartilage covering the femoral head is remarkably resistant to ischemia and is usually well preserved. The basic underlying cause of LPD is insufficient blood supply to the femoral head. The epiphyseal plate acts as a barrier to the supply of blood in children aged 4-10 years, and the ligamentum teres vessels become nonfunctional, causing the head to be at risk for osteonecrosis. Healing occurs by revascularization of the necrotic femoral head. The course of revascularization and reconstitution of the femoral head varies. The ultimate shape of the reconstituted femoral head depends on several factors, including the degree and site of necrosis and the magnitude of forces working across the femoral head. In some patients, the femoral head may return to normal, whereas in other patients, coxa plana and shortening and widening of the femoral head may develop. These changes may be associated with osteoarthrosis and intra-articular loose bodies. In most patients, the changes occurring in LPD affect only 1 hip. With bilateral disease, the changes are rarely symmetric. FrequencyUnited StatesThe frequency in the United States is similar to the worldwide frequency. InternationalApproximately 1 in 1200 children younger than 15 years is affected. Mortality/MorbidityThe diagnosis of LPD must be made as early as possible; patients who present after the age of 8 years have a poor prognosis. The prognosis for girls is worse than that for boys, and girls usually have a more severe form of the disease. The prognosis for patients in whom the onset of LPD occurs before the age of 6 years is favorable, with 80% having a good result; however, in children between 4 years of age and 5 years, 11 months of age who have lateral pillar involvement of classification B/C or C, the prognosis is less favorable.4 RaceLPD rarely occurs in blacks. SexThe male-to-female ratio is 3-5:1. AgePatients with LPD are typically aged 2-12 years. The mean patient age at presentation is 7 years.5 AnatomyThe femoral head is spherical and is covered by articular cartilage. The fovea is a just-off-center ovoid depression that serves as an attachment for the ligamentum teres (round ligament). The femoral head is supplied by a vascular ring at the base of the femoral neck from branches arising from the lateral and medial circumflex arteries. The superior and inferior gluteals contribute to the blood supply to a lesser extent. The anterior aspect of the vascular ring is within the joint capsule. Principally, the lateral epiphyseal arteries supply the femoral neck. The artery in the ligamentum teres supplies one third of the arterial supply to the femoral head in children but makes only a small contribution in adults. Clinical DetailsLPD is a dynamic condition. Results of the physical examination depend on the stage of the disease at the time of presentation. The child often has a limp with groin, thigh, or knee pain. Children who present with knee pain must be carefully examined for hip pathology. As the disease progresses, flexion and adduction contractures may develop, and lateral overgrowth of the femoral head cartilage may cause loss of abduction. Attempts at abduction lead to hinging and possible subluxation of the femoral head. Eventually, the hip may move in only the flexion-extension plane. Progressive loss of movement, adduction contractures, flexion with abduction, and obesity are poor prognostic signs. Lateral subluxation of the femoral head is also associated with a poor outcome. Several staging schema are used to determine severity of disease and prognosis; these include the Catterall, Salter-Thomson, and Herring systems.6 The Catterall classification is based on radiographic appearances and specifies 4 groups during the period of greatest bone loss. Catterall staging is as follows:
The Salter-Thomson classification simplifies the Catterall classifications by reducing the groups to 2. The first, called group A, includes Catterall groups I and II; for patients in this group, less than 50% of the head is involved. The second, called group B, includes Catterall groups III and IV; for patients in this group, more than 50% of the head is involved. For both classifications, if less than 50% of the ball is involved, the prognosis is better, whereas if more than 50% is involved, the prognosis is potentially poor. The Herring classification addresses the integrity of the lateral pillar of the head. In lateral pillar group A, there is no loss of height in the lateral one third of the head, and there is little density change. In lateral pillar group B, there is a lucency and less than 50% loss of lateral height. Sometimes, the head is beginning to extrude from the socket. In lateral pillar group C, there is more than 50% loss of lateral height. Preferred ExaminationPlain radiography remains the major modality for the evaluation of LPD. Staging of the disease is based on plain radiographic findings.1, 7, 8 Scintigraphy is a useful technique in early disease when plain radiographic findings may be normal; with scintigraphy, abnormalities become apparent earlier in the course of disease than they do with plain radiography. CT scans allow early diagnosis of bone collapse and curvilinear zones of sclerosis early in the disease process when plain radiography is less sensitive. CT scans can also demonstrate subtle changes in the bone trabecular pattern. Ultrasonography is useful in the preliminary diagnosis of transient synovitis of the hip and the onset of LPD.9 Hip effusion with capsular distention is well depicted on sonographic images.10, 11, 12, 13, 14 MRI is as sensitive as isotopic bone scanning and allows more precise localization of involvement than conventional radiography.15, 16, 17, 18, 19, 20 Angiography, venography, and arthrography have limited roles in the diagnosis of LPD. Limitations of TechniquesPlain radiographic findings may be entirely normal in early symptomatic disease. Although abnormalities become apparent with scintigraphy earlier in the course of disease than they do with radiography, abnormal scintigraphic findings are nonspecific; findings may be positive in patients with trauma, synovitis, and infections. CT scans allow the early diagnosis of bone collapse, but the use of CT is limited by the comparatively higher radiation dose. Ultrasonography is useful in the preliminary diagnosis of transient synovitis of the hip and the onset of LPD, but the diagnosis is based on a demonstration of hip effusion, which is a nonspecific finding. MRI is as sensitive as isotope bone scans and allows more precise localization of involvement than conventional radiography, but the changes seen as bone marrow edema and joint effusions are nonspecific. Angiography, venography, and arthrography are invasive procedures and do not provide significantly better clinical information for guiding therapeutic options. DIFFERENTIALSSection 3 of 12
Eosinophilic Granuloma, Skeletal Septic Arthritis Sickle Cell Anemia, Skeletal Other Problems to Be ConsideredBilateral disease Hypothyroidism Unilateral disease Septic arthritis RADIOGRAPHSection 4 of 12
FindingsEarly signs on radiographs include the following (see Images 1-15, 24)7:
Late signs on radiographs include the following:
Degree of ConfidencePlain radiographs have a sensitivity of 97% and a specificity of 78% in the detection of LPD. False Positives/NegativesSevere osteoarthritis and infective arthritis may mimic LPD. CT SCANSection 5 of 12
FindingsEarly signs on CT scans include the following (see Images 16-18):
Late signs on CT scans include the following:
Coronal reconstructions can show subchondral fractures, subtle buckling, or collapse of the articular surface. Degree of ConfidenceWith CT scans, the staging determined on the basis of plain radiographic findings is upgraded in 30% of patients. CT is not as sensitive as nuclear medicine or MRI. CT may be used for follow-up imaging in patients with LPD. False Positives/NegativesCT findings of osteoarthritis and infective arthritis may mimic those of LPD. MRISection 6 of 12
FindingsEarly in the disease, irregular foci of low signal intensity or linear segments replace the normal high signal intensity of bone marrow in the femoral epiphysis on T1- and T2-weighted images. Other findings include an intra-articular effusion and a small laterally displaced ossification nucleus, labral inversion, and femoral head deformity (see Images 19-21, 25).15, 16, 17, 18, 19, 20 Fat-suppressed or short-tau inversion recovery (STIR) sequences are more accurate than plain radiographs in showing degenerative changes of the articular cartilage. These MRIs demonstrate the influx of fluid into areas of articular cartilage irregularity. The asterisk sign is defined as findings of areas of low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in marrow. The double-line sign occurs in as many as 80% of patients and represents the sclerotic rim, which appears as a signal void. This sign is demonstrated as a line between necrotic and viable bone edges with a hyperintense rim of granulation tissue. Jaramillo et al have shown that multipositional MRI with an open magnet was comparable to arthrography for demonstrating containment of the congruency of the articular surfaces of the hip.15 However, in the evaluation of deformity or loss of the spherical nature of the femoral head, open MRI performed less well. Sebag et al showed dynamic gadolinium-enhanced subtraction MRI to be a simple and promising means of early recognition of ischemia in LPD.16 Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. Degree of ConfidenceMRI is as sensitive as isotopic bone scanning, and it allows more precise localization of involvement than conventional radiography. MRI is preferred for evaluating the position, form, and size of the femoral head and surrounding soft tissues. False Positives/NegativesThe differential diagnosis includes severe osteoarthritis, infective arthritis, and other causes of bone marrow edema and joint effusions. ULTRASOUNDSection 7 of 12
FindingsUltrasonography is useful in establishing the diagnosis of transient synovitis of the hip and the onset of LPD. Hip effusion, which results in capsular distention, is accurately documented on sonograms. Sonography allows aspiration of joint fluid for laboratory examination. Together, the results of clinical evaluation, radiography, and sonography determine the need for sonography-guided aspiration. Sonography-guided aspiration allows the selection of only those patients with septic arthritis for surgical drainage and shortens the procedure. Negative sonographic findings allow the exclusion of septic arthritis but not osteomyelitis. Capsular distention lasting longer than 6 weeks is associated with LPD. A chronologic, 4-part staging of LPD has been proposed on the basis of the sonographic findings. The stages reflect the degree of flattening and fragmentation and the reconstitution of the femoral head. Thickening of articular cartilage, associated synovitis, and lateral extrusion of the femoral head can be documented. Joint effusion is present in 74% of patients in stages I-II. Lateral extrusion increases from stage II onward until the healing stage.10, 11, 12, 13, 14, 21 Degree of ConfidenceAlthough not performed routinely, sonographic evaluation of patients with LPD is a simple and standardized procedure that can be useful for staging the disease and monitoring its course. It can also spare the patient from radiation exposure and lower treatment costs. Lateral extrusion and the onset of healing in patients with LPD can be shown earlier with sonograms than with radiographs. Hip sonography seems to be a reliable method for monitoring the containment of the femoral head in LPD.22 False Positives/NegativesChanges similar to those of LPD can be found in transient synovitis and other conditions that cause hip joint effusions. Joint effusion is not always present in patients with LDP. NUCLEAR MEDICINESection 8 of 12
FindingsTechnetium-99m diphosphonate uptake depends on the stage of the disease, but it does play a role in the diagnosis. Characteristic features include a photopenic void in proximal femoral epiphyses, as compared with the contralateral side, which usually can be seen by using a pinhole camera with the hip in maximal medial rotation, obviating the need of single-photon emission CT (SPECT). Scintigraphy may be helpful in early diagnosis. Initially, uptake is decreased in the femoral head because of an interruption in the blood supply. Later, uptake is increased in the femoral head as a result of revascularization, bone repair, and degenerative osteoarthritis. In addition, acetabular activity can be increased with associated joint disease. Degree of ConfidenceThe sensitivity of radionuclide scanning in the diagnosis of LPD is 98%, and the specificity is 95%. False Positives/NegativesSimilar activity patterns may occur with osteoarthritis or infective or inflammatory arthritis. The presence of a large joint effusion can simulate diminished perfusion caused by osteonecrosis. ANGIOGRAPHYSection 9 of 12
FindingsAngiography is performed only in rare cases. Early in the disease process, opacification of the joint with contrast material can reveal subtle flattening of the chondral surface of the femoral head and widening of the joint space. Angiographic findings may demonstrate an interruption in the superior capsular arteries and a generalized decrease of blood flow in the affected hip. Later in the disease process, the size and position of sequestered fragments can be identified by the distribution of revascularized osseous segments despite the demonstration of a smooth cartilaginous surface. Degree of ConfidenceVascular changes in LPD are nonspecific, and angiography is not performed routinely. INTERVENTIONSection 10 of 12
No radiologic intervention is possible. Primarily, treatment includes medical bedrest, analgesia, bracing, or surgery. However, some benefit may be derived by draining the hip effusion of toxic synovitis, although this benefit is not proven. Effusion caused by septic arthritis can be diagnosed with sonography; after diagnosis, aspiration and treatment should follow promptly.2, 10 Determining the prognosis is important at the time of presentation because more than 50% of patients with LPD do not require treatment. The earlier the stage of the disease at presentation, the better the prognosis. In the long term, approximately 50% of patients do not need treatment. Although osteoarthritis develops in some patients, most are able to function relatively well until their fifth or sixth decade of life.23 MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Legg-Calve-Perthes Disease excerpt Article Last Updated: May 28, 2008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
