Preliminary report on usefulness of magnetic resonance imaging for outcome prediction in early-stage Legg-Calvé-Perthes disease.

The usefulness of magnetic resonance imaging (MRI) for predicting prognosis was evaluated in 11 patients with unilateral early-stage Legg-Calvé-Perthes disease who were treated with a non-weight-bearing abduction brace. Six to 10 months after disease onset, severity of cartilage hypertrophy and physeal curvature of the femoral head were scored on MRI. Femoral head deformity was radiographically evaluated. Among five patients whose MRI score was 8 or greater, radiographic evaluation after the treatment was "poor" or "fair," whereas evaluation for the other six patients whose MRI score was 7 or less was "good." The MRI scores indicated possible occurrence of femoral head deformation. Treatment method should be considered carefully when the MRI score is high.     

Imaging in Legg-Calvé-Perthes disease

Imaging in Legg-Calvé-Perthes disease should help assess the severity and the stage of the disease, detect severe forms earlier, and provide guidance to therapy. However, due to the complexity of the disease, not all examinations can be performed at the same time with the same goals. The scope of this work is to provide an overview of all imaging techniques available today, and to help understand when to use a particular examination. Advantages and limitations of plain radiographs, bone scintigraphy, magnetic resonance imaging, arthrography, computed tomography, and ultrasonography are identified.     

Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease is an idiopathic hip disorder that produces ischemic necrosis of the growing femoral head. Permanent femoral head deformity is the most significant sequela. Experimental studies indicate that the pathologic repair process, which is marked by an imbalance of bone resorption and formation, contributes to the pathogenesis of femoral head deformity. Important prognostic factors include degree of deformity, age at disease onset, extent of head involvement, head-at-risk signs, and lateral pillar collapse. Treatment should be guided by age at disease onset, current best evidence, and prognostic factors. Patients aged <6 years at onset are best managed nonsurgically, whereas older patients may benefit from surgical treatment. Good surgical results have been reported in 40% to 60% of older patients (>8 years), indicating the need to develop more effective treatments based on the pathobiology of the disease.     

Arthrographic findings in Legg-Calvé-Perthes disease

Plain radiographs and arthrograms on 46 patients with Legg-Calvé-Perthes were evaluated. Measurements of containment including epiphyseal extrusion, caput index, femoral subluxation, percentage acetabular coverage, were determined. Only with arthrography are measurements of acetabular coverage, subluxation and epiphyseal extrusion consistent and reliable. The concept of eccentricity was developed to assist in the understanding of femoral containment.     

Nonoperative treatment in Legg-Calvé-Perthes disease

There is still discussion about the indication for and modalities about treatment of Perthes'disease.The main objective of treatment in Perthes'disease is prevention of deformation and malalignment of the hip joint.Most important for the evaluation of any therapy is the long term outcome, therefore we present this retrospective study on nonoperative treatment of perthes disease with orthoses compared to the natural history. 54 Patients with 59 involved hips, treated between 1945-1975 were clinically and radiologically evaluated.We divided the patients into two subgroups: Group 1 with nonoperative therapy.Group 2 with no therapy. The outcome shows correlation of the results with the degree of malalignment and necrosis.There was no statistically significant correlation between the two groups, but a slightly better outcome in the non-operative group compared to the natural history. The use of orthosis may be justified if there is improvement of the containment and reduction of the femoral head, otherwise surgical treatment like pelvic- and hip osteotomies to realign the hip joint should be considered.     

Significance of synovitis in Legg-Calvé-Perthes disease.

Synovitis is an important feature in Legg-Calvé-Perthes disease (LCPD) with a significant prognostically negative impact on clinical symptoms, cartilage biochemistry, mechanical properties of the cartilage, joint biomechanics, and prognosis toward healing with a congruent, spherical head of femur. Synovitis causes cartilage edema, deterioration of the cartilage's mechanical properties, cartilage hypermetabolism, and, subsequently, cartilage hypertrophy. This sequence of events could explain the clinical course, which consists of cartilage hypertrophy, lateral subluxation, anterolateral deformation of the head, and, subsequently, joint incongruence in prognostically poor cases of LCPD. A factor in the deformation of the hypertrophic cartilage of the epiphysis is decreased range of motion of the hip, because of pain caused by the increase in intracapsular pressure and the subsequent decrease in the "molding" ability of the acetabulum. Synovitis in LCPD causes an increased intracapsular pressure, the magnitude of which may, in some patients, intermittently compromise the blood supply to the proximal femoral epiphysis. Whether synovitis is the consequence of, or precedes, the loss of blood supply and epiphyseal necrosis is not yet established. Significant and persistent synovitis during the entire course of the disease emphasizes the importance of magnetic resonance imaging as the method of choice for the diagnosis and the prognosis, as well as the monitoring of therapy. The prognostically negative effects of synovitis suggest that more therapeutic efforts should be focused on the treatment of synovitis, from a palliative and prognostic point of view.     

The development of acetabular retroversion in children with Legg-Calvé-Perthes disease

BACKGROUND: Ezoe et al showed that the prevalence of acetabular retroversion in adults with Legg-Calvé-Perthes disease (LCPD) was 42% versus 6% in normal controls. Our purpose was to study the development of acetabular retroversion in children with LCPD and perhaps draw conclusions regarding cause and effect. METHODS: We reviewed all 271 patients with LCPD seen at our institution to identify those patients with axial imaging before closure of the triradiate cartilage. Fifty-three hips (44 patients) formed our study population; the 35 normal hips in those patients with unilateral disease served as an internal control. Acetabular version was measured on the axial cut with the largest femoral head cross-section. Diseased versus control hips were compared using a paired t test. Two disease-severity subgroups, Herring A or B (42 hips) and B/C or C (11 hips), were compared using an independent-samples t test. In those patients followed past skeletal maturity (16 of 53 hips), we evaluated final AP pelvic radiographs for acetabular retroversion (presence of a crossover sign). RESULTS: Before skeletal maturity, all but 1 patient in our series demonstrated positive acetabular version (anteversion). We found no significant difference between the diseased and control hips: mean acetabular version in LCPD hips was 13.6 +/- 4.3 versus 15.4 +/- 5.4 degrees in unaffected hips. More severe cases (B/C or C) exhibited significantly more relative retroversion (10.8 degrees) than less severe cases (14.6 degrees, P = 0.047). Of the 16 hips followed past skeletal maturity, 5 demonstrated crossover signs on anteroposterior pelvic radiographs, indicating a 31% prevalence of acetabular retroversion. CONCLUSION: Early after diagnosis, the prevalence of acetabular retroversion in our skeletally immature children with LCPD was extremely rare (1.8%), and there was no significant difference in version between the normal hips and hips with LCPD. However, over time, a child with a more deformed femoral head is more likely to develop acetabular retroversion, suggesting a cause-and-effect relationship. LEVEL OF EVIDENCE: Level III (case-control).     

Theoretical study of subluxation in early Legg-Calvé-Perthes disease

The relationship between mechanical subluxation and femoral head necrosis geometry in Legg-Calvé-Perthes disease (LCP) was investigated with a three-dimensional rigid body-spring method hip model. Femoral head models with progressively larger regions of necrosis, corresponding to the four Catterall grades, were placed in a spherical acetabular model and studied in static single-limb stance configuration, with variable mechanical rigidity of the necrotic segment. The degree of subluxation was dependent on the geometric region of involvement, mechanical properties of the segment, and direction of loading force. In general, femoral head subluxation was always in the direction of the necrosis, modified by the anatomic and force environment. In the neutral position, the Catterall I models exhibited minimal subluxation. The Catterall II model subluxated anteriorly as collapse occurred, and the Catterall III model subluxated anteriorly and superiorly. Lateral subluxation could be produced by changing the loading force to a more vertical orientation. The Catterall IV model collapsed directly along the line of force application rather than subluxating. Reorientation of models with minor necrosis could improve stability, but reorientation of models with extensive necrosis had minimal effect on subluxation behavior. Higher-grade LCP involvement may lead to early subluxation, particularly anteriorly, which is difficult to visualize radiographically. The appearance of lateral subluxation may signal a change in the mechanical environment of the hip from clinical progression of the disease. Femoral head reorientation (osteotomy) may improve femoral head stability when necrosis is limited but is unlikely to reduce subluxation or collapse when extensive necrosis is present.     

Long-term follow-up of a patient cohort with Legg-Calvé-Perthes disease

The purpose of this study was to evaluate prognostic risk factors related to a poor radiological outcome. The study consisted of 74 patients with Legg-Calvé-Perthes disease treated using a Thomas splint. The modified Herring lateral pillar classification and the reviewed Stulberg classification system were applied. A significant correlation between the Herring group and Stulberg was found (P=0.03). There was a significant correlation between age at onset of the disease and Stulberg outcome (P=0.05). The Herring classification correlated to the Stulberg outcome. An age of 7 years or more at onset was considered as a risk factor for a poor Stulberg outcome.     

Lateral shelf acetabuloplasty in the treatment of Legg-Calvé-Perthes disease

Although head containment is extremely important for the development of the acetabulum and femoral head, there are debates about conservative and surgical treatment. Shelf acetabuloplasty is an effective means of treatment as regards the coverage of the femoral head within the acetabulum, which is the most important issue for the normal development of the hip joint. Nineteen hips of 18 patients were evaluated radiographically using the acetabulum-head index of Heyman and Herndon and the center-edge angle for containment. It was shown that postoperatively both indices improve to increase the containment, thus demonstrating the effectiveness of shelf acetabuloplasty.     

Diffusion-weighted MRI reveals epiphyseal and metaphyseal abnormalities in Legg-Calvé-Perthes disease: a pilot study

Background  

Legg-Calvé-Perthes disease (LCP) is thought to be associated with ischemic events in the femoral head. However, the types and patterns of reperfusion after these ischemic events are unclear.     

Contrast-enhanced power Doppler imaging: comparison with scintigraphic phases of revascularization of the femoral head in Legg-Calvé-Perthes disease

The authors evaluated the usefulness of an ultrasound contrast agent (SHU 508A) to help identify different scintigraphic phases of revascularization of the femoral head in children with Legg-Calvé-Perthes (LCP) disease. Eighteen unenhanced and contrast-enhanced power Doppler images and scintigrams of the pathologic hip in 18 children with LCP disease were compared. The scintigraphic stages of Conway's classification for LCP disease (stage A, recanalization; stage B, neovascularization) were compared with the degree of vascularity and mean peak enhancement ratios obtained from analysis of Doppler sonograms. Qualitatively, the patient's age (< or = or >7 years old) at the time of examination had a significant effect on the degree of vascularity visualized on postcontrast ultrasound images according to the scintigraphic stages. Quantitatively, there were no differences for overall mean peak enhancement ratios between stages A and B. Power Doppler ultrasound increased visualization of Doppler signals significantly but did not help in differentiating scintigraphic phases.     

Acetabulum-head index measured on arthrograms in children with Legg-Calvé-Perthes disease

The acetabulum-head index (AHI), which can be used to assess the lateral displacement of the femoral head, was measured on both plain radiographs and arthrograms in 37 children with unilateral Legg-Calvé-Perthes disease. For the identification of the outermost part of the acetabulum on the arthrograms, two measuring points were used: A. the lateral border of the bony acetabulum (arthrogram I) and B. the lateral border of the labrum (arthrogram II). The reproducibility of the measurements, evaluated by duplicate calculations of the AHI on arthrogram II, which was obtained from the unaffected hips, was high; the root mean square error of the AHI was 3.3. On the plain radiographs, an AHI of 80 or less could be used as a 'guideline' to reveal early subluxation of the femoral head. The corresponding figures on arthrograms I and 11 were 70 and 85, respectively.