Prognostic evaluation of Legg-Calvé-Perthes disease by MRI. Part I: the role of physeal involvement.

Twenty-eight unselected hips affected by Legg-Calvé-Perthes disease (LCPD) in 24 patients from 1987 to 1994 had magnetic resonance imaging (MRI) performed. The patients were retrospectively reviewed at a mean follow-up of 5.4 years. An interobserver blind analysis was made to establish the reliability of four MRI parameters: extent of epiphyseal necrosis (EXT), lateral extrusion of the femoral head (LAT), physeal involvement (PHY), and metaphyseal changes (MET). The interobserver analysis resulted in a good reliability for all MRI parameters (concordance, >80%; K index, >0.45). A statistical correlation study (Spearman test) was then done between each MRI parameter and the condition of the hips at follow-up evaluated by Stulberg class and a personal scored system (total score) of clinical-radiographic condition. All MRI parameters appeared well correlated to the Stulberg class and to the total score (S > 0.66; p < 0.05). PHY resulted the strongest correlated parameter (S = 0.84 for Stulberg class; S = 0.91 for total score). Finally our statistical correlation study demonstrates physis involvement to have a high predictive value in LCPD; therefore it can be assumed as the main risk factor in formulating prognosis.

Prognostic evaluation of Legg-Calvé-Perthes disease by MRI. Part II: pathomorphogenesis and new classification.

The most widely used system of grading Legg-Calvé-Perthes disease (LCPD) is still the radiographic grouping by Catterall, although it lacks interobserver reliability, especially in the early stages. The predictive value of Salter-Thompson classification and Herring's "lateral pillar" classification are still being studied. In Part 1, we demonstrated the good reliability and the predictive value of four magnetic resonance imaging (MRI) indices (extension of necrosis, lateral extrusion, physeal involvement, metaphyseal changes) through their correlation to clinical and radiographic conditions of the hips at follow-up. The same good results were obtained by submitting to statistical analysis a second group of 31 patients (French series). On the basis of these statistical studies, a new classification has been proposed. It takes into account the extent of necrosis and two MRI risk signs: lateral extrusion and physeal involvement. The extent of necrosis up to or more than 50% separates two main groups, A and B. The associated MRI risk factors distinguished six classes with different prognoses. Appropriated treatment also is suggested for each class. Our experience on MRI in LCPD led us to draw a pathomorphogenetic model called "packed capsule." According to this biomechanical model, the femoral head is considered a segment of a sphere made of viscoelastic material and hermetically sealed. The deformation of the head depends on the behavior of the necrotic fluid collected inside the capsule under the weight-bearing forces. Finally, our suggestion in the treatment of Perthes disease is to relieve weight bearing up to the fragmentation stage, whether the diagnosis has been made by the use of MRI or without it. During the fragmentation stage, MRI is extremely useful in performing prognosis; at this time our classification can be applied, and the corresponding treatment can be followed.

Benign tumors of the pediatric spine: statistical notes.

A group of 50 pediatric patients affected with tumors or pseudotumors of the spine were studied with the purpose of determining the interval between the onset of symptoms and definitive diagnosis, the incidence of various symptoms, the statistical frequency based on age, sex, histologic type, localization, site. Also studied were diagnostic procedures adopted, therapy, recurrence, complications. The child affected with benign tumor pathology of the spine is rarely submitted early to appropriate diagnostic testing. Tumors are more frequently localized in the lumbar and thoracic spine and there is predilection for the vertebral arch. The most frequent histologic types are in decreasing order: histiocytosis X, osteoid osteoma, and aneurysmal cyst. Treatment is constituted by simple curettage in histiocytosis X, complete resection of the neoplasm in osteoid osteoma and osteoblastoma, partial resection associated with radiotherapy or selective embolization in aneurysmal bone cyst.