Background: Varying degrees of femoral deformity may result as Legg-Calvé-Perthes disease heals. Our aims were to investigate the prevalence of abnormalities of the acetabular labrum and cartilage, using noncontrast magnetic resonance imaging, and to correlate the findings with radiographic deformities that may exist after the healing of Legg-Calvé-Perthes disease.
Methods: In a sample of ninety-nine patients with healed Legg-Calvé-Perthes disease, anteroposterior and lateral radiographs were used to assess the Stulberg classification, femoral head size and sphericity, femoral neck morphology, and acetabular version. A subgroup of fifty-four patients (fifty-nine hips) underwent noncontrast magnetic resonance imaging of the hip an average of eight years after disease onset. The acetabular labrum was evaluated according to a modified classification system, and the acetabular cartilage was evaluated for the presence of delamination and defects. The association among abnormalities of the acetabular labrum, articular cartilage, and radiographic deformities was assessed.
Results: Abnormalities of the acetabular labrum and cartilage were found on magnetic resonance imaging scans in 75% and 47% of the hips, respectively. An alpha angle of ≥55° was the deformity most significantly associated with labral and cartilage abnormalities, followed by coxa brevis. Coxa magna and a higher greater trochanter showed a significant association with labral abnormalities only. Acetabular retroversion showed an increased risk for labral abnormalities when the alpha angle was normal. When deformities coexisted, the alpha angle showed the greatest relative risk for abnormality.
Conclusions: On the basis of magnetic resonance imaging evaluation of the hip, labral and cartilage abnormalities were a common finding in patients with healed Legg-Calvé-Perthes disease. Our results suggest that hip deformities are significantly associated with labral and cartilage abnormalities on magnetic resonance imaging, and the main predisposing factor was the asphericity of the femoral head with a reduced femoral head-neck offset.
Level of Evidence: Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Investigation performed at the Division of Pediatric Orthopaedics of the Departments of Biomechanics, Medicine, and Rehabilitation of the Locomotor System, and Division of Imaging Sciences, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
- Copyright © 2013 by The Journal of Bone and Joint Surgery, Incorporated
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