Bone maturation of MRI residual developmental dysplasia of the hip with discrepancy between osseous and cartilaginous acetabular index.

Quality of spontaneous amelioration of residual developmental dysplasia of the hip (DDH) is nowadays not possible to predict. Normal age-related values of the osseous acetabular index (OAI), cartilaginous acetabular index and labral acetabular index have been established on MRI. In this study, MRI of dysplastic hips has been evaluated, and further osseous acetabular maturation was followed-up over time on pelvic radiography to find a correlation between MRI findings and radiological evolution. This is a retrospective single-centre study. Children with DDH who had a pelvic MRI between February 2007 and June 2014 were included. AI was measured for osseous (OAI), cartilaginous (cartilaginous acetabular index) and labral (labral acetabular index) values on MRI. OAI was thereafter recorded on each available radiograph during follow-up. A total of 20 hips were included. The mean age at MRI diagnosis was 3.55 years. Two types of DDH were observed: harmonious dysplasia, associated with an osseous and cartilaginous defect (group A, n = 14), and divergent dysplasia, associated with an osseous defect but with sufficient cartilaginous coverage (group B, n = 6). The mean age at final radiological follow-up was 7.6 and 8.3 years (P = 0.7408), respectively. In group A, four (28.6%) children older than 6 years had an OAI of less than 18°, whereas only two (33.3%) children older than 6 years had an OAI less than 18° in group B (P = 0.0117). This study shows that, in one-third of cases, divergent dysplasia leads to a spontaneous recovery. MRI should be used early to accurately diagnose and follow-up DDH cases and allow surgeons to justify the required surgical treatment. Level of Evidence: IV.

Development of a biometric method to estimate age on hand radiographs.

Age estimation of living individuals aged less than 13, 18 or 21 years, which are some relevant legal ages in most European countries, is currently problematic in the forensic context. Thus, numerous methods are available for legal authorities, although their efficiency can be discussed. For those reasons, we aimed to propose a new method, based on the biometric analysis of hand bones. 451 hand radiographs of French individuals under the age of 21 were retrospectively analyzed. This total sample was divided into three subgroups bounded by the relevant legal ages previously mentioned: 0-13, 13-18 and 18-21 years. On these radiographs, we numerically applied the osteometric board method used in anthropology, by including each metacarpal and proximal phalange of the five hand rays in the smallest rectangle possible. In that we can access their length and width information thanks to a measurement protocol developed precisely for our treatment with the ORS Visual® software. Then, a statistical analysis was performed from these biometric data: a Linear Discriminant Analysis (LDA) evaluated the probability for an individual to belong to one of the age group (0-13, 13-18 or 18-21); and several multivariate regression models were tested for the establishment of age estimation formulas for each of these age groups. The mean Correlation Coefficient between chronological age and both lengths and widths of hand bones is equal to 0.90 for the total sample. Repeatability and reproducibility were assessed. The LDA could more easily predict the belonging to the 0-13 age group. Age can be estimated with a mean standard error which never exceeds 1 year for the 95% confidence interval. Finally, compared to the literature, we can conclude that estimating an age from the biometric information of metacarpals and proximal phalanges is promising.

Normal values of bony, cartilaginous, and labral coverage of the infant hip in MR imaging.

BACKGROUND: Magnetic resonance imaging (MRI) is becoming more popular in the evaluation of residual hip dysplasia. Normal values of the bony, cartilaginous, and labral coverage in MRI are not published. The aim of our study was to establish reference values for normal hips at different ages and to assess the interobserver variability of such measurements. METHODS: MRIs of 115 normal hips in 73 children were analyzed. The bony, cartilaginous, and labral acetabular index (AI bone/cartilage/labrum) was measured in the coronal plane just posterior to the inferior branch of the triradiate cartilage. To determine interobserver variability, measurements were made by 3 different observers. Percentile graphs were established from the Student t distribution of the measurements grouped by 2 years of age. RESULTS: Global interobserver variability for the measurement of the AI bone was excellent [intraclass correlation coefficient (ICC)=0.88]. For the AI cartilage and labrum the ICC was somewhat lower (ICC 0.78) but still rated as good. Age-dependent percentile graphs of the AI bone, cartilage, and labrum are presented. Although the AI bone decreased during childhood, the AI cartilage as well as the AI labrum stays relatively constant with the 50 percentile around 5 degrees for the AI cartilage and -5 degrees for the AI labrum. The 90 percentile is around 10 degrees for the AI cartilage and 0 degrees for the AI labrum. CONCLUSIONS: We present percentile graphs of age-related normal values. Although bony coverage increases during childhood, cartilaginous and labral coverage stay constant. We think that measuring an AI cartilage above 10 degrees or an AI cartilage above 0 degrees might be a good additional parameter to classify hips into the group of residual dysplasia. CLINICAL RELEVANCE: The knowledge of normal values for cartilaginous and labral coverage is a valuable adjunct in decision-making for secondary surgery in residual dysplasia. This was a retrospective cross-sectional study.

Fracture risk in unicameral bone cyst. Is magnetic resonance imaging a better predictor than plain radiography?

The classical indication for treating a simple bone cyst is usually the risk of fracture, which can be predicted based on three parameters: the bone cyst index, the bone cyst diameter, and the minimal cortical thickness. A retrospective review was carried out based on imaging of 35 simple bone cysts (30 humeral and 5 femoral). The three parameters were measured on standard radiographs, and on T1-weighted and T2-weighted MRI. The measurements were performed by two independent reviewers, and twice by the same reviewer. Kappa values and binary logistic regression were used to assess the ability of the parameters to predict the fracture risk. Inter- and intra-observer agreement was measured. T1-weighted MRI was found to have the best inter- and intraobserver repeatability. The bone cyst index was found to be the best predictor for the risk of fracture.