Age- and gender-specific variations of the epiphyseal tilt and epiphyseal angle in adolescents without hip pathology.

PURPOSE: To determine age-and gender-dependent variation of epiphyseal tilt and epiphyseal angle using CT in adolescents without hip pathology. METHODS: Pelvic CT scans were obtained in 132 adolescents for evaluation of abdominal pain. Radially oriented planes around the femoral neck were reformatted and the epiphyseal tilt and angle were measured in the anterior, anterosuperior and superior planes. Variations in the tilt angle and epiphyseal angle were assessed by age group from 12 to 18 years and gender by using a linear mixed model analysis. RESULTS: The epiphyseal tilt did not change (p = 0.97) with increasing age. Male patients exhibited smaller tilt angle in the anterosuperior plane (p = 0.003) but no difference was detected in the anterior (p = 0.17) or superior (p = 0.06) planes. The epiphyseal angle decreased with increasing age in the anterior (p = 0.03), anterosuperior (p = 0.001) and superior (p < 0.001) planes in male patients, with no variation in female patients (p = 0.92). Male patients had larger epiphyseal angles in the anterior (p = 0.02), anterosuperior (p < 0.001) and superior (p = 0.002) planes compared with female patients. CONCLUSION: We found no age-specific variations in the epiphyseal tilt and no difference in the epiphyseal tilt in male and female patients in the superior and anterior plane. The epiphyseal angle was smaller in female patients, however, the epiphyseal angle decreased with increasing age in male patients which corresponds to an increase in epiphyseal extension. The reference values reported in this study may serve as additional information in the evaluation of adolescents with hip pain and as reference for future studies investigating slipped capital femoral epiphysis and femoroacetabular impingement development. LEVEL OF EVIDENCE: Level III Diagnostic Study.

Three-dimensional hip cartilage quality assessment of morphology and dGEMRIC by planar maps and automated segmentation.

OBJECTIVE: The quantitative interpretation of hip cartilage magnetic resonance imaging (MRI) has been limited by the difficulty of identifying and delineating the cartilage in a three-dimensional (3D) dataset, thereby reducing its routine usage. In this paper a solution is suggested by unfolding the cartilage to planar two-dimensional (2D) maps on which both morphology and biochemical degeneration patterns can be investigated across the entire hip joint. DESIGN: Morphological TrueFISP and biochemical delayed gadolinium enhanced MRI of cartilage (dGEMRIC) hip images were acquired isotropically for 15 symptomatic subjects with mild or no radiographic osteoarthritis (OA). A multi-template based label fusion technique was used to automatically segment the cartilage tissue, followed by a geometric projection algorithm to generate the planar maps. The segmentation performance was investigated through a leave-one-out study, for two different fusion methods and as a function of the number of utilized templates. RESULTS: For each of the generated planar maps, various patterns could be seen, indicating areas of healthy and degenerated cartilage. Dice coefficients for cartilage segmentation varied from 0.76 with four templates to 0.82 with 14 templates. Regional analysis suggests even higher segmentation performance in the superior half of the cartilage. CONCLUSIONS: The proposed technique is the first of its kind to provide planar maps that enable straightforward quantitative assessment of hip cartilage morphology and dGEMRIC values. This technique may have important clinical applications for patient selection for hip preservation surgery, as well as for epidemiological studies of cartilage degeneration patterns. It is also shown that 10-15 templates are sufficient for accurate segmentation in this application.

Patterns of joint damage seen on MRI in early hip osteoarthritis due to structural hip deformities.

OBJECTIVE: The aim of this study was to evaluate differences in damage patterns assessed using magnetic resonance imaging (MRI) between hips with femoroacetabular impingement (FAI) and developmental dysplasia of the hip (DDH) as well as to correlate MRI findings with delayed Gadolinium enhanced MRI of cartilage (dGEMRIC) and with patient pain. DESIGN: This retrospective study included 40 patients (mean age 28.6 ± 11.2 years) who underwent dGEMRIC and morphological MRI of the hip. Twenty-one hips with FAI and 19 with DDH were investigated. A self-developed morphological grading (MRI score) and dGEMRIC evaluation were done on seven radial reformats obtained from an isotropic 3D True-fast imaging with steady state precession (FISP) sequence and an isotropic T1-mapping sequence. The observed damage patterns were summed up into sub-scores and a total MRI score. RESULTS: Labrum damage, paralabral cysts, and acetabular rim bone cysts were more common in DDH patients than in FAI patients. No significant differences were seen in the occurrence of cartilage damage, bone cysts, or osteophytes. In DDH (but not in FAI), the dGEMRIC index demonstrated a tendency for lower values in areas next to cartilage defects. There was no association between labrum damage and dGEMRIC index. A moderate correlation was seen between Western Ontario and McMaster Universities (WOMAC) pain score and cartilage damage, paralabral cysts, and the total MRI score. CONCLUSIONS: This study confirms a higher prevalence of labrum damage but not cartilage damage in patients with DDH in comparison to patients with FAI. In addition, our data suggests an association of cartilage damage and paralabral cysts with patient reported pain.

Femoroacetabular cam-type impingement: diagnostic sensitivity and specificity of radiographic views compared to radial MRI.

PURPOSE: To retrospectively assess the diagnostic sensitivity of 45° Dunn view and cross-table lateral radiographs for the assessment of cam deformity by comparison with radial MRI. MATERIALS AND METHODS: 60 cases with radiographs (38 a-p and 45° Dunn views, 22 a-p and cross-table lateral views) and radial MRI were assessed. Alpha angle measurements were obtained both for radiographs and radial MRI. Statistics included frequency analysis, bivariate linear correlation analyses of MRI and radiograph measurements and cross-table analyses testing for the sensitivity and specificity of radiographs for the detection of an alpha angle larger than 55°. RESULTS: 53.3% had the maximum alpha angle in the superior-anterior aspect of the femoral head-neck junction. Cam deformity was found in 45/60 cases (75%) in radial MRI. Pearson correlation demonstrated the Dunn view was most accurate for the superior-anterior aspect (.772, P<.001). The cross-table lateral views were best suited for the anterior-superior aspect (.511, P<.05). The sensitivity for cam deformity in the Dunn view was 96.4% vs. 70.6% in the cross-table lateral view. CONCLUSION: The 45° Dunn view can improve the first line of impingement diagnostics. Radial MRI however remains indispensable for pre-operative planning and the evaluation of symptomatic cases without obvious deformity.

Highly efficient green fluorescent protein-based kinase substrates.

We have developed a general strategy for designing efficient protein substrates of protein kinases by attaching a phosphorylatable peptide sequence to the C-terminus of His6-tagged green fluorescent protein (GFP). We found that several C-terminal attachment sites in GFP allow for correct presentation of the phosphorylatable tail to a variety of protein kinases. Using this strategy, we have constructed highly efficient GFP-based substrates for Src, c-Abl, protein kinase A, and protein kinase C betaII protein kinases. The engineered GFP substrate for Src (GFP235IYGEFG) is 300 times more efficient than the protein most commonly used as a Src substrate-rabbit muscle enolase.