Calculation of pediatric femoral fracture rotation from direct roentgenograms.

BACKGROUND: Radiologic determination of pediatric femoral fracture rotation has been debated. Measuring the antetorsion angle of the fractured femur by computed tomography and comparing it with the opposite side has been the method of choice for this purpose. However, no simple method for direct measurement of femoral fracture rotation exists in the literature. In this study, our aim was to test a mathematical method of measuring the axial plane malrotation from direct roentgenograms. MATERIALS AND METHODS: A pediatric femoral shaft fracture model was produced. The bone was secured to a wooden frame that allowed the distal part of the fracture to rotate around an axis. Radiographs were taken at known intervals of rotation ranging from the neutral position to 60° external rotation and to 60° internal rotation in 5° increments of rotation. Five independent, blinded observers measured the radiographs and calculated the fracture rotation according to a standard formula. Calculated rotation values were compared with known rotation values. RESULTS: Calculated rotation values were close to actual rotation values throughout the arc of rotation. The mean absolute error of five observers for all measurements of external and internal rotation was 3.97° (±0.83). The correlation coefficient between calculated and actual rotation values was 0.9927. The interobserver intraclass correlation coefficient for calculated rotation was 0.997. CONCLUSIONS: Absolute error and correlation coefficient values indicate that this method is accurate and reliable in determining the fracture rotation.

Risk factors for osteoporosis after renal transplantation and effect of vitamin D receptor Bsm I polymorphism.

OBJECTIVE: Rapid loss of vertebral or hip mineral density after renal transplantation is a major complication which occurs within 6-12 months. The aim of this study was to evaluate risk factors contributing to bone disease in the early stage after renal transplantation and the effect of vitamin D receptor (VDR) gene polymorphisms. METHODS: We prospectively followed for up to 12 months 44 patients (29 men and 15 women) with end-stage renal disease who underwent kidney transplantation. All patients received prednisone with either cyclosporine (CsA)/mycophenolate mofetil (MMF) or tacrolimus (Tac)/MMF therapy. Spine, hip, and whole body bone mineral density (BMD) was measured at 12 months after transplantation. According to World Health Organization recommendations, our patients were categorized as normal, osteopenic, or osteoporotic BMD levels. VDR alleles were genotyped as BB, Bb, or bb by polymerase chain reactions based on polymorphism at the Bsm I restriction site. RESULTS: Forty-six percent of patients were normal, 43% osteopenic, and 11% osteoporotic. Significant risk factors for osteoporosis among renal transplant recipients were younger age and pretransplant high intact parathyroid hormone (iPTH) levels. (P values .045 and .027, respectively). According to polymorphic group categorization, posttransplant serum Ca was significantly higher in patients with BB or Bb genotype than in those with bb genotype (P = .012). Although there was no statistical significance regarding iPTH levels, it was higher among Bb+BB than the bb genotype group. Also, first-year BMD analysis after transplantation according to Bsm I polymorphism showed significant differences in femur BMD levels according to the dual classification of polymorphism (P < .05). The BMD levels in the bb group was higher than in the Bb+BB group. CONCLUSIONS: Although high pretransplant iPTH levels and younger age enhanced posttransplant bone loss, functionally different alleles of the VDR gene may modulate bone turnover during the first year after renal transplantation.