Radiographic trabecular 2D and 3D parameters of proximal femoral bone cores correlate with each other and with yield stress.

UNLABELLED: Radiographic images of bone cores taken from cadaver proximal femora provided two-dimensional parameters of projected trabecular patterns that correlated highly with conceptually equivalent three-dimensional parameters in the same cores. Measurements also highly correlated with yield stress, suggesting that both parameters have similar biomechanical qualities. INTRODUCTION: We compared morphometric measurements of trabecular patterns in two-dimensional (2D) projection radiographic images of cores from cadaver proximal femoral bones with conceptually equivalent measurements from three-dimensional microcomputed tomography (3D microCT) images. METHODS: Seven cadaver proximal femora provided 47 excised cores from seven regions. Digitized radiographs of those cores were processed with software that extracts trabecular patterns. Measurements of their distribution, geometry, and connectivity were compared with 3D parameters of similar definition derived from microCT of those cores. The relationship between 2D and 3D measurements and yield stress was also examined. RESULTS: 2D measurements strongly correlated with conceptually equivalent measurements obtained using 3D microCT. In all cases, the correlation coefficients were high, ranging from r = 0.84 (p < 0.001) to r = 0.93 (p < 0.001). The correlation coefficients between 2D and 3D measurements and yield stress of the cores were also high (r = 0.60 and 0.82, p < 0.001, respectively). CONCLUSIONS: These findings provide correlative and biomechanical evidence supporting the qualitative similarity of 2D microstructural parameters extracted from plain proximal femoral core X-ray images to conceptually equivalent 3D microstructural measurements of those same cores.

Pneumothorax in the newborn. Changing pattern.

The clinical course of pneumothorax and its allied conditions was studied in 34 newborn infants who presented over a 2 1/2-year period. We found an overall incidence of 3/1000 live births. 11 term infants without obvious pulmonary pathology presented early (9 within minutes of birth); 6 of these had aspirated meconium or blood. The remaining 23 were preterm infants with hyaline membrane disease (HMD) and accounted for 68% of the infants in this series. In contrast, they presented late (mean 45 hours) and 16 were on continuous distending pressure (CDP) or intermittent positive pressure ventilation (IPPV) at the onset of pneumothorax. 15% of all infants with HMD who required CDP/IPPV developed pneumothorax; this increased incidence was most evident in infants who received CDP only. All except 2 of the 11 term infants in the first group were managed conservatively and all survived. Wehn pneumothorax occurred as a complication of HMD in preterm infants, 14 of the 16 infants required intrapleural drainage. Persistence or recurrence of pneumothorax occurred in 9 infants, 7 of whom were receiving CDP/IPPV at the time. Lung expansion was affected only after replacement with a patent chest drain through the same incision or insertion of a second drain on the same side of the chest. All 5 deaths occurred in the group of preterm infants with HMD. 3 resulted directly form respiratory failure due to severe HMD complicated by pneumothorax. We emphasize the increasing importance of pneumothorax as a complication of HMD in preterm infants, particularly in those receiving CDP. Successful management depends on prompt diagnosis and treatment of pneumothorax, which may occur as unexplained sudden deterioration at any time during the course of illness in this group of high risk infants.