ABSTRACT
Objective:To establish a model of patellar dislocation by femoral osteotomy or surgical release of medial retinaculum in immature rabbits, and observe morphological and trabecular microarchitectural changes in the trochlea.Methods:Forty rabbits at 3 months of age were included. All right knees underwent surgery, 20 knees were treated with femoral osteotomy and internal rotation of distal femur to increase femoral anteversion angle (Osteotomy group, OS group), and another 20 knees were treated with surgical release of medial retinaculum and overlap suture of lateral retinaculum (Soft tissue group, ST group). All left knees were acting as internal controls. Micro-CT scans for distal femur were acquired after 4 months post surgery. the height of Medial, central, and lateral trochlear, sulcus angle, and lateral and medial trochlear slope were measured to describe the trochlear morphology, and bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp), and bone mineral density (BMD) were calculated to evaluate the microarchitectural structure. All parameters were compared between groups.Results:In OS group, one rabbit sustained a hip dislocation without patellar dislocation. Three knees developed complete patellar dislocation in daily flexion position, and the remaining 16 patellae were dislocated when the knee was placed in the maximal extension position. In ST group, 15 knees were complete patellar dislocation in daily flexion position, and 5 knees were without dislocation. A local boss was formed proximal to the entrance of the groove and the articular cartilage was smooth, and no obvious osteoarthritis was observed in OS group. In ST group no boss was formed, while obvious cartilage degeneration and defect was seen. Compared to the control group, the central trochlear height and sulcus angle were greater in both groups, but without significant difference between the two groups. The Tb.Th was increased in both medial and lateral condyle, and Tb.N was decreased in medial condyle compared with its control knees in OS group. The BV/TV, Tb.Th, Tb.N and BMD were decreased and Tb.Sp was increased in both medial and lateral condyle compared with its control knees in ST group. Compared to the OS group, the BV/TV, Tb.Th, Tb.N and BMD were smaller and Tb.Sp was greater in both medial and lateral condyle in ST group, with significant differences.Conclusion:The model of patellar dislocation could be successfully achieved by femoral rotational osteotomy to increase femoral anteversion or surgical release of medial retinaculum and overlap suture of lateral retinaculum, and subsequent morphological and trabecular microarchitectural changes in the trochlea are different. Different bony and soft tissue factors should be addressed for different patients with patellar dislocation in clinical practice.
ABSTRACT
Objective To develop a method for rapid and accurate detection and identification of bacterial pathogens directly from body fluid specimens and to evaluate its application in clinical laboratory.Methods Bacteria DNA was extracted from 205 body fluid specimens with column-based kit,and the high variable V1 and V3 regions of bacterial 16S rRNA gene were amplified with broad-range primers.Amplicons were analyzed by pyrosequencing and the generated sequences were searched in the bacterial identification database.Traditional culture-biochemical method was also used for these specimens and the results were taken as the golden standard.SPSS 11.0 was used to calculate the sensitivity,specificity,false positive/negative rate,positive/negative predictive value and positive/negative likelihood rate of pyrosequencing method.Results The positive rate of bacteria culture was 39.5％ (81/205),among which 71 were infected with single bacterium,and 10 were infected with two species of bacteria.Compared with the culture identification results,pyrosequencing had a 100.0％ (71/71) concordance when applied to detect and identify bacterial pathogens from specimens with single specie bacterium infected.To specimens with two species bacteria infected,7 out of 10 specimens were in concordance with the culture identification results.Besides,pyrosequencing detected 10 positive specimens and identified bacterial pathogens infected in the 124 culture-negative specimens.Taken bacteria culture as the standard method,the sensitivity of pyrosequencing for identifying bacterial pathogen in body fluid was 100.0％,and with a specificity of 91.9％,the false positive rate was 8.1％,the false negative rate was 0.0％,the positive predictive value was 89.0％,the negative predictive value was 100.0％,and the positive and the negative likelihood rate were 12.4 and 0,respectively.Conclusion Pyrosequencing can be used to detect and identify bacterial pathogens directly from body fluid specimens with the advantages of rapidity,high sensitivity,high accuracy and high throughput.