Finite element analysis of new headless compression supporting screw for the treatment of unstable femoral neck fracture.

BACKGROUND: Femoral neck fracture is an unsolved challenge in orthopedics. The complication rate in particular is high. There remains a lack of consensus on the optimal choice of internal fixation for unstable femoral neck fracture. OBJECTIVE: The study aimed to develop a new headless compression supporting screw (HCSS) for the treatment of unstable foemoral neck fracture. METHODS: We designed a new HCSS and used a femoral neck fracture (Pauwels III fracture) model (left, fourth-generation composite, Sawbones) and three-dimensional finite element analysis to compare the biomechanical performance of HCSSs with that of cannulated compression screws (CCSs) for treatment of unstable femoral neck fracture. RESULTS: Maximum displacement, peak von Mises stress, peak strain, and rotation for the HCSS were smaller than those for the CCS. The stress was more widely distributed for the HCSS, whereas the stress was concentrated for the CCS. CONCLUSIONS: The HCSS resulted in better biomechanical stability than that from the CCS. For Pauwels III fractures the HCSS exhibits better resistance to shear forces and better support, providing a new clinical treatment.

A special healing pattern in stable metaphyseal fractures.

BACKGROUND AND PURPOSE: Metaphyseal fractures heal in a rapid fashion that is different from the bone shaft healing process. Animal studies have focused on diaphyseal fractures. We investigated the metaphyseal fracture-healing process in rabbits. ANIMALS AND METHODS: 60 rabbits (divided into 12 groups) underwent proximal tibial osteotomy, anatomical reduction, and fixation with screws. After surgery, the proximal tibiae were harvested at different time points for histology. RESULTS: No obvious osteonecrosis or bone resorption were found 2 weeks after surgery. From day 5 to week 5, woven bone or new trabeculae formed. From week 2, remodeling into lamellar bone started and reached a peak at week 6. These 3 stages overlapped. Histomorphometry showed that the structure changed as a unimodal curve. INTERPRETATION: The healing process of metaphyseal fractures appears to differ from the commonly studied healing process in diaphyseal fractures. It is rapid, and can be divided into 4 histological stages: cellular activation and differentiation, formation of woven bone, transformation of woven bone into lamellar bone, and further remodeling.

Serum microRNA-195 is down-regulated in breast cancer: a potential marker for the diagnosis of breast cancer.

MicroRNA-195 (miR-195) is a tumor suppressor that plays an important role in tumorigenesis. There are few studies on miR-195 expression in breast cancer patients and the results have been inconsistent; therefore, this study examined miR-195 expression in the serum of BC patients. Samples from 102 normal subjects and 210 subjects with BC who had detailed clinical follow-up information available were selected. An internal reference (miR-16) and serum miR-195 were amplified and quantitatively detected by SYBR green-based real-time RT-PCR. We analyzed the differences in miR-195 levels between BC and healthy cases and the relationships between the miR-195 level and TNM stage and other clinicopathological parameters. In addition, changes in miR-195 levels were examined for 21 BC cases using paired samples before and after neoadjuvant chemotherapy. miR-195 was downregulated in BC compared with control samples (P = 0.000, Mann-Whitney U test). The sensitivity and specificity of miR-195 in the diagnosis of BC were 69.0 and 89.2 %, respectively; whereas, the sensitivities of carcinoembryonic antigen (CEA) and carbohydrate antigen 153 (CA153) were only 15.08 and 21.1 %, respectively. Remarkably, serum miR-195 had higher sensitivity, 73.97 % (108/146), as a tumor marker in the diagnosis of early stage BC [ductal carcinoma in situ, tumor-node-metastasis (TNM) I, II] compared with the conventional tumor markers CA153 and CEA (12.41 and 7.59 %). Moreover, compared with CEA and CA153, miR-195 had a higher sensitivity for detecting the response to neoadjuvant chemotherapy and significantly increased, more than twofold, after neoadjuvant chemotherapy (P = 0.025, paired t test) in 52.381 % (11/21) of BC cases. However, there were no significant relationships between miR-195 expression and other clinicopathological parameters (TNM stage/pathotype/ER/PR/lymph node status). Our data indicate serum miR-195 is a promising tumor marker for BC diagnosis and general screening, especially for early stage BC. The high sensitivity of miR-195 to neoadjuvant chemotherapy may lay the foundation for future studies on the use of miRNA-based methods for monitoring BC treatment and therapy.

A new experimental model to study healing process of metaphyseal fracture.

BACKGROUND: There are few researches for the healing of metaphyseal fractures; moreover, the animal models to study the metaphyseal fractures are usually made by the oscillating saw osteotomy without reliable fixation, which is not in accordance with our current clinical practice. In this study, we established a new model to observe the healing process of metaphyseal fractures. METHODS: Eighteen New Zealand rabbits were used in the study. The fracture model was created by splitting the medial tibial plateau in rabbits, then reset, and fixed with compression screws. At 1, 2, 3, 4, 6, and 8 weeks postoperatively, the tibial specimens were collected; firstly, a general observation and an X-ray examination of the specimens was done, and then they were embedded in methylmethacrylate and cut into sections with hard tissue slicer. The sections were stained with Giemsa reagent and examined under light microscopy. RESULTS: There was no fracture displacement in the tibial specimens of all time points, except for one showing a collapse. No external callus formation could be observed by X-ray and general examination. After 1 week of the operation, the fracture gap was filled by mesenchymal tissue; 2 weeks postoperatively, a large number of woven bones were formed; from the third week onwards, the woven bone began to turn into lamellar bone, and new trabecular structure began to form. In all of the slices, no obvious chondrocytes formed in fracture areas; thus, there was no endochondral ossification. CONCLUSIONS: This model was an ideal fracture animal model and suitable for the study of metaphyseal fracture healing. The X-ray and histological images demonstrated that metaphyseal fracture healing was a process of direct bone healing through intramembranous bone formation under the conditions of minor trauma, good reduction, and firm fixation.