Focusing on OB-OC-MΦ Axis and miR-23a to Explore the Pathogenesis and Treatment Strategy of Osteoporosis.

Osteoporosis is a bone metabolic disorder characterized by decreased bone density and deteriorated microstructure, which increases the risk of fractures. The imbalance between bone formation and bone resorption results in the occurrence and progression of osteoporosis. Osteoblast-mediated bone formation, osteoclast-mediated bone resorption and macrophage-regulated inflammatory response play a central role in the process of bone remodeling, which together maintain the balance of the osteoblast-osteoclast-macrophage (OB-OC-MΦ) axis under physiological conditions. Bone formation and bone resorption disorders caused by the imbalance of OB-OC-MΦ axis contribute to osteoporosis. Many microRNAs are involved in the regulation of OB-OC-MΦ axis homeostasis, with microRNA-23a (miR-23a) being particularly crucial. MiR-23a is highly expressed in the pathological process of osteoporosis, which eventually leads to the occurrence and further progression of osteoporosis by inhibiting osteogenesis, promoting bone resorption and inflammatory polarization of macrophages. This review focuses on the role and mechanism of miR-23a in regulating the OB-OC-MΦ axis to provide new clinical strategies for the prevention and treatment of osteoporosis.

Targeting regulation of stem cell exosomes: Exploring novel strategies for aseptic loosening of joint prosthesis.

Periprosthetic osteolysis is a major long-term complication of total joint replacement. A series of biological reactions caused by the interaction of wear particles at the prosthesis bone interface and surrounding bone tissue cells after artificial joint replacement are vital reasons for aseptic loosening. Disorder of bone metabolism and aseptic inflammation induced by wear particles are involved in the occurrence and development of aseptic loosening of the prosthesis. Promoting osteogenesis and angiogenesis and mediating osteoclasts and inflammation may be beneficial in preventing the aseptic loosening of the prosthesis. Current research about the prevention and treatment of aseptic loosening of the prosthesis focuses on drug, gene, and stem cell therapy and has not yet achieved satisfactory clinical efficacy or has not been used in clinical practice. Exosomes are a kind of typical extracellular vehicle. In recent years, stem cell exosomes (Exos) have been widely used to regulate bone metabolism, block inflammation, and have broad application prospects in tissue repair and cell therapy.

SIX3 function in cancer: progression and comprehensive analysis.

The homeobox gene family encodes transcription factors that are essential for cell growth, proliferation, and differentiation, and its dysfunction is linked to tumor initiation and progression. Sine oculis homeobox (SIX) belongs to the homeobox gene family, with SIX3 being a core member. Recent studies indicate that SXI3 functions as a cancer suppressor or promoter, which is mainly dependent on SIX3's influence on the signal pathways that promote or inhibit cancer in cells. The low expression of SIX3 in most malignant tumors was confirmed by detailed studies, which could promote the cell cycle, proliferation, migration, and angiogenesis. The recovery or upregulation of SIX3 expression to suppress cancer is closely related to the direct or indirect inhibition of the Wnt pathway. However, in some malignancies, such as esophageal cancer and gastric cancer, SIX3 is a tumor-promoting factor, and repressing SIX3 improves patients' prognosis. This review introduces the research progress of SIX3 in tumors and gives a comprehensive analysis, intending to explain why SIX3 plays different roles in different cancers and provide new cancer therapy strategies.

Conservative management of avascular necrosis of the metacarpal head: A case report and brief review.

RATIONALE: Avascular necrosis (AVN) of the metacarpal head is rare, and there is no clear consensus on treatment. The main aim of this study was to discuss the possible pathologic-mechanics of its development, epidemiology, radiographic features, and outcome after conservative treatment. PATIENT CONCERNS: A 14-year-old male with a history of fractures in little finger complained of right-hand pain with a limited range of motion for 1 month. Diagnosis: Imaging examination confirmed the diagnosis of AVN in the long metacarpal finger and ring finger. INTERVENTIONS: The patient was treated using non-surgical management, such as splint immobilization, non-steroidal anti-inflammatory drugs, and physiotherapy. OUTCOMES: At the last follow-up 26 months later, the patient was in complete remission with no residual symptoms. Magnetic resonance imaging (MRI) confirmed excellent remodeling and regeneration in the metacarpal head. LESSONS: Metacarpal head necrosis typically occurs in adolescent patients with a history of trauma. Conservative treatment may sometimes have an excellent prognosis.

LncRNA DANCR and miR-320a suppressed osteogenic differentiation in osteoporosis by directly inhibiting the Wnt/ß-catenin signaling pathway.

Our study aimed to determine how lncRNA DANCR, miR-320a, and CTNNB1 interact with each other and regulate osteogenic differentiation in osteoporosis. qRT-PCR and western blotting were performed to determine the expression of DANCR, miR-320a, CTNNB1, and the osteoporosis- or Wnt/ß-catenin pathway-related markers T-cell factor 1 (TCF-1), runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). Interactions between CTNNB1, DANCR, and miR-320a were predicted by bioinformatics approaches and validated using a luciferase assay. Osteoblastic phenotypes were evaluated by ALP staining, ALP activity assay and Alizarin Red staining. The bilateral ovariectomy method was used to establish an in vivo osteoporosis model. Bone morphological changes were examined using hematoxylin and eosin (H&E) and Alcian Blue staining. The expression levels of DANCR and miR-320a in BMSCs derived from osteoporosis patients were upregulated, whereas CTNNB1 expression was downregulated compared with that in healthy controls. Importantly, we demonstrated that miR-320a and DANCR acted independently from each other and both inhibited CTNNB1 expression, whereas the inhibitory effect was additive when miR-320a and DANCR were cooverexpressed. Moreover, we found that DANCR overexpression largely abrogated the effect of the miR-320a inhibitor on CTNNB1 expression and the Wnt/ß-catenin signaling pathway in BMSCs during osteogenic differentiation. We further confirmed the results above in BMSCs derived from an osteoporosis animal model. Taken together, our findings revealed that DANCR and miR-320a regulated the Wnt/ß-catenin signaling pathway during osteogenic differentiation in osteoporosis through CTNNB1 inhibition. Our results highlight the potential value of DANCR and miR-320a as promising therapeutic targets for osteoporosis treatment.

Pseudogene PTENP1 sponges miR-214 to regulate the expression of PTEN to modulate osteoclast differentiation and attenuate osteoporosis.

BACKGROUND AIMS: Osteoporosis (OP) is a common bone metabolic disease with a high incidence. Our study aimed to explore the pseudogene PTENP1/miR-214/PTEN axis to modulate the osteoclast differentiation in osteoporosis. METHODS: Patients with osteoporosis were recruited in our study, and RANKL-induced osteoclast differentiation and ovariectomy-induced osteoporosis mouse model were established in vitro and in vivo, respectively. RESULTS: Pseudogene PTENP1 and PTEN were significantly down-regulated and miR-214 was up-regulated in osteoporosis patients. In addition, overexpression of PTENP1 or silence of miR-214 inhibited the expression levels of osteoclast specific markers and osteoclast differentiation induced by RANKL. Overexpression of PTENP1 or silence of miR-214 also inhibited the levels of phosphorylation of PI3K and AKT, p65 nuclear translocation, IκBα degradation and the expression level of NFATc1. AlsoSilence of PTENP1 or overexpression of miR-214 induced the osteoclast differentiation under normal physiological condition. Pseudogene PTENP1 sponged miR-214 to regulate the expression of PTEN. CONCLUSIONS: In an ovariectomy-induced osteoporosis mouse model, obvious pathological changes in bone tissues were found, and bone marrow mononuclear cells in this group were more likely to differentiate into osteoclasts. Therefore, pseudogene PTENP1 sponged miR-214 to regulate the expression of PTEN to inhibit osteoclast differentiation and attenuate osteoporosis by suppressing the PI3K/AKT/NF-κB signaling pathway.

A Comparative Study of Patients' Subjective Feelings Toward Total Hip Arthroplasty with Patient-Specific Instruments and Traditional Total Hip Arthroplasty.

OBJECTIVE: To determine whether differences exist in patients' subjective feelings, daily life, and surgical satisfaction between those who underwent surgery for developmental dysplasia of the hip (DDH) using patient-specific instruments (PSIs) and those who underwent traditional surgical total hip arthroplasty (THA). METHODS: We selected 30 adult patients with various types of DDH who underwent surgery during 2016-2017 at our hospital. The patients were divided into PSI surgery group and the traditional surgery group. All patients underwent follow-up, and we collected data on the Harris Hip Score, Oxford University Hip Score (OHS), Forgotten Joint Score (FJS-12), Visual Analogue Scale (VAS) score, patient satisfaction score, intraoperative surgical time, amount of bleeding and postoperative complications incidence for both groups. We then performed statistical analyses on the data. RESULTS: The Harris Hip Score, OHS, VAS score, patient satisfaction score, and mean bleeding volume did not differ statistically significantly (t-tests, P > 0.05). No statistically significant differences were found between surgical groups in the incidence of complication and sub-trochanteric osteotomy, or in the surgical side (chi-square tests, P > 0.05). For the experimental group, the FJS-12 score was 80.0 ± 12.0, and for the control group the score was 68.5 ± 16.1. The operative time of the experimental group was 138.4 ± 32.2 min, while that of the control group was 88.9 ± 26.8 min. The values of these data differed significantly (t-tests, P < 0.05). CONCLUSIONS: The novel PSI designed by our group has certain advantages for the short-term subjective feelings of patients after THA, but it may cause prolonged operative times.

Mixed Reality Combined with Three-Dimensional Printing Technology in Total Hip Arthroplasty: An Updated Review with a Preliminary Case Presentation.

Three-dimensional (3D) printing technology, virtual reality, and augmented reality technology have been used to help surgeons to complete complex total hip arthroplasty, while their respective shortcomings limit their further application. With the development of technology, mixed reality (MR) technology has been applied to improve the success rate of complicated hip arthroplasty because of its unique advantages. We presented a case of a 59-year-old man with an intertrochanteric fracture in the left femur, who had received a prior left hip fusion. After admission to our hospital, a left total hip arthroplasty was performed on the patient using a combination of MR technology and 3D printing technology. Before surgery, 3D reconstruction of a certain bony landmark exposed in the surgical area was first performed. Then a veneer part was designed according to the bony landmark and connected to a reference registration landmark outside the body through a connecting rod. After that, the series of parts were made into a holistic reference registration instrument using 3D printing technology, and the patient's data for bone and surrounding tissue, along with digital 3D information of the reference registration instrument, were imported into the head-mounted display (HMD). During the operation, the disinfected reference registration instrument was installed on the selected bony landmark, and then the automatic real-time registration was realized by HMD through recognizing the registration landmark on the reference registration instrument, whereby the patient's virtual bone and other anatomical structures were quickly and accurately superimposed on the real body of the patient. To the best of our knowledge, this is the first report to use MR combined with 3D printing technology in total hip arthroplasty.

LncRNA KCNQ1OT1 promoted BMP2 expression to regulate osteogenic differentiation by sponging miRNA-214.

BACKGROUND: Osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is of much significance for bone formation, the imbalance of it would result in osteoporosis and other pathological bone defects. Increasing evidences showed that long non-coding RNAs (lncRNAs) and miRNAs played vital roles in the regulation of osteogenic differentiation. LncRNA KCNQ1OT1 was often regarded as an imprinted lncRNA and was related to tumor progression, while its function in osteogenic differentiation remained unclear. METHOD: qRT-PCR was performed to detect the expression of KCNQ1OT1, miR-214 and osteogenesis-related genes BMP2, Runx2, OPN, and OCN. Western blotting was carried out to detect osteogenesis-related markers. The osteoblastic phenotype was evidenced by alkaline phosphatase (ALP) activity and Alizarin Red S accumulation detection. Bioinformatics and luciferase assays were used to predict and validate the interaction between KCNQ1OT1 and miR-214 as well as BMP2 and miR-214. RESULTS: KCNQ1OT1 was significantly up-regulated during the process of osteogenic induction while miR-214 was contrarily down-regulated. Knockdown of KCNQ1OT1 inhibited osteogenic differentiation and down-regulated BMP2 and osteogenesis-related genes. It was also confirmed that KCNQ1OT1 directly interacted with miR-214. Meanwhile, miR-214 could bind to 3'UTR of BMP2 and therefore inhibited its expression. Furthermore, co-transfection of miR-214 inhibitor could rescue the down-regulation of BMP2 and osteogenesis-related genes and osteogenic differentiation suppression induced by KCNQ1OT1 knockdown. Moreover, miR-214 inhibitor significantly reversed the decreased protein levels of p-Smad1/5/8, Runx2 and Osterix induced by shKCNQ1OT1. CONCLUSIONS: KCNQ1OT1 positively regulated osteogenic differentiation of BMSCs by acting as a ceRNA to regulate BMP2 expression through sponging miR-214.

Bone Defects in Revision Total Knee Arthroplasty and Management.

This article reviews the recent updates in revision of total knee arthroplasty (RTKA). We reviewed the recent articles on RTKA in databases including PubMed, Google Scholar, and SCOPUS. Total knee arthroplasty (TKA) involves the replacement of all three compartments of the knee in surgery of the knee joint to restore capacity and function. TKA is one of the most common and reliable surgical treatment options for the treatment of knee diseases. However, some patients require revision of TKA (RTKA) after primary TKA for various reasons, including mechanical wear, implant loosening or breakage, malalignment, infection, instability, periprosthetic fracture, and persistent stiffness. Unfortunately, the overall outcome of RTKA is not as satisfactory as for primary TKA due to the uncertainty regarding the actual success rate and the risk factors for failure. Cementation, modular metal augmentation, bone grafting, autologous bone grafting, allogenic bone grafting, impactation bone grafting, structural bone allografting, metaphyseal fixation, using porous titanium coated press fit metaphyseal sleeves and porous tantalum structural cones, and megaprostheses or customized prostheses are the currently available management options for RTKA. However, most of the management systems possess specific complications. Novel approaches should be developed to improve functional capacity, implant survival rates, and quality of life in a cost-efficient manner.

Protection Effect of Curcumin for Macrophage-Involved Polyethylene Wear Particle-Induced Inflammatory Osteolysis by Increasing the Cholesterol Efflux.

BACKGROUND Periprosthetic osteolysis, induced by wear particles and inflammation, is a common reason for failure of primary arthroplasty. Curcumin, a nature phenol from plants, has been reported to reduce the inflammation in macrophages. This study aimed to investigate the potential effect of curcumin on macrophage involved, wear particle-induced osteolysis and its mechanism. MATERIAL AND METHODS RAW264.7 macrophages were used to test the effects of polyethylene (PE) particles and curcumin on macrophage cholesterol efflux and phenotypic changes. A mouse model of PE particle-induced calvarial osteolysis was established to test the effects of curcumin in vivo. After 14 days of treatment, the bone quality of the affected areas was analyzed by micro-computed tomography (micro-CT) and histology, and the bone surrounding soft tissues were analyzed at the cellular and molecular levels. RESULTS We found that PE particles can stimulate osteoclastogenesis and produce an M1-like phenotype in macrophages in vitro. Curcumin enhanced the cholesterol efflux in macrophages, and maintained the M0-like phenotype under the influence of PE particles in vitro. Additionally, the cholesterol transmembrane regulators ABCA1, ABCG1, and CAV1 were enhanced by curcumin in vivo. We also found enhanced bone density, reduced osteoclastogenesis, and fewer inflammatory responses in the curcumin treated groups in our mouse osteolysis model. CONCLUSIONS Our study findings indicated that curcumin can inhibit macrophage involved osteolysis and inflammation via promoting cholesterol efflux. Maintaining the cholesterol efflux might be a potential strategy to prevent periprosthetic osteolysis after total joint arthroplasty surgery.

[Value of detecting bacterial 16S and 23S rRNA in interface membrane in diagnosis of periprosthetic joint infection].

OBJECTIVE: To explore the value of detecting bacterial 16S rRNA with 23S rRNA in the diagnosis of periprosthetic joint infection (PJI). METHODS: A prospective study was conducted among 67 patients with previous total hip arthroplasty (THA) undergoing a reoperation for infection (23 patients) or aseptic loosening (44 patients). Bacterial 16S rRNA and 23S rRNA in the interface membrane were detected by real-time PCR and their value in diagnosis of PJI was assessed. RESULTS: The 16S rRNA and 23S rRNA showed no significant difference in their power in the diagnosis of PJI. The detection of 16S rRNA/23S rRNA showed a higher sensitivity and a greater negative predictive value in PJI diagnosis than the detection of 16S rRNA+23S rRNA (95.7% vs 52.2%, P<0.01; 97.6% vs 79.6%, P=0.01). The specificity, positive predictive value, and accuracy of the 4 diagnostic strategies were not significantly different. CONCLUSIONS: The diagnostic power of 16S rRNA and 23S rRNA was similar in detecting PJI. Compared with the diagnostic strategy with 16S rRNA+23S rRNA, 16S rRNA/23S rRNA is more sensitive in detecting PJI.

[Effect of comprehensive care for chronic filariasis patients with lymphedema].

OBJECTIVE: To evaluate the effect of chronic filariasis patients with lymphedema after comprehensive cared. METHODS: A total of 386 chronic filariasis patients with lymphedema received the comprehensive care including soaking feet by TCM, washing feet by single Chinese medicine or clear water, preventing and eliminating invasive wound, physical training, raising the limb, and wearing suitable shoes. The attack frequency of inflammation of lymphatic vessels, the stage of lymphedema disease, and leg circumference were observed before and after the care. RESULTS: After the comprehensive care, the attack rates of inflammation of lymphatic vessels decreased from 9.65% to 4.67%, and there was a significant difference (χ2 =7.34, P=0.0067). The proportion of the patients with high stage of lymphedema disease decreased significantly (all P <0.01), and the average leg circumference decreased of 1.06 cm. The skin appearance improved significantly. Other signs, such as pitting edema, ulcer, and skin folds also improved significantly (all P <0.01). CONCLUSION: The comprehensive care for chronic filariasis patients with lymphedema has a remarkable effect and is worthy of further application.

[Epidemic trend of malaria in Suzhou City, Jiangsu Province, China from 2007 to 2012].

OBJECTIVE: To understand the epidemic trend of malaria in Suzhou City, Jiangsu Province, so as to provide the evidence for developing the strategies of malaria elimination. METHODS: The malaria information was collected from 2007 to 2012 through the reporting system of Suzhou epidemic information network and parasitic network system, and the results were analyzed statistically. RESULTS: From 2007 to 2012, there were 318 malaria cases reported. Among them, 28 cases (8.81%) were local residents with vivax malaria, and the annual incidence rate was 0.07/10(5). Among the floating population, there were 290 malaria cases (91.19%) and the annual incidence rate was 0.77/10(5), including 233 vivax malaria cases, 20 falciparum malaria cases, 1 ovale malaria case, and 1 mixed infection case. The malaria incidence rate of local residents dropped year by year in the past 6 years while that of floating populations increased. During the period of the later 3 years, no local malaria case was found. CONCLUSION: The malaria has been eliminated among the local residents while the malaria cases from floating populations increased. Therefore, we should strengthen the cross-regional joint malaria control and prevention, and the malaria management of entry-exit persons.

[Seasonal variation of blood pressure and related factors in Chinese adults: a survey of over 50 000 people in Suzhou, China].

OBJECTIVE: Seasonal variation in blood pressure had been observed in several studies on Western populations, but uncertainty remains about the strength of the relationship in other populations and the extent to which it was modified by other factors. METHODS: This study was based on cross-sectional data from the China Kadoorie Biobank study with 53 260 men and women from the Suzhou area involved. Linear regression model was used to analyze the association of blood pressure with outdoor temperature-overall and in various subgroups. RESULTS: Blood pressure varied with the seasons, ascending in winter and descending in summer. The difference in systolic blood pressure (SBP) between summer and winter was 8.8 mm Hg in men and 7.0 mm Hg in women. SBP was inversely correlated with outdoor temperature, especially above 10°C, with every 10°C colder temperature causing 6.1 mm Hg increase of SBP. The seasonal variation in SBP was more obviously seen in older people and in those with lower body mass index. CONCLUSION: Blood pressure was strongly and inversely associated with outdoor temperature in the population in Suzhou area. Seasonal variation of blood pressure should be considered when the hypertension screening programs, clinical management and data management on hypertensive patients.

[Survey of Toxoplasma gondii infection among pregnant women in Jiangsu Province, China].

OBJECTIVE: To understand the situation of Toxoplasma gondii infection among pregnant women in Jiangsu Province. METHODS: The pregnant women from 7 cities in Jiangsu Province were involved in this survey and the information was recorded according to the request of unified admission information of the case questionnaire of toxoplasmosis in Jiangsu Province. The specific antibodies IgM and IgG to Toxoplasma gondii in sera of these pregnant women were tested by ELISA. RESULTS: The specific antibody IgM to Toxoplasma gondii of all the respondents was negative. The positive rate of IgG was 3.98% (43/1 081), which was little different from the control group's 2.27% (4/176), and every city shared a similar positive rate. The positive rate of IgG of early pregnant women was 3.78%, which was also not obviously different from the 4.17% appearing in mid and late pregnant women. The respondents who previously had pathological abortions did not show positive IgG. Only 1.84% (8/435) of pregnant women had had the examinations related to Toxoplasma gondii before this survey. CONCLUSIONS: The rate of Toxoplasma gondii infection is low among pregnant women in Jiangsu Province. The situations in different areas are not far from each other. We should enhance the peri-conception tests of Toxoplasma gondii and take prevention and treatment countermeasures based on corresponding objects, and also further strengthen the healthy education.

[Relationship between behavior of weekly alcohol drinking and the prevalence of hypertension in adults of Suzhou city].

OBJECTIVE: To explore the relationship between weekly alcohol drinking behavior and the prevalence of hypertension. METHODS: Data was collected in a Kadoorie study of chronic disease in Wuzhong district, Suzhou city of Jiangsu province, China. Data from the baseline survey was used to describe the status of alcohol drinking and the prevalence of hypertension among local residents. Relationships between the frequency of alcohol drinking, consumption of alcohol, age when initiating weekly drinking behavior, drinking-related adverse conditions and the prevalence of hypertension, were studied by logistic regression. RESULTS: The rates on weekly alcohol drinking in the studied population were 40.7% in men and 0.6% in women. The amount of weekly average alcohol intake showed as 250.8 g in males and 47.2 g in females, with statistical significance seen between genders (P < 0.01). The prevalence rates of hypertension among male and female were 39.7% and 36.1% respectively, with significant difference (P < 0.01). Data from Multiple logistic regression analysis showed that when the frequency of alcohol drinking > or = 3 days per week or the weekly average alcohol intake > or = 100 grams, the risk would be higher to develop hypertension than in those non-drinkers (P < 0.01). The age of initiating behavior as weekly alcohol drinking younger than 20 years old or the dinking-related adverse condition appeared to be more than two kinds. The risks of developing hypertension were 1.50 times and 3.27 times than those non-drinkers in men but not in women. CONCLUSION: The frequency of drinking alcohol and the amount of alcohol intake per week was different between males and females. Along with the following factors as: increase of frequency on alcohol drinking per week, the amount of alcohol intake also increased. The advance of age related to the initiation of weekly drinking and the increase of alcohol-related adverse condition was also seen, the risk of hypertension showed an upward trend in males but not in females.

Could nonunion tissue be transformed capable of bone formation by negative pressure: a new alternative to treat bone nonunion?

Despite substantial advances in orthopaedic surgery, bone nonunion is still a matter of debate for orthopaedic surgeon to provide optimal options on treatment of nonunion. Negative pressure therapy has already been successfully used in dealing with complex kinds of soft tissue healing. Some studies show that negative pressure can induce mesenchymal stem cells to differentiate into osteoblasts and others suggest that there are some mesenchymal-like cells existing in the nonunion tissue which can be re-activated and transformed into osteoblasts under some circumstance. We hypothesized that under negative pressure the mesenchymal-like cells can be transformed into osteoblasts in nonunion site. Under negative pressure, both "seeds" and "soils" can be made for new bone formation. If our hypothesis is proved to be corrected, it could be an innovative method to treat the bone nonunion.

[Development of static three dimensional screw-plate system and the biomechanic features thereof, a comparative study].

OBJECTIVE: To develop a new internal fixation device and the matching tools for subtrochanteric fracture, investigate the biomechanical features thereof, and compare its effects with those of other instruments. METHODS: A new internal fixation device, static three dimensional screw-plate system: (STDSP) was developed based on the anatomical parameters and the biomechanical characteristics of proximal femur and combined with the biomechanical advantages of the model of three-dimensional plate and multiple-screws plate fixation. Sixteen paired cadaveric adult femurs were randomly divided into 2 equal groups: fracture healing group undergoing insertion of implant and then taking out thereof with a nail left, and fracture group with a trapezoid defect to mimic subtrochanteric fracture 4 of which were fixed with dynamic hip screw (DHS) and STDSP or Gamma nail and STDSP. All the specimens underwent A-P position four point bending test, axial compression test, torsion test, and destroyable test. RESULTS: (1) In the fracture group, A-P position four point bending test showed that the stretch displacement of STDSP group was (0.221 +/- 0.089) mm, significantly smaller than that of the Gamma nails group [(0.506 +/- 0.086) mm, t = 38.278 P = 0.000]; Axial compression test showed that the inferior displacement of the STDSP group was (2.804 +/- 0.585) mm, significantly larger than that of the Gamma nail group [(1.874 +/- 0.549) mm, t = -5.454, P = 0.012]; Torsion test showed that the torque values at 50 and 100 of the STDSP group were (3.78 +/- 0.84) J and (2.3 +/- 1.08) J, both significantly larger than those of the Gamma nail groups [(2.3 +/- 1.08) J and (4.35 +/- 1.81) J, t = -4.729 P = 0.018, and t = -3.227 P = 0.048] and those of the DHS group [(7.3 +/- 1.273) J and (4.325 +/- 0.88) J respectively, t = -3.242 P = 0.048]; and torsion destroyable test showed that the torque values at 200 of the STDSP group was (21.88 +/- 2.51) J, significantly larger than those of the Gamma nail and DHS groups, [(14.36 +/- 5.01) J and (15.475 +/- 1.924) J and (12.075 +/- 1.179) J, t = -3.323 P = 0.048, t = - 3.732 P = 0.034]. (2) In the fracture healing specimens, A-P position four point bending test showed that the radial degree displacement of the STDSP group was (1. 050 +/- 0.316) mm, significantly smaller than that of the DHS group [(1.261 +/- 0.364) mm, t = 3.4 P = 0.042]. CONCLUSIONS: More capable of resisting bending than DHS and less capable of resisting axial compression, STDSP is an excellent internal fixator with good biomechanical feature in treating subtrochanteric femoral fracture.