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The acquisition of rotation angle and pose information of precision spherical joint is of great importance for error motion prediction analysis and motion control. In the early stage, an analytical measurement model based on the equivalent magnetic charge method has been purposed to realize the rotation direction identification and rotation angle measurement. However, several shortcomings were observed such as complicated calculations and time-consuming, and the solution accuracy of the theoretical model was decreasing with the expansion of measurement range. To improve this situation, new modeling methods based on artificial neural network have been researched. This paper employs radial basis function (RBF), extreme learning machine (ELM), and RBF–ELM hybrid neural networks to construct measurement models, then analyzes and compares their effectiveness to obtain the optimal algorithm. Analysis results show that the RBF–ELM hybrid neural network has a better calculation accuracy than the others. Finally, the experimental data are used to train and test the network model, and the error between output angle of the model and the actual measured rotation angle is calculated. The comparison results show that the measurement model based on the RBF–ELM hybrid neural network has a higher calculation accuracy and generalization capability. Within the range of ±20°, the maximum error of rotation angle around the X and Y axes are $9'~48''$ and $6'~55''$ , respectively, and the root mean squared error is $1' 59''$. [ABSTRACT FROM AUTHOR]

Human amniotic epithelial cells (hAECs) have recently been recognized as a potential source of stem cells. The present study was designed to investigate the effects of mechanical stretch on the osteogenic differentiation of hAECs. As it has been previously reported that the physical environment is an important factor in maintaining the phenotype and functionality of differentiated cells, mechanical stretch was use to mimic the mechanical environment in the present study, with the following parameters: 5% elongation of the hAECs at a frequency of 0.5 Hz, with evaluation at 2, 6, 12 and 24 h time points. The osteogenic differentiation process of the hAECs followed by mechanical stimulation was evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting and immunocytochemistry. Additionally, in a parallel study, a runt-related transcription factor 2 (Runx2)/core binding factor α 1 (Cbfa1)-specific short hairpin RNA (shRNA) plasmid vector and a scrambled shRNA control plasmid was constructed for transfection into the hAECs prior to mechanical stimulation. The cultured hAECs exhibited a cobblestone-shaped epithelial-like phenotype and were positive for stage-specific embryonic antigen-4, cytokeratin-19, cluster of differentiation 44 and octamer-binding protein 4, as detected by flow cytometry, western blotting or confocal microscopy. The qPCR and western blotting data demonstrated that the mRNA and protein expression levels of Runx2/Cbfa1, alkaline phosphatase and osteocalcin were upregulated compared with the control group following stretching and they peaked at 12 h. These results indicated that the osteogenic differentiation of the hAECs was induced by mechanical stimuli. Additionally, the mRNA and protein expression levels of β-catenin and cyclin D were increased significantly following stretching; however, they were decreased following Runx2/Cbfa1-shRNA transfection as observed by RT-qPCR and western blotting. These results suggested that the Wnt/β-catenin pathway may have an important role in mechanical stretch-induced osteogenic differentiation of the hAECs. Furthermore, the combination of stretch and osteogenic induction medium had synergistic effects on the osteogenic differentiation. The results of the present study demonstrated that mechanical stimuli have an important role in osteogenic differentiation of hAECs via the Wnt/β-catenin signalling pathway, which may be a potential therapeutic strategy in bone regenerative medicine. [ABSTRACT FROM AUTHOR]

A centralized forecasting method is difficult to accurately follow load variation and weather diversity throughout the region in a bulk power system that covers a large geographical area. A distributed load forecasting method based on local weather information is proposed in this paper. First, the bulk power system is partitioned into some subnets based on local weather information. Second, separate forecasting models are established for subnets. These models are selected from load forecasting model base, which includes neural network, autoregressive integrated moving average model, autoregressive and moving average, gray model, and so on. Cosine distance is used to evaluate the similarity between vectors of influencing factors, so that representative samples can be selected from large data sets as training set for local load forecasting models. Finally, a system load forecasting model is developed to aggregate local load forecasts. Case study shows the advantages of the proposed method in a bulk power system. [ABSTRACT FROM PUBLISHER]

The objective of this study was to determine whether the modified Stoppa approach or the ilioinguinal approach is better for the treatment of acetabular fractures by comparing the results of those 2 approaches. A randomized trial was undertaken of 60 consecutive patients with acetabular fractures treated with either the modified Stoppa or the ilioinguinal approach. In addition to the patients' demographics, the assessed preopera-tive parameters included fracture pattern, associated injuries, time to surgery, and Injury Severity Score; intraoperative parameters included blood loss and operative time for each procedure; and postoperative parameters included wound drainage, blood transfusion, perioperative complications, early operative complications, late operative complications, quality of reduction, radiological results, and clinical outcomes. The study showed no significant differences in all measured preoperative variables between the 2 groups (all P>.05). In addition, no significant differences were found in the intraoperative complication rate, early operative complication rate, late operative complication rate, quality of reduction, radiological results, and clinical outcomes (all P>.05). However, compared with the ilioinguinal approach, the modified Stoppa approach reduced intraoperative blood loss -- and in doing so decreased wound drainage and the need for blood transfusion -- and shortened operative time (all P<.05). The authors recommend using the modified Stoppa approach rather than the classical ilioinguinal approach to treat acetabular fractures when anterior exposure of the acetabulum is required. [ABSTRACT FROM AUTHOR]

Heart failure often develops after acute myocardial infarction because the injured myocardial tissue fails to recover or regenerate. Stem cell transplantation using adult cell sources, such as adipose-derived stromal vascular fraction (SVF), draws extensive attention. In this study, SVF cells were isolated from rat adipose tissue and cultivated on enzyme-crosslinked gelatin hydrogels. Morphological features of cell development and spontaneous beating behavior from these cells were observed and recorded. Cardiac phenotypes were characterized via immunofluorescence staining, and the expression of cardiac-specific genes was measured via RT-PCR. The functional assessment of SVF-derived cardiomyocyte-like cells (SVF-CMs) was performed by detecting cellular calcium transient activities and pharmacological responses. Results showed that most SVF-CMs exhibited elongated myotubule shapes and expressed cardiac troponin I strongly. SVF-CMs expressed cardiac-specific RNA (including transcription factors GATA binding protein 4) and myocyte enhancer factor 2c, as well as the structural proteins, namely, sarcomere actinin alpha 2, cardiac troponin I type 3, cardiac troponin T type 2, and cardiac gap junction protein alpha 1. Their beating mode, calcium activities, and pharmacological responses were similar to those of native CMs. Spontaneously beating SVF-CMs can be derived from adipose tissue-derived SVFs, and enzyme-crosslinked gelatin hydrogel promoted the cardiac differentiation of SVF cells. [ABSTRACT FROM AUTHOR]

Neuroinflammation plays an important role in the recovery of brain injury in ICH. Macrophage is the major executor in the neuroinflammation and initiates neurological defects. Programmed death 1 (PD-1) delivers inhibitory signals that regulate the balance between T cell activation, tolerance, and immunopathology. PD-1 expression by macrophages plays a pathologic role in the innate inflammatory response. However, the exact role of PD-1 on inflammatory responses following ICH has not been well identified. In this experiment, PD-1 KO (PD-1 −/-) ICH mice and Wild-type (WT) ICH mice were caused by intracranial injection of type IV collagenase. The level of macrophage activation, inflammatory cytokines and fibrinogen-like protein 2 (Fgl-2) were detected using immunofluorescence staining and ELISA assays. In addition, brain edema and neurological scores of ICH mice were also measured. Our data demonstrated that ICH promoted PD-1 expression of macrophage and enhanced inflammatory cytokines and Fgl-2 concentrations. PD-1 −/- mice exhibited significantly higher expression of the inflammatory cytokines which initiate Fgl-2, than did their wild-type (WT) littermates. As a result, macrophage activation, cerebral edema and neurological deficit scores of PD-1 −/- mice were higher. In conclusion, our data demonstrate that PD-1 plays a vital role in brain inflammation via regulation of Fgl-2 after ICH, and that manipulation of PD-1 might be a promising therapeutical target in ICH. [ABSTRACT FROM AUTHOR]

The aim is to assess the association between computed tomography (CT) findings and clinical outcomes in posterior tibial plateau fractures (TPF). This is a retrospective analysis of the records of 23 patients with posterior TPF treated at our institution between 2004 and 2011. Two indices of residual articular displacement of posterior TPF (gap and step-off) were measured from CT images, and clinical outcomes were assessed using the Short Musculoskeletal Function Assessment (SMFA) questionnaire. Spearman's rank correlation coefficient analysis was used to evaluate the correlations between the postoperative posterior TPF radiological findings and the clinical outcomes. Both the intraobserver and the interobserver correlation coefficients were high (0.90 and 0.92, respectively), indicating excellent agreement between the reviewers for the assessment of residual displacement via CT scans. Additionally, residual articular step displacement showed a strongly negative correlation with clinical outcomes ( R  = 0.700, p  = 0.036), whereas the residual gap displacement did not ( R  = 0.400, p  = 0.505). More importantly, the medial posterior step displacement was significantly correlated with the clinical outcomes ( p  = 0.040), whereas the lateral posterior step displacement was not ( p  = 0.618). Based on the data of this study, the higher the step-off deformity of the medial posterior tibial plateau, the worse the SMFA. More attention should be paid to this factor when treating medial posterior TPF., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Objective: To evaluate the biomechanical effect of a nickel-titanium (Ni-Ti) three-dimensional memory alloy mesh in treating a canine tibial plateau collapse fracture model and to lay a foundation for further experiments in vivo ., Methods: Sixteen tibial plateau specimens of 8 adult Beagle dogs were harvested. Twelve specimens were taken to prepare canine tibial plateau collapse fracture models (Schatzker type Ⅲ) and randomly divided into groups A, B, and C, with 4 specimens in each group. Four normal tibia specimens were used as blank control group (group D). In groups A and B, the bone defects were repaired with Ni-Ti three-dimensional shape memory alloy mesh combined with autologous bone and simple autologous bone respectively, and fixed with the lateral plate and screw. In group C, the bone defect was directly fixed with the lateral plate and screw. By using a biomechanical tester, a progressive load (0-1 700 N) was loaded vertically above the femoral condyle. The maximum failure load was recorded and the stiffness was calculated according to the load-displacement curve., Results: The maximum failure loads in groups A, B, C, and D were (1 624.72±7.02), (1 506.57±3.37), (1 102.00±1.83), and (1 767.64±24.56) N, respectively; and the stiffnesses were (129.72±20.83), (96.54±27.05), (74.96±17.70), and (169.01±35.62) N/mm, respectively. The maximum failure load and stiffness in group A were significantly higher than those in groups B and C, but which were significantly lower than those in group D ( P <0.05)., Conclusion: Ni-Ti three-dimensional memory alloy mesh combined with autologous bone can repair the Schatzker type Ⅲ tibial plateau collapse fracture, which has better biomechanical properties than simple autologous bone grafting.

This comparative study aims to identify a biocompatible and effective crosslinker for preparing gelatin sponges. Glutaraldehyde (GTA), genipin (GP), 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDC), and microbial transglutaminase (mTG) were used as crosslinking agents. The physical properties of the prepared samples were characterized, and material degradation was studied in vitro with various proteases and in vivo through subcutaneous implantation of the sponges in rats. Adipose-derived stromal stem cells (ADSCs) were cultured and inoculated onto the scaffolds to compare the cellular biocompatibility of the sponges. Cellular seeding efficiency and digestion time of the sponges were also evaluated. Cellular viability and proliferation in scaffolds were analyzed by fluorescence staining and MTT assay. All the samples exhibited high porosity, good swelling ratio, and hydrolysis properties; however, material strength, hydrolysis, and enzymolytic properties varied among the samples. GTA-sponge and GP-sponge possessed high compressive moduli, and EDC-sponge exhibited fast degradation performance. GTA and GP sponge implants exerted strong in vivo rejections, and the former showed poor cell growth. mTG-sponge exhibited the optimal comprehensive performance, with good porosity, compressive modulus, anti-degradation ability, and good biocompatibility. Hence, mTG-sponge can be used as a scaffold material for tissue engineering applications.

Microbial transglutaminase (mTG) was used as a crosslinking agent in the preparation of gelatin sponges. The physical properties of the materials were evaluated by measuring their material porosity, water absorption, and elastic modulus. The stability of the sponges were assessed via hydrolysis and enzymolysis. To study the material degradation in vivo , subcutaneous implantations of sponges were performed on rats for 1-3 months, and the implanted sponges were analyzed. To evaluate the cell compatibility of the mTG crosslinked gelatin sponges (mTG sponges), adipose-derived stromal stem cells were cultured and inoculated into the scaffold. Cell proliferation and viability were measured using alamarBlue assay and LIVE/DEAD fluorescence staining, respectively. Cell adhesion on the sponges was observed by scanning electron microscopy (SEM). Results show that mTG sponges have uniform pore size, high porosity and water absorption, and good mechanical properties. In subcutaneous implantation, the material was partially degraded in the first month and completely absorbed in the third month. Cell experiments showed evident cell proliferation and high viability. Results also showed that the cells grew vigorously and adhered tightly to the sponge. In conclusion, mTG sponge has good biocompatibility and can be used in tissue engineering and regenerative medicine., Competing Interests: The authors declare there are no competing interests.

Objective: To investigate the effect of different electrical stimulation waves on orientation and alignment of adipose derived mesenchymal stem cells (ADSCs)., Methods: ADSCs were isolated from 5-week-old Sprague Dawley rats (weight, 100-150 g) and cultivated. The cells at passages 3-5 were inoculated to prepare cell climbing slices, subsequently was exposed to direct-current electrical stimulations (ES) at electric field strengths of 1, 2, 3, 4, 5, and 6 V/cm on a homemade electric field bioreactor (groups A1, A2, A3, A4, A5, and A6); at electric field strength of 6 V/cm, at 50% duty cycle, and at frequency of 1 and 2 Hz (groups B1 and B2) of square wave ES; at electric field strength of 6 V/cm, at pulse width of 2 ms, and at frequency of 1 and 2 Hz (groups C1 and C2) of biphasic pulse wave ES; and no ES was given as a control (group D). The changes of cellular morphology affected by applied ES were evaluated by time-lapse micropho-tography via inverted microscope. The cell alignment was evaluated via average orientation factor ( OF ). The cytoske-leton of electric field treated ADSCs was characterized by rhodamine-phalloidin staining. The cell survival rates were assessed via cell live/dead staining and intracellular calcium activities were detected by calcium ion fluorescent staining., Results: The response of ADSCs to ES was related to the direct-current electric field intensity. The higher the direct-current electric field intensity was, the more cells aligned perpendicular to the direction of electric field. At each time point, there was no obvious cell alignment in groups B1, B2 and C1, C2. The average OF of groups A5 and A6 were significantly higher than that of group D ( P <0.05), but no significant difference was found between other groups and group D ( P >0.05). The cytoskeleton staining showed that the cells of groups A5 and A6 exhibited a compact fascicular structure of cytoskeleton, and tended to be perpendicular to the direction of the electric field vector. The cellular survival rate of groups A4, A5, and A6 were significantly lower than that of group D ( P <0.05), but no significant difference was found between other groups and group D ( P >0.05). Calcium fluorescence staining showed that the fluorescence intensity of calcium ions in groups A4, A5, and A6 was slightly higher than that in group D, and no significant difference was found between other groups and group D., Conclusion: The direct-current electric field stimulations with physiological electric field strength (5 V/cm and 6 V/cm) can induce the alignment of ADSCs, but no cell alignment is found under conditions of less than 5 V/cm direct-current electric field, square wave, and biphasic pulse wave stimulation. The cellular viability is negatively correlated with the electric field intensity.

MiR-429 functions as a tumor suppressor and has been observed in multiple types of cancer, but the effects and mechanisms of miR-429 in osteosarcoma are poorly understood. This study is performed to evaluate the functions of miR-429 in the progression of osteosarcoma. Firstly, the miR-429 expression in osteosarcoma tissues and osteosarcoma cells was detected using real time PCR, and the relationship between miR-429 expression and overall survival of osteosarcoma was analyzed. Secondly, the effects of miR-429 on the migration, invasion, proliferation and apoptosis of osteosarcoma cells were evaluated using transwell assay, wound-healing assay, CCK-8 assay and flow cytometry, respectively. Proteins related to epithelial-mesenchymal transition (EMT), E-cadherin, Vimentin, N-cadherin and Snail, were also detected using Western blot. Finally, the target gene of miR-429 in osteosarcoma was predicted and verified using dual luciferase assay and the expression correlation between them was analyzed using Pearson's correlation. MiR-429 was down-regulated in osteosarcoma tissues and osteosarcoma cells; the expression level of miR-429 was associated with the prognosis of osteosarcoma. High level of miR-429 in osteosarcoma cells significantly suppressed the migration, invasion and proliferation of cells but induced cells apoptosis. Furthermore, high level of miR-429 in osteosarcoma cells obviously increased the expression of E-cadherin protein but decreased the expression of Vimentin, N-Cadherin and Snail proteins. EMT inducer ZEB1 was the target gene of miR-429 and the expression of ZEB1 was negatively related to the miR-429 expression in osteosarcoma. In conclusion, miR-429 may functions as a tumor suppressor and be down-regulated in osteosarcoma. MiR-429 may suppress the progression and metastasis of osteosarcoma by down-regulating the ZEB1 expression.

Gelatin hydrogel crosslinked by microbial transglutaminase (mTG) exhibits excellent performance in cell adhesion, proliferation, and differentiation. We examined the gelation time and gel strength of gelatin/mTG hydrogels in various proportions to investigate their physical properties and tested their degradation performances in vitro . Cell morphology and viability of adipose tissue-derived stromal cells (ADSCs) cultured on the 2D gel surface or in 3D hydrogel encapsulation were evaluated by immunofluorescence staining. Cell proliferation was tested via Alamar Blue assay. To investigate the hydrogel effect on cell differentiation, the cardiac-specific gene expression levelsof Nkx2.5, Myh6, Gja1, and Mef2c in encapsulated ADSCs with or without cardiac induction medium were detected by real-time RT-PCR. Cell release from the encapsulated status and cell migration in a 3D hydrogel model were assessed in vitro . Results show that the gelatin/mTG hydrogels are not cytotoxic and that their mechanical properties are adjustable. Hydrogel degradation is related to gel concentration and the resident cells. Cell growth morphology and proliferative capability in both 2D and 3D cultures were mainly affected by gel concentration. PCR result shows that hydrogel modulus together with induction medium affects the cardiac differentiation of ADSCs. The cell migration experiment and subcutaneous implantation show that the hydrogels are suitable for cell delivery., Competing Interests: The authors declare there are no competing interests.

Objective: To summarize the progress in treatment of pubic symphysis diastasis., Methods: Related literature concerning treatment of pubic symphysis diastasis was extensively reviewed and comprehensively analyzed in terms of anatomy, biomechanics, and treatment., Results: There are many fixation methods for treatment of pubic symphysis diastasis, which aims at restoring the stability of the anterior pelvic ring. External fixator is often used as a temporary fixation; tension band wire has been abandoned due to its poor biomechanical stability; screw loosening and plate breakage often appears when a single reconstruction plate is used; box plate significantly increases the biomechanical stability of anterior pelvic ring but it leads to a considerable surgical trauma; locking plate has been used for pubic symphysis diastasis recently, especially for osteoporotic fractures; percutaneous cannulated screw has the advantages of less trauma, less bleeding, and good stability, so it is good choice for treatment of pubic symphysis diastasis., Conclusion: There is no uniform standards about the treatment of pubic symphysis diastasis, but the minimally invasive treatment is an undeniable trend. Percutaneous cannulated screw has achieved satisfactory effectiveness, however, its biomechanical stability and anatomic channels need to be further studied.

Objective: To design the channels of parallel screws and cross screws for fixation of symphysis pubis diastasis through a small sample anatomic study on pubic symphysis and its neighbor structures so as to provide anatomical basis for minimally invasive fixation of symphysis pubis diastasis., Methods: Eight cadaveric pelvic specimens (6 men and 2 women) were transected along L5 and the proximal 1/3 of bilateral thighs, with intact lumbar spines. The spermatic cord, womb round ligament, and corona mortis were dissected; the distance to the i psilateral pubic tubercle was measured and subsequently the distance between pubic tubercles, the height of pubic symphysis, the diameter of outer edge of pubic tubercle, the thickness of pubic symphysis and 2 cm outside the pubic symphysis (upper, central, and lower 1/3 thickness of pubic symphysis) were measured to provide anatomical basis for the design of channels of parallel screws and cross screws., Results: Parallel screw fixation: the entry point of first screw was on the outer edge of pubic tubercle, and its exit point was on the outer edge of contralateral pubic tubercle; a cannulated screw with a diameter of 4.5 mm or 6.5 mm can be suitable for this channel. The entry point of second screw was 20 mm outside the pubic symphysis and 23 mm beneath the pubic symphysis, and its exit point was symmetrical with entry point; a cannulated screw with a diameter of 4.5 mm can be appropriate for the second channel. The direction of two screws was perpendicular to the pubic symphysis. Cross screw fixation: the entry point of cross screws was on one side of the pubic tubercle, and its exit point was 20 mm outside the contralateral pubic symphysis and 23 mm beneath the contralateral pubic symphysis; two cannulated screws with a diameter of 4.5 mm can be chosen for cross screws channels. The direction of two cross screws was intersected with the horizontal line of two pubic tubercles at an angle of 25 degrees respectively; besides, two cross screws formed an anteversion angle and retroversion angle of 5-10 degrees with pubic body plane, respectively., Conclusion: The channels of parallel screws and cross screws are feasible for fixation of symphysis pubis diastasis by analyzing the anatomical data of the pubic symphysis and its neighbor structures, but further biomechanical research is need to confirm the stability of two fixation methods.

Objective: To investigate the relationships between residual displacement of weight-bearing and non weight-bearing zones (gap displacement and step displacement) and hip function by analyzing the CT images after reconstruction of acetabular fractures., Methods: The CT measures and clinical outcome were retrospectively analyzed from 48 patients with displaced acetabular fracture between June 2004 and June 2009. All patients were treated by open reduction and internal fixation, and were followed up 24 to 72 months (mean, 36 months); all fractures healed after operation. The residual displacement involved the weight-bearing zone in 30 cases (weight-bearing group), and involved the non weight-bearing zone in 18 cases (non weight-bearing group). The clinical outcomes were evaluated by Merle d'Aubigné-Postel criteria, and the reduction of articular surface by CT images, including the maximums of two indexes (gap displacement and step displacement). All the data were analyzed in accordance with the Spearman rank correlation coefficient analysis., Results: There was strong negative correlation between the hip function and the residual displacement values in weight-bearing group (r(s) = -0.722, P = 0.001). But there was no correlation between the hip function and the residual displacement values in non weight-bearing group (r(s) = 0.481, P = 0.059). The results of clinical follow-up were similar to the correlation analysis results. In weight-bearing group, the hip function had strong negative correlation with step displacement (r(s) = 0.825, P = 0.002), but it had no correlation with gap displacement (r(s) = 0.577, P = 0.134)., Conclusion: In patients with acetabular fracture, the hip function has correlation not only with the extent of the residual displacement but also with the location of the residual displacement, so the residual displacement of weight-bearing zone is a key factor to affect the hip function. In patients with residual displacement in weight-bearing zone, the bigger the step displacement is, the worse the hip function is.

Objective: To observe the effectiveness of posterior approaches for the treatment of posterior coronal fractures of tibial plateau, and to analyze the fracture morphology, radiographic features, and the recognition of Schatzker classification., Methods: Between June 2003 and June 2009, 23 patients with posterior coronal fractures of tibial plateau were treated surgically by posterior approaches. There were 15 males and 8 females with an average age of 38 years (range, 32-56 years). All patients had closed fractures. Fracture was caused by traffic accident in 15 cases, by sports in 3 cases, and by falling from height in 5 cases. According to Moore classification, there were 10 cases of type I, 9 cases of type II, and 4 cases of type IV. The X-ray films, CT scanning, and three-dimensional reconstruction were performed. The time from injury to operation was 3-14 days (mean, 6 days)., Results: After operation, 17 cases had anatomical reduction and 6 had normal reduction. Incisions healed by first intention. All cases were followed up 12 to 36 months (mean, 24 months). The average fracture healing time was 7.6 months (range, 6-9 months). No related complication occurred, such as nerve and vessel injuries, failure in internal fixation, ankylosis, traumatic osteoarthritis, and malunion. According to Rasmussen's criteria for the function of the knee, the results were excellent in 14 cases, good in 7 cases, and fair in 2 cases with an excellent and good rate of 91.3%., Conclusion: Posterior coronal fracture of tibial plateau is rare, which has distinctive morphological features, and Schatzker classification can not contain it totally. The advantages of posterior approach include reduction of articular surface under visualization, firm fixation, less complications, and earlier functional exercise, so it is an ideal surgical treatment plan.