Objective To establish a three-dimensional finite element model of knee joint in patients with mild knee osteoarthritis in the absence of CT and MRI with thin layer thickness,and to analyze the stress distributions of the tibial plateau.Methods A female patient with mild knee osteoarthritis was selected as the study object,and received serial CT scan from pelvis to distal tibia of fibula.The obtained files in DICOM format were imported into Mimics software for extracting the bony structures of knee joint through threshold segmentation,and then optimizing the extracted structures with Edit Masks,Cavity Fill and Region Grow.The generated model of bony structures was imported into 3-matic for smoothing and wrapping,and Geomagic Wrap was used for bony structure processing with mesh doctor inspection,surface defect repair and surface fitting.The cartilages,meniscus and ligaments were established by contour extension,and assembled with bony structures in SolidWorks in the way of origin coincidence.After defining material properties and contact relationships,meshing,and setting constraints and loads in ANSYS software,the stress distributions of the tibial plateau when standing with both legs were analyzed.Results A complete knee joint model including bony structure,cartilage and ligament was successfully established.When standing with two legs,the peak value of contact stress was about 1.21 MPa,and the maximum stress was 0.72 MPa at the medial middle of tibial plateau and lateral tibial plateau.The 62.7%and 37.3%of the total load were borne by the inner and outer compartments.Conclusion The model of the total knee joint is established with CT extraction and software rendering,and the finite element analysis results meet clinical expectations,indicating that the model established by the proposed method is reliable and can be used for follow-up research.

Objective:To explore any effect of transcranial direct current stimulation (tDCS) on neurons, behavior, cerebral blood flow (CBF), vascular regeneration, and the expression of vascular endothelial growth factor (VEGF) and CD34 protein in rats modeling cerebral infarction.Methods:Thirty-two adult male Sprague-Dawley rats were randomly divided into a sham surgery group (Sham group), a model group (modeled with middle cerebral artery occlusion, MCAO group), an anode transcranial direct current stimulation group (A-tDCS group), and a cathode transcranial direct current stimulation group (C-tDCS group), each of 8. MCAO models were established in the rats of the MCAO, A-tDCS and C-tDCS groups using thread fixation. Twenty-four hours after successful modeling, both the Sham and MCAO groups were connected with electrodes without current stimulation, while the A-tDCS and C-tDCS groups were given 20 minutes of 200μA anodic or cathodic electrical stimulation daily, 5 days a week for 12 days. Before and 24 hours after the modeling, and then after the 12 days of treatment, the four groups received Longa neurobehavioral scoring. Moreover, three days after the modeling as well as after the 12 days of treatment, changes in CBF were observed using MRI. Any blood vessel regeneration was observed using immunofluorescence methods, and the expression of VEGF and CD34 proteins were detected using western blotting.Results:The rats in the MCAO, A-tDCS and C-tDCS groups exhibited various degrees of neurological deficit after the modeling. After the 12 days of treatment the average neurobehavioral scores of the A-tDCS and C-tDCS groups were significantly lower than that of the MCAO group, with the A-tDCS group′s average significantly lower than that of the C-tDCS group. Three days after the modeling, 3D-arterial spin labeling scanning showed a significant decrease in CBF around the ischemic lesion in the MCAO, A-tDCS and C-tDCS groups, but that had increased to varying degrees after 12 days of treatment. The changes in the A-tDCS and C-tDCS groups were significantly larger than in the MCAO group on average, with the former group improving significantly more than the latter. After the 12 days of treatment, new vascularization and the expression of VEGF and CD34 proteins were significantly higher in the A-tDCS and C-tDCS groups than in the MCAO group, with the change in the former group again significantly greater than in the latter.Conclusions:tDCS can relieve the symptoms of neurological deficits in rats with cerebral infarction, promote vascular regeneration, CBF, and expression of VEGF and CD34 proteins. Anodic is superior to cathodic stimulation.

Objective:To investigate the relationship between the CT images of a lateral condylar tibial plateau fractures and complete medial collateral ligament (MCL) injury.Methods:Data of 59 patients with lateral condylar fracture of tibial plateau complicated with MCL injury admitted to Tianjin Hospital from January 2020 to November 2021 were collected, including 32 males and 27 females, aged 42.4±12.3 years (range, 19-65 years), there were 26 cases of extension injury and 33 cases of flexion injury. The patients were separated into two groups: those with partial MCL injury and those with total rupture based on preoperative MR examination and intraoperative valgus stress test following fracture fixation. According to the ABC fracture classification of lateral condyle tibial plateau proposed by Sun et al., the fracture locations were determined on CT images, and the lateral plateau collapse depth (LPD) was measured. The relationship between LPD and MCL complete rupture was analyzed by receiver operating characteristic (ROC) curve.Results:Among 59 patients with lateral condylar tibial plateau fracture and MCL injury, 42 had partial injuries and 17 had complete ruptures. According to the ABC fracture classification, there were 26 cases of extension injury (involving area A), 21 cases of AB type, and 5 cases of ABC type; and 33 cases of flexion type injury, 19 cases of B type, 12 cases of BC type, and 2 cases of C type. All the 17 cases of MCL complete fracture occurred in extension injury, including type AB (14 cases) and type ABC (3 cases). The difference between the mean LPDs of the MCL full rupture group and the partial injury group was not statistically significant ( t=0.11, P=0.567), and the mean LPDs of both groups were 11.7±5.3 mm (range, 4.3-28.1 mm) and 11.5±4.8 mm (range, 3.8-23.6 mm), respectively. The area under the curve (AUC) of the ROC curve analysis was 0.504, and there was no statistical correlation between lateral platform collapse depth and MCL injury. Among the 26 patients with extensional injury area, MCL was completely ruptures in 17 cases and partially injury in 9 cases, LPD was 11.7±5.3 mm (range, 4.3-28.1 mm) and 6.6±1.8 mm (range, 3.8-9.4 mm), respectively, and the difference was statistically significant ( t=3.57, P=0.009). The best predictive cut-off value of LPD was 7.25 mm, the sensitivity was 88.2%, the specificity was 77.8%, and the AUC was 0.868. Conclusion:When the lateral condyle fracture of the tibial plateau is located in the extensional injury area (involving the A area in the ABC fracture classification) and the LPD measured on the CT image is greater than 7.25 mm, the complete rupture of the MCL should be considered. Clinical MCL repair is required after the fracture fixation surgery for improved surgical outcomes.

Objective:The aim of this study was to explore the associations of muscle size and density with handgrip strength(HGS)and the Timed Up and Go(TUG)test.Methods:Totally 301 participants living in the Xinjiekou community near Beijing Jishuitan Hospital were recruited for CT imaging of the hip and a 1-cm slice of the mid-thigh.The cross-sectional area and density of the gluteus maximus and the mid-thigh muscles were estimated by the Osirix viewer based on CT images.HGS and TUG were also performed in these subjects.Logistic regression analysis was used to evaluate the correlations of muscle density and size with TUG and grip strength.Results:In women, after adjustment for age and BMI, the density of the gluteus maximus was negatively correlated with TUG( P trend=0.0366), while the size of the gluteus maximus and the mid-thigh muscles was not correlated with TUG.In men, the density or size of these muscles was not correlated with TUG.After adjustment for age and BMI, the density of the gluteus maximus was positively correlated with grip strength( P trend=0.0334)and the size of the mid-thigh muscles was also positively correlated with grip strength( P trend=0.0155)in men, but they were not correlated with grip strength in women. Conclusions:There were sex differences in the relationship between muscle size or density and grip strength or timed up and go.The density of the gluteus maximus is associated with muscle strength and physical performance while the size of the mid-thigh muscles is correlated with muscle strength.

Objective:To analyze the risk factors of deep venous thrombosis (DVT) in patients with tibial plateau fracture during preoperative period.Methods:From July 2017 to October 2019, a total of 264 patients undergoing surgeries of tibial plateau fractures were enrolled. Duplex ultrasonography (DUS) during hospitalization was used to screen for DVT of the bilateral lower extremities. Patients were divided into DVT group and non-DVT group according to results of DUS. Data on demographics, comorbidities, injury-related data, fracture type, laboratory biomarkers were collected and compared between groups with and without DVT.Results:The incidence of preoperative DVT was 39.0% (103/264) among 264 patients with traumatic tibial plateau fractures, and distal thrombosis predominated in DVT group. There were 103 cases in DVT group. 55 were males and 48 were females. The average age was 54.00±11.12. According to the Schatzker classification of tibial plateau fractures, 7 cases belonged to type I, 37 to type II, 2 to type III, 11 to type IV, 29 to type V, and 17 to type VI. There were 161 cases in non-DVT group. 89 were males and 72 were females. The average age was 48.57±13.25. According to the Schatzker classification of tibial plateau fractures, 23 cases belonged to type I, 76 to type II, 2 to type III, 10 to type IV, 33 to type V, and 17 to type VI. Univariate analysis showed that age ( t=3.451, P=0.001), the type of tibial plateau fracture ( χ2=8.314, P=0.004), D-dimer ( χ2=18.552, P<0.001), APTT ( t=2.869, P=0.004), ALB ( t=2.292, P=0.023) and Hb ( t=1.983, P=0.048) were statistically different than those in non-DVT group. Multivariate analysis showed age ( OR=1.033, 95% CI: 1.009, 1.058; P=0.007), the type of tibial plateau fracture ( OR=1.829, 95% CI: 1.014, 3.299; P=0.045) and D-dimer ( OR=1.914, 95% CI: 1.057, 3.464; P=0.032) were independent risk factors. Conclusion:The incidence of DVT in patients with tibial plateau fractures during preoperative period is high, and distal thrombosis is the main part of venous thrombosis of lower extremity. The type of tibial plateau fracture, age and the level of D-dimer are independent risk factors of preoperative DVT in patients with tibial plateau fractures.

Objective: To investigate the clinical features of patients with hyperextension bicondylar tibial plateau fractures (HEBTPs), and assess surgical effectiveness of HEBTP and non-HEBTP fracture patients. Methods: From June 2014 to May 2017, 82 patients with bicondylar tibial plateau fracture were included in this study. There were 63 patients with 63 knees (76.8%) that had sustained non-HEBTPs, and 19 patients with 19 knees (23.2%) that had HEBTPs, including 49 males and 33 females with a mean age of 48.3 years (range, 22-76). Of the 19 HEBTPs patients, 4 cases were hyperextension valgus injury, 9 cases were hyperextension varus injury, and 6 cases were pure hyperextension injury. All patients were treated with open reduction internal fixation combined with bone grafting or non-bone grafting. All follow-up patients were evaluated clinically and radiographically, included the incidence of associated injuries, infection, posttraumatic osteoarthritis, range of motion (ROM) of knee, numeric rating scale (NRS) for assessment of pain, and Short Musculoskeletal Functional Assessment (SMFA) scores for assessment of knee function. The fracture healing and postoperative alignment were assessed with anteroposterior and lateral X-rays. Results: All patients were followed up for 12-22 months, the mean follow-up time was 15.4 months. Bone union was obtained in all patients, and the bone union time was 12.6 weeks (ranged: 12-16 weeks). At the last follow up, all patients had full range of motion. The incidence of significant associated injuries was 36.8% in the HEVBTP group compared with 15.8% in the non-HEBTP group. The incidence of popliteal artery injury, common peroneal nerve injury and ligament injury that needed repair in 19 HEBTPs patients was 21.1%, 26.3% and 31.6%, respectively, while the corresponding incidence of complications in 63 non-HEBTPs patients was 3.2%, 4.8%, and 9.5%, respectively. The NRS pain score of HEBTPs and non-HEBTPs at 12 months after surgery was 3.89±1.9 and 2.76±1.88, respectively. The value of HEBTPs patients was higher than that of non-HEBTPs patients, But the difference was not statistically significant. The SMFA scores of HEBTPs and non-HEBTPs patients at 12 months after surgery were 27.27±19.44 and 17.09±15.87, respectively. Patients with HEBTP had higher functional (SMFA) scores and a trend of higher pain scores than those with non-HEBTP, indicating associated soft-tissue damage and developed posttraumatic osteoarthritis. Conclusion The present showed that the HEBTP is a unique fracture. These injuries result in worse functional outcomes than non-HEBTP. Physicians must recognize the possible associated injuries (included ligaments, vessels and nerves), and the treatment effect of HEBTP is relatively poor.

Objective To investigate the diagnostic value of digital tomosynthesis in Schatzker classification of tibial plateau fractures.Methods A total of 43 patients with tibial plateau fractures who had underwent injured knee joints coronal tomosynthesis examinations and as well as digital radiography (DR) examinations including anteroposterior and lateral positions before the surgery were selected from January to June 2015.The imaging evaluation was performed by two diagnostic radiologists independently.Each radiologist consecutively performed Schatzker classification of the DR and tomosynthesis images of the knees of each patient.The consistent Schatzker classification results were finally given,while the inconsistent classification results were discussed.Recording the reading results of two methods and comparing the classification results of two methods with the subsequent intra-operative classification results,evaluating their consistency.Results Twenty-eight patients were included with 14 males and 14 females.The age ranged from 25 to 76 years old with an average of 48.5 years.Fifteen patients were excluded due to combined injuries and the low quality of imaging.Schatzker classification of tibial plateau fractures was performed with DR images,19 cases of fracture classification results were consistent with intra-operative classification,and 9 cases were inconsistent.Twenty-six cases of fracture classification results were consistent with intra-operative classification based on tomosynthesis images but 2 cases with inconsistent results.Intra-operative findings for each fracture were used as the gold standard for classification.The accuracy of the Schatzker classification for tibial plateau fractures were 68％ and 93％ in the two imaging techniques with significant difference (x2=5.143,P=0.016),respectively.The classification results of two imaging methods in 2 patients were both inconsistent with intra-operative classification.The fracture severity of 6 patients was underestimated when using DR images for interpretation,while 1 patient had a missed diagnosis of the lateral tibial plateau collapsed fracture.The consistency between the classification results of DR images as well as classification results of tomosynthesis images and intra-operative typing were moderately and highly consistent,respectively (Kappa coefficient were 0.604 and 0.908,respectively).Conclusion Schatzker classification of tibial plateau fractures was performed with DR images,the lateral tibial plateau collapsed fracture and the lateral plateau splitting fracture could be easily missed or misdiagnosed.However,tomosynthesis imaging could provide a higher accuracy.

Objective To assess the clinical value of cross raft screws technique in preventing postoperative collapse of tibial plateau fracture.Methods From September 2014 to November 2017,data of 14 patients with tibial plateau fracture who were treated by cross raft screws technique were retrospectively analyzed.There were 9 males and 5 females aged from 30-65 years old (average,44.4± 1.7 years).There were 8 patients that the thickness of subchondral cancellous bone measured preoperatively by CT data was less than 4 mm,and 6 patients that the thickness of subchondral cancellous bone measured intraoperatively was less than 4 mm.1/4 tubular plate was placed along the anterior rim of lateral tibial plateau,and the 3.5 mm cortical bone screws were fixed as bamboo raft from anterior to posterior through the plate.The collapse of tibial plateau after surgery were measured by CT scan after union of the fracture.The function of knee was evaluated by Rasmussen Anatomical and Functional Grading.Results The time of tubular plate procedure was 18 to 35 min (average,24.1±5.4 min).All 14 patients were successfully followed-up for 13.8±5.1 months.The height of collapse preoperatively by CT scan was 5-21 mm (average,8.00± 1.40 mm).3 days after the operation,the height between articular line and lateral articular surface was 0-2 mm (average,0.80±0.06 mm).Compared with CT data preoperatively,the collapse was corrected postoperatively that was proved by CT scan (P＜ 0.05).After the fracture was healed,according to CT data,the height between articular line and lateral articular surface was 0-2 mm (average,0.70±0.08 mm).Compared with CT data postoperatively,there was no postoperative collapse happened (P=0.466).The position and length of nails were placed appropriately.The average healing time of fracture was 3.6 months.There were no infection,nonunion and pain of tendon happened.The plate could be touched subcutaneously in 2 patients,who had no discomfort feelings.The patient's postoperative Rasmussen Anatomical Grading were 13-18 (average,16.7),including 8 cases excellent and 6 cases good.The postoperative Rasmussen Functional Grading was 18-28 (average,25.7),including 11 cases excellent and 3 cases good.Conclusion The cross raft screws technique is a good way to prevent the postoperative collapse of the lateral articular surface of tibial plateau.

Objective To explore the clinical effect of periarticular knee fractures combined with anterolateral ligament (ALL) avulsion fracture.Methods From June 2014 to November 2015,13 patients with ALL avulsion fracture in periarticular knee fractures were fixed by the star plate,cannulated or screws suture anchor,including 9 male and 3 female with the mean age of 39.5 years (range from 28 to 51 years).6 patients were diagnosed distal femoral fracture,4 tibial plateau fracture,and 3 tibial intercondylar eminence avulsion fracture which all combined with ALL avulsion fracture.Postoperatively,all patients were treated with the adjustable knee brace for 3 months.Results All patients were followed up for 4-20 months,the mean follow-up time was 13.5 months.The average surgical time was 130 min (range from 90 to 210 min).In all 13 patients,ALL was found and identified.Bone union was obtained in all patients,and the bone union time was 11.4 weeks (10-12 weeks).7 cases were fixed with star plate,5 cases were fixed with hollow screw,and 1 case was fixed with anchor.All follow-up patients underwent anteroposterior and lateral X-rays.Pain,swelling and functional recovery of the knee joint were observed.Patients were assessed postoperatively with International Knee Documentation Committee (IKDC) score,Lysholm score,and Tegner activity scale to evaluate the clinical effect.At the last follow-up,all patients had full range of motion of the knee joint which from 0° to approximate 120°.The Lysholm,objective IKDC were 86.5 and 84.6 respectively.Among the 13 patients evaluated,9 patients were graded A,and 4 patients were graded B by subjective IKDC.The Tegner activity scale at the last follow-up was 6.7.Incision of poor healing in 1 case,and got healed after 32 d cleaning dressing.Conclusion This study confirmed the presence of the ALL.The fixation of ALL avulsion fracture in periarticular knee fractures can be an effective procedure at a minimum follow-up of 13.5 months.

BACKGROUND:Tibial plateau fractures involving the posterolateral articular surface present a great challenge due to its complex anatomy.The posterolateral corner complex and the proximity of the common peroneal nerve restrict both the exposure of the joint surface and the ability to distract across the joint using a varus force.OBJECTIVE:To analyze the anatomy,morphology and classifications of the posterolateral fractures of the tibial plateau,and compare different surgical approaches and fixation materials.METHODS:A computer-based research of PubMed and CNKI databases was performed for the relative literatures published from 1990 to 2016 using the keywords of tibial plateau,posterolateral fragment,fixation in English and Chinese,respectively.The anatomy,morphology and typing of posterolateral fractures of the tibial plateau were analyzed and different surgical approaches and fixation materials were compared.RESULTS AND CONCLUSION:Posterolateral fractures of the tibial plateau should be treated in accordance with the intra-articular fracture principle,such as repairing joint surface to normal morphology,restoring the lower limb alignment,and maintaining joint mobility painlessly.Fractures are clarified according to Schatzker,AO,and three-column classification systems,but still need to be improved.To choose a proper surgical approach mainly depends on the fracture pattern.Biomechanics tests suggest that posterolateral locked plate exhibits excellent biomechanics characters,and can avoid the reduction loss caused by the shear force of fracture fragments.