After removal of unilateral molars in the rats,the changes in the articularcartilage and articular disc of the temporomandibular joint and HRP uptake of thelining cells of synovial membrane were observed with light,transmission and scanningmicroscopy.The HRP uptake activity of the lining cells was lowered and degenerative chan-ges were presented in ths articular cartilages following the removal of the molars.It is suggested that the temporomandibular joint is intimately integrated with theocclusion of the upper and lower teeth.Defect of the teeth on one side mayinduce occlusion disorders.These will certainly cause some changes of the structureand function of the temporomandibular joint.

The structure of the articular cartilage and disc of the temporomandibular jointin rats and monkey were studied with light,transmission and scanning electronmicroscopy.The articular cartilage covering the mandibular condyle is semilunar in shapeon cross section.Its thickest portion lies posterosuperiorly.The bony trabeculaesubjacent to the cartilage arrange vertically to the articular surface and concentrateto the thickest portion of the articular cartilage.The articular cartilage covering the mandibular fossa is similar to that on themandibular condyle,but contains fewer cartilage cells.Lacking a calcified areawith enlarged cartilage cells,the articular cartilage here may only be divided intothree areas.The articular disc consists of three areas:an upper,a middle,and a lowerone.The structure and ultrastructure of different parts of these cartilages with theirfunctions have been discussed.

Posttraumatic ankle arthritis caused by trauma, a common articular disease, mainly destroys the biomechanical balance of the ankle joint and results in degeneration of the joint.It often occurs in young people, leading to articular pain and stiffness and other symptoms which may deteriorate to end-stage posttrau-matic ankle arthritis with no intervention.At present, a variety of therapies are available for the disease. However, no domestic literature has addressed the choice and application of its treatment methods.To be useful in clinic, this review deals with the etiology, diagnosis and treatment (including choice, efficacy, indications and contraindications) of the disease.

3D printing is a new printing technology through which a three-dimensional solid structure is manufactured through printing layer by layer.Its manufacturing of a three-dimensional solid object is based on digital model files and results from layer by layer stack accumulation of powdery metal or plastic and other adhesive materials.In this review,we focus on application of 3D printing technology in orthopedic surgery.We talk about mould-making,preoperative planning,surgical protocols,customization of a navigation template and a personalized prosthesis and its application in bone tissue engineering.It improves therapeutic efficacy by making operative treatment more accurate,shortening operative time and providing personalized implants for the patients.This paper also summarizes the current situation of 3D printing in orthopedics and its future profile.

Objective The three-dimensional finite element analysis was done to analyze the mechanical stability of double screw internal fixation for talus neck fracture,the methods with different approaches and different placement methods as well as the optimal biomechanical environment of fracture section were discussed so as to provide reliable mechanical arguments for the selection of clinical internal fixators.Methods The acquired male adult ankle CT data were imported into Mimics for 3D reconstruction of the ankle joint model.After the model was fitted with the surface by Geomagic software,the model was imported into Solidwork software to establish the talus neck fracture model and the corresponding screw.The fixtures were assembled with the anterior-posterior parallel double screw,the anterior-posterior cross-double screw,the posterior-anterior parallel double screw,and the posterioranterior cross-double screw,respectively.The model data were imported to Abaqus 6.14 for analysis and calculation,followed by the meshing pretreatment using software Hypermesh 13.0.The Von Mises stress distribution of the lag screw and displacement of the fracture end were observed under different fixation modes.Results In the displacement and stress cloud diagrams of the fracture ends of the four groups,the displacement peaks of the fractures of the anterior to posterior double-screw parallel and cross-fixed groups were 0.399 3 mm and 0.418 6 mm,and the peak pressures were 7.721 MPa and 8.124 MPa,respectively.The displacement peaks of posterior to anterior double-screw parallel and cross-groups were 0.418 3 mm and 0.418 5 mm,the fracture end peak pressures were 4.848 MPa and 5.692 MPa,respectively.In the screw stress cloud diagram of the four internal fixation modes,the Von Mises stress peaks of the anterior-posterior parallel screw group and cross-screw group were 45.11 MPa and 50.18 MPa,and those of the posterior-anterior parallel screw group and cross-screw group were 30.65 MPa and 37.68 MPa,respectively.Conclusion In the posterior-anterior parallel screw fixation,the fracture end has the lowest stress,and the screw has dispersive stress and the stress peak is the lowest,which is superior to other three groups.Therefore,the posterior-anterior screw is better than anterior-posterior fixation,and the parallel fixation is better than cross fixation.

Objective To evaluate the efficacy and safety of continuous femoral nerve block (CFNB) versus patient controlled analgesia (PCA) for analgesia in primary total knee arthroplasty (TKA) through a Meta-analysis.Methods All randomized controlled trials (RCTs) which compared about the efficacy and safety of CFNB versus PCA for analgesia in primary TKA,were searched from Cochrane Library,Embase,PubMed,CBM,VIP,Wang Fang database and CNKI.At the same time,conference papers were identified manually.A quality assessment of the included literature was evaluated by Cochrane system evaluation manually.Revman 5.3 software was used for the Meta-analysis to compare visual analogue scale (VAS),hospital for special surgery knee score (HSS),western Ontario and McMaster university of orthopedic index (WOMAC),patient satisfactory degree,and incidences of complications (nausea,vomit,dizziness,somnolence,itch of skin,etc).Results Twenty-four RCTs involving 1896 patients were identified including CFNB (946 cases) and PCA (950 cases) application of TKA.The pooled results illustrated that CFNB could reduce VAS in rest (MD =-1.28,95％ CI-1.56,-1.00,P ＜ 0.05) and VAS in movement (MD =-0.98,95％ CI-1.38,-0.58,P ＜ 0.05),increase HSS (MD =2.13,95％ CI 0.12,4.14,P ＜0.05),reduce WOMAC(MD =-0.97,95％ CI-1.83,-0.11,P ＜ 0.05),increase patient satisfactory degree (RR =1.27,95 ％ CI 1.10,1.46,P ＜ 0.05) and at the same time reduce the incidences of nausea,vomit,dizziness,somnolence and itch of skin (RR =0.32,95％CI0.24,0.43,P＜0.05).Conclusion Compared with PCA,CFNB analgesia can reduce VAS,WOMAC score,improve the postoperative HSS and patient satisfaction degree,and decrease the risk of complications.

Objective:To analyze the morphology and distribution characteristics of subchondral bone cysts of the talus by CT three-dimensional reconstruction.Methods:A total of 176 patients diagnosed with subchondral bone cyst of the talus after CT scan of the ankle or foot from 2015 to 2020 were retrieved from the imaging report database of Tianjin Hospital, including 77 males and 99 females, aged 14-84 years［(56.1±14.0)years］. After three-dimensional reconstruction of the talus and cyst area by Mimics 20.0 software, an equal 2×2 grid configuration was constructed to divide the domed articular surface into four regions: anteromedial, anterolateral, posteromedial and posterolateral. For subchondral cyst of the talus, area involved under grid localization, gender, age and side of the onset were recorded. The anteroposterior diameter, transverse diameter, depth, surface area and volume of the subchondral bone cyst of the talus were measured.Results:Subchondral cyst of the talus was anteromedial in 131 patients (74.4%), anterolateral in 5(2.8%), posteromedial in 34(19.3%), and posterolateral in 6(3.4%). Subchondral cyst of the talus occurred in the older aged (≥60 years) for 78 patients (44.3%), in the middle aged (45-59 years) for 62(35.2%), in young adults for 32(18.2%), and in preadolescents for 4(2.3%). The age composition of the subchondral cyst of the talus involving the anteromedial, anterolateral, posteromedial and posterolateral regions was 59(49, 64)years, 44(39, 45)years, 61(54, 68)years and 40(22, 58) years, respectively (all P<0.01). There were no statistically significant differences in gender and side of the onset (all P>0.05). The anteroposterior diameter of the subchondral bone cysts located anteromedially, anterolaterally, posteromedially and posterolaterally was (9.7±4.4)mm, (3.5±1.1)mm, (10.3±4.4)mm and (2.1±0.8)mm, respectively; the transverse diameter was (5.4±1.7)mm, (3.9±1.8)mm, (5.9±2.2)mm and (3.4±1.1)mm, respectively; the depth was (7.1±2.4)mm, (3.2±2.2)mm, (8.2±3.0)mm and (3.9±1.9)mm, respectively; the surface area was 156.1(82.6, 198.2)mm 2, 23.0(21.4, 28.9)mm 2, 180.0(75.1, 230.4)mm 2 and 28.0(20.3, 36.7)mm 2, respectively; the volume was 77.1(37.1, 129.1)mm 3, 23.9(14.2, 37.8)mm 3, 104.6(37.7, 157.4)mm 3 and 13.0(10.4, 16.0)mm 3, respectively. When comparing the anteroposterior diameter, transverse diameter, depth, surface area and volume of the subchondral bone cysts in the anteromedial and posteromedial regions with the anterolateral and posterolateral regions, the differences were statistically significant (all P<0.01) except for the transverse diameter of the subchondral bone cysts in the anteromedial region and the anterolateral region ( P>0.05). In addition, the depth of subchondral bone cysts in the anteromedial region was significantly greater than that in the posteromedial region ( P<0.05). Conclusions:Subchondral bone cysts of the talar are commonly found in the middle- and old-aged population. Anteromedial lesions of the talar dome are the most commonly seen, with large and deeply involved cysts, followed by posteromedial lesions of the dome, while anterolateral and posterolateral lesions of the dome are less common and have smaller cyst sizes. An equal 2×2 grid configuration for talar cysts is useful in positioning and characterizing bone cysts, and can assist clinicians in accurately diagnosing and treating bone cysts.