Objective To evaluate the feasibility of the porous titanium/chitosan/hydroxyapatite (Ti/Ch/HA) composite scaffold as a bone repair substitute.Methods Additive manufacturing (3D printing) technology was used to fabricate porous Ti scaffolds as supporting structures.Chitosan/hydroxyapatite (Ch/HA) sponge was prepared within the macro-pores of Ti scaffolds using freeze drying technology.Thus,a kind of composite porous Ti/Ch/HA scaffold with good cell affinity was obtained.Osteoblastic cells were seeded and cultured in pure porous Ti scaffolds and composite Ti/Ch/HA scaffolds for 7 days.The cellular morphology,seeding efficiency and proliferation were examined and compared between the 2 kinds of scaffolds using scanning electron microscopy (SEM) and MTT assay.Results The SEM examination showed that the macro-pores of Ti/Ch/HA scaffolds were full of the composite sponge structure of Ch/HA,with a micropore size of 50 to 200 μm.Like the pure porous Ti scaffolds,composite Ti/Ch/HA ones have a compressive strength of 168.2 to 192.6 MPa,a yielding strength of 137.1 to 154.1 MPa,and a Young's modulus of 3.21 to 4.51 GPa.After culture for 7 days,a large number of flat cells adhered onto the surface of Ti scaffolds while the cells adhering onto the Ti/Ch/HA composite scaffolds were fusiform.The seeding efficiency of osteoblastic cells in the composite Ti/Ch/HA scaffolds (73.218％ ± 3.748％) was significantly higher than that in the pure porous Ti scaffolds (21.352％ ±4.365％) (P ＜0.05);the OD value of the composite Ti/Ch/HA scaffolds (0.783 ±0.043) was significantly higher than that of the pure porous Ti scaffolds (0.382 ± 0.036) (P ＜ 0.05).Conclusions Ti/Ch/HA composite scaffolds can match human bone in mechanical properties.Compared with pure porous Ti scaffolds,the Ti/Ch/HA composite ones are more suitable for adhesion and proliferation of osteoblasts,making them an ideal kind of bone repair substitute.

Objective To compare the compression properties of articular cartilage and polyinyl alcohol hydro-gel(PVA-H)as artificial carlage.Method Unconfined compression tests were conducted on articular card-lage and PVA-H,including stress-strain tests,creep tests and stress relaxation tests.The stress-strain rela-tionship of articular cartilage and PVA-H were measured.Result The compression modulus of articular card-lage was higher than that of PVA hydrogel.The average compression modulus of articular cartilage and PVA hydrogel was(3.6492±0.6199)Mpa and(1.5951±0.1469)Mpa,respectively.Condusions The experimental results revealed the differences existed between articular cartilage and PVA-H and this would be useful to fur-ther improve the mechanical properties of artificial cartilage.

Artificial knee joint simulation test is an important form in the research and evaluation of prosthetic material and design. Natural knee joint could not be tested by conventional instruments because of complex motion and load in movement. Simulation test designed for artificial knee is needed. At present, two kinds of simulation, namely simplification method and complete simulation, are widely used. Complete simulation can be used for simultaneous evaluation of material and design of prosthesis, whereas simplification method is only useful in evaluating the material of prosthesis. In international standards, there are already two protocols for artificial knee joint experiment, namely load control and displacement control. This paper also reviews the evaluation criteria and measurement standards for artificial knee joint simulation test, and then envisages the researches in future.
Arthroplasty, Replacement, Knee ; instrumentation ; Computer Simulation ; Computer-Aided Design ; Equipment Failure Analysis ; methods ; Humans ; Knee Prosthesis ; Prosthesis Design ; methods

The FE model of proximal humeral locking plate was established and analyzed to provide academic support of the proximal humeral locking plate failure. The stress distributions of the locking plate were observed under the situations of the fracture area providing support and without support. In summary, this type of locking plate cannot afford the stress at 120 degrees abduction position under the situation of fracture area provides without support. In order to reduce the probability of locking plate failure, it is recommended that using other type of locking plate instead or avoiding 120 degree abduction of the patient.
Bone Plates ; Equipment Failure Analysis ; Finite Element Analysis ; Humans ; Humeral Fractures ; Materials Testing ; Prosthesis Failure ; Stress, Mechanical

The mechanical model of knee is a system of constructional elements with specific restrains and material properties, which are deduced from the components of knee based on their functions and junctions. Kinematics and kinetics of knee can be calculated from the mechanical model. A review of some mechanical models of knee are shown in this paper.
Biomechanical Phenomena ; Computer Simulation ; Humans ; Knee Joint ; physiology ; Models, Biological ; Range of Motion, Articular ; physiology ; Stress, Mechanical

The orthopedics implants failure management system has been put forward according to the present status. The function of the system and typical failure case reasoning route also have been described. Furthermore, the analysis process has been presented by illustrating a typical failure case analysis.
Medical Records Systems, Computerized ; Orthopedic Procedures ; instrumentation ; Prosthesis Design ; Prosthesis Failure ; Software Design

A sagittal plane model of knee joint based on crossed-four-bar-linkage-based tibiofemoral joint model has been developed using geometric and force equilibrium constraints. The model predicts and explains the movement of contact point on the patella and femur, variation of patellar and patellar tendon angle, variation of patellar mechanism angle and variation of patellofemoral contact force and patellar tendon force. The computed results agree well with the published experimental results.
Biomechanical Phenomena ; Humans ; Knee Joint ; anatomy & histology ; physiology ; Models, Biological ; Movement ; physiology ; Patella ; anatomy & histology ; physiology

Objective: To construct ¹³¹I-the fifth generation polyamidoamine (PAMAM(G5.0)) with targeting peptide Ser-Arg-Glu-Ser-Pro-His-Pro (SRESPHP; SR) or Gly-Pro-Leu-Pro-Leu-Arg (GPLPLR; GP) and double targeting peptide SR/GP, and evaluate the targeting ability in medullary thyroid carcinoma (MTC) model. Methods: PAMAM(G5.0), PAMAM(G5.0)-SR, PAMAM(G5.0)-GP and PAMAM(G5.0)-SR/GP were radiolabeled with ¹³¹I by chloramine T method. The radiolabeled yield and radiochemical purity were determined by thin layer chromatography. MTC xenografts were developed and the percentage radio-activity of injection dose per gram of tissue (%ID/g) in tumor and organs was measured at 24 h post-injection. Region of interest (ROI) was drawn and the tumor/non-tumor (T/NT) ratios at 4, 8 and 24 h post-injection were calculated and compared among different groups. One-way analysis of variance, repetitive measurement analysis of variance and Dunnett-t test were used to compare the data of different groups. The relationship between %ID/g and T/NT was analyzed with Pearson correlation. Results: The radiolabeled yield was more than 75% and radiochemistry purity was more than 90%. The difference of %ID/g at 24 h post-injection was significant (F=14.400, P<0.001) in tumors of all groups. The radioactive uptake in tumor of ¹³¹I-PAMAM(G5.0)-SR group was the highest at 24 h post-injection((1.80±0.18) %ID/g). There were significant differences of T/NT ratios among different groups(F=4.776, P<0.05)and between different time points(F=8.630, P<0.05). Compared with negative control group (Na¹³¹I), the T/NT ratios significantly increased in ¹³¹I-PAMAM(G5.0)-SR group at 4, 8 and 24 h post-injection (t=4.169, 7.123 and 4.032, all P<0.05) and in ¹³¹I-PAMAM(G5.0)-GP group at 4 h post-injection (t=5.893, P<0.05). The T/NT ratio in ¹³¹I-PAMAM(G5.0)-SR group was higher than that in ¹³¹I-PAMAM(G5.0)-GP group at 24 h post-injection (t=2.871, P<0.05). Conclusions PAMAM(G5.0)-SR, PAMAM(G5.0)-GP and PAMAM(G5.0)-SR/GP can target the MTC models. ¹³¹I-PAMAM(G5.0)-SR has the best biological properties and may provide a new precision method for MTC diagnosis, treatment and prognosis evaluation.