BACKGROUNDControversies about the rational positioning of the tibial component in unicompartmental knee arthroplasty (UKA) still exist. Previous finite element (FE) studies were rare, and the results varied. This FE study aimed to analyze the influence of the tibial component coronal alignment on knee biomechanics in mobile-bearing UKA and find a ration range of inclination angles.

METHODSA three-dimensional FE model of the intact knee was constructed from image data of one normal subject. A 1000 N compressive load was applied to the intact knee model for validating. Then a set of eleven UKA FE models was developed with the coronal inclination angles of the tibial tray ranging from 10° valgus to 10° varus. Tibial bone stresses and strains, contact pressures and load distribution in all UKA models were calculated and analyzed under the unified loading and boundary conditions.

RESULTSLoad distribution, contact pressures, and contact areas in intact knee model were validated. In UKA models, von Mises stress and compressive strain at proximal medial cortical bone increased significantly as the tibial tray was in valgus inclination >4°, which may increase the risk of residual pain. Compressive strains at tibial keel slot were above the high threshold with varus inclination >4°, which may result in greater risk of component migration. Tibial bone resection corner acted as a strain-raiser regardless of the inclination angles. Compressive strains at the resected surface slightly changed with the varying inclinations and were not supposed to induce bone resorption and component loosening. Contact pressures and load percentage in lateral compartment increased with the more varus inclination, which may lead to osteoarthritis progression.

CONCLUSIONSStatic knee biomechanics after UKA can be greatly affected by tibial component coronal alignment. A range from 4° valgus to 4° varus inclination of tibial component can be recommended in mobile-bearing UKA.

Adult ; Arthroplasty, Replacement, Knee ; methods ; Finite Element Analysis ; Humans ; Knee Joint ; surgery ; Male ; Stress, Mechanical ; Tibia ; surgery ; Treatment Outcome

Objective To study the method of emergency blood collection during a long-distance voyage to ensure blood transfusion treatment.Methods Ten voluntary blood donors were recruited, a base unit of blood was collected and preserved.Reactions of the blood donors were observed, and the blood quality was tested.Results The success rate of blood collection was 90% and the qualification rate was 100%.Conclusion Emergency blood collection during a long-distance voyage is feasible,which can help ensure blood supply in peace time or war time.

OBJECTIVETo investigate the effect of the treatment of periapical diseases with recombinant human netic protein (rhBMP-2) composite in dog models so as to provide basis for its clinical application.

METHODSThe endotoxin-bacteria mixed fluid was injected into each root canal of the experimental teeth of dogs and the animal periapical were built. The rhBMP-2 composite was mixed by rhBMP-2, TCP, collagen and metronidazole and used in the treatment cal diseases in dog models as root apex screen. The imageology and pathology research were went on.

RESULTSThe effective rate of the experimental group was remarkably higher than that of the carrier group and the control group with remarkable ference (P < 0.05). The quality of the repair of tissue was obviously better than the two other groups.

CONCLUSIONThe rhBMP-2 composite is a promising biological root-canal filling material.

Animals ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; Collagen ; Dogs ; Humans ; Periapical Diseases ; Recombinant Proteins ; Root Canal Filling Materials ; Transforming Growth Factor beta

OBJECTIVETo evaluate the ability of a polycaprolactone/polylactic acid (PCL/PLA) membrane to inhibit epidural scar adhesion after laminectomy, and observe the responsive changes of the pain media in the spinal cord.

METHODSL(1), L(3) laminectomies were performed on 96 Wistar rats. The rats were divided into 3 groups: None-implant Control Group (NC), Autologous free fat graft group (AFFG) and PCL/PLA membrane group (PCL/PLAm). The rats were killed at 1, 3, 6, and 12 weeks postoperatively. Epidural scar formation and adhesion were observed grossly and histologically. Reverse transcription polymerase chain reaction (RT-PCR) were used to analyses the expression of Transforming growth factor beta (TGF-beta) in the epidural scar. Immunohistochemistry stain and RT-PCR were performed to evaluate the expression of the substance P and the c-fos gene in the relevant spinal cord, and the results were analyzed statistically.

RESULTSGross evaluation and histological evaluation showed that in the NC lamina defect site had much scar tissue and had wide and tight adhesions to the dura; in the AFFG, with the fat degrading gradually, the adhesions were increased; whereas in the PCL/PLAm group, there were slightly adhesions to the dura. RT-PCR showed that the expression of the TGF-beta was much less in the PCL/PLAm group than in the NC group. The insertion of the PCL/PLA membrane and the fat patch reduced the expression of the substance P and the c-fos gene in the spinal cord.

CONCLUSIONThe insertion of the PCL/PLA membrane reduces scar formation and separates fibrosis tissue from the dura, the results indicate that PCL/PLA membrane is an effective way of reducing peridural scar formation and preventing the failed back surgery syndrome.

Animals ; Biocompatible Materials ; Cicatrix ; prevention & control ; Female ; Lactic Acid ; Laminectomy ; adverse effects ; Membranes, Artificial ; Polyesters ; Polymers ; Postoperative Complications ; prevention & control ; Prosthesis Implantation ; Proto-Oncogene Proteins c-fos ; biosynthesis ; Rats ; Rats, Wistar ; Spinal Cord ; metabolism ; Spinal Diseases ; prevention & control ; Substance P ; biosynthesis ; Tissue Adhesions ; prevention & control

BACKGROUNDLateral compartmental osteoarthritis (LCOA), a major complication after medial mobile-bearing unicompartmental knee arthroplasty (UKA), is highly associated with the increased stress of the lateral compartment. This study aimed to analyze the effects on the stress and load distribution of the lateral compartment induced by lower limb alignment and coronal inclination of the tibial component in UKA through a finite element analysis.

METHODSEight three-dimensional models were constructed based on a validated model for analyzing the biomechanical effects of implantation parameters on the lateral compartment after medial Oxford UKA: postoperative lower limb alignment of 3° valgus, neutral and 3° varus, and the inclination of tibial components placed in 4°, 2° valgus, square, and 2° and 4° varus. The contact stress of femoral and tibial cartilage and load distribution were calculated for all models.

RESULTSIn the 3° valgus lower limb alignment model, the contact stress of femoral (3.38 MPa) and tibial (3.50 MPa) cartilage as well as load percentage (45.78%) was highest compared to any other model, and was increased by 36.75%, 47.70%, and 27.63%, respectively when compared to 3° varus. In the condition of a neutral position, the outcome was comparable for the different tibial tray inclination models. The inclination did not greatly affect the lateral compartmental stress and load distribution.

CONCLUSIONSThis study suggested that slightly varus (undercorrection) lower limb alignment might be a way to prevent LCOA in medial mobile-bearing UKA. However, the inclination (4° varus to 4° valgus) of the tibial component in the coronal plane would not be a risk factor for LCOA in neutral position.