A Modified Flexor Tendon Suture Technique Combining Kessler and Loop Lock Flexor Tendon Sutures

OBJECTIVES: In the present study, a novel single knot tenorrhaphy was developed by combining the modified Kessler flexor tendon suture (MK) with the loop lock technique. METHODS: A total of 48 porcine flexor digitorum profundus tendons were collected and randomly divided into six groups. The tendons were transversely cut and then repaired using six different techniques, the MK method, double knot Kessler-loop lock flexor tendon suture (DK), and single knot Kessler-loop lock flexor tendon suture (SK), each in combination with the epitendinous suture (P), and the same three techniques without P. Furthermore, by performing the load-to-failure tests, the biomechanical properties and the time taken to complete a repair, for each tenorrhaphy, were assessed. RESULTS: Compared to the MK+P method, DK+P was more improved, thereby enhancing the ultimate tensile strength. The SK+P method, which required fewer knots than DK+P, was easier to perform. Moreover, the SK+P repair increased the force at a 2-mm gap formation, while requiring lesser knots than DK+P. CONCLUSION: As opposed to the traditional MK+P method, the SK+P method was improved and exhibited better biomechanical properties, which may facilitate early mobilization after the repair.

Constitutive law of healthy gallbladder walls in passive state with damage effect

Biomechanical properties of human gallbladder (GB) wall in passive state can be valuable to diagnosis of GB diseases. In the article, an approach for identifying damage effect in GB walls during uniaxial tensile test was proposed and a strain energy function with the damage effect was devised as a constitutive law phenomenologically. Scalar damage variables were introduced respectively into the matrix and two families of fibres to assess the damage degree in GB walls. The parameters in the constitutive law with the damage effect were determined with a custom MATLAB code based on two sets of existing uniaxial tensile test data on human and porcine GB walls in passive state. It turned out that the uniaxial tensile test data for GB walls could not be fitted properly by using the existing strain energy function without the damage effect, but could be done by means of the proposed strain energy function with the damage effect involved. The stresses and Young moduli developed in two families of fibres were more than thousands higher than the stresses and Young's moduli in the matrix. According to the damage variables estimated, the damage effect occurred in two families of fibres only. Once the damage occurs, the value of the strain energy function will decrease. The proposed constitutive laws are meaningful for finite element analysis on human GB walls.

Biomechanical Properties of the Cornea Using a Dynamic Scheimpflug Analyzer in Healthy Eyes

PURPOSE: To investigate biomechanical properties of the cornea using a dynamic Scheimpflug analyzer according to age. MATERIALS AND METHODS: In this prospective, cross-sectional, observational study, participants underwent ophthalmic investigations including corneal biomechanical properties, keratometric values, intraocular pressure (IOP), and manifest refraction spherical equivalent (MRSE). We determined the relationship of biomechanical parameters and ocular/systemic variables (participant's age, MRSE, IOP, and mean keratometric values) by piecewise regression analysis, association of biomechanical parameters with variables by Spearman's correlation and stepwise multiple regression analyses, and reference intervals (RI) by the bootstrap method. RESULTS: This study included 217 eyes of 118 participants (20–81 years of age). Piecewise regression analysis between Corvis-central corneal thickness (CCT) and participant's age revealed that the optimal cut-off value of age was 45 years. No clear breakpoints were detected between the corneal biomechanical parameters and MRSE, IOP, and mean keratometric values. Corneal velocity, deformation amplitude, radius, maximal concave power, Corvis-CCT, and Corvis-IOP exhibited correlations with IOP, regardless of age (all ages, 20–44 years, and over 44 years). With smaller deformation amplitude and corneal velocity as well as increased Corvis-IOP and Corvis-CCT, IOP became significantly increased. We provided the results of determination of confidence interval from RI data using bootstrap method in three separate age groups (all ages, 20–44 years, and over 44 years). CONCLUSION: We demonstrated multiple corneal biomechanical parameters according to age, and reported that the corneal biomechanical parameters are influenced by IOP.

Research advances on the role of extracellular matrix in pulmonary fibrosis / 基础医学与临床

Pulmonary fibrosis(PF)is characterized by extensive deposition of extracellular matrix(ECM),changes in biomechanical properties of ECM result from the process of PF actively drive disease progression.Several matrix protein candidates correlate with fibrotic pathologies,ECM may offer many novel therapeutic targets.

Corneal biomechanical properties after femtosecond laser assisted LASIK with the corneal visualization Scheimpflug technology and ocular response analyzer / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the changes of corneal biomechanical properties before and after femtosecond laser assisted LASIK(FS-LASIK)using Corneal Visualisation Scheimpflug Technology(Corvis ST)and Ocular Response Analyzer(ORA), and the correlation with other myopic parameters. <p>METHODS:Sixty three patients(63 eyes)who had myopic femtosecond laser assisted LASIK(FS-LASIK)were enrolled in the study. The right eye of each patient was analyzed in this study. The corneal biomechanical parameters pre-operative and 1mo post-operative was measured with the Corvis ST(Oculus, Wetzlar, Germany)and ORA(Reichert, Buffalo, New York, USA). Comparison of the biomechanical property values before and after surgery was peformed using Paired <i>t</i>-test or Mann-Whitney <i>U</i>. Pearson or Spearman correlations were used to evaluate the relationship between parameters.<p>RESULTS: The postoperative 1^st A-time, Vin, 2^nd A length, Vout, HC time and Radius demonstrate significant decreases comparing with preoperative values(<i>P</i>=0.00, <i>P</i>=0.00, <i>P</i>=0.00, <i>P</i>=0.00, <i>P</i>=0.00, <i>P</i>=0.00 respectively). The postoperative 2^nd A-time, DA and PD significantly increases(<i>P</i>=0.00, <i>P</i>=0.00, <i>P</i>=0.00), however, the 1^st A length had no significant difference after surgery. The CH and CRF were significantly lower after FS-LASIK(<i>P</i>=0.00, <i>P</i>=0.00). A statistically significant correlation coefficient was found between preoperative central corneal thickness(CCT)with postoperative-preoperative changes of 1^st A-time, 2^nd A-time, DA and Radius respectively(<i>P</i>=0.01, <i>P</i>=0.04, <i>P</i>=0.03, <i>P</i>=0.01). <p>CONCLUSION:There were significantly changes of corneal biomechanical properties after FS-LASIK surgery. The changes of corneal biomechanical properties after FS-LASIK can be reflected by some parameters of Corvis ST and ORA. The mainly influence of corneal biomechanical alteration was possibly correlation with corneal thickness.

Biomecbanical parameter of normal rabbit cornea / 中华实验眼科杂志

BackgroundIt has been proved that,after being forced,the biological soft tissue has stable biomechanical characteristics.However,there is rare study on corneal biomechanics.Rabbit is a main animal for experimental study in ophthalmology.But the biomechanical study of cornea in normal rabbit has not been reported.ObjectiveThis study was to investigate the biomechanical properties of normal rabbit central cornea and acquire the parameter. Methods Ten rabbits were sacrificed and the whole corneas were obtained and 20 central cornea specimens with 7 mm×5 mm of rabbit were prepared and tested on BOSE electroforce 3220-AT biomechanics machine under the room temperature and suitable humidity environment.Uniaxial tension,stress between strain,relaxation and creep were performed and the curves were drawn.The data was collected by wintest system to evaluate the biomechanical parameters of rabbit corneal tissue. ResultsThe maximum distortion intension of rabbit cornea was (7.7432±0.6099)MPa.After three cyclic loading,the stress gradually attenuated and the stress and strain flattened as the time change with the relaxation rate 30.33％.The deformation of the specimens enhanced with time decrease with the creep rate 24.33％. ConclusionsThe biomechanical characteristics of normal rabbit cornea are revealed in this study,which offer the basis for the experimental research of rabbit model aimed at corneal disease.

Micro-CT observation on blood vessels in tibial metaphysis of ovariectomized mice / 上海第二医科大学学报

Objective To observe the distribution of blood vessels in tibial metaphysis in ovariectomized and control mice by micro-CT(?CT),and investigate the relationship between bone regional blood supply and osteoporosis. MethodsForty mice were randomly divided into ovariectomy group(n=20) and control group(n=20).Four weeks after operation,?CT analysis was conducted to observe the bone blood vessel distribution after silicone rubber perfusion,and bone mineral density measurement,?CT bone microarchitecture analysis and biomechanical test were performed. Results Bone mineral density,bone microarchitecture in ?CT analysis,biomechanical properties and bone blood vessel distribution in ?CT analysis of ovariectomy group were significantly lower than those of control group(P

Effect of bionics pulsed electromagnetic fields on the biomechanical property of ovariectomized osteoporosis rats / 中国康复理论与实践

@#ObjectiveTo observe the effect of bionics pulsed electromagnetic fields (BEMF) on the biomechanical property of ovariectomized Wistar rats.MethodsForty 6 month old female Wistar rats were randomly divided into four different groups: ovariectomy group (group A), sham operation group (group B), BEMF+ovariectomized group (group C) and estrogen+ovariectomized group (group D). All rats were subjected to bilateral ovariectomy except group B. 8 weeks after operation, rats of group D were given estrogen 0.5 mg/kg/2 w. Rats of group C were exposed to BEMF, 1 h /d. Rats of group A and B were given nothing as control groups. All treatments was being kept for 10 weeks. After treatments finished, measuring the biomechanical property of femur and lumbar spine.ResultsThere were significant differences in the biomechanical property between group D and group A, and group C and group A (P<0.05).ConclusionBEMF can improve the biomechanical property of ovariectomized Wistar rats significantly and increase the capability of resisting fracture significantly.

Preventive effect of bionics-pulsed electromagnetic field on biomechanical property of bone / 第三军医大学学报

Objective To study the protective effect of bionics-pulsed electromagnetic field (BEMF) on the biomechanical property of the bones of Wistar rats. Methods Thirty-two 3-month-old female Wistar rats were divided into 4 groups (n=8 in each group). The 8 rats of group A (the control) were treated normally and received injections of saline in the same amount of drugs for the rats of other 3 groups. The rats of group B received injections of desamethasone (1 mg/kg, 2 intramuscular injections/week). The rats of groups C and D received injections of desamethasone in the same procedure as that of group B. In addition, the rats of group C received daily subcutaneous injections of calcitonin in the dosage of 2 IU/kg and those of group D were irradiated with BEMF once daily. The results of the 3 kinds of therapeutic procedures were observed 8 weeks later. Results After the irradiation of BEMF, the biomechanical parameters of the lumbar vertebrae and the femur were far higher in the rats of group D than in those of group B. Conclusion BEMF irradiation is effective to prevent the decrease of biomechanical properties of the bones of the rats.

Effect of pulsed electromagnetic fields of different daily treatment durations on biomechanical properties of femur in ovariectomized rats / 中华物理医学与康复杂志

Objective To observe the effect of pulsed electromagnetic fields(PEMFs)of different daily treatment durations on biomechanical properties of femur in ovariectomized rats,so as to find out the optimal daily treatment time.Methods Fifty female Sprague-Dawley rats were randomly divided into five groups:(1)SHAM control(no PEMFs treatment),(2)OVX control(no PEMFs treatment),(3)OVX I(PEMFs treatment at 8Hz fre- quency with 3.8 mT intensity,20 min daily for 30 days),(4)OVX 11(PEMFs treatment at 8 Hz frequency with 3.8 mT intensity,40 min daily for 30 days),and(5)OVXⅢ(PEMFs treatment at 8Hz frequency with 3.8 mT in- tensity,60 rain daily for 30 days).All the rats were subject to bilateral overiectomy except those in the SHAM control group.The biomechanical properties of the femur were assessed after 30 days of PEMFs treatment.Results The values of the parameters of the biomechanical properties obtained with the OVX control group were significantly lower than those of the other 4 groups(P0.05).Conclusion PEMFs of the three different daily treatment durations can maintain the biomechanical properties of the femur in ovariectomized rats.Under certain in- tensity(3.8 mT)and frequency(8 Hz),PEMFs of the three different treatment durations can significantly maintain biomechanical properties of femur in ovariectomized rats approximately to the nomal level,but among the three groups,the difference is not significant.It was shown that exposure to PEMFs for 20 to 60 minutes daily had similar effect of maintaining biomechanical properties of the femur in ovariectomized rats.

Effect of amylin on biomechanical properties of the femur in glucocorticoid-induced osteoporosis rats / 医学研究生学报

Objective:To investigate the effect of amylin on biomechanical property of the femur in glucocorticoid-induced osteoporosis rats. Methods:Four groups of female Wistar rats(3 months old) were treated for 12 weeks as follows: ⅠNormal Control;ⅡDXM;Ⅲ DXM+AMY;Ⅳ DXM+Vitamin D_3.By intramuscular injection of dexamethasone(DXM)1mg/kg twice a week during the first 8 weeks,the animal model of Glucocorticoid induced osteoporosis was established.After 12 weeks,biomechanical properties of the femur were measured. Results:After the treatment with AMY,Bone structural mechanical(diameter) and geometrical parameters(displacement,peak load) of the femur were significantly increased(vs.DXM group,P

Determination of the Overlapping Area of Patellofemoral and Tibiofemoral Joint Sliding above the Femoral Condylar Facet and the Biomechanical Property of the Area / 中国运动医学杂志

Objective: To determine the overlapping area of the femoral condyle facet on which the patellofemoral and tibiofemoral joint surfaces move and to measure the pressures on such area in order to better design the length of femoral trochlea prosthesis in patellofemoral arthroplasty. Methods: Eight fresh cadaver knees were mounted on Instron 8501 biomechanics tester,and simulated physiologically weight-bearing situation of knee from standing to flexion position. Such overlapping area was drawed up with stain method and the contact pressures were measured with Fuji pressure film. Results: There existed an overlapping contact area on the femoral condyle facet within the patellofemoral contact area when knee flexion was 75? or larger. The tibiofemoral contact pressure was higher than the patellofemoral pressure in the area. Conclusion: The femoral trocher prosthesis should cover the whole contact area of patellofemoral joint.

Effects of Pore Size on Osteoconduction at the Porous Hydroxyapatite / 대한정형외과학회잡지

PURPOSE: Porous hydroxyapatite is resorbable and osteoconductive, so it is slowly replaced by ingrowing new bone. Optimal pore geometry for osteoconduction, however, has not been determined yet. The objective of this investigation was to assess both the histological response and the reinforcing effects of bone ingrowth within the porous hydroxyapatite implants depending on pore size. MATERIALS AND METHODS: Four kinds of cylindrical types (50, 100, 300, 500 micrometer) of porous hydrox-yapatite were prepared. Fifty-six white rabbits were divided into 4 groups and porous hydroxyapatite block was inserted through the medial cortical window of a proximal tibia. Histomorphological changes were examined using light microscopy and scanning electron microscopy. Biomechanical compression test was performed using a material test machine. RESULTS: Hydroxyapatite implants appeared to have no early adverse effects, such as inflammation and foreign body reaction. Osteoconduction through the pores was found in all four implants and new bone was found on the surface of pores with no histologically demonstrable intervening nonosseous tissue. At four weeks after implantation, new bone was arranged in a concentric pattern around the vessel, similar to osteon. New bone formation through pores was most evident at 300 micrometer-sized type. At 8 weeks, active osteoconduction was also found at 50 micrometer-sized type. Evidence of bone marrow formation within porous hydroxyapatite was found. In a biomechanical study, ultimate compression strength significantly increased in the 300 micrometer-sized type, after 8 weeks implantation compared to preimplantation. CONCLUSIONS: Porous hydroxyapatite implanted into rabbit tibia showed biological fixation and osteointegration. A pore size of 300 micrometer was most effective for bone ingrowth. Osteoconduction also took place in 50 micrometer-sized cylindrical pores.

Effect of Stay-suture on Peripheral Nerve Tension / 대한정형외과학회잡지

The purpose of this study is to confirm the effectiveness of stay-suture which is commonly used in the procedure of end to end anastomosis, to find out general biomechanical properties of peripheral nerve with gradual stretching and to evaluate the histological difference after breakage of the nerve. The sciatic nerves of adult rabbits were excised and they were grouped by I and II. Group I was composed of 14 normal sciatic nerves and group II, 14 sciatic nerves sutured with 5-0 nylon after transection. They were stretched on the "Instron" universal testing machine at a constant rate of 200mm/min until breakage took place and the results were compared. The mean maximal tensile strength was 13.6N in group I and 2.1N in group II, representing about one seventh value. The mean ultimate tensile strength was 4.2MPa in group I and 0.9MPa in group II, representing about one fifth value. In load-elongation curve of group I, viscoelastic property was noted as all other biological tissues have. The mean modulus of elasticity was 19 in normal sciatic nerves, which is somewhat lower value than other tissues, indicating superior elastic property of peripheral nerves. Transverse histologic examination showed that epineurium lost its continuity earlier than perineurium, implying perineurium is a more resistant structure than epineurium. However, to confirm this, it is thought to be necessary to examine the nerves serially during distraction at each different status. In conclusion, stay-suture provided about one fifth of ultimate tensile stress, implying its usefullness of resisting excessive tension in end to end anastomosis of peripheral nerves. Normal sciatic nerves showed viscoelastic property with mean modulus of elasticity of 19.

Biomechanical Properties of the Growing Long Bone / 대한정형외과학회잡지

Bone is a heterogenous and anisotrophic material exhibiting elastic, viscoelastis and plasticproperties. A considerable amount of information is now available regarding biomechanical properties and mechanisms of fractures of mature long bones, but less is known about the properties of the growing bones. In order to assess the biomechanical properties under tension, rabbits growing bones were loaded with Instron Modal 1,000 until fracture occurred. Two hundred tibiae of 100 New Zealand white immature rabbits were divided into 6 experimental groups according to maturity and size. Group I-R(40 right tibiae of 1-month old rabbits), Group I-L (40 left tibiae of 1-month old rabbits), Group II-R(20 right tibiae of 3-month old rabbits), Group II-L (20 left tibiae of 3-month old rabbits), Group III-R(40 rigth tibiae of 5-month old rabbits), and Group III-L(40 left tibiae of 5-month old rabbits). The following results were obtained. 1. Fracture type was transverse.or nearly transverse in 170 out of the total 200 tibiae(85%).