Abstract The fracture of the prosthetic stem after prosthetic replacement of femoral head is not rare. In this study, the photoeastic instrument was used to study the stress distribution on the prosthetic stem following its insertion and to analyse the factors influencing the fracture of the stem. Through the examination of 9 places in 8 cases, it was found that:(1) The removal of femoral calcar and the inframedullary filling of the bone cement directly influenced the stress distribution. (2) The valgus or varus condition of the prosthesis would lead to stress concentration on the stem. (3) Once lossening of the prosthesis occured it would change the preliminary installingstress distribution in the upper femur which would lead to fatigue fracture. Ths experimental data and clinical observation would provide scientific basis forthe prevention of fracture of prosthetic stem following prosthetic replacement of femoral head.
In the present study, swine thighbone samples with different water contents were prepared through process of dehydration. The influence of water content on the biotribological behavior of the bone tissue was studied with nanoindentation test, reciprocating sliding test and impact wear test. It is shown that the water contents had significant influence on the mechanical properties and biotribological behavior of the swine thighbone samples. In this experiment condition, with decreasing water content, the hardness and elastic modulus of the swine thighbone samples increased, while the tribological properties significantly decreased. The viscoelasticity of bone tissue decreased with decreasing water content, which mainly resulted in different wear mechanisms of the bone tissue samples under applied loading.
In the process of positron emission tomography (PET) data acquiring, respiratory motion reduces the quality of PET imaging. In this paper, we present a correction method using three level grids B-spline elastic method to correct denoised and reorganized sinograms for respiratory motion correction. Using GATE simulates NCAT respiratory motion model to generate raw data which are used in experiment, the experiment results showed a significantly improved respiratory image with higher quality of PET, and the motion blur and structural information were fixed. The results proved the method of this paper would be effective for the elastic registration.
Due to lack of the practical technique to measure the biomechanical properties of the ocular cornea in vivo, clinical ophthalmologists have some difficulties in understanding the deformation mechanism of the cornea under the action of physiological intraocular pressures. Using Young's theory analysis of the corneal deformation during applanation tonometry, the relation between the elasticity moduli of the cornea and the applanated corneal area and the measured and true intraocular pressures can be obtained. A new applanation technique has been developed for measuring the biomechanical properties of the ocular cornea tissue in vivo, which can simultaneously acquire the data of the applanation area and displacement of the corneal deformation as well as the exerted applanation force on the cornea. Experimental results on a rabbit's eyeball demonstrated that the present technique could be used to measure the elasticity moduli and creep properties of the ocular cornea nondestructively in vivo.
【Abstract】 Objective To explore the midterm efficacy of superelastic cage implantation for the treatment of osteonecrosisof femoral head (ONFH). Methods From July 1996 to January 1998, 54 patients (75 hips) of ONFH were treatedwith superelastic cage and followed up. Among 54 patients, 5 patients were lost to follow up and 3 patients were dead of myocardialinfarction, renal failure and gastric cancer, respectively. Forty-six patients completed follow up including 32 males and14 females, aged from 21 to 61 with an average of 39 years old. Twenty-nine hips were classified as Ficat Stage Ⅱ and 36 as StageⅢ . Harris score was 58.20 ± 13.82. All patients were evaluated both cl inically and radiographically. Results Postoperatively,forty-six patients (65 hips) were followed up for 86 to 125 months with an average of 8 years and 8 months. Harris score was 80.78 ± 18.77. Twenty-nine hips were rated excellent, 21 good, 2 fair and 13 poor．A total of 76.9% of overall cl inical results were rated as good or excellent. Eight hips (12.3%) with the cage broken were turned to total hip replacement. Radiographicevaluation: 16 hips (24.6%) rated as grade Ⅰ , 34 (52.3%) grade Ⅱ and 15 (23.1%) grade Ⅲ . Conclusion Superelastic cage implantation is one of alternative treatments for ONFH at early and midterm stages. However, long-term follow-up is needed to know whether it is able to cure ONFH and whether cages will be broken as time passes by.
Objective To find a simple, practical and cheap way in suturation to prevent incision complications after celoscope surgery. Methods Using the elastic snell needle to stitch small incision under laparoscopy. Chosed 3 120 cases using the elastic snell needle to stitch stratified suturation as research group, and 3 120 cases by using trditional arc shaped needle in celoscope surgery as control group. The incident rate of incisional hernia and incision bleeding among groups were compared. Results In research group, the incident rate of incision bleeding was 0.16%, among which was 0.15% in epigastrium group, 0.18% in hypogastrium group, while in control group, the incident rate of incision bleeding was 0.68%, among which was 0.64% in epigastrium group, 0.70% in hypogastrium group. The incident rate of incision bleeding was obviously decreased (P＜0.05), and the incident rate of incision bleeding in hypogastrium group was obviously decreased as well (P＜0.05), compared research group and control group. In research group, the incident rate of incisional hernia was 0.07%, among which was 0 in epigastrium group, 0.12% in hypogastrium group, 0.15% in gerontism group, while in control group, the incident rate of incisional hernia was 0.44%, among which was 0.24% in epigastrium group, 0.59% in hypogastrium group, 0.99% in gerontism group, and the incident rate of incisional hernia after surgery was obviously decreased (P＜0.05), the incident rate of incisional hernia after surgery in hypogastrium group was obviously decreased as well (P＜0.05), comparing research group and control group. Conclusions Using the elastic snell needle to stitch small incision under laparoscopy, the peritoneal layer and muscular layer can be apposition sutured in the case without prolonging incision and costing more, hidden hernia and abdominal wall defects located at the incision can be found, ligation and stitched, thereby the incident rate of incisional hernia and incisional bleeding after celoscope surgery are significantly reduced.
Perioperative monitoring of blood coagulation is critical to better understand causes of hemorrhage, to guide hemostatic therapies, and to predict the risk of bleeding. Point-of-care (POC) coagulation monitoring devices assessing the viscoelastic properties of whole blood may overcome several limitations of routine coagulation tests in the perioperative setting. The advantage of these techniques is that they have the potential to measure the clotting process, starting with fibrin formation and continue through to clot retraction and fibrinolysis at the bedside, with minimal delays. Furthermore, the coagulation status of patients is assessed in whole blood, allowing the plasmatic coagulation system to interact with platelets and red blood cells, and thereby providing useful additional information on platelet function. Viscoelastic POC coagulation devices are increasingly being used in clinical practice, especially in the management of patients undergoing cardiac and liver surgery, assessment of hypo-and hypercoagulable states, guiding pro- and anticoagulant therapies, monitoring of antiplatelet therapy and procoagulant therapy. To ensure optimal accuracy and performance, standardized procedures for blood sampling and handling, strict quality controls and trained personnel are required.
In order to understand how the biomechanical properties of rabbit cornea change over time after corneal ablation, 21 healthy adult rabbits were used in this study, with the left eye as experimental side and the right eye as the control side. Firstly, a lamellar knife was used to remove a portion of the anterior corneal surface tissue (30%~50% of the original corneal thickness) from the left eye of each rabbit, as an animal model simulating corneal refractive surgery. Secondly, postoperative experimental rabbits were kept for one, three, or six months until being euthanized. Strip specimens were produced using their corneas in vitro to perform a uniaxial tensile test with an average loading-unloading rate of approximately 0.16 mm/s. Finally, the visco-hyperelastic material constitutive model was used to fit the data. The results showed that there was a significant difference in the viscoelastic parameters of the corneas between the experimental and the control eyes at the first and third postoperative months. There was a difference in tangential modulus between the experimental and the control eyes at strain levels of 0.02 and 0.05 at the third postoperative month. There was no significant difference in biomechanical parameters between the experimental and the control eyes at the sixth postoperative month. These results indicate that compared with the control eyes, the biomechanical properties of the experimental eyes vary over postoperative time. At the third postoperative month, the ratio of corneal tangential modulus between the experimental and the control eyes significantly increased, and then decreased. This work lays a preliminary foundation for understanding the biomechanical properties of the cornea after corneal refractive surgery based on rapid testing data obtained clinically.
ObjectiveTo evaluate the effectiveness of titanium elastic nails for severe displaced proximal humeral fractures in older children. MethodsBetween April 2009 and July 2012, 31 cases of severe displaced proximal humeral fractures were treated with closed or open reduction and fixation with 2 titanium elastic nails, and the clinical data were retrospectively analyzed. There were 23 boys and 8 girls, aged from 10 to 15 years (mean, 12.8 years). The causes of injury were sports injury (16 cases), traffic accident (11 cases), and falling from height (4 cases). The interval from injury to operation was 6 hours to 7 days (mean, 72 hours). According to Neer-Horwitz classification, 17 cases were rated as type III fracture and 14 cases as type IV fracture. There were 21 cases of metaphyseal fractures and 10 cases of epiphyseal fractures. ResultsSatisfactory reduction of fracture and stable fixation were obtained in all patients (closed reduction in 23 cases and open reduction in 8 cases). Primary healing was achieved in all incisions; no infection and neurovascular injury occurred. All patients were followed up 12-36 months with an average of 20 months. X-ray films showed that all fractures healed at 7-10 weeks (mean, 8 weeks). During follow-up, no disturbance of development or angulation deformity caused by premature physeal closure or bone bridge formation was observed. At last follow-up, the average Neer score of the shoulder was 95.7 (range, 83-100). The appearance and motion of the shoulder were normal. There was no significant difference in the upper extremity length between affected side and contralateral side[(67.68±2.56) cm vs. (67.61±2.54) cm; t=-1.867,P=0.072]. ConclusionTitanium elastic nails for severe displaced humeral fractures in older children is a safe and effective method with a low complication incidence.
This study aimed to investigate biomechanical properties of synthetic implants for reconstructive surgery of pelvic floor dysfunction. In this dissertation, we chose four synthetic implants, i.e. total pelvic floor repair system (PROLIFT), gynecone TVT obtutator system (TVT-O), intra-vaginal sling placement device (IVS) and acellular dermal matrix (Renov), for tensile test respectively. The biomechanical properties of four synthetic implants were measured and analyzed using a material testing machine (Instron 4302 versatile material testing machine). The biomechanical parameters included ultimate stress strength, modulus of elasticity, maximum load and maximum elongation. The results showed that the maximum load of the four symthetic implants was TVT-O > IVS > PROLIFT > Renov, and the maximum load of TVT-O was significantly higher than PROLIFT and Renov ( P < 0.05). The ultimate stress strength was TVT-O > IVS > PROLIFT > Renov, with no significant differences among them ( P > 0.05). The maximum elongation of the four implants was TVT-O > PROLIFT > IVS > Renov, and the maximum elongation of TVT-O and PROLIFT were both significantly higher than Renov ( P < 0.05). The modulus of elasticity was IVS > Renov > TVT-O > PROLIFT, with no significant differences among them ( P > 0.05). Taken together, the present study demonstrates that the modulus of elasticity of IVS was the highest in the four synthetic implants; TVT-O had the highest mechanical strength; The maximum load, ultimate stress strength and maximum elongation of Renov were all the lowest; The mechanical properties of PROLIFT was the most stable, and its modulus of elasticity was the lowest in the four synthetic implants, which had good extensibility and elasticity. Therefore, it is necessary to pay attention to the biomechanical properties of new pelvic reconstructive materials for the clinical pelvic reconstructive surgery.