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OBJECTIVE@#To construct a three-dimensional (3D) finite element mechanical model of total hip arthroplasty for comparison of biomechanical differences of the hip joint following capsule repair and postoperative rehabilitation.@*METHODS@#Six frozen specimens of hip joint posterior capsule ligament complex were collected in a bone-capsule-bone manner, and the load-strain curve and other mechanical properties of the specimens were tested using a universal material testing machine. Thin-section CT data of the pelvis and lower limbs obtained from a volunteer were imported into Mimics software to construct a 3D model of the hip joint. Digital models of the cup, femoral prosthesis and joint capsule were created in CATIA software and imported into Mimics to simulate total hip arthroplasty; the assembled data were imported into ABAQUS software. The properties of the capsule were set according to results of the mechanical test, anatomical studies, and constitutive equations, and the biomechanics of the anatomically repaired and conventionally repaired capsules were compared during hip flexion.@*RESULTS@#The results of testing on the 6 capsule specimens showed a mean ultimate tensile strain of (39.21±5.23)% and a mean of ultimate tensile strength of 1.65±0.38 MPa. The stress-strain curve of the finite element model was consistent with the results of mechanical test on the specimens and the biochemical characteristics of the capsule. The stress was distributed evenly in the anatomically repaired capsule during hip flexion but not in the capsule repaired through the conventional approach; the tensile stress in the lower part of the conventionally repaired capsule reached the ultimate tensile stress measured on the capsule specimens at a 90° flexion.@*CONCLUSIONS@#The finite element model allows dynamic, quantitative and visual assessment of stress distribution in the hip joint capsule, and compared with the conventional approach, anatomical repair can achieve better biomechanical properties of the capsule.
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Humans , Arthroplasty, Replacement, Hip , Biomechanical Phenomena , Finite Element Analysis , Hip Joint/surgery , Prognosis , Stress, MechanicalABSTRACT
Objective To investigate the effect of neuropeptide Y (NPY) on the osteoblastic differentiation of murine MC3T3-E1 cells and its mechanism related to the Wnt signaling pathway.Methods The murine MC3T3-E1 cells were divided into 4 groups according to the stimulators added:phosphate buffered saline (PBS) (control) and different concentrations of NPY (10-8 mol/L,10-10 mol/L and 10-12 mol/L).The cellular proliferation was detected with MTT assay after 1,3,5,7 and 9 days.The cells were identified with cell immunochemistry and Western Blot to find out the most effective concentration of NPY at different time points under osteoblastic condition.The cells were then divided into 4 groups:PBS,NPY,NPY + NPY receptor antagonist,and NPY + DKK1.Western blot was used to determine the expression of β3-catenin and p-GSK-3β in each group.Nuclear signaling activity of β3-catenin was observed using immunofluorescence staining.Results NPY significantly improved the proliferation of MC3T3-E1 cells at 7 and 9 days (P ＜0.05).NPY (10s mol/L and 10-10 mol/L) groups and NPY (10-10 mol/L and 10-12 mol/L) groups significantly improved the ALP activity at 4 and 14 days respectively (P ＜ 0.05).At 4 days,the expression of ALP protein was significantly decreased in the NPY + DKK1 group and the NPY + NPY receptor antagonist group compared with that in the NPY group (P ＜ 0.05).Although the expression levels of [β-catenin and p-GSK-3β protein were uninfluenced in either case,NPY significantly stimulated the nuclear signaling activity of β3-catenin.Conclusions NPY may significantly increase the expression of ALP protein in MC3T3-E1 ceils during osteoblastic differentiation.This effect might be mediated through the canonical Wnt signaling pathway.
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BACKGROUND:Reducing blood loss could help to prevent the complications of total knee arthroplasty, relieve the swelling and discomfort postoperatively and accelerate the rehabilitation. OBJECTIVE:To explore the methods for reducing blood loss during total knee arthroplasty. METHODS:Totally 63 patients undergoing primary unilateral total knee arthroplasty were divided into two groups. Group 1 included 27 patients who received the conventional surgical techniques using tourniquet during the whole procedure with wound drainage, as control group. Group 2 included 36 patients who received the modified procedure only using tourniquet during prosthesis implantation without wound drainage, as experimental group. In the experimental group, we stitched the capsule closely. The preoperative and postoperative hemoglobin, decrease of hemoglobin, knee pain score, range of motion blood transfusion rate and wound healing were compared between the two groups. RESULTS AND CONCLUSION:(1) There was no significant difference in preoperative hemoglobin between the two groups. At 1, 4 and 7 days postoperatively, the hemoglobins were significantly lower in the control group than in the experimental group, and the decreases of hemoglobins were significantly lower in the control group than in the experimental group. (2) Knee pain score was not significantly different between the two groups. (3) The range of motion of the knee was significantly larger in the experimental group than in the control group at 7 days. (4) Blood transfusion rate was 18.5%in the control group, and wound healing was poor in one patient. There was no transfused case and wound problem in the experimental group. All wounds were healed normally. (5) There was no infection or hematoma in two groups. (6) With the modified procedure, we could reduce blood loss during total knee arthroplasty without blood transfusion after surgery, which was helpful to postoperative rehabilitation.
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BACKGROUND:Vascularuzed fibular graft is one of the effective methods for repair of large segmental bone defects in the extremities OBJECTIVE:To explore the clinical effects of vascularized fibular graft for repairing large segmental bone defects in the extremities. METHODS:Twenty-eight non-malignant patients who received vascularized fibular graft for repairing large segmental bone defects in the extremities and were folowed up for more than 20 months were enroled. After lesion removal, vascularized fibula bone graft was used to repair the bone defects. If cases combined with soft tissue defects, fibula flap or anterolateral thigh flap was adopted. RESULTS AND CONCLUSION: Al patients were folowed up for 20 months to 6 years. The grafted bones were healed with the surrounding bone at 3-8 months after fibula bone grafting. The grafted bone was enlarged near to the diameter of recipient bone at 10-22 months after grafting. Based on the Enneking system, the average score of large segmental tibia bone defects was 24.2 points with 81% limb function recovered and 94.1% patient satisfaction; the average score of large segmental femur bone defects was 26.3 points with 87.7% limb function recovered and 100% patient satisfaction; the average score of large segmental bone defects of the distal radius and ulna was 21.75 points with 72.5% limb function recovered and 100% patient satisfaction. These findings reveal that vascularized fibular graft for repairing large segmental bone defects in extremities can effectively promote bone healing and reduce disability, infection, amputation rate; moreover, patients are satisfied with the postoperative recovery of limb function.
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BACKGROUND:Recently, the number of elder patients with femoral neck fracture increased. It is controversial if patients aged over 75 years should receive total hip replacement or hemiarthroplasty. To select a reasonable surgical manner is of great significance for increasing surgical safety, improving hip joint function, elevating quality of life, decreasing postoperative complications, and reducing revision rate. OBJECTIVE:To retrospectively analyze data of patients aged over 75 years after hip replacement, to compare the advantages and disadvantages, and to find a precise indication. METHODS:Case data of 171 patients undergoing total hip replacement (observation group) (n=51) or hemiarthroplasty (control group) (n=120) were included. Their differences were compared using basic diseases, operation time, bleeding amount, postoperative complications, postoperative hospitalization day, Harris score at 1 week and 3 months after operation. RESULTS AND CONCLUSION:Patients in both groups were fol owed up for 3 to 39 months (averagely 23 months). No significant difference in basic diseases, average age, postoperative complications, postoperative hospitalization day, and Harris score at 1 week was detected between the two groups (P>0.05). Harris score and excellent and good rate at 3 months were better in the total hip replacement group than that in the hemiarthroplasty group (P<0.05). Results indicated that strict choice of indication achieved good short-period efficiency in two groups. Thus, hip function of elder patients was early recovered. Quality of life was obviously elevated. The recovery of hip function was relatively better at 3 months in observation group. The incidence of postoperative complications did not increase obviously. These results suggested that besides sufficient preparation, total hip replacement should be the first choice for elder patients.
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BACKGROUND:The number of complications after hip replacement, such as infection, implant loosening, fracture prosthesis wear, osteolysis, and recurrent dislocation, had drastical y increased. These complications would induce the increased occurrence of total hip revision. OBJECTIVE:To analyze the causes and treatment measures of revision after total hip replacement. METHODS:The reasons for revision, the prosthesis selection, the treatment of bone defect and the postoperative rehabilitation were discussed in 33 cases after total hip replacement. The prosthesis for revision included general metal ring and lining (21 cases), large head and cup (8 cases), polyethylene cup (4 cases), general femoral components (15 cases, including 11 cases fixed by bone cement), and lengthening femoral components (18 cases, including 9 cases fixed by bone cement and 6 cases of combined components). RESULTS AND CONCLUSION:Al 33 patients were fol owed up for 24-60 months, averagely 36.5 months. After revision, wound healed perfect, and the prosthesis was reliable. No case suffered from infection or dislocation. Hip joint function was greatly improved. Harris score was increased from 37.1 preoperatively to 91.3 postoperatively. Medium-or short-period clinical fol ow-up results demonstrated that if the indication of revision was right, bone defects were handled perfectly, prosthesis was chosen correctly, one-stage total hip revision can get a good clinical efficacy.
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BACKGROUND:Differences of knee anthropometry between individuals are significant, while preoperative templating is not accurate in predicting the prosthesis size. OBJECTIVE:To improve the accuracy of pre-operative plan in predicting the prosthesis size in total knee arthroplasty using digital technologies. METHODBetween January 2013 and May 2004, 50 patients (20 men and 30 women;aged 54-82 years;mean age, 67.8 years) received primary total knee arthroplasty for osteoarthritis and were retrospectively analyzed. According to the treatment, the patients were divided into two groups. The digital group, a series of 21 patients, underwent 64-row MDCT before total knee replacement. CT images were imported into Mimics, and three-dimensional models of femur and tibia were reconstructed. Then, computer-aided design files of different sizes of prostheses provided by the manufacturers were imported into Mimics, too. Surgical simulation of osteotomy and prostheses implantation were performed in Mimics, component size was determined by the contour of distal femur and proximal tibia. The control group, a series of 29 patients, underwent primary total knee arthroplasty using conventional approaches. The agreement between preoperative plan and the actual prosthesis size was assessed during the surgery. Postoperative X-ray of low limb was taken to evaluate the accuracy of sizing and the efficacy of digital technologies was assessed. RESULTS AND CONCLUSION:The intraoperative and postoperative evaluation showed inaccurate sizing of femoral and tibial components in 1 case in digital group and in 11 cases in conventional group. The accuracy of prediction was 95%in digital group and 62%in conventional group, with significant differences between the two groups (P<0.05). Four overhanging and two notching cases were observed in conventional group, but none in digital group. The digital technologies provide an effective means for accurate prediction of prosthesis size and personalized surgical simulation.
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BACKGROUND:For the patients with proximal humeral fractures or serious complications, internal fixation is the effective method that cannot influence the activity of the shoulder with few trauma. OBJECTIVE:To investigate the biomechanical characteristics of percutaneous plate combined with anatomical locking plate fixation for the treatment of proximal humeral fractures. METHODS:Seventy-five patients with proximal humeral fractures were selected from Department of Orthopedics, the Third Affiliated Hospital of Guangzhou Medical University between March 2007 and December 2011. The healing after the locking plate fixation and the shoulder joint score after internal fixation were observed. The biomechanical advantages of locking plate fixation in the treatment of proximal humeral fractures were analyzed. RESUTLS AND CONCLUSION:Al the 75 patients were fol owed up for 6-24 months, average 13.3 months. The X-ray film after treatment showed al the screws were in correct position with satisfactory fracture reduction, and the fractures were healed without neurovascular injury and humeral head necrosis;one case had infection and healed after treatment, 72 cases had no shoulder pain, while three cases had occasional shoulder pain. The Neer score was excel ent in 57 cases, good in 11 cases, moderate in seven cases and poor in none, and the excel ent and good rate was 90.7%. Compared with other fixation implants, the locking plate fixation in the treatment of proximal humeral fractures has the advantages of high fixation strength and satisfactory effect, becoming the first choice for the clinical treatment of proximal humeral fractures.