Objective To investigate the effects of patient bone mass differences on the stability of unicondylar knee arthroplasty(UKA)prostheses.Methods A UKA finite element model was established to quantify the effects of five different bone quality conditions on the proximal tibial von Mises stress,bone-prosthesis fixation interface contact stress,and bone-prosthesis fixation interface micromotion,using the medial knee force and joint motion predicted by the individualized UKA musculoskeletal multibody dynamics model as boundary conditions.Results The influences of bone strength on the proximal tibia von Mises stress and bone-prosthesis fixation interface contact stress were not obvious,and the difference in peak values of the proximal tibia von Mises stress between two groups of models with the largest difference in bone strength was not more than 5％,and the difference in peak values of the bone-prosthesis fixation interface contact stress was only 2.37 MPa.However,the influence of bone strength on the bone-prosthesis fixation interface micromotion was significant,and the weaker bones were more prone to cause the bone-prosthesis fixation interface micromotion.However,bone strength had a significant effect on the bone-prosthesis fixation interface micromotion,and weak bone was more likely to cause changes in the bone-prosthesis fixation interface micromotion.Compared to patients with the neutral bone quality,the prosthesis fixation interface micromotion increased by 84.67％at 20％gait cycles for patients with the weakest bone quality.Conclusions UKA patients with a weaker bone quality have a higher risk of prosthesis loosening.It is recommended that surgeons should carefully choose their surgical strategy in order to reduce the rate of postoperative revision in UKA.

Objective To investigate the effects of patient bone mass differences on the stability of unicondylar knee arthroplasty(UKA)prostheses.Methods A UKA finite element model was established to quantify the effects of five different bone quality conditions on the proximal tibial von Mises stress,bone-prosthesis fixation interface contact stress,and bone-prosthesis fixation interface micromotion,using the medial knee force and joint motion predicted by the individualized UKA musculoskeletal multibody dynamics model as boundary conditions.Results The influences of bone strength on the proximal tibia von Mises stress and bone-prosthesis fixation interface contact stress were not obvious,and the difference in peak values of the proximal tibia von Mises stress between two groups of models with the largest difference in bone strength was not more than 5％,and the difference in peak values of the bone-prosthesis fixation interface contact stress was only 2.37 MPa.However,the influence of bone strength on the bone-prosthesis fixation interface micromotion was significant,and the weaker bones were more prone to cause the bone-prosthesis fixation interface micromotion.However,bone strength had a significant effect on the bone-prosthesis fixation interface micromotion,and weak bone was more likely to cause changes in the bone-prosthesis fixation interface micromotion.Compared to patients with the neutral bone quality,the prosthesis fixation interface micromotion increased by 84.67％at 20％gait cycles for patients with the weakest bone quality.Conclusions UKA patients with a weaker bone quality have a higher risk of prosthesis loosening.It is recommended that surgeons should carefully choose their surgical strategy in order to reduce the rate of postoperative revision in UKA.

Objective To investigate the biomechanical effects of the backside design of tibial trays on the bone-prosthesis fixation interfaces in unicompartmental knee arthroplasty(UKA).Methods Finite element models of medial knee arthroplasty were constructed using a fixed UKA prosthesis.The knee joint load and joint motion under walking motion were considered as boundary conditions,and the differences in tibial von Mises stress,contact stress,and micromotion of the bone-prosthesis fixation interface of the UKA tibial trays with big keel,small keel,two-peg with fin,three-oblique peg,and three-upright peg types were compared.Results At the maximum medical knee force moment,compared to the two-peg with fin type,the tibial von Mises stress,contact stress,and micromotion of the bone-prosthesis fixation interface decreased by 8%and 15.9%and increased by 9.9%for the big keel type;decreased by 12.3%and increased by 7.5%and 0.9%for the small keel type;decreased by 10%,10.5%,and increased by 1.2%for the three-oblique peg type;and decreased by 7.7%,14.7%,and 1.6%for the three-upright peg type,respectively.However,the maximum micromotion of the bone-prosthesis fixation interface occurred at 21%of the gait cycle.Compared to the two-peg with fin type,the micromotion of the bone-prosthesis fixation interface increased by 11.6%for the big keel type,increased by 1.6%for the small keel type,decreased by 0.4%for the three-oblique peg type,and decreased by 2.3%for the three-upright peg type.Conclusions To improve the long-term fixation effects of tibial prostheses,it is recommended to focus on a two-upright peg with fin or small keel designs when UKA tibial trays are designed,which can effectively balance the stress transfer and interface micromotion,thereby ensuring prosthesis stability and reducing the risk of aseptic loosening.

Humans ; HIV Infections ; HIV-1 ; Integrases ; China ; Drug Resistance, Viral ; Mutation

BACKGROUND:Intramedul ary nails and locking plates are widely used for two-part proximal humerus fracture. Which is better for two types of implants in patients remains controversial. OBJECTIVE:To determine the clinical outcome of intramedul ary nails versus locking plates for two-part proximal humerus fracture according to Cochrane Meta analysis. METHODS:We searched PubMed, SCI, Embase, the Cochranel Library and CBMdisc, VIP information, Wanfang Database, and CNKI for randomized control ed trials and quasi-randomized control ed trials on intramedul ary nails and locking plates for two-part proximal humerus fracture. RevMan 5.2 software was used to analyze operation time, intraoperative blood loss, fracture healing time, postoperative complications (heterotopic ossification, pain, screw penetration, necrosis of humeral head), and Constant Score. RESULTS AND CONCLUSION:Six articles of clinical control ed trials were included with 259 patients. 131 patients received intramedul ary nails, and 128 patients received locking plates. Meta-analysis displayed that no significant difference in fracture healing time, heterotopic ossification, pain, necrosis of humeral head and Constant Score was detected between intramedul ary nails and locking plates for two-part proximal humerus fracture. Operation time, intraoperative blood loss, and screw penetration were significantly less in the fixation with intramedul ary nails than that in locking plates (P<0.05). These findings suggested that compared with locking plates, intramedul ary nails method for two-part proximal humerus fractures could reduce screw penetration.