| Background:Knee osteoarthritis is a common disease with high disability rate in the elderly in China.With the further aggravation of aging society,the incidence rate of knee osteoarthritis has increased significantly.The incidence rate of incidence of knee osteoarthritis in Chinese population aged-60 years is 10%-17%,and the incidence rate of people over 60 years old is increased to 50%.The incidence rate of people over 70 years old is 70%,according to the data.40.In the 20 years of 1990-2010,the incidence rate of knee osteoarthritis in China increased by 45%,and the disability rate ranked second in the world,reaching 21.3%.Total knee arthroplasty(TKA)can effectively relieve the pain of knee joint,increase the range of motion of knee joint,and improve the quality of life of patients.It is the main treatment of middle and late stage osteoarthritis.Total knee arthroplasty(TKA)is a mature surgical technique.However,extensive soft tissue release,osteotomy and synovium dissection are required in TKA,which can cause massive bleeding on the surface of soft tissue and cancellous bone.In addition,the bleeding point under the pressure of tourniquet is not obvious,the posterior capsule field of vision is narrow,hemostasis is difficult and other factors lead to incomplete intraoperative hemostasis,combined with the partial exposure of bone hemorrhage on the intercondylar osteotomy surface of prosthesis,resulting in more postoperative blood loss.According to literature reports,TKA postoperative bleeding as high as 1426-1790ml,a large number of bleeding after blood transfusion,not only consume valuable blood resources,but also lead to a series of complications of postoperative anemia,such as poor wound healing,deep vein thrombosis and pulmonary embolism,which seriously affect the physical and mental health of patients.Therefore,in-depth study of hemostasis measures after total knee arthroplasty,reduce perioperative bleeding,has a very important positive significance.At present,a variety of methods and measures to reduce bleeding after total knee arthroplasty have been reported,such as autologous blood storage and reinfusion,intraoperative blood recovery machine application,reasonable application of tourniquet,improvement of postoperative drainage,limb position placement and application of tranexamic acid.In the above methods,the placement of postoperative limb position and the improvement of postoperative drainage are simple and feasible measures.Clinical reports show that both can significantly reduce the amount of bleeding after TKA.The mechanism of reduction of bleeding after TKA in flexion position is that flexion of knee joint increases the tension of joint capsule and skin around the wound.At the same time,flexion of knee joint makes the vein angle,reduces the speed of venous return and reduces the bleeding of local wound.Postoperative clipping and drainage can cause hematoma in the knee joint cavity,increase the local pressure in the cavity and inhibit the capillary bleeding of the joint capsule,which is called "hematoma packing effect",so as to reduce the bleeding after TKA.In addition,the knee joint cavity is mainly a closed cavity formed by the lower end of femur,the upper end of tibia,patella and joint capsule.With the movement of knee joint,the position of femur,patella and tibia will also move relatively,resulting in the change of joint cavity volume.When the knee joint flexes,the femur and tibia begin to rotate at the midpoint of the rotation center of the knee joint,the patella gradually moves down and falls into the intercondylar fossa,and the volume of the joint cavity decreases accordingly.The volume of articular cavity decreases with the increase of knee flexion angle,which in turn promotes the "hematoma packing effect".It can be seen that maintaining the knee flexion position after knee arthroplasty can reduce the velocity of venous blood return,increase the tension of local joint capsule,reduce bleeding,and maintain the knee flexion position to reduce the volume of knee joint cavity,combined with postoperative clipping drainage.It can form"hematoma packing effect" as soon as possible and form the hemostatic effect of double factors.However,the larger the flexion angle and the longer the maintenance time,the lower the oxygenation of the wound edge and the more complications such as wound necrosis.In addition,the long time of maintaining the knee flexion position and clamping drainage after operation will lead to numbness,pain and other discomfort.The purpose and content of this study is to determine which flexion position the limb should be maintained in after TKA,which can effectively reduce the volume of knee joint cavity,promote the formation of "hematoma packing effect",reduce the bleeding after TKA,and make the patients get good postoperative comfort.Chapter 1 The experimental study on the effect of different knee flexion angles on the volume of knee joint cavityObjective:To study the effect of different knee flexion angles on the volume of knee joint cavity,arid to provide theoretical basis for perioperative blood management of TKA.Methods:28 patients with knee arthroscopic surgery,the knee joint in the extension position,flexion 30 degrees,flexion 45 degrees,flexion 60 degrees,flexion 75 degrees,flexion 90 degrees,intra-articular injection of saline filling,measurement of cavity content product value and comparative analysis.Results:The volume of knee joint cavity was 106±26ml in extension,79±21ml in 30°flexion,62±16 in 45°flexion,54±13ml in 60°flexion,51±12ml in 75°flexion and 50±12ml in 90° flexion.There were significant differences in volume between the two adjacent groups(P<0.001).Conclusion:The volume of knee joint cavity changes with the change of knee flexion angle.The larger the flexion angle is,the smaller the volume of knee joint cavity is.With the gradual increase of knee flexion angle,the trend of joint cavity volume decreasing gradually weakened.Chapter 2 The experimental study on the relationship between different flexion angles and patients’comfort after total knee arthroplastyObjective:To study the relationship between knee flexion angle and knee comfort after TKA,and to provide theoretical basis for perioperative blood management of TKA.Methods:A total of 100 patients with total knee arthroplasty were divided into 5 groups:group A with 30° flexion,group B with 45°flexion,group C with 60° flexion,group D with 75°flexion and group E with 90°flexion.All patients were treated with vacuum drainage for 4 hours.Vas-c was used to score the patients’ comfort 4 hours after operation,and the scores of the two groups were recorded and compared.Results:The vas-c score was 1.55±1.23 in group A,2.00±1.26 in group B,3.55±1.50 in group C,5.00±1.75 in group D and 6.15±1.93 in group E.There was no significant difference between group A and group B(P>0.05),there was significant difference between group B and group C(P<0.05),there was significant difference between group C and group D(P<0.05),and there was significant difference between group D and group E(P<0.05).Conclusion:After TKA,when the angle of knee flexion is lower than 45°and the drainage time is 4 hours,the patient is in a relatively comfortable state.When the angle of knee flexion is 60° or more,the comfort of the patient is significantly decreased and there is obvious discomfort.Chapter 3 The clinical study of hip flexion and knee flexion 45°combined with intra-articular injection of tranexamic acid to reduce postoperative bleeding after knee arthroplastyObjective:To study the effect of knee flexion and hip flexion 45° after TKA combined with tranexamic acid intracavitary injection clamping drainage on postoperative bleeding of knee arthroplasty,so as to provide basis for clinical decision-making.Methods:96 patients after TKA were randomly divided into experimental group and control group.In the experimental group,500 mg tranexamic acid was injected into the articular cavity,and the knee and hip joints were flexed 45 degrees.In the control group,the drainage tubes were clamped for 4 hours.HB reduction,blood loss,blood transfusion,joint range of motion,pain score and knee circumference increment were measured and compared between the two groups.Results:Compared with the control group,Hb decreased 56%,blood loss decreased 32.7%,blood transfusion decreased 23%,pain score decreased 15%,joint range of motion increased 3°and knee circumference increased 25%in the experimental group.There was no complication in both groups.Conclusion:Intra articular injection of tranexamic acid combined with 45 degree hip and knee flexion can effectively reduce the amount of bleeding after TKA without increasing the risk of complications. |
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