| Research Purpose:In this study,two flexion angles(30 degree、45 degree)and three flexion durations(6h、24h、48h)were selected for a 2×3 cross combination using the factorial design analysis method.By comparing the effects of different flexion positions postoperatively on blood loss and knee function in patients with total knee arthroplasty,in order to find out the optimal angle and the duration of flexion postoperatively after total knee arthroplasty.Research Methods:From January 2019 to December 2019,we selected 102 patients who were clinically diagnosed with primary knee osteoarthritis and underwent unilateral total knee arthroplasty under general anesthesia in the Department of three level of first-class comprehensive hospital.The factorial design was used,factor 1 are: knee flexion angle,and the two levels are flexion 30 degree and flexion 45 degree respectively.Factor 2 was the the duration of flexion,and the three levels were flexion for 6h,24 h and 48 h respectively.The patients were divided into six groups of A1,A2,A3,B1,B2 and B3 by stratified randomization,with 17 patients in each group.Group A1: knee flexion 30 degree,maintained for 6h;group A2: knee flexion 30 degree,maintained for 24h;Group A3,knee flexion 30 degree,maintained for 48 h.Group B1: knee flexion 45 degree,maintained for 6h;group B2: knee flexion 45 degree,maintained for 24 hours;group B3: knee flexion 45 degree,maintained for 48 h.Blood routine examination was performed on the 3rd day after surgery to calculate the total blood loss and hidden blood loss.On the 3rd and 7th day after surgery,the range of motion(ROM)of the affected limb was measured with a standard hand-held joint angle protractor,and the knee function was evaluated with the hospital for special surgery knee function scale(HSS score scale).The incidence and transfusion rate of wound infection,subcutaneous ecchymosis,deep vein thrombosis and other related complications were recorded within one week after surgery.Research Results:1.Blood loss:(1)Total blood loss: The total blood loss after surgery in the six groups was arranged from small to large: B2 < A3 < B3 < A2 < B1 < A1.The main effect of different flexion angles on total blood loss after surgery was not significant(P=0.477 > 0.05);the main effect of the different durations of flexion on total blood loss after surgery was significant(P=0.031 < 0.05);and there was no interaction effect of different flexion angles and the durations of flexion on total blood loss(P=0.657 > 0.05).Furthermore,the total blood loss of patients in different durations of flexion groups was compared: the total blood loss of patients in flexion 6h group was greater than that in flexion 24 h group and 48 h group(P=0.016 < 0.05,P=0.031 < 0.05);the total blood loss of patients in flexion 24 h group and 48 h group was not statistically significant(P=0.801 >0.05).(2)Hidden blood loss: The hidden blood loss in the six groups was arranged from small to large: B2 < A3 < B3 < A2 < B1 < A1,and the proportion of hidden blood loss in the total blood loss was 42.55% ~ 48.83%.The main effect of different flexion angles on postoperative hidden blood loss was not significant(P=0.613 > 0.05),the main effect of different durations of flexion on postoperative hidden blood loss was significant(P=0.047 < 0.05),and there was no interaction effect of different flexion angles and different durations of flexion on postoperative hidden blood loss(P=0.877 > 0.05).Furthermore,the hidden blood loss of patients in different durations of flexion groups was compared: the hidden blood loss in the 6h flexion group was greater than that in flexion 24 h group and 48 h group(P=0.029 < 0.05,P=0.035 < 0.05),and there was no significant difference between the 24 h flexion group and the 48 h flexion group(P=0.936 > 0.05).2.ROM(1)On the 3rd day after surgery,ROM in the six groups was arranged from large to small:B2 > B3 > A3 > B1 > A2 > A1;on the 7th day after surgery,ROM was arranged from large to small: B2 > A3 > B3 > A2 > B1 > A1;ROM on the 7th day after surgery was higher than that on the 3rd day after surgery in the six groups.(2)Intra-group effect analysis showed that the change of ROM after surgery had a time effect,and the difference between ROM on the 3rd and the 7th was statistically significant(P=0.000 < 0.01).Different measurement time and different flexion angle had interaction effect on postoperative ROM(P=0.041 < 0.05),but no interaction effect with different durations of flexion(P=0.067 > 0.05).(3)The intergroup effect analysis showed that the main effect of different flexion angles on postoperative ROM was significant.The postoperative ROM of patients in the flexion 45 degree group was higher than that of patients in the flexion 30 degree group,and the difference was statistically significant(P=0.023 < 0.05).The main effect of different durations of flexion on postoperative ROM was significant(P=0.003 < 0.01).Different flexion angles and different durations of flexion had interactive effects on postoperative ROM(P=0.013 < 0.05).Furthermore,the ROM of patients in different durations of flexion groups was compared: the ROM of 24 h flexion group and 48 h flexion group was significantly larger than that of 6h flexion group(P=0.001 < 0.01,P=0.007 < 0.01).There was no significant difference between 24 h flexion group and 48 h flexion group(P=0.601 > 0.05).3.HSS score(1)On the 3rd day after surgery,the HSS scores of the six groups were arranged from large to small: B2 > B3 > B1 > A2 > A3 > A1;on the 7th day after surgery,the HSS scores were arranged from large to small as B2 > A3 > B3 > B1 > A2 > A1.The HSS score of the six groups on the 7th day after surgery was higher than that on the 3rd day after surgery.(2)Intra-group effect analysis showed that postoperative HSS score had a time effect,and the difference between HSS score on the 3rd day after surgery and that on the 7th day after surgery was statistically significant(P=0.000 < 0.01).Different measurement time and different flexion angle had no interaction effect on HSS score(P=0.975 > 0.05),and no interaction effect with different durations of flexion(P=0.109 > 0.05).(3)The intergroup effect analysis showed that the main effect of different flexion angles on postoperative HSS score was significant.The postoperative HSS score of patients in the flexion 45 degree group was higher than that of patients in the flexion 30 degree group,and the difference was statistically significant(P=0.021 < 0.05).The main effect of different durations of flexion on postoperative HSS score was significant(P=0.019 < 0.05).Different flexion angles and different durations of flexion had an interactive effect on postoperative HSS score(P=0.017 < 0.05).Furthermore,the HSS score of patients in different durations of flexion groups was compared: the postoperative HSS score of 24 h flexion group was significantly higher than that of 6h flexion group(P = 0.006 < 0.01),and there was no significant difference compared with 48 h flexion group(P = 0.062 > 0.05);there was no significant difference between 6h flexion group and 48 h flexion group(P = 0.350 > 0.05).4.Related complications:There were no statistically significant differences in the incidence of incision infection,subcutaneous ecchymosis,deep vein thrombosis and other postoperative complications and blood transfusion rates among the six groups within one week after surgery(P > 0.05).Research Conclusion:1.Blood loss:(1)Flexion angle and the duration of flexion play an independent role in reducing the total and latent blood loss.(2)The total blood loss and hidden blood loss were independent of the knee flexion angle.(3)The duration of flexion is too short(6h),which has limited effect on reducing the total blood loss and the hidden blood loss.Knee flexion can effectively reduce the total blood loss and the hidden blood loss within 24 h.2.ROM:(1)After total knee arthroplasty,the affected limb was in flexion position,and the change of ROM after surgery had a time effect,that is,the ROM was gradually improved with the extension of time,while the postural strategy of flexion 45 degree and maintenance of 24 h had the most significant effect on improving ROM.(2)The effect of measurement time on ROM will be affected by the flexion angle,but not by the duration of flexion.(3)After total knee arthroplasty,the ROM will be significantly different due to the flexion angle(30 degree,45 degree)and the duration of flexion(6h,24 h,48h),and the flexion angle and the duration of flexion will affect each other to improve the effect of ROM.(4)After total knee arthroplasty,knee flexion 45 degree has a better effect on improving postoperative ROM than flexion 30 degree.The improvement of postoperative ROM is not positively correlated with the duration of flexion.Short-term knee flexion(6h)has limited effect on improving ROM.3.HSS score:(1)After total knee arthroplasty,knee flexion posture was adopted,and the postoperative HSS score had a time effect,that is,the HSS score was increased with the extension of time,and the posture strategy of flexion 45 degree and maintenance of 24 h had the most significant effect on the improvement of HSS score.(2)The effect of measurement time on HSS score was not affected by the size of flexion angle and the duration of maintenance.(3)After total knee arthroplasty,the HSS score was significantly different due to the flexion angle(30 degree,45 degree)and the duration of flexion(6h,24 h,48h),and the flexion angle and the duration of flexion had an effect on the improvement of HSS score.(4)After total knee arthroplasty,knee flexion 45 degree had a better effect on improving postoperative HSS score than flexion 30 degree.Short-term knee flexion(6h)had a limited effect on improving postoperative HSS score,while knee flexion 24 h could effectively improve the effect of postoperative HSS score.4.Postoperative complications:Low knee angle(≤45 degree)and short duration of knee flexion(≤48h)after total knee arthroplasty did not increase the incidence of related complications and transfusion rate,and the postural strategy of knee flexion 45 degree within 24 hours after total knee arthroplasty was safe.In summary,knee flexion 45 degree 24 h after surgery is the best limb management strategy to effectively reduce total and hidden blood loss and improve knee function after total knee arthroplasty. |
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