Excised host tissues weight: New Indicators of Total Knee Arthroplasty Worthy of Attention

Abstract

Background: Knee osteoarthritis (KOA) is a crippling disease and affects many people around the world. Total knee arthroplasty (TKA) is an effective way to treat this disease. The objectaives of this study to compare the weight of the total knee arthroplasty implants and the weight of the natural knee in different groups and also to analyze facts which may affect the weight of surgical host excision. Methods: In total, 105 consecutive TKAs were enrolled in this prospective cohort study with three different brands of knee prostheses. Patients meeting the criterion were divided into the normal bone mass group, the osteopenia group or the osteoporosis group according to the results of preoperative bone density examination. The removal of bone and soft tissues that were collected during TKA operations of each group were weighed and compared with the total weight of the knee prosthesis (including implanted bone cement). Multivariate logistic stepwise regression analysis was conducted to identify indicators affecting host removal weight.Results: The average host removal weight was (132.56±36.88)g for normal bone mass group, (112.86±23.65)g for osteopenia group and (103.74±20.66)g for osteoporosis group. There were statically differences among the three groups. There was a significant difference between the normal bone mass group and the osteopenia group (P=0.003), while no difference between the osteopenia group and the osteoporosis group (P=0.154). No differences were found in the TKA components weight, bone cement weight and knee joint weight gained after TKA among all groups. Stepwise multiple regression analysis using the weight of excised host tissues as a dependent variable and BMD level, gender, age and other available indicators as independent variables revealed that BMD level(B=9.057, p=0.008), gender(B=21.692, p<0.001), Kellgren-Lawrence grade(B=13.790, p=0.003) are significant factors affecting excised host tissues weight. Conclusion: There is a positive correlation between the weight of the host removals of TKA and the patient's bone density. BMD level, gender and K-L stage of KOA were the main factors affecting the weight of the host removal.