Following Total Knee Replacement (TKA), lower limb edema reduces the efficacy of surgery. The lack of a categorization of swelling causes using adequate medical tests is the source of the dismal outcomes of trials on therapies for swelling. There’s no gold standard here. By interviewing a wide variety of specialists from other fields, this study attempted to clarify the reasons of TKA postoperative edema and how to identify them through signs and medical testing. The results of a thorough examination of the literature and diverse expert consultation are trustworthy and scientific. After TKA, there were several reasons of edema in the lower extremities. Blood test results might reveal an inflammatory reaction, inadequate venous return, muscle injury, and the status of recovery.