To analyse the timing and location of deep vein thrombosis (DVT) formation in the lower limbs of patients after total knee arthroplasty (TKA) by ultrasonography.

The clinical data of 1 108 patients underwent primary unilateral TKA in Luoyang Orthopedic-Traumatological Hospital of Henan Province from January to December 2023 were retrospectively studied. The formation of DVT in each time period was recorded and analyzed. The time and location of thrombus formation were analyzed, and the daily thrombus formation rate were calculated.

The DVT formation rate after TKA was 42.3%. The thrombus formation rate was higher from the day of surgery to the second postoperative day, accounting for 98.0% of the total thrombi; few thrombi formed from the third to the fifth postoperative day. From the sixth to the eighth postoperative day, the thrombus formation rate began to rise again, and the thrombi formation after the sixth day accounted for 2.0% of the total thrombi. As for the thrombus formation site, the single-vessel thrombus formation rate was 74.2%, of which the proximal thrombus formation rate was 9.0% and the distal thrombus formation rate was 91.0%; the multi-vessel thrombus formation rate was 25.8%, and the proximal thrombus complicated with multi-vessel thrombus formation rate was 78.6%.

After primary TKA, the first two days is the peak period of thrombosis, three to five days shows no thrombus formation, and six to eight days may form a small amount of thrombus; therefore, for primary TKA, thrombus screening at the third day after surgery can improve the detection rate of DVT, and the distal vein should be examined after the proximal thrombus is detected, which is conducive to the discovery and the treatment of DVT, and to prevent serious complications.