Application of Ice for Postoperative Total Knee Incisions - Does this Make Sense? A Pilot Evaluation of Blood Flow Using Fluorescence Angiography

Abstract

Introduction Total knee arthroplasty (TKA) is a common procedure with significant advances over the past several years, many pertaining to improved perioperative pain control. Cryotherapy is one method thought to decrease swelling and pain postoperatively. To our knowledge no study has directly visualized the effect cryotherapy has on skin blood flow following TKA. The primary aim was to determine if cryotherapy (icing) affects peri-incisional skin blood flow and if this is lessened with an alternate placement of the ice. We hypothesized that blood flow would decrease following cryotherapy, and this decrease would be greater with ice placed directly over the incision as compared to placement along the posterior knee. Methods This study included 10 patients who underwent TKA. During the postoperative hospitalization, they were given an injection of indocyanine green dye. A baseline image was recorded of the skin blood flow. Images were then collected following a five-minute interval placement of ice over the incision. The experiment was then repeated with the ice placed along the posterior knee. Results There was an approximate 40% decrease in skin blood flow following placement of the ice compared to baseline. We observed a greater decrease in blood flow when ice was placed over the incision as compared to when ice was placed posterior to the knee (p ≤ 0.020). Conclusion We found a significant decrease in peri-incisional blood flow with icing of the knee. Physicians should be cognizant of this when recommending cryotherapy to patients after surgery, especially in at-risk wounds.

Keywords: blood flow; cryotherapy; fluorescence angiography; pain; total knee arthroplasty.

Figure 1. A baseline image is shown in (A), followed by an image captured immediately after the ice was removed from the anterior (incisional) knee (B). The ImageJ capture points are shown in (C) and (D) for the respective photos

The indocyanine green dye within the blood vessels shows up as white on the images, while dark areas are devoid of blood flow.

Figure 2. A baseline image of the blood supply to the knee (A), followed by five minutes of icing to the posterior aspect of the knee (B)

Note the reduced blood flow following icing compared to the baseline image.

Figure 3. Percentage change in blood flow from baseline for incisional and posterior areas of the knee