An Unna boot is a special dressing of inelastic gauze impregnated with zinc, glycerin, or calamine that becomes rigid when it dries. It is used for managing venous leg ulcers and lymphedema in patients who are ambulatory. When the patient walks, the rigid dressing restricts outward movement of the calf muscle, which directs the contraction force inward and improves the calf-muscle pumping action, thereby improving venous flow. An Unna boot does not provide compression and is contraindicated for arterial insufficiency.
How to apply an Unna boot
Follow these steps:
1 Gently wash and dry the extremity and apply moisturizer.
2 Clean any wound that is draining and apply an appropriate topical dressing. The topical product should be one that can remain in place for several days without changing.
3 Flex the patient’s foot to 90 degrees and maintain that position throughout the application.
4 Begin applying the bandage on the top of the foot at the base of the toes.
5 Wrap twice around the base of the toes without tension.
6 Continue wrapping up the leg using a spiral technique and overlapping each previous layer by 75%. The bandage should be loosely wrapped around the foot and heel and around the leg in a spiral fashion; do not use tension. This technique covers the leg with at least two layers.
7 Continue to wrap to 1 inch below the knee (one fingerwidth below the posterior bend of the knee).
8 As you wrap, smooth and mold the bandage with your hands. Cut the bandage as needed to prevent wrinkles, pleats, and folds. Restart the wrap where the bandage was cut.
9 Cut any excess bandage upon reaching the knee.
10 According to specific product instructions, apply a cover wrap, usually an elastic or cohesive bandage, using 50% overlap.
- Start the cohesive wrap at the center of the ball of the foot, with the lower edge at the base of the toes.
- Continue wrapping up the foot with 50% overlap.
- Upon reaching the heel, pull 6 to 7 inches of bandage away from the roll. While the bandage is stretched, wrap it around the heel area.
- When reaching the ankle, stretch the bandage out another 6 inches followed by relaxing the bandage back to 50% tension.
- Wrap around the ankle two turns at 50% tension.
- Continue wrapping up the leg with 50% tension and 50% overlap, stopping at the top of the paste bandage. NOTE: An overlap of 50% more or less will result in inconsistent higher and lower compression pressures.
- Cut any excess bandage upon reaching the top.
11 Observe the skin distal to the bandage for adequate circulation (color, pulse, warmth).
12 Secure the wrap with tape. Initial and date the wrap.
These tips will help you apply the Unna boot and manage it appropriately.
- Wrap from the toes upward to below the knee.
- Apply the boot in a spiral fashion, with 75% overlap.
- Apply the boot directly over any wound. You don’t need a separate dressing unless the wound is draining.
- Cut the boot frequently during application to avoid pleats, folds, or wrinkles that may cause skin damage as the boot dries.
- An Unna boot can stay in place for 3 to 7 days, but should be changed when the wrap begins to loosen or if it becomes saturated with drainage.
- If your patient has to take a shower, wrap a towel around the top of the boot, cover the lower leg with a plastic bag, secure the top with an Ace wrap, and drape the excess plastic over the Ace wrap.
How to remove an Unna boot
Here is guidance for removing an Unna boot:
- You can use bandage scissors to remove the boot (or unwrap it).
- Start at the bottom of the boot and cut upward to the ankle.
- Cut on the side opposite of the ulcer, and use caution to keep the scissors away from the anterior tibial area to prevent trauma.
Nancy Morgan, cofounder of the Wound Care Education Institute, combines her expertise as a Certified Wound Care Nurse with an extensive background in wound care education and program development as a nurse entrepreneur. Read her blog “Wound Care Swagger.”