I've had three knee surgeries, two knee replacements and one revision of the right knee. The last surgery they used a different type of dressing. I don't know if it fits your situation but it might. The vacuum pump discussed was simply a small portable devise, battery powered, about the size of a deck of cards but lighter.

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Vacuum-assisted closure (VAC) is a method of decreasing air pressure around a wound to assist the healing. It’s also referred to as negative pressure wound therapy.

During a VAC procedure, a healthcare professional applies a foam bandage over an open wound, and a vacuum pump creates negative pressure around the wound. This means the pressure over the wound is lower than the pressure in the atmosphere. The pressure pulls the edges of the wound together.