Undermining in a wound refers to a separation of the wound edges from the surrounding healthy tissue, often creating a "pocket" under the wound surface. It is a type of wound complication that can occur when a wound is not healing properly. Undermining can be caused by various factors, including pressure, shear, moisture, and infection, which can cause the wound to enlarge and prevent proper healing.

Undermining can have a significant impact on wound closure and healing, as the separation of the wound edges from the surrounding tissue can prevent the wound from closing properly. To close an undermining wound, the clinician may need to remove any damaged or infected tissue, clean the wound and control infection, and promote granulation tissue formation.

Undermining can also refer to a surgical technique used to free the wound edges and decrease tension on the wound, allowing for faster wound healing and less chance of scar spreading and keloid formation. However, this technique cuts blood vessels and nerves, which can slow wound healing and create an area of anesthesia that is generally temporary.

In summary, undermining in a wound can refer to a separation of the wound edges from the surrounding healthy tissue or a surgical technique used to free the wound edges. It can be caused by various factors and can have a significant impact on wound closure and healing.