Chronic ulcers or non-healing ulcers are defined as spontaneous or traumatic lesions, typically in lower extremities that are unresponsive to initial therapy or that persist despite appropriate care and do not proceed towards healing in a defined time period with an underlying etiology that may be related to systemic disease or local disorders.

There are many types of non-healing ulcers that may include venous, arterial, diabetic, pressure, and traumatic ulcers. The normal wound healing process is dynamic and complex having three phases: inflammation, tissue formation, and tissue remodeling.