The aim of this prospective study is to assess the utility of treatment of leg ulcers using a skin substitute, Integra®, assessing the quality of wound skin healing and transcutaneous oxygen pressure in the distal region of the wound.

This is a multi-centre study on 60 patients who have a lower limb ulcer.

Inclusion Criteria:

• patient with a lower limb ulcer, regardless of origin (arterial, venous or mixed, diabetic foot ulcer) present for more than 6 months or large in size (> 10 cm²)
• patients in whom the surgeon has recommended that an Integra® matrix be implanted (even if the patient is not taking part in the study) before the dermo-epidermal graft to obtain a richly vascularised neodermis.
• not eligible for skin flap surgery,
• the patient or patient's representative has agreed to sign the information letter before any investigation required by the research.

Exclusion Criteria:

• circumferential wound,
• wound infection
• immunosuppressed patient,
• known allergy to bovine collagen, bovine glycosaminoglycans or silicone,
• patients under legal guardianship,
• pregnant women
• patients whose health would compromise follow-up for at least 18 months,
• patients whose mental health would compromise completion of the self-evaluation questionnaires.
• wound located in an area not visible by the patient (as no self-assessment would be possible).

The study population will be patients with "difficult" lower limb ulcers, whose wounds have not responded to directed healing for more than 6 months or who have a wound > 10 cm².