Hypertensive leg ulcer, also called Martorell ulcer, represents 1 to 15% of leg ulcers in hospital. These ulcers are painful, long to heal, and hospitalization is sometimes necessary for analgesia and debridement of necrotic tissue. Strong opioids are often required, and are responsible of many side effects. Martorell ulcer arises predominantly in women over 60 years of age, with history of vascular disease, and therefore with a higher risk of adverse event. Pain is also part of the physiopathology, inducing a vasospasm which increases ulcer extension and ischemia.

This is why pain management is one of the main challenge in treatments of these ulcers.

Continuous nerve block of lower limbs are often used during per and postoperative orthopaedic surgery. Few adverse events and rare serious adverse events related to local anesthesic are reported (respectively <1% and <1/1000), and few adverse events related to catheter are reported (<1%). Its benefits have been proved on post-operative pain management and reeducation.

The aim of this study is to assess analgesia provided by continuous sciatic nerve block, in patients with hypertensive leg ulcer, during hospitalization.

Thirty patients will be enrolled on a 3-years period. They will receive a continuous sciatic nerve block with ropivacaïne 0,2%, during 7 days.

Pain intensity will be assessed by 4 datas : numerating rating scale (NRS) at rest, during wound care, maximal and mean. These datas will be collected over two 3-days period : the first 3 days of hospitalization, in which pain treatment will be prescribed depending on pain intensity of the patient ; and the first 3 days of ropivacaïne treatment.

The main evaluation criteria will be at least a 50% decrease of one of the pain NRS when receiving ropivacaïne.

Time to healing, microcirculation evolution measured by Transcutaneous Oxygen Pressure (TcPO2), and quality of life of patients will be collected over a 6 months follow-up.

Inclusion Criteria:

• Age >18 years old
• Hospitalized for hypertensive leg ulcer with severe pain :
• For which pain intensity has been collected over the first 3 days before catheter insertion (D0)
• With severe pain (mean or at wound care) in spite of acetaminophen treatment (NRS ≥ 5/10), and/or with adverse events related to weak or strong opioids.
• patients' written informed consent obtained

Exclusion Criteria:

• Patients with moderate pain after 3 days of usual pain management in hospitalization : mean NRS<5/10 the 24 hours before D0
• pregnant women
• other ulcer causes, local or systemic infection
• not able to provide informed consent or to answer the pain evaluation
• dialysis patients
• unstable active diseases
• Charcot foot
• Known allergy to any local anesthetics
• Ankle-brachial index <0,6
• hemodynamically significant stenosis on arterial Doppler ultrasound
• current clopidogrel or prazugrel treatment the 10 days preceding catheter insertion
• current clopidogrel or prazugrel treatment the 10 days preceding catheter insertion, with contraindication to salicylic acid
• current anticoagulant treatment, with contraindication to LMWHs or UFH