The post-operative pain generated by prosthetic knee replacement surgery is known to be moderate to severe during two or three days following surgery.

The most popular analgesic technique after prosthetic knee replacement surgery remains the femoral block (FB), whether in single injection or continuous infusion. In major knee surgery, FBs provide better analgesia compared to systemic morphine and FBs provide the same analgesia that obtained with epidural analgesia but with fewer associated adverse effects.

Although FBs provide excellent post-operative analgesia after total knee prosthesis, they also provide a significant quadricepsia weakness that increases the risk of severe falls and complications, and hinders the rapid rehabilitation process. For these reasons, alternative analgesic techniques have emerged in recent years.

To avoid the quadricipital motor block generated by FBs, some authors proposed the administration of local anesthetics in the adductor channel, also known as the Hunter channel, in order to produce a pure sensory block. With the development of ultrasound, the adductor channel is easily visualized in the middle of the thigh. This allows the adductor channel block (ACB) to be realized with a high success rate. ACB appears to decrease postoperative pain and morphine consumption. It also significantly improves the ability of patients to walk around after Total Knee Arthroplasty (TKA) surgery.

With the same goal of quadricipital savings, the use of the analgesic technique by periarticular infiltration of local anesthetics (ILA) has spread in recent years, due to the fact that an analgesic technique of simple realization and without apparent danger, and this despite limited evidence of its effectiveness.

The Croix-Rousse Hospital is a university hospital in Lyon with a highly developed orthopedic surgery center, producing approximately 550 TKA per year. During the year 2016, approximately half were benefited from post-operative analgesia management by ACB, and the other half by the implementation of the ILA.

To date few studies have been interested in comparing these two analgesic techniques in knee prosthesis surgery.

Inclusion Criteria:

• Major patients (≥18 years),
• Having an American Society of Anesthesiology score (ASA) I to III
• To benefit from first and unilateral prosthetic replacement surgery of knee under spinal anesthesia,
• Having social security scheme,
• Having received informed information and having signed informed consent

Exclusion Criteria:

• Pregnant women (diagnosis of interrogation),
• Breastfeeding women
• Patients under tutorship or curatorship,
• Persons who can not receive sufficient information because of disturbances of superior functions or because of insufficient command of the French language according to the judgment of the investigator,
• A history of chronic neuropathic pain in the leg to be operated on,
• Patients who have undergone prior surgery on the knee to perform surgery,
• Contra-indication to loco-regional anesthesia: known allergy to local anesthetics,
• Contra-indication to the use of ROPIVACAINE: known hypersensitivity to the active substance or other amide-linked local anesthetics, hypovolemia
• A morbid obesity (Body Mass Index (BMI)> 40),
• Severe renal insufficiency (Glomerular Filtration Rate (GFR) <30mL / min),
• Severe hepatic impairment (prothrombin rate PR <50%),
• Heart failure (left ventricular ejection fraction (LVEF)<40%),
• Transplanted patients,
• A history of drug abuse,
• The taking of chronic morphine for 6 months in systematic,
• Any inability to understand visual scale,
• An inability to walk pre-existing,
• Participation in other interventional research, excluding physiological studies and other interventional research that does not interfere with the analysis of the primary endpoint (as determined by the investigator).