Title: Ropivacaine versus Bupivacaine as Preventive Analgesia in Surgical Incision Site In Patients With Ankle Fracture Background: Ankle fractures are about 10% of the fractures associate to sports and with an incidence of 0.11 of 1000 adult patients. Weber classification system divides ankle fractures in three types according to the anatomy of lateral malleolus. B fractures starts at tibia pilon. Stable fractures are easily treated in conservative way. (12) Unstable fractures are treated surgically with anatomic reduction and internal fixation. However, it's been reported that even with successful reduction surgically great results are not always achieved. Local wound infiltration blocks the pain in its origin, surgical site by itself, without alter motor function. Practically without presenting adverse events with this method. it´s accurate for ambulatory surgery.

Main Objetive: To compare preventive analgesia with local anesthetic in surgical site with ropivacaine or bupivacaine in ankle fracture patients treated surgically with open reduction and internal fixation.

Method: Two groups with ankle fractures which will be informed and the patients will sign informed consent, after that the patients will be assign to a group (Ropivacaine or bupivacaine). The patient will be prepared for surgical treatment according to his doctor. It will be applied traditional anesthesia. It will be applied before beginning surgery in bupivacaine group 25 mg and in ropivacaine group 37.5 mg at least 10 minutes before starting surgery. After that the patient will have the traditional dose of analgesic treatment.The group will evaluate the pain with VAS 0-10 at 4,8,12 and 24 hours after surgery. The group will register data and will make statistic analysis. It will be elaborated the conclusion an elaboration of a report.

Resources: The group counts with human resources of the group of investigators. The hospital has in emergency department almost three patients with ankle fractures each day which require surgical treatment. The hospital has x ray service to valuate the ankle fracture and with computer system to analyze it. The hospital has the software for statistical analysis.

Experience: The group is formed with orthopedic surgeons with more than 5 years in treatment of ankle fractures. Investigators have the support of pain medicine group in hospital and with anesthesia coordinators. Investigators have a group of orthopedic residents which will be encharged of ilfiltration wound site.

Time: September 2016 to February 2017.

Inclusion Criteria:

• Patient with afiliation to IMSS
• Patient with ankle fracture that requires surgical treatment with open reduction and internal fixation
• Patient that accept to participate in the study whit a sign of document.

Exclusion Criteria:

• Politrauma patients (Patients with another fracture)
• Patients who dont accept to participate in the study
• Neuropathy in inferior limps that limits pain perception
• Open ankle fractures

We consider that we can had a better result with higher dosis of local anesthetic, and the comparation with a placebo group would be a better analysis.