Ultrasound-guided Genicular Nerve Block for Total Knee Arthroplasty (GenTKR)

Knee Osteoarthritis affects one third of the population over 65 years old. Total knee arthroplasty (TKA) has become one of the most frequent surgical procedures in the world. During the last years it went from being a long hospital stay surgery to a fast track procedure. Currently models employ high volume local infiltration techniques (LIA). The genicular nerve block (GNB) appears as alternative in this patients.

The objective of this study is to evaluate the analgesic results of genicular nerve block after TKA in a small cohort of patients.

35 patients scheduled for TKA underwent to GNB were included. Pain measurement.

An observational study of a series of 35 cases will be carried out based on the casuistry of TKR surgery of the investigator's center. The performance of analgesic blockade called GNB in adult patients, ASA physical status I-III, which will undergo TKR, will be part of the multimodal analgesia strategy.

After compliance with the inclusion criteria, with the acceptance and signature of the informed consent by the participating patients, the following procedure will be followed:

1. Patients will be routinely assessed by an anesthesiologist of the service, later they will enter the operating room, where the vital signs will be monitored and the usual anesthetic technique will be used for TKR, that is, spinal anesthesia.
2. To perform the blocks a 90 mm needle was used, with a 30mm extension connected to a 20ml syringe with a mixture of 20ml of 0.2% ropivacaine + 200 micrograms of adrenaline. The needle will be advanced with an out-of-plane technique and 4 ml of the described solution will be placed in each of the 5 nerves to be blocked: Superomedial genicular nerve (SMGN), Superolateral genicular nerve (SLGN), Inferomedial genicular nerve (IMGN), Inferolateral genicular nerve (ILGN) and Recurrent tibial genicular nerve (RTGN) .
3. The pain assessment will be carried out during the night after the intervention (approximately 12 hours) and the next morning (approximately 24 hours). The pain will be objectified by (VAS) (0-10) by a nurse, blind to the analgesic treatment. The use of rescue opioids will be indicated in case of VAS ≥ 3, data that will also be analyzed. In the room, the pharmacological treatment established as an institutional protocol will continue. It should be noted that these data as well as demographic data, intraoperative times, and relevant post-operative data (hematocrit, complication) were obtained from the clinical records of the electronic file of the program used in the internal network of the Barcelona Clinic Hospital
4. Researchers will record those variables aimed at evaluating the intensity of acute postoperative pain 24 hours after TKR (Pain score ≥ 4 in any time).

These results will be included, anonymously, in an Excel database made for this purpose for further analysis. The variables will be recorded in a single intervention

Eligibility Criteria:
Inclusion Criteria:

* Subjects undergoing TKR
* Acceptance to participate
* ASA physical status II-III
* Age \> 18 years

Exclusion Criteria:

* Refusal to participate in the study
* Allergy to local anesthetics
* History of substance abuse