GENIFEM Trial: Postoperative Pain After Total Knee Arthroplasty (TKA)

Motor-sparing analgesic interventions for patients undergoing total knee arthroplasty (TKA) are a key component of fast-track surgery.

The investigators want to estimate treatments effects, inclusion rate, and feasibility of conducting a future randomized controlled superiority trial and to assess whether the short-term postoperative analgesic effect and ambulation after a Genicular - Infiltration Between Popliteal Artery and Capsule of Knee (iPACK) block in patients undergoing unilateral primary TKA is superior to Femoral triangle - iPACK block and Local Infiltration Analgesia (LIA).

The study is a prospective, double-blind, triple-arm superiority pilot randomised controlled trial with a randomization rate 1:1:1.Group I will receive a Genicular - iPACK block, group II a Femoral Triangle - iPACK block and group III LIA.

The primary study outcome is the proportion of patients that are able to mobilise (defined as walk 10 meters with assistance) with a numerical rating scale (NRS) of equal or less than 4 without the use of opioids at 4-6 hours after TKA. Secondary outcomes are efficacy (measured in NRS, total morphine consumption, total morphine titrations), functionality (quadriceps strength, timed-up-and-go, 6-minute walk test, inpatient falls), frequency of opioid related adverse events, discharge readiness, patient satisfaction, health-related quality of life, length of stay (LOS), complications after TKA and adverse events related to the study interventions.

Total knee arthroplasty (TKA) is one of the most frequently performed orthopedic surgical procedures for the treatment of osteoarthritis of the knee. Fast-tract recovery protocols emphasize the importance of early mobilization and physiotherapy to improve functional recovery, reduce postoperative complications, and decrease the economic burden of TKA. As the patients having TKA typically have severe pain postoperatively, multimodal analgesic regimen in many institutions includes interventional analgesia modality, such as nerve blocks, to facilitate early mobilization. At this time however, no universal recommendation exists on what constitutes the optimal nerve block technique that provides favorable balance between motor sparing for ambulation and analgesia.

Various motor-sparing nerve blocks (e.g., femoral triangle block, adductor canal block, obturator nerve blocks, Infiltration Between Popliteal Artery and Capsule of Knee (iPACK), genicular nerve block and Local Infiltration Analgesia (LIA)) are viable options for interventional analgesia in patients undergoing TKA. By this study in patients having TKA, the investigators aim to compare the analgesia and ambulation between the genicular nerve block iPACK versus Femoral triangle nerve block + iPACK versus LIA.

Eligibility Criteria:
Inclusion Criteria:

* ≥18 years of age at screening
* Scheduled to undergo elective primary unilateral TKA
* American Society of Anaesthesiologists (ASA) physical status 1, 2 or 3
* Mentally competent to provide informed consent, to report pain intensity and to use patient-controlled analgesia
* Physically able to perform independently the baseline functionality tests

Exclusion Criteria:

* Obesity (BMI\>40)
* Previous open knee surgery
* Revision TKA or bilateral TKA
* Contraindication to the following study medication: ropivacaine, morphine, midazolam, ketorolac, propofol, remifentanil, clonidine, dexamethasone, acetaminophen
* Uncontrolled anxiety, psychiatric, or neurological disorder that might interfere with study assessments
* Chronic widespread pain
* Radicular pain in index legClinical Study Protocol Version 1.0
* Preoperative strong opioid use within 3 days before surgery (with the exception of weak opioids: tramadol and codeine)
* Any chronic neuromuscular deficit affecting the peripheral nerves or muscles of the surgical extremity
* Impaired kidney function (Chronic kidney disease (CKD) G4-G5 according to Kidney Disease: Improving Global Outcomes (KDIGO) classification)
* Alcohol or drug abuse
* Pregnant, nursing or planning to become pregnant before treatment. Women of reproductive age will be tested on pregnancy prior to start of the study. Participants who get pregnant after the treatment during the follow-up period will not be excluded