Total knee arthroplasty (TKA) is a common orthopedic procedure in which effective postoperative pain management is important for early mobilization and rehabilitation. Various regional anesthesia techniques are used as part of multimodal analgesia protocols to improve postoperative pain control. Genicular nerve block has recently been introduced as a potential motor-sparing technique that may enhance postoperative analgesia when used alone or in combination with other regional blocks.

The aim of this randomized controlled study is to evaluate whether the addition of ultrasound-guided genicular nerve block to femoral nerve block improves early postoperative analgesia in patients undergoing primary unilateral total knee arthroplasty under combined spinal-epidural anesthesia.

A total of 80 patients aged 18-80 years scheduled for elective primary unilateral TKA will be included and randomly assigned to two groups using sealed envelopes. One group will receive femoral nerve block alone (Group F), while the other group will receive femoral nerve block combined with genicular nerve block (Group FG). Postoperative pain scores using the visual analog scale (VAS), epidural patient-controlled analgesia consumption during the first 24 hours, and the time to additional analgesic requirement will be recorded and compared between the groups.

The aim of this prospective, randomized controlled study is to evaluate whether the addition of an ultrasound-guided (USG) genicular nerve block (GNB) to a standard femoral nerve block (FNB) improves postoperative analgesia compared with FNB alone in patients undergoing primary unilateral total knee arthroplasty (TKA).

All patients will undergo surgery under combined spinal-epidural anesthesia. After administration of the spinal block and placement of the epidural catheter, participants will be randomly assigned to one of two groups.

Group F (Control): Participants will receive an ultrasound-guided femoral nerve block using 20 mL of 0.25% bupivacaine.

Group FG (Intervention): Participants will receive an ultrasound-guided femoral nerve block (20 mL of 0.25% bupivacaine) combined with a four-point ultrasound-guided genicular nerve block targeting the superomedial, superolateral, inferomedial, and inferolateral genicular nerve branches. Each branch will receive 5 mL of 0.25% bupivacaine.

Postoperative analgesia will be standardized in both groups using an epidural patient-controlled analgesia (PCA) device operating in bolus-only mode (5 mL bolus, 20-minute lockout interval) containing fentanyl (3 µg/mL) and bupivacaine (0.5 mg/mL).

The primary outcome measure will be the total volume of epidural analgesic solution consumed during the first 24 hours after surgery. Secondary outcome measures will include postoperative pain intensity assessed using the Visual Analog Scale (VAS) at predefined time points (0, 2, 8, 12, and 24 hours), time to first additional analgesic requirement, and the incidence of postoperative side effects such as nausea or dizziness.

Inclusion Criteria:

Patients aged ≥18 years

Scheduled for elective total knee replacement surgery

American Society of Anesthesiologists (ASA) physical status I-III

Planned to receive femoral nerve block with or without genicular nerve block

Ability to provide written informed consent

Exclusion Criteria:

Refusal to participate

Contraindication to regional anesthesia

Coagulopathy or ongoing anticoagulant therapy incompatible with nerve block

Infection at the injection site

Known allergy to local anesthetics

Severe hepatic or renal insufficiency

Cognitive impairment preventing pain assessment

Chronic opioid use or opioid dependency

he researchers will share de-identified individual participant data (IPD) underlying the results reported in this study, including demographic data (age, gender, BMI) and primary/secondary outcomes (24-hour epidural consumption and VAS scores). Data will be available to researchers who provide a methodologically sound research proposal approved by the principal investigator. Supporting documents, including the Study Protocol, Statistical Analysis Plan (SAP), and Informed Consent Form (ICF), will also be available. Access will be granted starting 9 months after publication and ending 36 months after the publication date. Data sharing is subject to a signed data access agreement and confirmation of institutional ethics committee approval for the requester's secondary analysis. Requests should be directed to the corresponding author.

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Start Date: 9 months after publication of the study results.

End Date: 36 months after publication of the study results.

De-identified individual participant data (IPD) will be made available to researchers who provide a methodologically sound research proposal. The proposed research must aim to address specific clinical or statistical questions relevant to the study's scope (total knee arthroplasty analgesia). Proposals will be reviewed by the principal investigator to ensure scientific merit. Access will be granted following the signing of a data access agreement and confirmation of institutional ethics committee approval for the secondary analysis. Requests should be directed to the corresponding author via the official institutional email.

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