Ultrasound Guided Combined Adductor Canal, Superior Genicular Nerves and Anterior Femoral Cutaneous Nerves Blocks in Comparison With Periarticular Local Anesthesia Infiltration in Primary Total Knee Arthroplasty

Pain management after total knee arthroplasty continues to evolve, as effective early postoperative analgesia is essential for patient satisfaction, early mobilization, improved functional outcomes, and reduced hospital stay. Multimodal analgesia strategies have been developed to optimize pain control while minimizing opioid consumption, including periarticular injection and peripheral nerve blocks.

Femoral nerve block has traditionally been used for analgesia after total knee arthroplasty; however, its associated quadriceps weakness may delay mobilization and increase the risk of falls. Consequently, the adductor canal block has gained popularity because it provides predominantly sensory blockade while preserving quadriceps muscle strength.

The sensory innervation of the knee joint is complex and involves branches from the femoral, tibial, common peroneal, saphenous, and obturator nerves. Genicular nerve blocks specifically target the sensory innervation of the knee capsule and have emerged as a promising technique for postoperative pain management. In this study, higher volumes of local anesthetic will be used for the superior genicular nerve blocks to improve coverage of the posterior knee capsule, while the inferolateral genicular nerve block will be avoided because of the potential risk of motor weakness and foot drop.

As the medial parapatellar approach is the most common surgical approach for total knee arthroplasty, the anterior femoral cutaneous nerve, which supplies the anteromedial aspect of the distal thigh and knee, may represent an additional target for postoperative analgesia.

Periarticular injection is a surgeon-administered analgesic technique that provides effective early postoperative pain relief without affecting quadriceps strength and has become widely adopted in total knee arthroplasty.

The aim of this study is to compare the analgesic efficacy of a combined approach using adductor canal block, superior genicular nerve blocks, and anterior femoral cutaneous nerve block with periarticular injection in patients undergoing total knee arthroplasty. We hypothesize that adding superior genicular nerve blocks and anterior femoral cutaneous nerve block to adductor canal block will provide superior postoperative analgesia compared with periarticular injection.

A prospective randomized blinded trial will be conducted at Qassim University Hospital after obtaining written informed consent. Adult patients undergoing primary unilateral total knee replacement, aged above 18 years, with a body mass index below 40 kg/m² and American Society of Anesthesiologists physical status I-II will be included. Patients with contraindications to spinal anesthesia, allergy to study medications, opioid dependence, previous knee surgery, chronic neuropathic pain, or regular use of analgesics other than nonsteroidal anti-inflammatory drugs will be excluded.

All patients will undergo routine preoperative assessment and laboratory investigations. In the operating room, standard monitoring will be applied, intravenous access established, and crystalloid infusion commenced.

Spinal anesthesia will be performed under aseptic conditions using hyperbaric bupivacaine, followed by intravenous sedation with midazolam, fentanyl, and propofol infusion. All patients will receive prophylactic antibiotics and tranexamic acid, with supplemental oxygen and capnography monitoring throughout the procedure.

All surgeries will be performed using a standardized surgical technique by the same surgical team, while regional anesthesia procedures will be performed by the same anesthesiologists. Outcome assessors and data analysts will remain blinded to group allocation.

Postoperative analgesia will include regular paracetamol and ketorolac, with intravenous morphine provided as rescue analgesia when required. After discharge, patients will receive oral paracetamol and celecoxib, with tramadol and antiemetics prescribed as needed.

• Periarticular Infiltration (Procedure): A total volume of 50 mL containing 49 mL bupivacaine 0.25% and dexamethasone 8 mg will be infiltrated by the surgeon before prosthesis implantation into the posterior capsule, medial and lateral gutters, quadriceps mechanism, patellar tendon, and medial periosteum.
• Ultrasound-Guided Triple Block Technique (Procedure): Patients will receive a mixture of 45 mL of 0.25% bupivacaine and 8 mg dexamethasone. A total of 15 mL will be injected into the adductor canal, 10 mL for the anterior femoral cutaneous nerve blocks, and 10 mL each for the superior medial and superior lateral genicular nerve blocks.

Primary outcomes

• End of Analgesia Time [Within the first 24 hours after surgery.]: Time from spinal anesthesia until the first Numeric Rating Scale (NRS) pain score ≥ 4. Analysed as time-to-event using Kaplan-Meier curves and the log-rank test (Cox regression if needed). Patients without pain (NRS ≥4) by 24 hours are censored at 24 hours

Secondary outcomes

• Total Morphine Consumption (mg) [From end of surgery until hospital discharge (same day, approximately 6 to 9 hours)]: Total cumulative morphine consumption during hospital stay
• Total Tramadol Consumption (number of capsules) [From hospital discharge until the last diary entry (approximately 16 hours after arrival home)]: Total tramadol consumption after hospital discharge
• Heart rate (Beat/minute) [From end of surgery until hospital discharge, assessed up to 12 hours]: Heart rate measurements recorded postoperatively every 30 minutes in the recovery unit, then hourly in the day surgery unit until discharge.
• Blood pressure (mmHg) [From end of surgery until hospital discharge, assessed up to 12 hours]: Blood pressure measurements recorded postoperatively every 30 minutes in the recovery unit, then hourly in the day surgery unit until discharge.
• Patient Satisfaction Score [At 24 hours after the end of surgery]: Patient satisfaction with postoperative analgesia rated on a numeric scale from 0 (completely dissatisfied) to 10 (completely satisfied), obtained by telephone call.
• Length of Hospital Stay [From operating room admission until same-day hospital discharge, assessed up to 24 hours]: Minutes
• NRS pain score at each time point [From PACU arrival until the last home diary entry, assessed up to 24 hours]: NRS (0-10) recorded at PACU arrival, 30, 60, 90 and 120 min, then at DSU arrival and hourly until discharge, and at set intervals in the home diary
• Time to first ambulation [From DSU arrival until first ambulation, assessed up to 12 hours]: Minutes from DSU arrival to first ambulation
• Postoperative nausea and vomiting [From PACU arrival until hospital discharge, assessed up to 12 hours]: Incidence of PONV and antiemetic use (number of episodes and dose)

Sex: All, ages: 18 Years to any

Inclusion Criteria:

1. ASA: I - II
2. Gender: Male \& Female
3. Age: 18and above
4. BMI less than 40 kg/m2
5. Patients are scheduled for primary unilateral total knee arthroplasty.

Exclusion Criteria:

1. Patients with contraindications to spinal anesthesia
2. Failed spinal anesthesia.
3. ASA III - IV
4. Body mass index (BMI)≥40,
5. A known allergy or contraindication to the drugs used in this study.
6. Previous surgery at the same knee
7. Renal impairment.
8. Patients who suffer from chronic neuropathic pain or on regular pain medications other than NSAIDs.

• OMAR S Almisnid, Anesthesia Consultant, Principal investigator, Department of Anesthesia, College of Medicine, Qassim University