Effect of Posterior Femoral Cutaneous Nerve Block on Postoperative Posterior Lateral Knee Analgesia in Patients With TKA

Total knee arthroplasty (TKA) is one of the most common surgical procedures worldwide. Although surgical and anesthesia techniques have become more mature, poor postoperative pain control after TKA is still an important problem for patients and clinicians. Peripheral nerve blocks (PNBs) have been widely used in clinical practice for postoperative analgesia after TKA.The combinations of PNBs available for postoperative analgesia after TKA include femoral/obturator , femoral/sciatic/obturator, lumbar plexus/sciatic, and femoral/sciatic, and the combination of PNBs has been shown to be effective for postoperative analgesia after TKA in a study of TKA. Meta-analysis of postoperative pain management modalities, it was concluded that blocking multiple nerves was superior to blocking any of the nerves, periarticular infiltration, or epidural analgesia, while the combination of femoral and sciatic nerve block was overall the best postoperative analgesia for TKA. The investigators found that even in patients who underwent a single combined sciatic nerve and saphenous nerve block + continuous femoral nerve block, poor quality of sleep and pain in the affected limb were still common in the postoperative period, and the complaints of pain in the affected limb were mainly centered on the posterior side of the knee (popliteal fossa) and the margins. The area where the patient's complaints were concentrated was within the range of superficial skin sensation innervated by the posterior femoral cutaneous nerve, which is a pure sensory nerve that originates from the lumbosacral plexus, descends through the lower border of the pectineus muscle, and sends out three branches, among which the posterior femoral cutaneous branch innervates superficial sensation in the posterior thigh and popliteal fossa, and the innervation of the posterior femoral cutaneous nerve is not only limited to the posterior thigh and popliteal fossa, but may also extend to the ankle joint. even extend to the ankle joint. The investigators hypothesized that a posterior femoral cutaneous nerve block could reduce pain in the posterior side of the knee in patients after TKA, and there is a theoretically feasible anatomical basis for this hypothesis. Pain is one of the most important factors affecting the quality of sleep in patients, and pain relief may potentially improve the quality and prolong the duration of sleep in patients, thus providing the conditions for comfortable medical treatment and a good prognosis.

Inclusion criteria

• Patients who are >45 years of age; intended to undergo elective first TKA under general anesthesia
• ASA grade II-III.
• Agreed to participate in this study and signed the informed consent form.
• BMI less than 28Kg/m2.

Exclusion criteria

• Patients who refuse to participate in the trial
• Preoperative inability to communicate due to speech and hearing impairment, etc.
• History of allergy to local anesthetics or opioids
• Contraindications to nerve block operation.