Analgesic Efficacy of Anterior Femoral, Genicular and Adductor Canal Nerve Block

Overview

Recently, more distal approach to femoral nerve branches (saphenous) in the adductor canal in the medial compartment of the thigh have shown to provide comparable anesthesia and analgesia without quadriceps muscle weakness than traditional femoral nerve blocks (FNB) after total knee arthroplasty (TKA). Adductor canal block (ACB) has the unique advantage of providing localized analgesia to the peripatellar and intra-articular aspects of the knee joint without reducing the patient's ability to perform a straight leg raise. However, it does not adequately address the incisional pain component on the anterior surface of the knee innervated by anterior femoral cutaneous nerve. This pain may be improved by addition of the anterior femoral block (AFB). Additionally, the ACB does not provide analgesia to the posterior aspect of the knee, which is commonly moderate to severe after surgery. This pain may be decreased by addition of the genicular block, also known as the iPACK block (interspace between the popliteal artery and the capsule of the knee). There is no study that has evaluated the potentially analgesic benefits of the AFB or the iPACK block combined with ACB after TKA. Therefore, the investigators designed this randomized, prospective, and double-blinded study to assess our hypothesis that the addition of the AFB and/or iPACK block to the ACB will improve analgesic effects, decrease pain scores, deceased opioid requirement, and as well as facilitate early recovery and improve patient satisfaction with pain management in patient after TKA.

Postoperative pain associated with total knee arthroplasty (TKA) can pose significant challenges in the recovery process of the patients undergoing this procedure. Traditionally, opioids have played a significant role in treating postoperative pain. It is well established that opioids are highly effective in relieving pain at rest, but are less effective in relieving pain associated with motion (e.g. ambulation, passive motion, and physical rehabilitation). Furthermore, the use of opioids for analgesia is associated with well-known side effects (such as: nausea, vomiting, constipation, ileus, bladder dysfunction, respiratory depression, pruritus, drowsiness, sedation, and allergic reaction). These opioid side effects, which range in severity, can significantly interfere with the rehabilitation process and contribute to a delay in hospital discharge. Significant interest exists in the application of regional anesthetic techniques as an adjuvant to traditional opioid analgesics for pain control in patients after TKA. Specifically, the incorporation of femoral nerve blocks (FNB) as an adjunct in postoperative pain control has been widely reported in the anesthesia literature. While it has shown to be effective in post-operative pain control, it has introduced additional challenges for physical therapy and raised new concerns regarding the associated quadriceps muscle weakness. Until adequate quadriceps function returns, the need for knee immobilization devices to protect patients with traditional FNB from falls interferes with the early recovery process and the achievement of physical therapy milestones.