Evaluation of the Analgesic Benefit of Adding the Blocks of the Intermediate and Medial Femoral Cutaneous Nerves in Addition to the Femoral Triangle Block for Postoperative Analgesia After a Knee Replacement Surgery

Evaluation of the Analgesic Benefit of Adding the Blocks of the Intermediate and Medial Femoral Cutaneous Nerves in Addition to the Femoral Triangle Block for Postoperative Analgesia After a Knee Replacement Surgery

Evaluation of the Analgesic Benefit of Adding the Blocks of the Intermediate and Medial Femoral Cutaneous Nerves in Addition to the Femoral Triangle Block for Postoperative Analgesia After a Knee Replacement Surgery: A Randomized Controlled Clinical Trial

Total knee replacement surgery can be associated with a significant postoperative pain burden and an inability to mobilize adequately, which can lead to the failure of the ambulatory course. Indeed, early mobilization is beneficial in this context in order to prevent complications related to immobility. The optimization of postoperative analgesia is therefore a key issue for the success of this intervention in an outpatient setting or during a short-term hospitalization since an adequate pain relief facilitate the earlier mobilization of the operated joint. Modern postoperative analgesia protocols recommend a multimodal approach, including the use of acetaminophen, anti-inflammatories, opioids and others as well as the use of nerve blocks. Some nerve blocks used for total knee replacement surgery, such as the femoral nerve block, do not preserve the motor skills of the operated limb, which may alter the clinical trajectory due to delayed mobilization due to weakening of the quadriceps, one of the extensor muscles of the knee. Currently, one of the blocks used to spare the motor functions is the block of the femoral triangle. Unfortunately, this block of the femoral triangle does not fully cover the skin component of the surgical incision used for a total knee arthroplasty. A solution to obtain a better quality of pain relief at the level of the cutaneous incision would be to add a block of the para-sartorial compartment, which makes it possible to cover the nerve territories not covered by the femoral triangle block. The hypothesis of this study is that the addition of the para-sartorial compartments (PACS) block, which aims to block the intermediate cutaneous femoral nerve, will improve the postoperative analgesia after total knee replacement surgery, compared to the classical isolated approach of the femoral triangle block (FTB).

Despite many advances, the postoperative analgesia offered by the present techniques remains imperfect, the femoral triangle block does not make it possible to completely cover the cutaneous component of the classic midline incision used for a total knee arthroplasty. This incision would fall more under the anterior cutaneous femoral nerves, more specifically the intermediate and medial cutaneous femoral nerves. A recently described approach offers the prospect of better covering this skin incision, by specifically blocking these nerves using the same needle path as for the femoral triangle block. Although the feasibility of this approach has been studied in healthy volunteers and in a few clinical cases, no randomized controlled study has been conducted to determine whether the addition of cutaneous femoral nerve blocks offers an analgesic benefit in the population undergoing total knee replacement surgery. This is therefore necessary in order to assess whether this approach improves the clinical trajectory of patients receiving a total knee arthroplasty.

In addition to the injection performed in the femoral triangle, two injections of 5 mL of 0.5% ropivacaine + epi 1:400 000 will be performed below the sartorius muscle (subsartorial compartment) and above the sartorius muscle (suprasartorial compartment). For all patients, an infiltration between popliteal artery and capsule of the knee block (IPACK) will be performed concomitantly, in order to block the sensory branches of the innervation posterior to the knee with 15 ml of ropivacaine 0.3% + epi 1:400 000.

This block is currently the most used in practice and is considered a standard of care. It consists of a single injection of 15 ml of 0.5% ropivacaine + epi 1:400 000 under the sartorius muscle, lateral to the femoral artery, at the level of the apex of the femoral triangle For all patients, an infiltration between popliteal artery and capsule of the knee block (IPACK) will be performed concomitantly, in order to block the sensory branches of the innervation posterior to the knee with 15 ml of ropivacaine 0.3% + epi 1:400 000.

This intervention was selected because it has the potential to optimize analgesia by skin coverage of the upper third of the surgical incision. The intervention will be performed as follows: The intermediate femoral cutaneous nerve will be visualized at the supralateral level of the sartorius muscle, in a duplicature of the fascia lata. The needle will be inserted at the same puncture site as for the femoral triangle block, with a latero-medial orientation in the plane (intracanalar compartment). In addition to the injection performed in the femoral triangle, two injections of 5 mL of 0.5% ropivacaine + epi 1:400 000 will be performed in addition, below the sartorius muscle (subsartorial compartment) and above the sartorius muscle (suprasartorial compartment).

The high frequency linear ultrasound probe will be positioned midway between the superior edge of the patella and the anterosuperior iliac spine. It will then be moved to visualize the apex of the femoral triangle, confirmed by visualization of the sartorius muscle laterally and the long adductor medially. The needle will be inserted with a latero-medial orientation in the plane. The initial injection will be a single injection of 15 ml of 0.5% ropivacaine + epi 1:400 000 under the sartorius muscle, lateral to the femoral artery, at the level of the apex of the femoral triangle.

It will be performed in order to block the sensory branches of the innervation posterior to the knee with 15 ml of ropivacaine 0.3% + epi 1:400 000.

The Pain Intensity short form questionnaire (PROMIS) is universal rather than disease-specific. The first two items in the Pain Intensity item bank assess pain intensity utilizing a 24-hour recall period (items include the phrase "the past 24 hours") while the last item asks patient to rate their pain intensity "right now."

The Pain Intensity short form questionnaire (PROMIS) is universal rather than disease-specific. The first two items in the Pain Intensity item bank assess pain intensity utilizing a 7-day recall period (items include the phrase "the past 7 days") while the last item asks patient to rate their pain intensity "right now."

Postoperative pain levels will be assessed every 6 hours for the first 24 hours after the surgery using a numerical scale where 0 = no pain and 10 = worst pain imaginable

The rate of complications or adverse effects during the first 24 hours will be assessed, such as local anesthetic toxicity, nausea, vomiting, pruritus and acute urinary retention.

The quality of sleep of the patient will be evaluated, rated on a scale where 0 = insomnia and 10 = excellent quality sleep.

QoR15 is a valid questionnaire to measure the quality of recovery after surgery and anaesthesia, which includes 15 questions. Each of the 15 items are scored by the patient from 0 (worst score) to 10 (optimal score), giving a lowest possible score of 0 (worst outcome), and a highest possible score of 150 (optimal outcome).

The satisfaction of the patient will be evaluated, rated on a scale where 0 = completely dissatisfied and 10 = fully satisfied.

Inclusion Criteria: 18 years and over, requiring a primary total knee arthroplasty 'American Society of Anesthesiologists' classification 1 to 3 Exclusion Criteria: Refusal or unable to consent Contraindications to a peripheral nerve block; Inability to communicate with the healthcare team or the research team; Inability to understand follow-up instructions or questionnaires; Chronic pain requiring the intake of the equivalent of more than 60 mg of morphine daily; Pregnancy; Patients weighing less than 50 kg (to limit the risk of intoxication with local anesthetics).