The Efficacy of Local Infiltration Analgesia for Postoperative Pain Management After Total Knee Arthroplasty

The aim: to evaluate peripheral nerve blocks with and without local infiltration analgesia regarding the postoperative analgesic efficacy, the ability of early motion and ambulation in patients following primary total knee arthroplasty.

Primary Hypothesis: peripheral nerve blocks with (LIA+) and without (LIA-) local infiltration analgesia provide similar postoperative pain relieving effects after primary total knee arthroplasty.

Secondary Effects: peripheral nerve blocks with (LIA+) and without (LIA-) local infiltration analgesia provide similar ability to recover after primary total knee arthroplasty.

The objectives:

1. To compare postoperative pain control effects between LIA+ and LIA- groups of patients after primary total knee joint replacement surgery.
2. To assess the ability of early motion and ambulation after total knee joint replacement surgery between the LIA+ and LIA- groups.
3. To estimate opioid consumption and its adverse effects in LIA+ and LIA- groups of patients after primary total knee arthroplasty.
4. To compare the patient's postoperative satisfaction rates in LIA+ and LIA- groups of patients after primary total knee arthroplasty.

Methods:

The prospective, double-blinded study includes American Society of Anesthesiologists (ASA) I-III patients, aged 18-90 years, admitted for primary total knee arthroplasty. Preoperatively patients will be blindly randomized into one of two groups: LIA+ (peripheral nerve blocks with local infiltration analgesia) and LIA- (placebo group, peripheral nerve blocks without local infiltration analgesia). Group assignment will be concealed by opaque envelopes that will be opened only after enrollment. The anesthesiologist performing the block will be aware of the treatment, but the participant and outcomes assessor will be blinded to group assignment.

The anesthesiologist will perform peripheral nerve blocks under the guidance of a linear ultrasound transducer probe. The femoral triangle and distal adductor canal blocks will be performed. The femoral triangle block will be performed at the level where the medial border of the sartorius muscle intersects the medial border of the adductor longus muscle with an injection of 10 ml of 0.125% bupivacaine. A local anesthetic will be injected laterally to the femoral artery. The distal adductor canal block will be performed at the level where the femoral vessels (artery and vein) dive deeper from the sartorius muscle with an injection of 10 ml of 0.125% bupivacaine. A local anesthetic will be injected under the femoral artery. The orthopedic surgeon will perform local infiltration analgesia with 150 mg of bupivacaine, 0.3 mg of epinephrine and 90 ml of normal saline in LIA+ group and with 0.3 mg of epinephrine together with 120 ml of normal saline in LIA- group.

At the perioperative period, all patients from both groups will receive a standardized anesthetic and analgesic. Premedication of midazolam 2.5-5 mg and dexamethasone 4 mg will be given to all patients and a slow fluid infusion of crystalloids with 1 g of tranexamic acid and 10 mg of ketamine started once an intravenous cannula will be placed. Spinal anesthesia after identification of the subarachnoid space will be performed with 15 mg of levobupivacaine. After that, peripheral nerve blocks will be performed under the ultrasound guidance. Patients will be sedated with intravenously administered propofol during the surgery. At the end of the operation, local infiltration with or without bupivacaine (depending on the group of patients) will be performed. After the surgery, patients will be transferred to the post-anesthesia care unit (PACU).

At the postoperative period for analgesia NSAIDs will be available to both groups of patients. NSAIDs such as dexketoprofen 50 mg, acetaminophen 1 g - 3 times per day and dexketoprofen/tramadol 25/75 mg will be administered after the surgery. Opioids will also be available to patients as intramuscular boluses of pethidine 50 mg or morphine 10 mg without restriction and administered for moderate or severe pain (VAS pain score of 5 or greater out of 10).

The postoperative pain control efficacy will be assessed at 3, 6, 24 and 48 hours after the surgery using the visual analogue scale (VAS) from 0 to 10 (0 - no pain, 10 - worst imaginable pain) at rest, during active and passive 45-degree knee flexion. All the requirements of additional analgesics and their adverse effects will be recorded.

The extent of motor blockade and the ability of early motion will be evaluated at 3, 6, 24, 48 hours after the surgery. Patients will be asked to flex the foot, flex the knee and to lift the straight leg. The possible motion at 3, 6, 24 and 48 hours postoperatively will be assessed with the Bromage scale grades: Grade I - free movement of legs and feet; Grade II - just able to flex knees with free movement of feet; Grade III - unable to flex knees, but with free movement of feet; Grade IV - unable to move legs or feet.

The patients ability of early ambulation will be evaluated using the Timed Up and Go (TUG) test at 24 and 48 hours after the surgery. To do the TUG test, patients will have to sit down on the bed, get up from the bed, walk 3 meters forward, turn, walk back 3 meters to the bed and sit down. The time taken by a patient to perform this test will be calculated with a chronometer.

After the conversation with each patient and assessment of the postoperative pain control efficacy, the ability of early postoperative motion and ambulation, the rate of patient satisfaction will be evaluated using a 10 point scale from 0 (completely unsatisfied) to 10 (totally satisfied) at 3, 6, 24, 48 hours after the surgery.

According to the study protocol, both groups of patients will be compared in terms of postoperative pain control, opioid consumption, early motion and ambulation ability, the incidence of complications (if any), and patients satisfaction rates over time of clinical recovery.