Continuous Adductor Canal Blocks Vs. Low Dose Femoral Nerve Blocks For Early Rehabilitation After Total Knee Arthroplasty

Study Summary

Recently, several articles have suggested or reported that Adductor Canal Blocks (ACBs) offer adequate or equal analgesia and may promote better performance in early rehabilitation following Total Knee Arthroplasty (TKA) when compared to the more commonly used Femoral Nerve Block (FNB). A common feature of these studies has been the use of moderate to high concentration local anesthetics (e.g. 0.2% or 0.5% Ropivacaine respectively) which when injected by a large motor nerve will inevitably cause weakness. However, the practice at our institution has long been a continuous femoral nerve block (CFNB) with a lower concentration local anesthetic (0.0625% Bupivacaine). Over the past several years the investigators have performed several thousand CFNBs using this technique which has offered the advantage of minimal motor weakness and adequate analgesia. The primary goal of this study is to determine if our established practice of using a low concentration continuous FNB inserted about 5cm caudal to the groin crease (the apex of the femoral triangle) using a low infusion rate of 2ml/hr is comparable to the emerging practice of inserting a Continuous Peripheral Nerve Block (CPNB) in the anatomic adductor canal (AC) - infusing at 4ml/hr. A secondary goal is to study the effect of cumulative volume of local anesthetic infused through a FNB when at a rate of 2ml/hr compared to a rate of 4ml/hr in the 48-hour postoperative period. Definitions of the location of the adductor canal are debated heavily in literature, but they seem to agree that the middle 1/3 of the thigh contains the proximal AC while the distal 1/3 of the thigh contains the adductor hiatus - the terminal end of the AC. Our study will require placement of the continuous ACB no more distal than 20cm cephalad to the superior pole of the patella due to placement prior to surgery and the need to keep the dressing out of the operative field. The CACB catheter will also not be placed any more proximal than 20cm dista

Primary Outcome

Ability to walk 75 feet if performed on POD#2 is usually considered the main criterion for discharge at UPMC Passavant. The patient is accompanied/supervised by physical therapist using a walker but without active intervention by therapist, unless necessary. The earliest day on which the patient achieves the 75-feet unassisted walk will be recorded for comparison among the arms/groups.

Conditions Studied

Interventions

• DRUG Bupivacaine
• PROCEDURE Continuous Femoral Nerve Block
• PROCEDURE Nerve Block, Continuous Adductor Canal
• PROCEDURE Continuous Sciatic Nerve Block

Study Locations (1)