Continuous Adductor Canal Blocks Vs. Low Dose Femoral Nerve Blocks For Early Rehabilitation After Total Knee Arthroplasty
Condition: Pain, Postoperative; Total Knee Arthroplasty (TKA)
MeSH terms: Pain, Postoperative
Study type: Interventional
Phase: Phase 4

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
      distal to the ASIS. In addition to other exclusion criteria, these measurements will create
      an exclusion for patients with an iliac-to-patella distance less than 40cm. Iliac to Patella
      distance (IPD) will be measured at the pre-operative interview on the day of surgery with a
      measuring tape. External palpable landmarks of the Anterior superior iliac spine and the
      superior pole of the patella will be used.

      The primary outcome is based upon the ability to perform rehabilitation exercises
      postoperatively to the extent that criteria for discharge can be met. The primary outcome
      measured is the time at which a patient gains the ability to successfully perform a 75-feet
      unassisted walk. On the Day of Surgery (DOS), prior to any walking attempt, a secondary
      outcome measure will be to perform a 5-second sustained straight leg raise. Other secondary
      outcomes will be the number of days admitted prior to discharge, and average pain scores on
      DOS, Postoperative Day (POD) #1, and POD#2. The Day of discharge will also be used as a
      secondary outcome. Earlier discharge is becoming a goal of almost all healthcare systems to
      minimize costs.
    

Detailed description: 
      The three arms are as follows:

        1. The control group; Continuous Femoral Nerve Block - Low Dose (CFNB-LD) will be patients
           randomized to our standard therapy comprised of a low dose/concentration Continuous
           Femoral Nerve Block inserted approximately 5cm distal to the groin crease with a rate of
           2ml/hr.

        2. Higher dose (HD) CFNB; - block placed in same location as CFNB-LD but with a higher dose
           rate of 4ml/hr. This higher rate could afford more pain control but may cause more
           quadriceps or hip flexor weakness.

        3. Continuous Adductor Canal Block (CACB) group will have a catheter inserted 20-30cm
           proximal to the superior pole of the patella, and an infusion rate of 4ml/hr, but with
           similar dressing to make it appear like those in group 1 and 2.

      Acute Pain/Regional anesthesiologists and fellows will be performing all research procedures
      in the same locations that the investigators routinely perform regional nerve blocks: our
      preoperative holding area adjacent to the operating room suites at University of Pittsburgh
      Medical Center (UPMC) - Passavant.

      All three groups have a set rate that will not increase. There also will be no bolus orders
      given on the floors, however IV and PO medications will be available to decrease discomfort.
      These medications are ordered to be given upon request (PRN); upon patient request.
      Down-regulation of doses will also not be allowed as that would cause uncertainty as to which
      regimen may contribute most to postoperative weakness. The only adjustment allowed will be to
      turn off the nerve block infusion completely on POD #1 if a dense motor block of the
      quadriceps or iliopsoas (hip flexor) exists, as this condition does not facilitate
      participation in rehabilitation exercises. The frequency of early-removal of nerve block will
      be recorded for all three groups.

      CFNB groups Continuous Femoral Nerve Block placement: The skin of the right or left groin
      will be sterilized and draped under sterile conditions, the femoral nerve will be identified
      using ultrasound just below the inguinal crease and the local anesthetic will be infiltrated
      subcutaneously. The needle is inserted at the lateral edge of the probe and directed toward
      the nerve using ultrasound assistance. When in proximity of the nerve, 15ml of 0.2%
      ropivacaine will be injected through the needle with repeat aspiration every 5 ml. The nerve
      block catheter will be placed 3-5 cm past the needle tip and secured with steri strips and
      bio-occlusive dressing.

      CACB group Continuous Adductor Canal Block placement: The distance from the ASIS to the
      superior pole of the patella will be measured and the distance recorded. This
      Iliac-to-Patella distance (IPD) will be divided into proximal and distal halves, and the
      halfway point marked. The length of the IPD will need to be a minimum of 40cm for inclusion.
      The insertion site will need to be 20cm proximal to the superior pole of the patella and at
      least 20ml distal to the ASIS. The attending anesthesiologist / acute pain attending either
      perform or supervise regional anesthesia fellows to place the CACB no more proximal than the
      halfway mark of the IPD. For example, if a patient has an IPD of 50cm, the halfway mark will
      be at 25cm and this would be the site of insertion as it would be within the anatomic
      adductor canal and would be adequately removed from the surgical site. The skin of the right
      or left anterior-medial thigh will be sterilized and draped under sterile conditions. The
      sartorius muscle and femoral artery will be identified by an ultrasound at the marked
      IPD-halfway-mark. There, local anesthetic will be infiltrated subcutaneously. The needle is
      inserted in the direction of the hyperechoic nerve and the hypoechoic femoral artery using
      ultrasound assistance. When the needle tip is deep to the sartorius and in proximity of the
      artery, 15ml of 0.2% ropivacaine will be injected through the needle with repeat aspiration
      every 5 ml. The nerve catheter will be placed 3-5 cm past the needle tip and secured with
      steri-strips and bio-occlusive dressing. The CACB rate will be 4ml/hr of bupivacaine 0.0625%.

      By design, Observers should only be aware of a singular kind of patient; those with CPNBs.

      The dressing of the cACB will be very similar to the CFNB and the standard yellow connector
      piece will be secured to the skin with bio-occlusive covering, and the location will be at
      level of the anterior superior iliac spine (ASIS). This standardized dressing will serve to
      aid in blinding the observers as to which kind of continuous block the patient received.
      Labeling of the catheter and dressing will not differ. The nerve block billing record will
      contain the information on the particular approach used.

      Sciatic nerve block placement: the corresponding right or left gluteal area will be
      sterilized and draped under sterile conditions, the sciatic nerve will be identified by an
      ultrasound in the lower gluteal region where a local anesthetic will be infiltrated
      subcutaneously. A trans-gluteal approach will be used to inject normal saline through the
      needle to assist catheter placement; the catheter will be introduced for 3-5 cm past the
      needle tip and secured with steri strips and tegaderm. No local anesthetic will be
      administered until the postoperative period.
    

Intervention name(s): Continuous Femoral Nerve Block; Nerve Block, Continuous Adductor Canal; Continuous Sciatic Nerve Block; Bupivacaine
Intervention type(s): Procedure; Procedure; Procedure; Drug
Intervention description(s): A 27g plastic catheter placed below the inguinal crease to perform a conduction blockade of the sensory components of the femoral nerve in order to decrease pain in the knee after total knee arthroplasty; A 27g plastic catheter placed on the anterior medial thigh midway between the groin and knee to provide a local anesthetic conduction blockade of the sensory components of the femoral nerve in order to decrease pain in the knee after total knee arthroplasty; A transgluteal approach to the sciatic nerve is use to place a 27g catheter. It will only be dose postoperatively after verifying sciatic nerve function still intact. The infusion will be 0.003% bupivacaine at 2ml/hr. This is not the intervention of interest, but our institution's predominant practice is to include the sciatic nerve block as part of the analgesic regimen for total knee arthroplasty.; The concentration of the continuous infusion of bupivacaine though the peripheral nerve catheters will be 0.0625% for the femoral and adductor canal blocks and the concentration for the sciatic continuous catheter will be 0.03%.
Other intervention name(s): Continuous Nerve Block, Femoral; Continuous Peripheral Nerve Block; Continuous Nerve Block, Adductor Canal; Continuous Peripheral Nerve Block, Adductor Canal; Nerve Block, Sciatic Continuous
Intervention MeSH terms: Bupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Continuous Femoral Nerve Block; Continuous Adductor Canal Block