Efficacy of iPACK After Unilateral TKA
Condition: Arthroplasty Complications; Pain, Joint; Arthritis Knee; Regional Anesthesia Morbidity
MeSH terms: Arthralgia
Study type: Interventional

Summary: 
      Total knee arthroplasty (TKA) is a common orthopedic procedure associated with severe
      postoperative pain which may limit patient rehabilitation and hospital discharge. Although
      various analgesic techniques have been proposed, there is currently no consensus on the
      optimal protocol to improve functional outcomes following TKA. The ideal analgesic regimen
      post TKA should enable adequate pain control, early mobilization and physical therapy,
      shorten hospital stay, reduce the risk of postoperative complications and improve patient
      satisfaction. Our hypothesis is iPACK (Interspace between the Popliteal Artery and the
      Capsule of the posterior Knee) peripheral nerves anesthetic block is superior to
      Periarticular local Infiltration Analgesia (LIA)which is commonly given by the surgeons
      during the TKA in terms of pain relief and early mobilization.
    

Detailed description: 
      Background: Total Knee Arthroplasty (TKA) is one of the most frequent procedures performed by
      orthopedic surgeons. Research has found that orthopedic surgeries are the most painful
      procedures.(1) Unrelieved pain post orthopedic surgery is a stressor that can cause altered
      physiologic changes and negative effects on every organ system of the body. Untreated pain
      can result in complex pathophysiology than the pain caused by the original injury or disease.
      This can have both detrimental physical and psychological consequences for patients, as well
      as a substantial economic impact due to increased costs of health care and lost productivity.
      (2) The anatomy of sensory supply to the knee joint is complex with contributions from both
      the lumbar and sacral plexuses. The anterior-medial compartmental innervation consists of
      branches from the femoral nerve, including the saphenous nerve, the medial femoral cutaneous
      nerve and the nerve to vastus medialis. The lateral femoral cutaneous nerve, the common
      peroneal nerve, and the nerves to vastus intermedius and lateralis innervate the knee
      anterolaterally. The posterior group consists of the popliteal nerve plexus that ramifies
      around the genicular vasculature in the popliteal fossa. The popliteal nerve plexus is
      derived from the tibial nerve and the posterior branch of the obturator nerve. The posterior
      group supplies intra-articular innervation to the menisci, the peri-meniscular joint capsule,
      the cruciate ligaments, the infra-patellar fat pad, and the posterior part of the fibrous
      knee capsule.(3) The medial para-patellar arthrotomy performed for total knee arthroplasty,
      through the anteromedial integument of the knee and the extra-articular medial retinacular
      complex, evokes pain mediated by the infra-patellar branch of the saphenous nerve, the medial
      retinacular nerve (the terminal branch of the nerve to vastus medialis), and the anterior
      branch of the medial femoral cutaneous nerve. This procedure will not affect the
      extra-articular nerve branches to the anterolateral portion of the knee from the common
      peroneal nerve, the nerves to vastus intermedius and lateralis, and the lateral femoral
      cutaneous nerve. The intra-articular excision evokes pain from structures innervated by the
      posterior group. (4) Ultrasound-guided Femoral Nerve Block (FNB) is one of the most commonly
      used techniques that has been shown to significantly improve analgesia and reduce
      postoperative opioid consumption after TKA. However, FNB may lead to quadriceps muscle
      weakness, limiting ambulation and increasing the risk of falls, making physical
      rehabilitation results unsatisfactory.(5) Recently, there has been increased interest in the
      Adductor Canal Block (ACB) for pain relief after total knee arthroplasty. (6) The adductor
      canal is a pyramidal, musculoaponeurotic tunnel from the apex of the femoral triangle to the
      adductor hiatus, running between the vastus medialis muscle anterolaterally and the adductor
      longus and adductor Magnus muscles posteromedially. It is covered in its entire length by the
      vastoadductor membrane. The contents of the adductor canal include the superficial artery and
      vein, saphenous nerve, the nerve to vastus medialis, the posterior branch of the obturator
      nerve, and in some cases, the medial cutaneous nerve and the anterior branch of the obturator
      nerve. The advantage of this technique rests in the fact that it provides localized
      motor-sparing analgesia, with similar opioid consumption and side effects when compared with
      FNB.(7) However, ACB does not provide analgesia to the posterior aspect of the knee, which
      can be moderate to severe after surgery. This pain may be ameliorated by the addition of the
      ultrasound-guided local anesthetic infiltration of the Interspace between the Popliteal
      Artery and the Capsule of the posterior Knee (iPACK). (8) Although this technique seems to
      provide many advantages, it may present some limitations and risks like intravascular
      injection and injury due to the presence of the popliteal vessels near the target. Although
      the use of ultrasound guidance decreases this risk, significant bleeding and serious
      complications can still occur due to the inability to recognize and compress the source of
      bleeding. (4)

      Methods: In this study we are going to recruit 169 participants to compare them in two
      groups. group-1 iPACK (n=85) will receive Adductor Canal Block (ACB) + iPACK and group 2 LIA
      (n=84) ACB+ periarticular Local Infiltration Analgesia (LIA). All participants, care provider
      (nurses & assistant anesthetists) and outcome assessors (physiotherapist) will be blinded to
      the group allocation. Only the anesthesiologist responsible for perioperative care performing
      the ACB and iPACK blocks will be aware of the randomization. All peripheral nerve blocks will
      be performed with complete aseptic technique and under ultrasound guidance. Periarticular LIA
      will be performed by the surgeon with the landmark technique base. This study will be
      conducted in six months' duration. All patients will consent for spinal anesthesia, ACB, and
      iPACK and they will be instructed how to report pain on a 10 cm long Numerical Rating Scale
      (NRS) postoperatively.

      The primary outcome, severity of pain (NRS) will be evaluated in Post Anesthesia Care Unit
      (PACU). The secondary outcome, time to mobilization along with pain score will be recorded in
      the ward after 2 hours of surgery then every 12 hours until the patient discharged home.
      Quadriceps muscle strength will be evaluated with the knee range of motion (ROM). A
      completely straight knee joint (extension) will measure 0° and a fully bent knee will have a
      flexion of at 130° degrees. The Timed-Up-and-Go (TUG) tests to evaluate functional recovery
      after TKA. The TUG test measures the time it takes a patient to get up from a chair, walk 3
      m, and return to the sitting position in the chair.

      On arrival to operation room (OR), all eligible participants will have intravenous (IV)
      cannula in situ and monitors according to the Association of Anesthetists of Great Britain
      and Ireland (AAGBI). Under complete aseptic technique, spinal anesthesia will be performed
      with pencil point 25 Gauge (Whitacre) needle with heavy Bupivacaine 0.5% and Fentanyl 15
      micrograms (mics) total 3 milliliters (ml). After spinal anesthesia, each participant will
      receive either ultrasound-guided ACB+iPACK or ACB+ periarticular LIA.

      Description of peripheral nerve blocks technique:

      Adductor Canal Block (ACB): The skin is disinfected and the transducer (SonoSite 8-14 MHz) is
      placed anteromedially, approximately at the junction between the middle and distal third of
      the thigh. The saphenous nerve is usually identified as anterior and lateral to the femoral
      artery. The needle (Pajunk Germany100 mm) will be inserted in-plane from lateral-to-medial
      orientation and advanced toward the femoral artery deep to the sartorius muscle. Once the
      needle tip is visualized anterior to the artery and after careful aspiration, 1-2 mL of local
      anesthetic will be injected to confirm the proper injection site. If injection of local
      anesthetic does not appear to result in its spread around the femoral artery, additional
      needle repositions and injections may be necessary. A total of 20 millilitres (ml) of
      Bupivacaine 0.25% will be injected.

      Interspace between the popliteal artery and the capsule of the posterior knee (iPACK):

      The patient will be placed in a supine position with the lower extremity flexed at the knee
      and abducted at the hip. To begin scanning, the transducer will be placed on the lower third
      of the medial thigh to visualize the femur and the femoral vessels in cross-section. The
      transducer then will be slide caudally to observe the femoral artery as it dives into the
      popliteal fossa through the adductor hiatus to become the popliteal artery. At this point,
      the transducer will be moved posteriorly and inferiorly to visualize the space between the
      popliteal artery and the shaft of the femur just superior to the femoral condyles. The needle
      will be inserted, in a plane, from the anterior end of the transducer in a medial to the
      lateral trajectory, keeping the needle parallel to the acoustic shadow of the femur. With the
      needle tip resting 2 cm beyond the lateral border of the artery, 20 mL of Bupivacaine 0.25%
      will be injected, after negative aspiration of blood, to infiltrate the tissue space in
      divided doses as the needle is withdrawn.

      Periarticular Local Infiltration Analgesia (LIA):

      A mixture of Bupivacaine 0.25% 20 ml + epinephrine 100 mics ± lornoxicam 8 mg ± morphine 10
      mg ± tranexamic acid 1 gm in 40 ml normal saline (NS) will be injected into the posterior
      capsule and the medial and lateral ligaments just before implantation: after insertion of the
      implants and into the capsule and retinacular tissues. The remaining solution (approximately
      20 mL) will be used to infiltrate the muscle and subcutaneous tissues.

      Postoperatively all participants will be prescribed 1 gm Paracetamol oral every 6 hours +
      buprenorphine transdermal patch 5 mics ± celecoxib 200 mg every 12 hours ± oxycodone 10 mg
      every 12 hours ± pregabalin 75 mg every 12 hours for breakthrough pain.

      Sample Size:

      In King Khalid University Hospital, we are approximately doing annually 300 TKA cases.
      Assuming that and confidence level of 95%, margin of error 5% Raosoft® recommended sample
      size is 169.

      Data Collection:

      The data will be collected by the outcome assessors who will be unaware of group allocation
      and will record their findings in patient's file and on predesigned form. Patients
      demographic data, duration of surgery, tourniquet time, PACU stay, postoperative heart rate,
      mean arterial pressure, pain score, knee range of motion (ROM), time-up-go (TUG), time to
      hospital discharge, patient and surgeon satisfaction and any complication will be recorded.

      Statistical Analysis:

      Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS)
      version 24.0 software (SPSS Inc., Chicago, IL, USA).
    

Intervention name(s): iPACK; Periarticular local infiltration analgesia (LIA)
Intervention type(s): Procedure; Procedure
Intervention description(s): Interspace between the popliteal artery and the capsule of the posterior knee (iPACK):
This is basically ultrasound guided peripheral nerve block performed by the anesthesiologists at the posterior side of the knee to control pain after TKA.; A mixture of Bupivacaine 0.25% 20 ml + epinephrine 100 mics ± lornoxicam 8 mg ± morphine 10 mg ± tranexamic acid 1 gm in 40 ml normal saline (NS) will be injected into the posterior capsule and the medial and lateral ligaments just before implantation: after insertion of the implants and into the capsule and retinacular tissues. The remaining solution (approximately 20 mL) will be used to infiltrate the muscle and subcutaneous tissues. This intervention is commonly performed by the operating orthopedic surgeon to control pain after TKA.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: This study is conducted to evaluate posterior knee pain after unilateral Total Knee Arthroplasty (TKA) comparing iPACK (Interspace between the popliteal artery and the capsule of the posterior knee) and Periarticular Local Infiltration Analgesia (LIA) under spinal anesthesia. All patients will receive Adductor Canal Block (ACB) to cover pain from anteromedial aspect of knee. 169 adult patients will be recruited in this study and will be divided into two groups; group-1 iPACK (n=85) will receive Adductor Canal Block (ACB) + iPACK and group 2 LIA (n=84) will receive ACB+ periarticular Local Infiltration Analgesia (LIA). The primary outcome, severity of pain (NRS) will be evaluated in Post Anesthesia Care Unit (PACU). The secondary outcome, time to mobilization (ROM and TUG tests) along with pain score will be recorded in the ward after 2 hours of surgery then every 12 hours until the patient discharged home.
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Knee arthroplasty; Pain control; iPACK; Local infiltration analgesia; Early rehabilitation