Migration Rate for Continuous Adductor Canal Block Catheters After Primary Total Knee Arthroplasty Surgery: a Comparison Between Two Insertion Techniques

Joint replacement surgeries are often followed by significant early postoperative pain,necessitating effective pain management with minimal side effect. Over the years, variousanalgesic modalities have been employed, but each comes with its own limitations. Opioidsare a commonly used class of oral and intravenous/intramuscular pain medications thatprovide excellent analgesic control, yet are associated with side effects, such asnausea, vomiting, sedation, constipation and respiratory depression. Non‐steroidalanti‐inflammatory drugs (NSAIDs) are frequently used as adjuvants alongsideacetaminophen, but use is contraindicated in patients with bleeding disorders, gastriculcers, or renal or liver impairment.Peripheral nerve blocks have emerged as a highly effective pain management option withminimal side effects. Historically, femoral nerve blocks were used to control pain afterknee replacement surgeries; however, the associated motor block delayed patientmobilization and hospital discharge. In contrast, adductor canal blocks (ACB) havedemonstrated effective pain relief without causing important quadriceps weakness. WhileACB is generally safer, it can be associated with complications such as vascularpuncture, nerve injury, and, in rare cases, local anesthetic systemic toxicity (LAST).The use of ultrasound guidance, along with proper technique, significantly reduces thelikelihood of these complications.One limitation of any single‐shot nerve block is the variability in the duration of itseffect, depending on the local anesthetic used. CACBs address this issue by providingprolonged length for ACB and longer pain control. However, the insertion of CACBcatheters carries similar risks to those of single‐shot nerve blocks, in addition to thepotential for catheter migration outside the adductor canal, which leads to loss ofeffectiveness. With proper techniques to increase safety and effectiveness, CACB holdsgreat potential as a mainstay of postoperative analgesia for knee arthroplasty patients.At Mount Sinai Hospital ‐ Sinai Health System, CACB has become standard practice for kneearthroplasty patients. The catheter tip is placed near the saphenous nerve in themid‐thigh region under ultrasound guidance. The ISAFE (Interfascial plane between theSArtorius muscle and FEmoral artery) approach is used for catheter insertion, which hasbeen shown to reduce catheter dislodgement by 26.3% compared to the conventionaltechnique. Another technique for CACB catheter insertion, named OOPS (Out Of Planeparallel to Saphenous nerve), has demonstrated a lower incidence of catheter migrationoutside the adductor canal when compared to the conventional insertion technique. In theOOPS technique, the catheter is inserted through an ultrasound guided out‐of‐planemanner, parallel to the saphenous nerve, ensuring that it remains securely within theadductor canal, reducing the likelihood of dislodgement with patient movement.SIGNIFICANCE Currently, no published studies directly compare the migration rates of theISAFE and OOPS techniques for CACB catheter insertion. Effective postoperative analgesiapromotes early ambulation, accelerating recovery and potentially reducing hospital stays.Techniques that minimize catheter migration can lead to better outcomes, while inadequatepain control remains a significant factor contributing to prolonged hospital stays.Optimized inserted CACB catheters facilitate same‐day discharge and may help reducehealthcare costs.OBJECTIVES The primary objective of this study is to compare the migration rates of CACBcatheters when inserted using the ISAFE or OOPS techniques in patients undergoing primarytotal knee arthroplasty surgery.The secondary objective is to evaluate postoperative pain, analgesic requirements andcatheter‐related complications.HYPOTHESIS Both the ISAFE and OOPS techniques for CACB catheters insertion will result insimilar catheters migration rate.METHODS This will be a prospective, randomized, controlled trial, blinded for bothpatient and evaluator, which will recruit patients undergoing unilateral primary totalknee arthroplasty at Mount Sinai Hospital ‐ Sinai Health System. The recruitment ofpatients will start after approval from Hospital's Research and Ethics Board. Patientswho meet the inclusion criteria will then be approached and informed about the details ofthe study in simple language. A written consent will be taken if the patients decide toparticipate in the study.Perioperative management and interventions:The subjects will have surgeries booked in advance and the details of the surgical datewill be provided at the Pre Admission Unit (PAU) for pre‐anesthesia consult a few daysbefore surgery. The details of the study will be explained to the patient and a consentform will be provided for the patient to take home to review. The patients will have atleast 24 hours between pre anesthesia consult and the surgery to decide and consent forparticipation in the study.The research participants will be randomized to one of the two groups using acomputer‐generated random numbers table. Randomization will be done at the start of thestudy and all numbers will be allocated to one of the two study groups:Interventional group: ISAFE group; Control group: OOPS group. Once the numbers aregenerated, the method to allocate participants to the respective study intervention willbe sequentially numbered opaque sealed envelopes. Every patient will receive a studynumber following the order of entrance in the study. The researcher who collects the datawill be blinded to which group each patient will be randomized to. All patients willreceive the same perioperative management with the exception of the CACB catheterinsertion technique, which will depend on the assigned group. The sealed envelopescontaining details of the insertion technique associated with each number will beprepared at the start of the study. Once the patient is recruited, the professionalperforming the CACB catheter insertion will open the envelope associated with the numberto perform the allocated technique. The list of study numbers and the allocated groupswill be kept by the research assistant under password protection and will be shared withother researchers at the end of the study. The research coordinator and the assessor, whoperforms ultrasound on postoperative day 1 (POD1) for catheter position, will be blindedto the randomization. The person performing the CACB catheter insertion will not beblinded as the professional will need to know which approach to use.Perioperative management for all the patients will be the same. All the patients will bebrought to the block room where a safety check will be performed by the block room team.Standard Canadian Anesthesia Society monitoring will be done. Midazolam 0.5 ‐2 mg andfentanyl 25‐ 150 mcg can be administered for anxiolysis and analgesia. The ipsilateralthigh is cleaned with chlorhexidine and alcohol sticks and ACB (15‐20 ml of 0.5%ropivacaine with epinephrine 1: 200000) and IPACK block (10‐15 ml of 0.25% ropivacainewith epinephrine 1: 200000) will be performed under ultrasound guidance (Sonosite X‐portultrasound machine). Cumulative dosage of ropivacaine will be pre‐emptively calculated tobe less than 3 mg/kg, and volumes of injected solutions will be adjusted accordingly. Allpatients will receive spinal anesthesia, after the peripheral nerve blocks.Intraoperatively, the patients will also receive Cefazolin IV (2 g if weight < 120 kg and3 g if weight > 120 kg), tranexamic acid IV (20 mg/kg), dexamethasone IV (0.1 mg/kg),Ondansetron IV (4 mg). The surgeons will infiltrate the surgical site with 200 mg of 0.2%Ropivacaine at the end of the procedure.After surgery the patients will be transferred to the Post Anesthesia Care Unit (PACU).In the PACU an Pajunk® (Sonolong® Continuous Peripheral Nerve Block Catheter) CACBcatheter will be inserted under sonographic guidance (Sonosite X‐port). The CACB catheterwill be inserted postoperatively to avoid any displacement due to intraoperative movementor tourniquet inflation and deflation. To rule out intravascular placement of thecatheter, 5‐10 ml of normal saline with epinephrine 1:200000 will be injected through theCACB catheter after negative aspiration and patient monitored for any heart rate changes.The catheter will be secured using glue and adhesive device to mitigate possiblemigration. After applying sterile dressing, the catheter will be connected to anelastomeric pump that can deliver Ropivacaine 0.2% at a rate of 5 ml/h, for up to 60 h,as per Mount Sinai Hospital ‐ Sinai Health System practice for CACB. The patients will bedischarged home by the orthopedic team, after meeting the discharge criteria, and can gohome with the infusion if the patients leave the hospital before completing 48 hours ofthe infusion. The patients will be educated about monitoring for local anesthetictoxicity, transient muscle weakness and details of removing the catheter after infusionbottle finishes. A printed educational pamphlet containing all the above details willalso be provided to the patient at discharge. The pamphlet also contains the contactnumber of Acute Pain Service (APS), where the patient can contact the anesthesiadepartment in case of any adverse effects or questions about the nerve block catheter.The patients are contacted by a member of the Acute Pain Service team by phone, oncedaily, for the duration of the infusion. This is already done as a standard of care forall knee arthroplasty patients.The CACB catheter insertion technique will be according with the group the patient israndomized to.ISAFE group:Patient is positioned in supine position, with the hip abducted and the knee slightlyflexed. A linear high‐frequency transducer is applied in the transverse plane in themid‐thigh area, at the level where the superficial femoral artery (FA) lies underneaththe midpoint of the sartorius muscle (SM). The needle is inserted in‐plane, coming fromlateral to medial, from a point of entry through the skin 2‐3 cm lateral to theultrasound probe. The needle is advanced piercing through the posterior fascia of the SMapproximately 1‐2 cm lateral to the FA, and entering the adductor canal. The needle angleis then decreased further, and is directed beneath to the posterior fascia of SM. Theneedle is advanced into inter‐fascial space between the FA and SM. Hydro‐dissection withsaline or Dextrose 5% is necessary for opening up the inter‐fascial space and separatingthe FA from the SM. Once the needle tip has passed the "12 o'clock" position of the FA, acontinuous nerve block catheter is inserted through the needle into an antero‐medialposition to the artery, thereby facilitating over‐threading the catheter a smalldistance.OOPS group:Patient is positioned in supine position, with the hip abducted and the knee slightlyflexed. A linear high‐frequency transducer is applied in the transverse plane in themid‐thigh area, at the level where the superficial FA lies underneath the midpoint of theSM. After local infiltration of skin and subcutaneous, the Tuohy needle is inserted in anout of plane manner, lateral to the FA. After entering the adductor canal, the probe isturned 90 degrees to see the needle in plane. After flattening the needle gently, thecatheter is threaded into the canal.Standard post operative oral analgesic regimen will be prescribed for all the patients,including: Acetaminophen 650 mg QID; Celebrex 100‐200 mg BID; Hydromorphone 1‐2 mg prnQ4h.Sample size The sample size was calculated based on two previous studies looking intomigration rate for CACB catheters. One study evaluated 97 patients and demonstrated thatISAFE technique results in 18.6% migration rate, while the conventional technique showedan incidence of migration of 44.9%. Another study involved 67 patients, and showed amigration rate of 14.7% for the OOPS technique, in comparison to 72.7% of migration forthe conventional technique. If an average estimated migration rate for the tunneledtechniques (ISAFE and OOPS) from these two studies (16.65%) is considered and the averagemigration rate for the conventional technique, from the same studies (58.8%), a sample of20 subjects in each group would be needed for a comparison between tunneled andconventional, considering alpha of 5% and a power of 80%. Considering this sample of 40subjects as enough for a study comparing migration rates between two techniques, and thehypothesis for this study is that ISAFE and OOPS techniques are equivalent in terms ofcatheter migration, a base sample of 40 patients is defined. Considering for possibledrop‐outs during the study execution, a range of 20% is added, reaching a total of 48patients (24 in each group).Study data analysis The normal distributed variables will be described as mean ± standarddeviation. The non normal distributed variables will be presented as median(minimum‐maximum). Qualitative variables will be described as frequency of occurrence.The statistical tests that will be used are Student t test, Kruskal Wallis and Chi squaretest. SPSS 13.0 for Windows (SPSS Inc, Chicago, IL, USA) and GraphPad Prism Version 4.00for Windows (GraphPad Software, San Diego, CA, USA) will be used for statisticalanalysis.