Ultrasound Guided Repositioning of a New Suture-Method Catheter for Adductor Canal Block
Ultrasound Guided Repositioning of a New Suture-Method Catheter for Adductor Canal Block
This is a randomized clinical trial in healthy volunteers. 12 volunteers will have
 suture-method catheters placed in the adductor canal of each leg using the long-axis plane
 and short-axis plane technique. The investigators will inject LA in both catheters to confirm
 correct position. Following return of cold sensation the catheter is then displaced
 intentionally. The orifice is identified by injection of isotonic saline to ensure a proper
 displacement (spread outside of the adductor canal) and the distance from the delivery
 orifice of the catheter to the adductor canal is noted. A second investigator will assess
 distance from the LA delivery orifice of the catheter to the adductor canal using
 hydrodissection with isotonic saline to pinpoint the delivery orifice and subsequently
 reposition the catheter to obtain LA spread within the adductor canal. Successful
 repositioning is defined as a combination of LA spread within the adductor canal and loss of
 cold sensation on the medial part of the lower leg.
The study objective is to investigate whether it is possible to reposition a displaced
 suture-method catheter using ultrasound.

 A peripheral nerve catheter will be inserted on each side under US guidance. An investigator
 will insert one catheter in the short-axis plane of the adductor canal using an in plane
 technique: The needle is inserted through the vastus medialis into the adductor canal and
 exits superficial to the femoral artery through the sartorius muscle.

 The second catheter is inserted from proximal to distal direction in the long-axis plane
 using a combination of in-plane and out-of-plane techniques.

 10mL of isotonic saline is used for hydro-dissection for both catheter insertions to
 facilitate placement. Both catheters are injected with 15 mL LA with an immediate assessment
 of the spread being within or outside the adductor canal.

 Loss of cold sensation in the cutaneous saphenous nerve innervation area will be evaluated 15
 minutes after injection by another investigator, who is blinded to allocation and
 randomization.

 Following return of normal sensory function the catheter is then intentionally displaced at
 least 2 cm outside the adductor canal in the direction of the entry or exit site according to
 randomization. The distance from the LA delivery orifice of the catheter to the adductor
 canal is noted. Adequate displacement requires that injection of isotonic saline does not
 result in spread within the adductor canal.

 A third investigator will assess distance from the LA delivery orifice of the catheter to the
 adductor canal and subsequently reposition the catheter using saline to pinpoint location of
 the delivery orifice. Once the catheter is repositioned LA is injected. The US scan during LA
 injection is performed with a fourth investigator present to evaluate for satisfactory spread
 within the adductor canal. The 2 investigators will not communicate regarding the assessment
 of spread within the adductor canal.

 Evaluation of cold sensation on the medial part of the lower leg is performed 15 minutes
 after 15mL LA (lidocaine 10 mg/mL) injection by investigator 2. The catheters are then
 removed and the study is completed.

 Distance from catheter delivery orifices to the adductor canal is defined as following:

 Distance from the LA delivery orifice to the fascia surrounding the adductor canal is noted
 in the short axis group. The distance from the LA delivery orifice to the penetration of the
 aponeurosis lying just below the sartorius muscle is noted in the long axis group. Both
 represent anatomical reference points for the adductor canal.

 Satisfactory spread within the adductor canal is defined as following:

 The LA injection spreads deeper along the lateral side of the femoral artery, observed in the
 two-dimensional plane while producing minimal displacement of the roof and the overlying
 sartorius muscle.

 The injection may spread occasionally superficially over the femoral artery within the canal
 and will then force the artery deeper. If the injection spreads more medially and
 superficially over the saphenous nerve and femoral artery in an anterolateral to
 posteromedial direction, initially resembling the injections within the adductor canal but
 separates the sartorius muscle from the femoral artery by lifting the sartorius muscle
 medially off the hyperechoic roof of the adductor canal it is considered not to spread within
 the adductor canal.13

 Successful primary placement and subsequent repositioning is defined as the combination of
 satisfactory spread within the adductor canal (assessed using SAX visualization of the
 adductor canal for both catheters) and loss of cold sensation.
Inclusion Criteria:

 -  Male or female ≥18 years of age.

 -  ASA classification ≤ II.

 -  Written informed consent obtained from subject and ability for subject to comply with
 the requirements of the study.

 Exclusion Criteria:

 -  Previous surgery or ongoing pain or other disability of investigated region resulting
 in sensory or neurologic deficits in the investigated region.

 -  Allergy to LA.

 -  Pregnancy (all female participants will be tested for urine hCG), breastfeeding, or
 unwilling to practice birth control during participation in the study.