Comparison of catheter tip migration using flexible and stimulating catheters inserted into the adductor canal in a cadaver model.

Use of adductor canal blocks and catheters for perioperative pain management following total knee arthroplasty is becoming increasingly common. However, the optimal equipment, timing of catheter insertion, and catheter dislodgement rate remain unknown. A previous study has suggested, but not proven, that non-tunneled stimulating catheters may be at increased risk for catheter migration and dislodgement after knee manipulation. We designed this follow-up study to directly compare tip migration of two catheter types after knee range of motion exercises. In a male unembalmed human cadaver, 30 catheter insertion trials were randomly assigned to one of two catheter types: flexible or stimulating. All catheters were inserted using an ultrasound-guided short-axis in-plane technique. Intraoperative knee manipulation similar to that performed during surgery was simulated by five sequential range of motion exercises. A blinded regional anesthesiologist performed caliper measurements on the ultrasound images before and after exercise. Changes in catheter tip to nerve distance (p = 0.547) and catheter length within the adductor canal (p = 0.498) were not different between groups. Therefore, catheter type may not affect the risk of catheter tip migration when placed prior to knee arthroplasty.