 On day 2 the catheter position is assessed with US during injection of LA and the distance from catheter orifice to arteryfascia is determined. A sensory assessment is performed. If there is no loss of cold sensation the catheter is registered as displaced and is therefore manually repositioned and injected with LA using US guidance. Assessment of cold sensation is repeated. Further, two investigators will independently watch a video clip of the injection procedure to assess whether the position is within the adductor canal. Total duration of participation for the individual volunteers will be 2 days. 