Knotted femoral nerve catheter.

We describe a case of knotting of a femoral nerve catheter which prevented removal by traction after knee replacement surgery. In this context, early surgical removal should be performed as bacterial colonization of femoral catheters is common. Radiological imaging of the catheter may assist decision-making about whether to persist with traction and what surgical approach is required. Minimizing the length of catheter inserted to less than 10 cm makes knotting unlikely, but will decrease the chance of achieving lumbar plexus blockade which could improve analgesia if the catheter passes centrally.