How long does a femoral block last?

I had a knee surgery yesterday and i was given a femoral block. Today it has been over 12 hours and i still have no feeling in my thigh and knee and my thigh is yellow. Why is this? Is this bad? Should I call the doctor? Please help! Thanks.

[Neuro Forum]

Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.

Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.

The duration of anesthesia (lack of feeling of pain, commonly referred to as numbness) following a nerve block depends on what substance was used (which type of anesthetic) and the amount administered. The duration can certainly be for several hours, and your lack of feeling does not necessarily imply there has been a complication. Complications of nerve block include nerve injury, but this is not common. If your concerns persist, contacting your physician to further discuss them is recommended.  

Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.