Final answer:
The true statement is that axillary nerve blocks can be used for shoulder surgery. Nerve blocks are performed using local anesthetics that block nerve conduction leading to numbness and pain relief during surgical procedures.
Step-by-step explanation:
The correct statement among the options provided is: B) Axillary nerve blocks can be used for shoulder surgery. The axillary nerve is a branch of the brachial plexus, which provides innervation to the shoulder, and an axillary nerve block can be used for surgeries in that area. Femoral nerve blocks are indeed used for knee surgeries, but they do not provide complete pain relief as mentioned in option A; they mainly provide analgesia to the anterior aspect of the thigh and knee but some pain might still be perceived since other nerves like the sciatic nerve also supply the knee. As for option C, femoral nerve blocks can indeed provide some analgesia for hip surgeries, but due to the innervation pattern of the hip, a more comprehensive approach including other nerve blocks might be needed for complete pain relief. Lastly, option D is incorrect because lumbar plexus blocks are not commonly used for foot and ankle surgery; instead, the sciatic nerve block from the sacral plexus would be more appropriate for such procedures.
Local anesthetics like lidocaine work by blocking voltage-gated sodium channels, which is crucial to stop the propagation of pain signals in nerve fibers, leading to the numbness and pain relief associated with nerve blocks.