Overview
Regional nerve blocks are commonly used as an adjunct to general anesthesia for many of my larger knee operations. The goal is to provide excellent pain control during and immediately after surgery while preserving as much strength and function in the leg as possible. The blocks are typically performed by the anesthesia team in the preoperative holding area before surgery. Patients are often lightly sedated, and a long-acting local anesthetic is placed around selected nerves that provide sensation to the knee. Patients still receive general anesthesia and are asleep for the operation. The nerve block is an additional form of anesthesia designed primarily to improve pain control during the hours surrounding surgery.
Adductor Canal and IPACK Blocks
The two blocks most commonly used around the knee are the adductor canal block and IPACK block. The adductor canal block primarily provides pain relief to the front and inner portion of the knee. The IPACK block is used to provide additional pain relief to the back of the knee. One of the major advantages of these techniques is that they are designed to provide predominantly sensory pain relief while minimizing motor weakness. This is particularly important following knee surgery because patients need enough strength in the leg to stand, walk, and begin their rehabilitation.
When Do I Recommend a Block?
I routinely recommend regional nerve blocks for total knee arthroplasty and commonly use them for larger arthroscopic or reconstructive procedures such as ACL reconstruction and patellofemoral stabilization. I generally do not use nerve blocks for routine knee arthroscopy because the expected postoperative pain usually does not justify an additional procedure. For the larger operations, however, I think the benefit is substantial and generally recommend the block.
What Should I Expect?
The block is performed before surgery and typically provides significant pain relief during the early postoperative period. I generally tell patients to expect approximately 10-12 hours of significant benefit, although the exact duration varies between patients and depends on the medications and techniques used by the anesthesia team.
The goal is not to eliminate every sensation in the leg. In fact, preserving strength is one of the advantages of these blocks. Most patients are still able to activate the muscles of the leg and begin walking after surgery as their overall condition allows. As the block begins to wear off, discomfort gradually returns. This gives patients an opportunity to begin their prescribed pain medication before the block has completely resolved and stay ahead of the postoperative pain.
Are There Risks?
These blocks have an excellent safety profile. Persistent nerve irritation can occur but is very rare.
Is a Nerve Block Required?
No. A nerve block does not change the operation itself or the expected long-term result of the surgery. Its purpose is to improve the patient's comfort during and immediately after the procedure. For larger knee operations, I generally recommend it because I believe the improvement in early pain control outweighs the small additional risks. Ultimately, however, the decision belongs to the patient, and proceeding either with or without a nerve block is acceptable.