Knee replacement surgery can bring pain relief to individuals, but managing discomfort during and after the procedure is a concern. Healthcare providers often use various pain management techniques. A nerve block involves injecting medication near specific nerves to temporarily prevent pain signals from reaching the brain.
Understanding Nerve Blocks for Knee Surgery
Their fundamental purpose is to interrupt pain signals originating from specific nerves around the knee, preventing these messages from traveling to the brain. This is achieved by injecting local anesthetics near the nerves, which temporarily block the transmission of electrical impulses. For knee procedures, commonly targeted nerves include the femoral nerve, which primarily affects the front of the thigh and knee, and the adductor canal block, which targets the saphenous nerve and innervates the medial aspect of the knee. Sometimes, a sciatic nerve block or genicular nerve block might also be used to address pain in other areas of the knee or leg.
How Nerve Blocks Are Administered
An anesthesiologist administers a nerve block before or after knee replacement surgery. The process begins with cleaning the skin, and a local anesthetic may then be given to numb the skin. For precise placement of the medication, the anesthesiologist uses ultrasound guidance. This imaging technology allows them to visualize the nerves and surrounding structures in real-time, ensuring the injection is delivered to the exact location. During the injection, patients feel pressure rather than sharp pain, and a single nerve block takes only about 5 to 10 minutes, with the full effect taking an additional 15 to 20 minutes to develop.
Advantages of Nerve Blocks for Knee Replacement
They provide superior pain control in the immediate period following the operation, which is often when pain is most intense. This enhanced pain management can significantly reduce the need for opioid pain medications. Reducing opioid use helps minimize common side effects such as nausea, constipation, and excessive sedation, contributing to a more comfortable recovery. With better pain control and fewer side effects, patients can often begin mobilization and participate in physical therapy sooner. Early engagement in rehabilitation is important for regaining knee function and can contribute to a faster overall recovery process.
What to Expect After the Nerve Block
After a nerve block, the leg will feel numb and may have reduced strength or movement, which can last for several hours to a day or two. While the duration varies, the effects typically persist for about 18 to 48 hours. As the medication gradually wears off, sensation and muscle control will return, and some achiness in the knee may increase. It is important to manage pain as the block fades, often with oral pain medications prescribed by the healthcare team. Due to the temporary reduction in feeling and strength, patients should exercise caution with walking and use assistive devices as advised, to prevent falls or injury.