Advances in Joint Surgery Anesthesia Provide Preemptive Pain Control
New techniques help stop joint surgery pain before it starts.
Not too many years ago, having joint replacement usually meant general anesthesia for surgery followed by grogginess and the need for strong narcotic pain-relievers afterwards. But now many surgeons are turning to newer regional and local anesthesia techniques when performing joint replacements, as research and experience are showing their benefits both during surgery and in recovery and rehabilitation afterwards.
Regional vs. General Anesthesia
Unlike general anesthesia, which knocks patients out so that they don’t experience pain during surgery, regional anesthesia allows patients to remain awake and blocks pain sensations for one area of the body. Joint replacement surgery is typically done with one of two types of regional anesthesia: a spinal block or an epidural block, says orthopaedic surgeon Michael Marks, MD, vice president of business development and former chief of staff at Norwalk Hospital in Norwalk, Conn.
In a spinal block, the doctor injects an analgesic into the fluid surrounding the spinal cord in the lower back to produce an effect that can last for up to several hours. In an epidural block, the anesthetic is delivered to the epidural space – the outermost part of the spinal canal – through a catheter, which is left in place during surgery for the administration of pain medication.
Newer methods of anesthesia, often used along with spinal or epidural blocks – or in some cases with general anesthesia – include regional nerve blocks, which involve applying an anesthetic directly to the nerves (most commonly the femoral nerve for the knee and the brachial plexus for the shoulder) that supply the joint, and local infiltration, the administration of an anesthetic to the soft issues of the joint itself, Dr. Marks says.
Although nerve blocks have been available for some time, advances in ultrasound are making them more accessible – and precise, says Howard Konowitz, MD, a pain management specialist and anesthesiologist at Gottlieb Memorial Hospital in Maywood, Ill. “With ultrasound we are able to see under the skin and see the arteries, veins, nerves, muscle and tissue,“ he says. “While we were doing it with other techniques prior to that, to actually visualize and see the nerve and put the medication right there where you can see it gives you a much higher success rate.”
When longer relief is needed, the surgeon may place a tiny catheter next to the nerve and connect it to a pump to administer an anesthetic for up to three days after surgery. “What you get is a way to extend the anesthesia or the numbing effect of the local anesthetic longer than the chemistry of just doing a single shot, making people more comfortable in the first painful days after surgery,” he says.
Some research suggests that people who have regional and local anesthesia experience less pain than those who have general anesthesia only, because they provide preemptive pain control – in essence, they stop pain before it starts, says Dr. Konowitz. “There is all sorts of literature that shows the nerves do better and pain control is better if the nerves are blocked and the brain doesn’t get the message of surgery going on.”
There is also evidence that people who have nerve blocks are less likely to experience a problem called complex regional pain syndrome, in which trauma to the nerve, such as that which can occur with surgery, leads to long-term pain. “In those cases the joint may look good but they end up with more pain than when they started,” says Dr. Konowitz.
Beyond Pain Relief
But improved pain relief is not the only benefit of regional and local analgesia. Research shows these newer techniques may also offer these other direct or indirect benefits over general anesthesia:
Less need for narcotic analgesics. For people, who have had joint surgery, the use of narcotics for post-surgical pain relief can cause a number of unwanted side effects, including grogginess, nausea and vomiting. In a recent review of 10 studies of femoral nerve blocks for total knee replacement published in the journal Anesthesiology, use of the blocks was found to reduce narcotic consumption at 24 and 48 hours after surgery. “Because numbing the nerves keeps people more comfortable the first few days after surgery, when pain is typically at its worst, some are able to avoid narcotics completely,” says Dr. Konowitz, who often uses regional nerve blocks for many joint surgeries. “Some patients tell me they never get their [painkiller] prescriptions filled.” When the analgesia wears off, the pain may be manageable with milder analgesics and nonsteroidal anti-inflammatory drugs, he says.
Less blood loss during surgery. General anesthetics can cause veins to dilate, which increases bleeding risk during surgery. Studies of people having total hip replacement have shown that those receiving regional anesthesia have approximately 30 percent less blood loss compared to those having the procedure under general anesthesia. A 2006 study in the Canadian Journal of Surgery found that people who had regional analgesia for total hip replacement were also significantly less likely to require blood transfusions those having general anesthesia.
Reduced risks from immobility. Being immobile after surgery can lead to a range of problems including lung problems and blood clots. Regional and local anesthetics may help reduce this risk by enabling patients to be active sooner, says William J. Hopkinson, MD, professor and vice chairman of reconstructive surgery and joint replacement at Loyola University of Chicago and chief of orthopaedic surgery at Edward Hines, Jr. VA Hospital. “Any time people can use their limbs earlier and get up and walk earlier that alone reduces lung problems and breathing issues and the development of other problems, because they can get up and get around and get vertical and start moving,” says Dr. Hopkinson. “The quicker you walk the less likely you are to get a blood clot.”
Quicker recovery time. When a joint is painful after surgery, it’s natural to resist moving it to avoid more pain. But moving the joint is crucial to its functioning. By blocking pain in the first painful days after surgery regional nerve blocks and local anesthetics can help people move their joints and better tolerate physical therapy, says Dr. Konowitz. For knees, femoral nerve blocks can relieve pain, while allowing enough sensation to begin exercise soon after surgery.
Choosing the Right Anesthesia
While regional and local anesthesia techniques appear to have many benefits over general anesthesia, they are not without risks, including potential cardiac risks of getting too much analgesia, particularly if using epidural blocks, regional nerve blocks and local analgesics together, says Dr. Marks.
Furthermore, spinal and epidural anesthesia are not appropriate for everyone, including those with spinal fusion, which would make placement of the needle difficult, or those with bleeding disorders for whom a puncture could cause dangerous bleeding around the spinal cord. In these cases, regional nerve blocks and local analgesia can still be useful for pain relief after surgery, says Dr. Marks.
Researchers are continuing to study the benefits or regional and local analgesia as well as ways to improve upon it. This includes improving the regional nerve blocks for hips, which have been less successful than those for the shoulder and knee, as well as finding the doses and placement of anesthetics to provide optimal pain relief while still enabling patients to move.
“The pain fibers are small land the motor fibers are bigger, so theoretically you could [adjust anesthetic levels] to block the pain fibers and keep the motor fibers working,” says Dr. Hopkinson. “There is research on better ways to do that.”
For now, doctors recommend joint replacement patients speak with their surgeon before surgery to discuss pain-relief options, including whether their anesthesiologists use regional nerve blocks and/or local infiltration as well as their experience with those newer methods.
The goal, Dr. Konowitz, is not only to improve joint outcome, but to make the process of getting there easier. “When you look at how you can help someone have a better surgical experience, aside from giving you a good joint replacement, x-rays and pictures, it’s how you get that result.”